JP2002320340A - Charge/discharge control circuit and charging type power source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the life of a charging type power source unit and reduce a consumption current of a charge/discharge control circuit of the power source unit. SOLUTION: A voltage dividing circuit 1, a voltage detecting circuit 2 for overcharge, a voltage detecting circuit 3 for overdischarge and a control circuit 4 are connected in parallel with a secondary battery of a power source. The control circuit 4 detects a state of the secondary circuit from the voltage detecting circuits 2, 3, and outputs a signal VS for controlling power supply to an external apparatus or charge by using an external power source. Further, the control circuit reduces a current flowing in the voltage dividing circuit by controlling a switching element 5 installed in series with the voltage dividing circuit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge / discharge control circuit capable of controlling charging / discharging of a secondary battery and a rechargeable power supply using the circuit.

[0002]

2. Description of the Related Art As a conventional rechargeable power supply comprising a secondary battery, a power supply as shown in a circuit block diagram of FIG. 2 has been known. For example, it is disclosed in Japanese Unexamined Patent Application Publication No. 4-75430 "Rechargeable power supply device". That is, the secondary battery 101 is connected to the external terminal -VO or + VO via the switch circuit 103. Further, the secondary battery 101
And a charge / discharge control circuit 102 connected in parallel. The charge / discharge control circuit 102 has a function of detecting the voltage of the secondary battery 101. If the voltage of the secondary battery 101 is either in an overcharged state (a state in which the voltage is higher than a predetermined high voltage value) or in an overdischarged state (a state in which the voltage is lower than a predetermined low voltage value), the switch circuit A signal is output from the charge / discharge control circuit 102 to turn off 103. Therefore, in the case of the overcharge state, the switch circuit 103
Is turned off to stop charging the secondary battery 101 from the primary power supply connected to the external terminals -VO and + VO. In the case of an overdischarge state, the switch circuit 103 is similarly turned off to stop supplying energy to a load connected to the external terminals -VO and + VO (for example, a mobile phone operated by a secondary battery). That is, the charge / discharge control circuit 102 controls the switch circuit 103 between the secondary battery 101 and the external terminal, thereby preventing unnecessary charging of the secondary battery 101 from the external terminal, Battery 101
This prevents a transient decrease in the storage capacity of the secondary battery 101 due to the supply of energy to the load connected to the external terminal.

As another embodiment, a rechargeable power supply device as shown in a circuit block diagram of FIG. 30 is known. In FIG. 30, a secondary battery 101 is connected to an external terminal -VO or + VO via a switch circuit 103 and a current sensing resistor 104. Further, the secondary battery 101
, A charge / discharge control circuit 102 and an overcurrent detection circuit 105 are provided in parallel. Charge / discharge control circuit 10
2 has a function of detecting the voltage of the secondary battery 101,
When the voltage 01 is in the overcharge state or the overdischarge state, a signal is output from the charge / discharge control circuit 102 to turn off the switch circuit 103. When an abnormality occurs in the load and an overcurrent state occurs, the current sensing resistor 10
4 is monitored by the comparator 21 and compared with the voltage of the reference voltage circuit 106.

If the voltage value of the reference voltage circuit 106 is
REF [V], the resistance value of the current sense resistor 104 is R
[Ω] (At this time, the ON resistance of the switch circuit 103 is R
And the current flowing there is I
If [A], when I ≧ VREF / R [A] (1), the output of the comparator circuit 21 changes from “H” to “L”, the transistor 107 turns off, and the constant current source 108
The capacitor 109 is charged by the switch, and after a certain delay time, the output of the comparator circuit 302 changes from "H" to "H".
It becomes “L”, and the switch circuit 103 is turned off. That is, the constant current source 108, the capacitor 109, and the transistor 107 form a delay circuit for delaying the output of the comparator circuit 302. The delayed signal is input to the comparator circuit 302 together with the signal of the reference voltage circuit 106. The output of the comparator circuit 302 is operated so as to turn off the switch circuit 103.

Further, as a conventional rechargeable power supply device using a secondary battery and a charge / discharge control circuit, a power supply device as shown in a circuit block diagram of FIG. 37 is known. For example, Japanese Unexamined Patent Application Publication No. 4-75430, “Rechargeable power supply device”
Is disclosed. That is, the secondary battery 2 is connected to the external terminals + V and -V via the switch transistors 372 and 373.
4 and a charge / discharge control IC 21 are provided in parallel. The charge / discharge control IC 21 has a function of detecting the voltage of the secondary battery 24 and controlling the impedance of the switch transistors 372 and 373 according to the detected voltage level.

For example, the voltage of the secondary battery 24 is
When the voltage exceeds the overcharge voltage by the charging power supply connected to V and -V, the switch transistor 372 is turned off from ON.
To stop charging the secondary battery 24 from the external terminal. Conversely, when a portable device such as a video camera is connected to the external terminal and electricity is supplied to the portable device from the secondary battery 24, the voltage of the secondary battery drops and drops below the overdischarge voltage. The switch transistor 373 is turned off from on to prevent discharge. One of the transistor 372 and the transistor 373 functions as a transistor, and the other functions as a diode. The substrate of each transistor is connected to each source so that it can function as a transistor during charging and discharging.

[0007]

However, in the conventional charge / discharge control circuit shown in FIG. 2, since the current consumption by itself is large, the life of the secondary battery as an energy supply source is shortened. There was a problem that. As a result, there is a problem that the use time of the device driven by the secondary battery is shortened. Furthermore, when the storage capacity of the secondary battery is reduced and the battery is overdischarged, the power supply is provided in the power supply even though the supply of energy from the secondary battery to the external device is stopped by the switch circuit. The current consumption of the charge / discharge control circuit itself promotes further overdischarge,
There was a problem of accelerating the deterioration and shortening of the life of the battery.

An object of the present invention is to provide a rechargeable power supply comprising a long-life secondary battery by reducing the current consumption of a charge / discharge control circuit in order to solve such a conventional problem. It is intended to be. FIG.
Has the following various disadvantages. That is, a charger is externally connected to the terminals -VO and + VO,
In a state where the secondary battery 101 is being charged, the switch circuit 103 is turned off when the secondary battery is fully charged.
I do. By turning off, the electric potential at both ends of the secondary battery 101 decreases, and the charging state, that is, the switching circuit 10
3 turns on. At such a voltage before and after the completion of charging, detection of full charge sometimes oscillates in an unstable manner.

As described in the background art, if an overcharge occurs during charging of a secondary battery, a charge / discharge control circuit operates to turn off a switch circuit for controlling charging of the secondary battery. However, since the charge / discharge control circuit is connected in parallel with the secondary battery, current consumed during operation is supplied from the secondary battery. When a current is supplied to the secondary battery, a voltage drop occurs, the voltage drops below the overcharge detection voltage, and the switch circuit is turned on. For this reason, (the secondary battery voltage rises due to charging → rises to the overcharge voltage → the secondary battery voltage drops due to the operation of the charge / discharge control circuit → the secondary battery voltage rises again due to charging), and the same operation is repeated to overcharge the battery There was a problem that could not be transferred to. The same problem also occurs when the overdischarge state is released while the battery in the overdischarge state is being charged.

If the logic of the switch circuit is not determined when the charge control circuit is connected to the secondary battery for the first time, the initial state becomes unstable, and the voltage value of the secondary battery is normal. There is also a problem that the battery may be overcharged or overdischarged. When the overdischarge of the secondary battery progresses and the voltage value drops below the minimum voltage at which the voltage detection circuit or control circuit in the charge / discharge control circuit operates, the output of the voltage detection circuit or control circuit is undefined. State. In other words, since the voltage of the secondary battery has dropped further from the overdischarged state, charging cannot be performed because the charge / discharge control circuit cannot operate the switch circuit normally even if charging is performed from the primary power supply. It becomes possible. That is, if the voltage of the secondary battery drops below the minimum voltage of the charge / discharge control circuit even once, charging becomes impossible, so that the secondary battery cannot be used again.

Another problem of the conventional example is that a charger is connected to both ends of a secondary battery, and when the secondary battery is charged, the polarity of the charger is made different from the polarity of the secondary battery. When connecting to the charge / discharge control circuit, so-called reverse connection,
There is a problem that the latch-up of the CMOS IC constituting the charge / discharge control circuit causes the charge / discharge control circuit to malfunction, causing a large current to flow to the secondary battery to deteriorate it.

As another problem, when an abnormality occurs in a load connected to both ends of the secondary battery and an excessive current flows from the secondary battery, the switch circuit 103 is turned off by the overcurrent detection circuit. Or turn off this switch circuit
This causes a problem that the voltage of the secondary battery rapidly increases, thereby increasing the reference voltage value of the overcurrent detection circuit, closing the switch circuit 103 again, and causing oscillation.

It is an object of the present invention to provide a charge / discharge control circuit which does not malfunction so as to solve the conventional problems as described above. Further, when two secondary batteries are connected in series and used, the conventional example has the following disadvantages.
That is, the two rechargeable batteries are subject to one-sided burrs due to their life. However, even in this case, if the sum of the two voltages is equal to or higher than a certain voltage, there is no problem in using the voltage. In the conventional example, since the voltage of each battery is monitored, the sum voltage cannot be monitored.
Since the use has to be stopped, the use time of the device is significantly shortened. Also, if the battery is charged in the same manner as the other normal battery due to the occurrence of one-sided swelling, the one-sided swelling is further promoted and the life of the battery is significantly shortened.

Further, in a conventional rechargeable power supply device, as shown in FIG. 37, two switch transistors are provided between an external terminal and a secondary battery, and each substrate is connected to an external terminal. Because the configuration is such that the potential of the source electrode of the transistor on the terminal side and the source electrode of the transistor on the secondary battery side, it is assembled separately from the charge / discharge control IC. As a result, it is difficult to reduce the size of the battery. There was a problem that the cost was high.

Therefore, an object of the present invention is to provide a small and inexpensive
Another object of the present invention is to provide a highly reliable charge / discharge control circuit for a rechargeable battery device and a rechargeable power supply device.

[0016]

[Means for Solving the Problems] (Means 1) In order to solve the above-mentioned problems of the prior art shown in FIG. The detection circuit is provided with switch means for limiting current consumption. More specifically, the voltage dividing circuit, which is a part of the power supply voltage detecting circuit, is provided with switch means for limiting current consumption.

Further, according to the present invention, the current consumption is suppressed by current limiting means for limiting the entire current consumption flowing through the error amplifier. For example, the present invention adds a power ON / OFF function as current limiting means to the error amplifier of the overcharge detection circuit, and uses the signal of the overdischarge detection circuit to turn on / off the error amplifier.
The FF was controlled to reduce battery current consumption during overdischarge.

According to the present invention, in a charge / discharge control circuit, a switch circuit for controlling current consumption is provided in a buffer circuit for externally outputting a potential of a connection point of each battery constituting a secondary battery. And The switch means is controlled by a control circuit provided in the charge / discharge control circuit. In particular, the control circuit controls the switch means of the buffer circuit to be turned on only in an overdischarge state in which the capacity of the secondary battery is reduced.

Further, in the present invention, in the charge / discharge control circuit, each of the overcharge voltage detection circuits for monitoring the voltage of the secondary battery and the reference voltage source of the overdischarge voltage detection circuit are used as one. Furthermore, when a plurality of secondary batteries are connected in series, an overcharge voltage detection circuit and an overdischarge voltage detection circuit that monitor the voltage of each battery are configured. A different reference voltage of a voltage detection circuit for monitoring the voltage of each battery is supplied by one reference voltage generation circuit.

According to another aspect of the present invention, there is provided a charge / discharge control circuit which includes an overcharge detection voltage division circuit for obtaining an overcharge detection divided voltage of a secondary battery and an overdischarge for obtaining an overdischarge detection divided voltage. Both functions of the detection voltage dividing circuit are constituted by one overdischarge / overcharge detecting voltage dividing circuit.

(Means 2) In order to solve the above-mentioned problem of the prior art shown in FIG. 30, in the present invention, a voltage detection circuit detects overcharge or overdischarge set in a secondary battery in a charge / discharge control circuit. After the reset, the voltage is reset to a voltage that is more easily detected as overcharge / overdischarge than the set voltage, and the signal timing is set so that the switch circuit is turned off after the reset.

Further, the present invention relates to a charge / discharge control circuit,
The delay circuit is provided between the voltage detection comparator and the control circuit. The delay circuit is configured such that the logic circuit is fixed for a certain period of time when the secondary battery is connected, the switch circuit is turned on, and the rechargeable power supply can be used from the beginning.

Further, according to the present invention, the voltage of the external terminal of the power supply device is input to the charge / discharge control circuit, and the charger is connected to the power supply device even if the voltage of the secondary battery is lower than the minimum operating voltage of the charge / discharge control circuit. When connected, the circuit configuration was such that the switch circuit could be controlled. Further, the present invention has a configuration in which the output signal of the control circuit always outputs a signal for turning off the switch circuit when the secondary battery is reversely connected in the charge / discharge control circuit. More specifically, the output of the voltage detection circuit that determines the output of the control circuit is always set to the ON state of the switch circuit.
F. More specifically, the switch circuit turns off the output of the constant voltage circuit related to the output of the voltage detection circuit.

Further, in the present invention, a latch function is provided in the overcurrent detection circuit in the charge / discharge control circuit, and once the overcurrent is detected, the latch is not released unless the load is removed. (Means 3) In order to solve the above-described conventional problem shown in FIG. 37, the present invention monitors a voltage of each of two secondary batteries in a charge / discharge control circuit, and according to the monitored voltage value, Is switched.

In the present invention, a voltage detecting circuit is provided by providing a resistor between terminals from which the sum voltage is output so that the sum voltage of the two batteries can be monitored.
Further, the present invention has a configuration in which one transistor is connected in series between the external terminal and the secondary battery. In order to form a single transistor, a structure in which a substrate of the transistor is provided between a source electrode and a drain electrode of a transistor for switching is adopted.

Further, the present invention provides a semiconductor substrate having a semiconductor film provided on an insulating film capable of freely controlling a transistor substrate (hereinafter referred to as an SOI substrate; SOI is a silicon substrate).
n On Insulator).

[0027]

In the charging / discharging control circuit constructed as in the means 1, the current consumption is reduced by the current consumption limiting switch provided in the voltage detection circuit. In the battery charge / discharge control circuit configured as described above, especially when the battery is in the overdischarge state, the current consumption of the overcharge detection circuit is cut, so that the power consumption in the overdischarge state of the battery is reduced. To prevent battery deterioration.

Further, since a plurality of error amplifiers are replaced by one multi-input type error amplifier, the chip area can be significantly reduced. With such a configuration, the current consumption of the buffer circuit is reduced to a necessary minimum,
A charge / discharge control circuit with low current consumption and a long-life rechargeable power supply device can be obtained.

In the charge / discharge control circuit constructed as described above, the reference voltage source can be constituted by less than half, so that the current consumption can be reduced and the number of components (chip size in the case of an integrated circuit) can be reduced. Can be reduced. In the charge / discharge control circuit configured as described above, the voltage dividing circuit for detecting the voltage is configured in half in principle. Therefore, the current flowing therethrough is also reduced to half the value in comparison with the charge / discharge control circuit in which the voltage dividing circuit is separately formed.

In addition, the number of components can be reduced because the voltage dividing circuit is also used for detecting overcharge voltage and detecting overdischarge voltage. When formed as an integrated circuit, the chip size can be reduced by reducing the number of components. In the charge / discharge control circuit configured as the means 2, after detecting overcharge or overdischarge, the detection voltage in the overcharge or overdischarge state is reset to a level at which overcharge or overdischarge is detected. Further, after that, by turning off the switch circuit, the voltage detection circuit is prevented from malfunctioning due to the voltage fluctuation of the secondary battery due to the switch circuit being turned off.

Further, since the control circuit operates after a delay time of a certain time after the operation of the voltage detection comparator, an excessive through current does not flow at one time, thereby preventing a voltage drop of the secondary battery. Can be. Further, for example, at the time of charging, the detection operation becomes more reliable because the voltage of the secondary battery increases even during the delay period. Furthermore, since the delay circuit determines the logic for a certain period when the secondary battery is initially connected, the control circuit turns on the switch circuit, and the rechargeable power supply can be used from the initial connection of the secondary battery.

Further, even if the voltage value of the secondary battery falls below the minimum operating voltage of the charge / discharge control circuit, the switch circuit can be controlled reliably, and even if the voltage of the secondary battery becomes extremely low, charging is ensured. Done in Further, when the connection is reversed, the switch circuit is always turned off, so that the charger and the secondary battery are electrically separated. Therefore, the secondary battery is not affected at all by the reverse connection state of the charger.

Further, the latch function provided in the overcurrent detection circuit has an effect that oscillation at the time of overcurrent detection can be avoided. In the charge / discharge control circuit configured as in the above-described means 3, a resistor is provided between the terminals from which the sum voltage is output, so that voltage detection can be performed.

By switching the overcharge detection voltage in accordance with the voltage value of one battery, charge / discharge control with a small difference between the two voltage values can be performed. Further, the substrate potential can be set independently for each transistor. Further, the area of the transistor can be reduced.

[0035]

Embodiment 1 Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram of a first embodiment of a charge / discharge control circuit in the means 1 of the present invention.
When this charge / discharge control circuit is applied to a power supply device,
It operates using the secondary battery as a power source. That is, the secondary battery is connected to the power terminals -VB and + VB to supply power.

The power supply includes a resistor 1 of power supply voltage dividing means for dividing the power supply voltage, voltage detection circuits 2 and 3 for detecting two output voltages of the power supply voltage division means, and voltage detection circuits 2 and 3 respectively. A control circuit 4 for outputting a final control signal VS according to the output signal of the control signal 3 is connected in parallel with each other.

The voltage detection circuits 2 and 3 are specifically shown in FIG.
Reference voltage source 42 for power supply terminal -VB as shown in FIG.
And a comparator circuit 41 that receives the output of the voltage dividing resistor as an input. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit.
The power supply voltage division circuit 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery as a power supply. The power supply voltage division circuit 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit that detects overdischarge of a secondary battery as a power supply. In the case of the present invention, the power supply division circuits input to each voltage detection circuit may be separately provided. In the case of FIG. 1, the voltage division circuit 1 is an example of a charge / discharge control circuit provided in common to the voltage detection circuits. The control circuit 4 receives a signal relating to overcharge and overdischarge of the secondary battery from each of the voltage detection circuits 2 and 3, and outputs a signal VS for turning on or off the switch circuit of the power supply device.

The control circuit 4 also controls a switch element 5 provided to limit the current flowing through the voltage dividing resistor 1. A voltage dividing resistor, which is a power supply voltage dividing circuit, is a circuit in which a plurality of resistors are simply connected in series. Therefore, if the power supply lines -VB and + VB are simply connected directly to the voltage dividing resistor, a large direct current flows. The switch element 5 is inserted between the power supply line -VB and the voltage dividing resistor 1, and is controlled by a signal from the control circuit 4 or a signal generated from another circuit.

The resistance of the switch element 5 connected in series to the voltage dividing resistor 1 is preferably as small as possible. If the resistance value of the voltage dividing resistor 1 is not set to a value sufficiently smaller than the resistance value, the output of the voltage dividing resistor 1 is affected by the resistance value of the switching element. Therefore, it is preferable to directly connect the power dividing line to the end of the voltage dividing resistor 1, rather than providing the voltage dividing resistor 1 in the middle as shown in FIG. .

As shown in FIG. 1, when the switching element is an insulated gate field effect transistor, the ON resistance of the transistor is reduced by setting the voltage between the source and the gate electrode of the transistor to the power supply voltage level. be able to. As the voltage dividing resistor 1, a high-resistance polycrystalline film having a sheet resistance of about 10 kΩ / □ is used in order to reduce the current flowing therethrough. The resistance value of the voltage dividing resistor 1 is designed to be a high resistance value of about 10 MΩ. The ON resistance of the switch element 5 is designed to be a low resistance value of at most several kΩ, and is set to about 1/1000 or less of the resistance value of the voltage dividing resistance 1. The ON resistance is reduced to prevent the voltage detection circuit from shifting. Since the OFF resistance of the transistor 5 is sufficiently larger than the resistance value of the voltage dividing resistor 1, almost no current can be consumed when the transistor 5 is OFF.

FIG. 4 is a circuit block diagram in which a P-type insulated gate type field effect transistor is inserted between the voltage dividing resistor 21 and the power supply terminal + VB in the charge / discharge control circuit of the present invention. The overcharge detection voltage detector 22, the overdischarge detection voltage detector 23, and the control circuit 24 are designed in the same manner as the embodiment of FIG. However, since the switching element 25 is a P-type insulated gate transistor, if the switching element 25 is to be turned off, + VB is connected to the terminal 2.
6 is input to the gate of the switch element, and -VB is input to the terminal 26 when it is desired to turn on. The ON resistance is sufficiently low because -VB is applied to the gate voltage of the transistor 25.

FIG. 5 is a circuit block diagram of a charge / discharge control circuit according to the present invention when a switch element is inserted on both sides of a voltage dividing resistor. An N-type insulated gate field effect transistor 35 and a P-type transistor 36 are provided at both ends of the voltage dividing resistor 31.
Are formed. The overcharge voltage detection circuit 32, the overdischarge voltage detection circuit 33, and the control circuit 34 are formed in the same manner as in the embodiment of FIGS. By inserting both switch elements 35 and 36 on the power supply side as shown in FIG. 5, the power supply voltage dividing circuit can be operated quickly. Also, since the switching elements are almost equally inserted into the dividing circuit, there is an effect that the ON resistance of the switch element hardly affects the output of the voltage dividing circuit.

The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate where the divided voltage of the voltage dividing resistor 1 has little variation. (Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to the drawings.

In FIG. 6, when the voltage value of the reference voltage circuit 11 is Vref, when the voltage of the battery becomes equal to or lower than the overdischarge detection voltage VKAH of the equation (2), the voltage of the terminal 16 becomes
It becomes “Low” level, indicating that the battery is in the over-discharge state. When the voltage exceeds the overcharge detection voltage VKAJ of the equation (3), the voltage of the terminal 17 becomes “High” level, and the battery is in the overcharge state. Indicates that there is.

VKAH = (R1 + R2 + R3) × Vref / (R2 + R3) (2) VKAJ = (R1 + R2 + R3) × Vref / (R3) (3) That is, R1? The value of R3,
By setting the values of VKAH and Vref, VKAH, VKAJ
Can be set arbitrarily. The error amplifier 13 of the overcharge detection circuit has a power ON / OFF function. When the output of the error amplifier 12 of the overdischarge detection circuit is at a “Low” level, the power is turned off. When the output is at a “High” level, the power is turned on. Becomes Error amplifier 1 when power off
3 cuts the current consumption without operating, and
Is fixed at the “Low” level. That is, the operation of the error amplifier 13 is controlled by the output of the error amplifier 12.

The over-discharge detection voltage VKAH and the over-charge detection voltage VKAJ have the relationship of equation (4) from equations (2) and (3). VKAH <VKAJ (4) That is, in a state where overdischarge is detected, it is not necessarily an overcharge state, and it is not necessary to operate the error amplifier 13 of the overcharge detection circuit. Therefore, the present invention becomes possible.

FIG. 7 shows a circuit example of an error amplifier having a power ON / OFF function. Input terminals 61 and 62 respectively
The divided voltage and the reference voltage are input. The error amplification operation is performed during the period when the “High” level voltage is input to the operation control terminal 63. As a result of the overdischarge state, the voltage of the terminal 16 becomes “Low” level,
The transistors M1 and M2 are turned off to cut the current consumption, and the transistors M3 and M4 are turned on to fix the output terminal 17 to the “Low” level.

Next, another embodiment of the present invention will be described with reference to FIG. The reference voltage generation circuit 11 and the first error amplifier (M11, M11)
12, M13 and M14), a second error amplifier (configured from M16, M17, M18 and M19), and a transistor M15. The outputs from the reference voltage generation circuit 11 are input to the transistors M14 and M18, respectively, as inputs to the first and second error amplifiers.
Although not shown in FIG. 8, the divided voltage of the battery obtained by the divided voltage means is similarly set to the transistor M.
13 and M19 are entered as inputs b and d. Signals indicating the battery charge / discharge state are output from the outputs a and c of each error amplifier.

In FIG. 8, in order to limit the current consumption of both the first and second error amplifiers, a current limiting transistor M15 as current limiting means is connected in series to each error amplifier. With the current limiting transistor M15, the total current consumption of the first and second error amplifiers can be reduced to the same level as the current consumption of one error amplifier.

Next, an embodiment in which a plurality of error amplifiers are integrated into one multi-input type error amplifier will be described with reference to FIG. FIG. 10 shows a battery charge control circuit diagram when two batteries are connected in series. Battery 18,
The circuits of FIG. The transistor M1 forming the error amplifier shown in FIG.
The pair of the transistors M16 and M18 constituting the error amplifier of the next stage with M2 and M14 is an amplifier circuit of the same configuration, so if one transistor pair is omitted, the circuit shown in FIG. 9 is obtained. FIG. 9 is a diagram of a circuit of a two-input type error amplifier and a reference voltage circuit as an error amplifier.

In FIG. 9, N1, N2, N3, N
Focusing on N4 and N5, N5 is an error amplifier in which the constant current sources N1 and N2 are active broad and N3 and N4 are a source-coupled pair. The N3 gate input voltage (b) and the N4 gate input voltage (reference The voltage can be compared (or amplified) to obtain an output at a.

Since the voltage between the gate and the source of N1 and N2 is the same, the current flowing through N1 and N2, that is, N3 and N2
It is assumed that the current flowing through 4 is always the same. Therefore, the gate input voltage (reference voltage) of N4 becomes N3
Is higher than N4, the resistance component of N3 decreases, and the output a becomes Low.
Go down to the side. If the gate input voltage (b) of N3 is lower than the gate input voltage (reference voltage) of N4, N3 becomes N4.
OFF, the resistance component of N3 increases, and the output a rises to the High side.

Similarly, N2, N6, N4, N7, N
Paying attention to 5, N5 is a conventional error amplifier in which N5 is a constant current source, N2 and N6 are active loads, N4 and N7 are source-coupled pairs, and the N7 gate input voltage (d) and the N4 gate input voltage ( By comparing (or amplifying) the reference voltage, an output can be obtained at c.

Since the voltage between the gate and the source of N2 and N6 is the same, the current flowing through N2 and N6, that is, N4 and N6
It is assumed that the current flowing through 7 is always the same. Therefore, if the gate input voltage (d) of N7 is higher than the gate input voltage (reference voltage) of N4, N4 turns on more than N4, the resistance component of N7 decreases, and the output c drops to the low side. If the gate input voltage (d) of N7 is lower than the gate input voltage (reference voltage) of N4, N7 turns OFF more than N4, the resistance component of N7 increases, and the output c rises to the High side.

Therefore, when comparing (or amplifying) different voltages with respect to the same reference voltage, the reference voltage is compared (or amplified) by inputting the reference voltage to the gate of N4 and the other voltages to the gates of N3 and N7, respectively. The amplified outputs can be obtained at a and c, respectively.

The transistor N5, which is a current limiting transistor for determining the current consumption of the error amplifier, is commonly used. It can be driven by the current consumption of the amplifier. Although the present invention has been described with reference to an Nch transistor input type error amplifier, the present invention can also be applied to a Pch transistor input type error amplifier.

Embodiment 3 Hereinafter, Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 11 is a circuit block diagram of the charge / discharge control circuit of the present invention. Two batteries 111 and 112 are used as secondary batteries and a power supply terminal + VB of the charge / discharge control circuit.
And -VB in series. The voltage of the battery 111 is divided by a voltage dividing circuit 113, and the divided voltage is detected by an overcharge and overdischarge voltage detection circuit 115. The output of the voltage detection circuit 115 is input to the control circuit 117. The control circuit 117 outputs a signal VS for turning off between the secondary battery and an external terminal of the power supply when each battery is in an overcharged state or an overdischarged state. Therefore,
The control circuit 117 is composed of only a logic circuit. Similarly, the battery 112 is configured to detect an overcharged state and an overdischarged state by the voltage dividing circuit 114 and the voltage detecting circuit 116. The detection result is similarly input to the control circuit 117 as a digital signal. Therefore, when any one of the batteries 111 and 112 becomes overcharged or overdischarged, the control circuit 117 cuts off the electrical connection between the battery and the external power supply and stops the progress of overcharge and overdischarge. Since the charging characteristics and the discharging characteristics of the two batteries are not exactly the same, it is necessary to separately control overcharge and overdischarge.

The buffer 118 is connected to each battery during connection.
This is a circuit for outputting the potential VI to the outside as a signal B. The state of charge / discharge balance between batteries can be detected by the signal B. The buffer circuit 118 is provided so that no current is consumed to the outside from the potential VI at the connection point. FIG. 12 shows a more specific circuit diagram of the buffer circuit. The buffer circuit is supplied with power from both the secondary batteries + VB and -VB. In the buffer circuit, the node VI is inputted to the transistors 92 and 93 to the operational amplifier which is a component thereof. This connection point potential VI is substantially an intermediate potential of the entire secondary battery power supply. Therefore, transistors 92 and 93
A large current flows through. Therefore, a switch transistor 9 for cutting current is connected in series with the transistors 92 and 93.
1 is connected. This current cutting transistor 91
Is controlled by the control circuit via the gate electrode 95 so as to be turned off in the overdischarge state. The constant current circuit 94 is inserted for stable operation of the buffer circuit.

As described above, the current consumption of the charge / discharge control circuit can be reduced by stopping the operation of the buffer circuit to which the intermediate potential is input when in the overdischarge state. Also,
By inserting the current cut transistor 91, an independent signal can be output from the terminal B when the buffer circuit is not operating. For example, a signal indicating an overdischarge state, a normal state, or an overcharge state can be output from the B terminal. In a normal state, the connection potential of the two batteries is output. In the overdischarge or overcharge state, the state can be output at a digital signal level of + VB or -VB by pulling up or pulling down the B terminal. That is, the current cutting transistor inserted into the buffer circuit has a function of not only cutting the current of the buffer circuit but also outputting a different type of signal from the terminal B.

(Embodiment 4) Hereinafter, Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 13 is a circuit block diagram of the charge / discharge control circuit of the present invention. The secondary battery to be charged is connected to the power terminals -VB and + VB. Power supply terminal -VB, +
VB includes a voltage dividing resistor 1 which is a voltage dividing circuit for dividing the voltage of the secondary battery, comparators 52 and 53 which are voltage detecting circuits for detecting a divided voltage of the voltage dividing resistor 1, and outputs of the comparators 52 and 53. A control circuit 4 which receives the signal and outputs a final control signal VS is connected in parallel.

The voltage detection circuit is composed of two voltage detection circuits, an overcharge voltage detection circuit and an overdischarge voltage detection circuit. The overcharge voltage detection circuit is composed of a comparator circuit 52 which receives as input a reference voltage source VR and a divided voltage between the resistors R1 and R2. The over-discharge voltage detection circuit is composed of a comparator circuit 53 which receives as input a reference voltage source VR and a divided voltage between the resistors R2 and R3. The resistance values of R1, R2, and R3 of the voltage dividing resistor 1 are designed in relation to the reference voltage source VR so that the output of the comparator 52 is inverted when overcharged and the output of the comparator circuit 53 is inverted when overdischarged. Have been. When the voltage of the secondary battery reaches the overcharge region or the overdischarge region, the output of each comparator circuit is inverted and input to the control circuit 4. The control circuit 4 receives the signals from the comparator circuits 52 and 53 and outputs an output V that turns off the switch circuit of the power supply device so that overcharging or overdischarging does not proceed further.
Outputs S to the switch circuit. As shown in FIG. 13, the reference voltage VR is used for both the overcharge and overdischarge comparator circuits.

FIG. 14 is a circuit diagram of the reference voltage source. For example, an enhancement type N-type insulated gate field effect transistor 61
And a display type N-type insulated gate field effect transistor 62 are connected in series. Each gate electrode is connected to each connection terminal. From the connection terminal, a constant voltage Vref independent of the secondary battery voltage fluctuation corresponding to the threshold voltage difference of each transistor with respect to -VB is output. The reference voltage source is not limited to the example of FIG. 14 and consumes energy of the secondary battery. Therefore, as shown in FIG. 13, by using the reference voltage source for both of the voltage detection circuits, not only the number of components but also the current consumption can be reduced for a circuit provided with separate reference voltage sources.
The current consumption of the charge / discharge control circuit is an important parameter that determines the life of the secondary battery. In particular, in the case of an over-discharge state in which the voltage of the secondary battery has decreased, the life of the voltage of the secondary battery suddenly decreases along with the energy consumption. Therefore, the function of the charge / discharge control circuit with the minimum current was the point of producing a long-life rechargeable power supply.

FIG. 15 shows that the secondary batteries are two batteries 71 and 7.
2 shows a circuit block of a charge / discharge control circuit in the case where 2 is used in series. As in the embodiment shown in FIG. 15, when the secondary battery is composed of a plurality of batteries,
It is necessary to provide a circuit for independently detecting the voltage of each battery and controlling the charging / discharging voltage. Generally, the voltage of a battery is determined by the constituent materials of the battery. Therefore, when a device that functions with a power supply requires a high voltage, a high voltage is often achieved by connecting batteries in series as shown in FIG.
As shown in FIG. 15, the charge / discharge control circuit shown in FIG. 13 is connected to the batteries 71 and 72. A control circuit 79, which is a common circuit, includes comparators 75, 76,
In response to the signals from 77 and 78, a signal VS for controlling the switch circuit is output.

In the circuit of FIG. 15, each of the batteries 71 and 72 has a positive voltage side + VB with respect to the ground voltage level G.
And the voltage on the negative voltage side -VB. Therefore, FIG.
In the case where two batteries 71 and 72 are connected in series as shown in (1), it is preferable to detect the respective voltages with voltages from + VB and -VB. A reference voltage source VR1 based on + VB is input to the comparators 75 and 76 which are voltage detection circuits of the battery 71. On the other hand, a reference voltage source VB based on -VB is input to the comparators 77 and 78, which are voltage detection circuits of the battery 72. The reference voltage sources VR1 and VR2 have different references from + VB and −VB. Generally, when the purpose of charge / discharge control of a battery is aimed at, the overcharge and overdischarge voltages are the same. Thus, although the references are different, each requires a reference voltage source to obtain the same value.

FIG. 16 shows an example of a reference voltage circuit which outputs the same constant voltage from + VB and -VB. This is a circuit in which another enhanced insulated gate field effect transistor is connected in series to the reference voltage circuit shown in FIG. That is, the connection between the transistors 82 and 83 in FIG. 16 is the same as that of the reference voltage circuit in FIG. 14, and the transistor 81 is additionally connected. In this circuit, VR1 and VR1 are connected from the connection point of each transistor.
2 is output. VR1 is a constant voltage Vre with respect to + VB.
Output f. Further, VR2 outputs the same constant voltage Vref with respect to -VB. Therefore, the reference voltage circuit of FIG. 16 can output two constant voltages without increasing current consumption. If VR1 and VR2 of FIG. 15 are formed by one reference voltage circuit (there is only one current path between + VB and -VB) as shown in FIG. 16, the secondary battery is constituted by a plurality of batteries. In this case, the charge / discharge control circuit can be formed without increasing current consumption.

As described above, the present invention has a configuration in which a single reference circuit is used as a reference voltage source, which has been required up to the number of comparator circuits for voltage detection. The charge / discharge control circuit of the present invention requires a plurality of comparator circuits due to its configuration, and furthermore, low current consumption is the most important parameter for improving the life of the secondary battery. Therefore, the present invention is invented from a simplified charge / discharge control circuit, and has a great effect.

Further, if a current cutting transistor is connected in series to the common constant voltage circuit used in the present invention and the transistor is controlled by the control circuit to cut the current, further reduction in current consumption can be achieved. Also in this case, since there is only one constant current circuit, it can be achieved without complicating the circuit.

(Embodiment 5) FIG. 17 is a circuit block diagram of Embodiment 1 in the means 2 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, the secondary battery supplies power by connecting to the power supply terminals -VB and + VB.

The power supply includes a voltage dividing resistor 1 of power supply voltage dividing means for dividing the power supply voltage, voltage detecting circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, respectively.
A control circuit 4 that outputs a final control signal VS based on output signals of the respective voltage detection circuits 2 and 3 is connected in parallel with each other.

The voltage detection circuits 2 and 3 are specifically shown in FIG.
Reference voltage source 42 for power supply terminal -VB as shown in FIG.
And a comparator circuit 41 that receives the output of the voltage dividing resistor as an input. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit.
The power supply voltage division circuit 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery as a power supply. The power supply voltage division circuit 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit that detects overdischarge of a secondary battery as a power supply. In the case of the present invention, the power supply division circuits 1 input to each voltage detection circuit may be separately provided. In the case of FIG. 17, the power supply dividing circuit 1
It is an example of a charge / discharge control circuit provided in common to both voltage detection circuits. The control circuit 4 controls each of the voltage detection circuits 2
And input the signal regarding overcharge and overdischarge of the secondary battery from 3 and turn on or off the switch circuit of the power supply device.
To output a signal VS.

For example, a case where a charging power source is connected to a secondary battery connected between the terminals -VB and + VB via a switch circuit and the secondary battery is charged will be described. In the charged state, the voltage across the secondary battery-
VB and + VB gradually increase. When the secondary battery is overcharged, the output signal of the overcharge voltage detection circuit 2 is inverted. The voltage for recognizing this overcharged state differs depending on the secondary battery. For example, in the case of a lithium ion battery, 4.3
V is set. That is, the output of the overcharge voltage detection circuit 2 is designed to be inverted when the voltage of the secondary battery is charged up to 4.3 V from the division circuit of the voltage division circuit 1. The inverted signal output from the voltage detection circuit 2 is
It is fed back to the voltage dividing circuit 1. That is, the signal of the voltage detection circuit 2 is input to the gate electrode of the voltage division control transistor 175 that controls the divided voltage of the voltage division circuit 1. In response to the inverted output signal of the voltage detection circuit 2, the voltage division control transistor 175 is immediately turned on to further increase the divided voltage and operate so that the voltage detection circuit 2 can output the inverted signal stably. When the voltage dividing control transistor 175 is turned on, even if the voltage of the secondary battery fluctuates as low as 4.0 V, for example, the voltage of the resistor R1 is at a level at which the voltage detection circuit 2 is sufficiently inverted.

As described above, in the overcharge detection circuit composed of the voltage division circuit 1 and the overcharge voltage detection circuit, after detecting the overcharge, the overcharge detection voltage is reduced to a low value by the detection signal. The configuration is such that stable overcharge detection is performed by resetting. After resetting to a low value, the control circuit 4 outputs a signal VS for turning off the switch circuit.
Is output. By turning off the switch circuit, the voltage of the secondary battery decreases by the voltage corresponding to the product of the charging current and the internal resistance of the battery, and becomes only the voltage generated by the chemical potential inherent in the lithium ion battery. That is, the voltage is reduced by the voltage drop due to the internal resistance. However, before that, since the overcharge detection voltage has been reduced and reset from 4.3 V to 4.0 V, the output of the voltage detection circuit 2 keeps detecting the overcharge. Therefore, the reduced voltage 0.3V (4.3V-4.0V) for resetting the overcharge needs to be set larger than the voltage drop due to the internal resistance of the secondary battery during charging. Generally, the voltage of the difference between the initial setting voltage and the resetting voltage is between 0.2V and 0.5V. 0.5V
With the above setting, the overcharge range is widened, and the use range in the normal state is narrowed. That is, the life is shortened.

FIG. 18 is a diagram showing signal timing of each circuit. The overcharge detection voltage a is the overcharge voltage 4.
The rechargeable battery is charged to 3V and is reduced to 4.2V and reset. A split voltage control transistor 175 is provided to reduce from 4.3V to 4.2V. The output of the voltage detection circuit 2 is fed back to the gate voltage of the divided voltage control transistor 175. That is, when the voltage of the secondary battery becomes 4.3 V, the output of the voltage detection circuit 2 is inverted from + VB to -VB. The voltage of −VB is input to the voltage division control transistor 175. The voltage division control transistor 175 turns on, the division ratio of the bleeder resistance changes, and the voltage at the overcharge detection point becomes 4.3V.
Is reset to a low value from 4.2V to 4.2V. The output signal Vs of the control circuit 4 changes from + VB to 0V after the time Δt after resetting, thereby turning the switch circuit from ON to O.
Outputs a signal to be changed to FF. In order to form Δt, the output of the voltage detection circuit 2 can be shifted by a delay circuit to delay the signal.

The above description has been made in connection with overcharge detection. Even in overdischarge, stable operation can be achieved by using the same configuration. In the case of overdischarge, the reset level is set in a direction to increase in reverse to the overcharge. (Embodiment 6) Hereinafter, Embodiment 2 in the means 2 of the present invention will be described.
Will be described with reference to the drawings.

FIG. 19 is a circuit block diagram of Embodiment 2 of the means 2 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, the secondary battery supplies power by connecting to the power supply terminals -VB and + VB. The power supply includes a resistor 1 of power supply voltage dividing means for dividing the power supply voltage, voltage detection circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, and output signals of the voltage detection circuits 2 and 3 respectively. Circuits 191 and 19 for temporally delaying
2 and a control circuit 4 that outputs a final control signal VB based on output signals of the delay circuits 191 and 192 are connected in parallel with each other.

The voltage detection circuits 2 and 3 are specifically shown in FIG.
Reference voltage source 42 for power supply terminal -VB as shown in FIG.
And a comparator circuit 41 to which the output of the voltage dividing resistor 1 is input. The voltage detection circuit 2 is for overcharge detection, and the voltage detection circuit 3 is an overdischarge detection circuit.
The voltage division resistor 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery as a power supply. The voltage division resistor 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit that detects overdischarge of a secondary battery as a power supply. In the case of the present invention, the voltage division resistors input to each voltage detection circuit may be separately provided.

In the case of FIG. 19, the voltage dividing resistor 1 is an example of a charge / discharge control circuit provided commonly to each voltage detection circuit. The delay circuits 191 and 192 are circuits for generating a time delay when the voltage detection circuits 2 and 3 detect overcharge or overdischarge and the output signal is inverted. The control circuit 4 controls each of the delay circuits 191 and 1
A signal relating to overcharge and overdischarge of the secondary battery is input from 92, and the switch circuit of the power supply device is turned ON or OFF.
To output a signal VS. Therefore, the control circuit 4
Is composed of a logic circuit. Further, the switch circuit of the power supply device is turned ON or OFF by the signal VS. However, even if there is a capacitance or a resistance component at the input terminal of the switch circuit, it is necessary to change the signal VS within a predetermined time. 4, the output terminal VS needs to have low impedance. The control circuit 4 is, for example, a MOSFET
(Metal-Oxide-Semiconductor-Field-Effect-Transisto
In the case of realizing r), it is necessary to increase the number of transistor elements to form a logic circuit, and to increase the size of the final output stage in order to reduce the impedance of the output terminal VS. Therefore, when the control circuit 4 turns ON or OFF the signal VS, a through current is consumed.
Not only the control signal 4 but also the voltage detection circuits 2 and 3 generate a through current when the output is inverted. With these through currents,
The voltage of the secondary batteries connected in parallel may be reduced.

The control circuit 4 receives the signals of the delay circuits 191 and 192 and determines the logic of the signal VS.
However, when the battery is initially connected, the delay circuits 191 and 192
Is indeterminate, the signal VS output from the control circuit 4 does not have the logic of correctly detecting the voltage of the secondary battery, and the switch circuit 103 malfunctions. When these phenomena occur, charging or discharging is forcibly controlled even if a secondary battery having a normal voltage value is connected to the charge / discharge control circuit.

The delay circuits 191 and 192 are provided to prevent these malfunctions. That is, a time delay is created after the signal of the voltage detection circuit 2 or 3 is inverted, and a signal is input to the control circuit 4, so that the through current between the voltage detection circuit 2 or 3 and the control circuit 4 at the time of voltage detection is reduced. To prevent them from occurring at the same time. Further, since there is a time delay, for example, at the time of charging, the secondary battery has an overcharge voltage, and the charging of the secondary battery is continued until the signal VS of the control circuit 4 is inverted even after the voltage detection circuit 3 operates. Therefore, the detection operation becomes more reliable.

Further, the delay circuit is configured to secure the logic at the time of initial power-on for a certain period. Specifically, as shown in FIG. 20, CMOSFE is connected between the power supply terminals + VB and -VB.
A capacitor 205 is formed between the output terminal VOUT and the power supply terminal -VB by forming an inverter by T. in this case,
The input terminal VIN is changed from + VB to -VB by the capacitor 205.
When a signal that changes to is input to the output terminal VOUT
By the time the inverted signal that changes from VB to + VB is output, the CR circuit is established and a delay occurs due to the impedance of the capacitor 205 and the Pch transistor 203. Also,
The output terminal V is also used when the power is initially turned on (when a secondary battery is connected).
The OUT voltage is delayed by the capacitor 205 until it reaches the + VB voltage. That is, the -VB voltage is initially maintained for a certain period.

In FIG. 20, the input terminal VIN is supplied from + VB.
Although a delay is realized when the input terminal VIN changes from -VB to + VB, a delay is realized when the input terminal VIN changes from -VB to + VB.
What is necessary is just to connect the capacitor 205 between VB. In order to realize the delay circuit, even if the delay circuit is constituted by the constant current circuit 226, the Pch transistor 203 and the capacitor 205 as shown in FIG.
An effect similar to that of the circuit of FIG.

FIG. 22 shows that the output terminal VOUT changes from + VB
This circuit creates a delay when changing to -VB, and keeps -VB for a certain period at the time of initial power-on. With the configuration shown in FIG. 23, it is possible to generate a delay when the output terminal VOUT changes from -VB to + VB. As described above, depending on the configuration of the delay circuit, the timing for delaying and the logic at the time of initial application can be freely set. Although the delay circuit is described by MOSFET for convenience, it is apparent that the delay circuit can be realized by other elements. Further, these delay circuits are merely examples, and the problem can be solved by using other circuits.

The charge / discharge control circuit according to the present invention is suitable for an integrated circuit provided on the same semiconductor substrate with little variation in the divided voltage of the voltage dividing resistor. (Embodiment 7) Embodiment 3 of the means 2 of the present invention will be described below with reference to the drawings.

FIG. 24 is a circuit block diagram of a rechargeable power supply device according to the present invention. The difference from the circuit of the conventional power supply device is that the voltage of the terminal -VBO is applied to the charge / discharge control circuit 102. FIG. 25 is a circuit block diagram of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, the secondary battery supplies power by connecting to the power supply terminals -VB and + VB. Also, the terminal V newly prepared in the present invention
e is connected to the external terminal -VO of the power supply device. The power supply has a voltage dividing resistor 1 of power supply voltage dividing means for dividing the power supply voltage.
And voltage detection circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, respectively, and a control circuit 4 for outputting a final control signal VS based on output signals of the voltage detection circuits 2 and 3 are parallel to each other. It is connected to the.

In the case of the present invention, a voltage dividing resistor for generating a divided voltage input to each voltage detecting circuit may be separately provided. In the case of FIG. 25, the voltage dividing circuit 1
It is an example of a charge / discharge control circuit provided in common for each voltage detection circuit. The control circuit 4 controls each of the voltage detection circuits 2
And from 3, a signal relating to overcharge and overdischarge of the secondary battery and a signal of the terminal -VO of the power supply device are input from Ve,
Each signal outputs a signal VS for turning on or off the switch circuit of the power supply device. That is, since the control circuit 4 is configured by a logic circuit, and the power supply is a secondary battery, the signal VS of the control circuit 4 becomes unstable when the voltage of the secondary battery further decreases from the overdischarge state. State. For example, the output of the control circuit 4 is connected to a C-MOS (Comp
lementary-Metal-Oxide-Semiconductor) In the case of an inverter, a sufficient voltage is applied between + VB and -VB to operate the circuit, and -V is applied to the input terminal VIN.
If the same potential as B is applied,-is applied to the output terminal VS.
The voltage of VB is output. When the voltage between + VB and -VB falls below the minimum operating voltage of the inverter, the output terminal VS becomes-
The voltage of VB is not output. Output terminal V of control circuit
Since S is connected to the switch circuit of the power supply device, it is impossible to control charging and discharging of the power supply device below the minimum operating voltage of the control circuit. In this case, the following inconvenience occurs.

That is, the secondary battery 101 is charged and discharged by the power supply device shown in FIG.
F to stop the energy supply to the external load.
However, since the secondary battery 101 is connected to the charge / discharge control circuit 102, only the consumed current of the charge / discharge control circuit 102 is consumed, and a considerable time has passed since the transition to the overdischarge state. After that, the secondary battery becomes equal to or lower than the minimum operating voltage of the control circuit 4, and the control signal VS shown in FIG.
Becomes unstable. Once the power supply enters this state, even if charging is attempted from the primary power supply, the switch circuit performs unstable operation, and in the worst case charging becomes impossible. Therefore, in order to solve this, in the present invention, the output unit of the control circuit 4 in FIG. 25 is configured as shown in FIG. C-MO
The power supply of the S inverter is the voltage between + VB and Ve, and the terminal
The configuration is such that the voltage of the output terminal VS is also controlled by the potential of -VB.

As shown in FIG. 24, the terminal + VB is the positive terminal of the secondary battery, the terminal -VB is the negative terminal of the secondary battery, and the terminal Ve.
Are connected to the external terminal -VO of the power supply device. When the power supply device is discharging, the switch circuit 103 is ON in FIG.
Are almost equal. This is because in the output circuit of FIG. 26, the voltage of the secondary battery is applied between + VB and Ve,
The terminal -VB is applied with substantially the same potential as the terminal Ve, is cut off by the Nch transistor 269, and the output of the output terminal VS is controlled by the voltage of the terminal VIN. Do the same thing. When the voltage of the secondary battery drops and becomes lower than the minimum operating voltage of the circuit of FIG. 26, the signal of the output terminal VS becomes unstable, but shows stable operation when charging from the primary power supply. When charging, a voltage higher than the voltage of the secondary battery is applied between the terminals + VO? -VO in FIG. At this time, the + terminal B of the secondary battery and the external terminal +
Since the VO is common, the external terminal -VO is lower than the -terminal A of the secondary battery. In this state, a voltage is applied from the charger between + VB and Ve in FIG.
Since the voltage difference between VB is small, the Nch transistor 26
9 turns ON, the C potential becomes equal to the potential of the terminal Ve, and the signal of the output terminal VS becomes equal to + VB. This means that, even when the voltage of the secondary battery is low when the charger is connected, the output terminal VS of the control circuit becomes the same as + VB potential,
The control of the switch circuit is performed reliably.

When the voltage of the secondary battery (the voltage between + VB and -VB) is smaller than the voltage of the charger (the voltage between + VBB and Ve), the C-MOS inverter at the output of the control circuit 4 becomes Nch
It functions to turn on the transistor 269. The threshold voltage (inversion voltage) of the inverter circuit 266 is Pch
It can be changed by the size of the transistor or the Nch transistor or the like, and by setting this to be equal to or higher than the minimum operating voltage of the control circuit 4, the operation described so far can be surely performed.

For convenience, the output of the control circuit of the present invention is
Although described in S, it is clear that other elements can also be realized. The problem can be solved even if another circuit is used as the circuit of the output unit. The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate with less variation in the divided voltage of the voltage dividing resistor.

(Embodiment 8) Embodiment 4 of the invention 2 will be described below with reference to the drawings. FIG. 27 is a circuit block diagram of Embodiment 4 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is,
A secondary battery is connected to power terminals -VB and + VB to supply power.

The power supply includes a voltage dividing resistor 1 of power supply voltage dividing means for dividing the power supply voltage, voltage detecting circuits 2 and 3 for detecting two output voltages of the power supply voltage dividing means, respectively.
A control circuit 4 that outputs a final control signal VS based on output signals of the respective voltage detection circuits 2 and 3 is connected in parallel with each other. The voltage detection circuit 2 is for overcharge detection,
The voltage detection circuit 3 is an overdischarge detection circuit. The voltage division resistor 1 and the voltage detection circuit 2 constitute an overcharge voltage detection circuit that detects overcharge of a secondary battery as a power supply. The voltage division resistor 1 and the voltage detection circuit 3 constitute an overdischarge voltage detection circuit that detects overdischarge of a secondary battery as a power supply. In the case of the present invention, the voltage dividing resistors 1 input to each voltage detection circuit may be separately provided. FIG.
In the case of 7, the voltage dividing resistor 1 is an example of a charge / discharge control circuit provided commonly to the voltage detection circuits. The control circuit 4 receives a signal relating to overcharge and overdischarge of the secondary battery from each of the voltage detection circuits 2 and 3, and outputs a signal VS for turning on or off the switch circuit of the power supply device.

FIG. 28 is a circuit diagram of a reference voltage circuit that generates a reference voltage input to the comparator circuit of voltage detection circuit 2 or 3. The voltage of the secondary battery is applied across the reference voltage circuit. The reference voltage circuit is transistor 2.
This is a circuit that outputs a reference voltage VR that does not depend on a voltage change of the secondary battery from a connection point between the transistor 01 and the transistor 202. The transistor 201 is a depletion type MOS
It is a field effect transistor, and the transistor 202 is an enhancement type MOS field effect transistor.
The transistors 201 and 202 are the same conductivity type N-type transistors. Both gate electrodes are connected to the reference voltage output terminal.

Further, when the semiconductor integrated circuit constituting the charge / discharge control circuit is formed by a CMOS circuit, the charge / discharge control circuit is latched up when the power supply is connected in the positive or negative direction. As a means for setting the output of the reference voltage circuit to the intermediate potential of the secondary battery when the latch-up occurs, an intermediate potential setting means is provided at the reference voltage output terminal VR. In the embodiment of FIG. 28, the intermediate divided output IN2 of the voltage dividing resistor is connected via a diode 283. The intermediate divided output IN2 is set to a substantially intermediate value between the secondary batteries + VB and -VB. Therefore, when the charge / discharge control circuit has latched up, the reference voltage output has a value reduced by about 0.6 V which is the forward voltage of the diode 283 from the intermediate divided output IN2. Since this value is substantially an intermediate voltage of the voltage of the secondary battery, the voltage detection circuit outputs a signal via the control circuit 4 so that the switch circuit is turned off.

The embodiment shown in FIG. 28 is an example in which means for setting the output of the reference voltage circuit of the voltage detection circuit to an intermediate potential is provided to prevent malfunction of the switch circuit due to latch-up. Runaway can be prevented if the switch circuit is turned off by latch-up. Therefore, the switch circuit may be turned off when the output of the control circuit 4 is latched up.

The present invention is indispensable for a CMOS IC that malfunctions due to latch-up when the power supply is reversely connected. (Embodiment 9) Embodiment 5 of the means 2 of the present invention will be described below with reference to the drawings. FIG. 29 is a circuit block diagram of Embodiment 5 of the charge / discharge control circuit in the means 2 of the present invention. 29, external terminals -VO, + VO, a switch circuit 103, a current sensing resistor 104, and a secondary battery 1
01, reference voltage circuit 106, transistor 107, constant current source 108, capacitor 109, pull-down high resistance 1
11 is the same as FIG.

The output of the comparator 21 changes from “H” to “H” when the current exceeds the current represented by the above-described equation (1), as in FIG.
It becomes “L”, the transistor 107 is turned off, and the capacitor 109 is charged by the constant current source 108. When the voltage of the capacitor 109 becomes higher than the voltage value VREF of the reference voltage 106, the output of the comparator 22 becomes “H” →
It becomes “L”, and the switch circuit 103 is turned off. At this time, the comparator 22 has a latch function, and holds this state when the output of the comparator 22 becomes “L”.

The latch function is provided by the comparator 21.
Is released by the output of. FIG. 31 shows a circuit diagram of a comparator with a latch function. When the voltage of the negative input terminal 314 becomes higher than that of the positive input terminal 313,
The voltage of the output terminal 315 becomes “L”. At this time, the output of the inverter 317 becomes “H”, and the input on the minus side becomes “H”. As a result, even if the voltage of the plus input terminal slightly fluctuates, the output of the comparator with latch function 22 is latched at “L”.

While the load is connected, the switch circuit 103 is turned off. Therefore, the negative input terminal of the comparator 21 is pulled up to + VO by a load connected to an electronic device such as a video, and an overcurrent is generated. State is maintained. Thereafter, when the load is removed, the negative input voltage of the comparator 21 is reduced to “L” by the high resistance 111 for pull-down, so that the output of the comparator 21 becomes “H”. Since the output of “H” sets the latch release terminal 316 of the comparator 22 with a latch function to “H”, the output of the comparator 22 with a latch function becomes “H”.
And the latch is released.

In FIG. 29, the overcurrent detection circuit includes a voltage detector for detecting the voltage across the overcurrent detection resistor 104 provided between the external terminal -VO and the switch circuit 103; It comprises a delay circuit for temporally delaying the output of the voltage detector, and a voltage detection circuit with a latch-up function for detecting the voltage of the output of the delay circuit.
The voltage detection circuit includes a reference voltage generation circuit 106 and a comparator circuit 21. The delay circuit includes a constant current source 108, a capacitor 109, and a transistor 107. In the description so far, the charge / discharge control circuit 102 and the overcurrent detection circuit 105 have been described as being configured separately.

However, the charge / discharge control circuit includes the charge / discharge control circuit 102 and the overcurrent detection circuit 1 described in the embodiment of the present invention.
05 may be included. (Embodiment 10) FIG. 32 is a circuit block diagram showing Embodiment 1 of the means 3 of the charge / discharge control circuit of the present invention. When applied to a power supply device, this charge / discharge control circuit operates using the secondary battery as a power supply. That is, two secondary batteries are connected in series to the power supply terminals -VB and + VB, and are supplied as power. The power supply is connected to a voltage dividing resistor 1 of power supply voltage dividing means for dividing the power supply voltage, and a voltage detection circuit 2 for detecting the output voltage of the power supply voltage dividing means.

The voltage detection circuit 2 is, specifically, a comparator circuit 4 having the input of the reference voltage source 43 and the output of the voltage dividing resistor 1 for the power supply terminal -VB as shown in FIG.
4. The voltage dividing resistor 1 and the voltage detecting circuit 2 constitute a circuit for detecting a sum voltage of a secondary battery as a power supply. The voltage detection circuit 2 outputs a signal VS for turning on or off a switch circuit of the power supply device.

The charge / discharge control circuit of the present invention is suitable for an integrated circuit provided on the same semiconductor substrate where the division voltage of the voltage division resistor 1 has little variation. It is also apparent that the present invention can be applied to the case of three or more secondary batteries in series. As described above, by detecting each of the sum voltages of the batteries constituted by the secondary batteries, it is possible to perform the optimal charge / discharge control even in the state where the voltage of each battery has one-sided verification. Therefore, the life of the secondary battery can be improved.

(Embodiment 11) The following describes means 3 of the present invention.
A second embodiment will be described with reference to the drawings. FIG.
FIG. 9 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment in the means 3 of the present invention. The voltage detection circuit 3 includes a secondary battery 6
The overcharge detection voltage V1 of the secondary battery 7
, And is output by the control circuit 8 as an output signal VS. At the same time, the voltage of the secondary battery 6 is detected by the voltage detection circuit 2, and the detection voltage V3 is set to a voltage smaller than the overcharge detection voltage V1. Similarly, the voltage of the secondary battery 7 is detected by the voltage detection circuit 4, and the detection voltage V4 is set to a voltage lower than the overcharge detection voltage V2. The output signals of these voltage detection circuits 2 and 4 are input to the voltage detection circuits 5 and 3, respectively, and change the voltage values of the overcharge detection voltages V2 and V1 of the voltage detection circuits 5 and 3.

More specifically, when a charger is externally connected to terminals + VB and -VB to charge secondary batteries 6 and 7, the original overcharge detection voltage V of voltage detection circuits 3 and 5 is used.
Let 1 and V2 be 4.2V. However, if the secondary battery 6
When the charging performance deteriorates remarkably, only the secondary battery 7 is charged and the difference between the two voltage values increases. To prevent this, the detection voltage V3 of the voltage detection circuit 2 is set to about 3.2 V. If the voltage of the secondary battery 6 does not exceed 3.2 V due to deterioration, the detection of the voltage detection circuit 5 is performed. The voltage V2 is set to a value lower than 4.2V, and when the voltage V2 is exceeded, the detected voltage value is set to 4.2V. This setting is performed by the output signal of the voltage detection circuit 2.

Similarly, the deterioration of the secondary battery 7 is monitored based on the output signal of the voltage detection circuit 4, and when the voltage of the secondary battery 7 does not exceed 3.2 V due to the deterioration, The voltage V1 is set to a value lower than 4.2 V, and when the voltage V1 is exceeded, the original detection voltage value is set to 4.2 V. This setting is performed by the output signal of the voltage detection circuit 4.

In the description, 3.2 V and 4.2 V
Was used as an example, but these values depend on the battery characteristics, and are of course not limited to these values. FIG. 35 shows a specific circuit for realizing the block diagram of FIG. The output of the voltage detection circuit 4 is input to the gate of a transistor 9 connected in parallel to a part of the resistor R3.
Can be changed.

Similarly, the output of the voltage detection circuit 2 is changed by turning on or off the transistor 10 connected in parallel to a part of the resistor connected in parallel to the secondary battery 7. The overcharge detection voltage V2 can be changed. (Embodiment 12) Embodiment 3 of the means 3 of the present invention will be described below with reference to the drawings.

FIG. 36 is a block diagram showing a rechargeable power supply according to the present invention and a charge / discharge control circuit therefor. External terminal +
A secondary battery 101, a voltage detection circuit 2 for detecting the voltage of the secondary battery with respect to V and -V, and a control circuit 3 for controlling the impedance of the switch circuit 5 are connected in parallel with each other. A switch circuit 5 is connected in series between the secondary battery 101 and the external terminal -V, and the electrical connection between the external terminal and the secondary battery 101 is performed by electrical control. The control circuit 3 performs an input logic process on the output of the voltage detection circuit 2 and outputs a signal for turning on or off the switching circuit 5.

For example, when a power supply for charging is connected to an external terminal and the secondary battery 101 is charged from the power supply, when the voltage of the secondary battery 101 becomes higher than the overcharge voltage level, a voltage detection circuit is provided. 2 is inverted and the control circuit 3
Is input to The switch circuit 5 is turned off from the control circuit 3
Signal is output to stop charging. Conversely, when an electronic device that consumes power such as a video camera is connected to the external terminals + V and −V and power is supplied from the secondary battery 101 to the electronic device, the voltage of the secondary battery 101 is overdischarged. When the voltage drops below the voltage level, the signal of the voltage detection circuit 2 is inverted to a signal opposite to the normal voltage range. Then, the control circuit 3
A signal to turn off the switch circuit 5 is output to stop the discharge. The normal voltage range is an intermediate state between the overcharge level and the overdischarge level.

In the rechargeable power supply described above, the voltage detection circuit 2, the control circuit 3, and the switch circuit 5 can be constituted by semiconductor integrated circuits arranged on the same substrate. FIG.
FIG. 3 is a circuit diagram of an embodiment of a switch circuit used in the charge / discharge control circuit of the present invention. A switch circuit is provided between the external terminal -V and the minus terminal 34 of the secondary battery. In the switch circuit, an N-type insulated gate field effect transistor (hereinafter referred to as an N-type MISFET) 31 is provided between an external terminal -V and a minus terminal 34 of the secondary battery. An N-type MISFET 32 and an N-type MISFET 33 are provided between V and the minus terminal 34 of the secondary battery, respectively. Three N-type MI
The gate electrodes 31G, 32G and 33G of the SFET are controlled by a control circuit.

For example, when a power supply for charging is connected to an external terminal and the secondary battery is being charged, the transistors 31 and 32 are turned on and the transistor 33 is turned off.
are doing. When the charging is overcharged, the output of the voltage detection circuit is inverted, and a signal is output from the control circuit such that the switch circuit is turned off. That is, the transistors 31 and 33 are turned off and only the transistor 32 is kept on.

When a portable device such as a video camera is connected to the external terminal and power is supplied from the secondary battery to the portable device, the switch circuit in FIG. 38 is controlled to be turned on. That is, the transistors 31 and 33 are ON
Then, the transistor 32 is off. When an overdischarge state is caused by supplying power, the output signal of the voltage detection circuit is inverted, and a signal for turning off the switch circuit is output from the control circuit. That is, transistors 31 and 32
Is turned off, and only the transistor 33 is turned on.

In the normal state, it is possible to detect whether the battery is operating in the charge state or the discharge state by comparing the voltage between the external terminal -V and the minus terminal 34 of the secondary battery. . The control circuit controls the impedance of the transistors 32 and 33 by detecting the charge state and the discharge state. That is, the control circuit has a function of detecting charging or discharging.

In the switch circuit of FIG. 38 described above, only one transistor 31 flows through the battery. Therefore, in general, a transistor having a large current driving capability can be formed in half of the conventional transistor in order to reduce the voltage drop in the switch circuit. The transistors 32 and 33 of the switch circuit of the charge / discharge control IC of the present invention are switching transistors for selectively connecting the substrate of the current driving transistor 31 to either the external terminal or the negative terminal of the secondary battery. . Therefore, the current driving capabilities of the substrate potential switching transistors 32 and 33 may be small. The current driving capability of the transistor 31 generally requires several A, while the transistor 3
The current driving capabilities of the transistors 2 and 33 are as small as 1/1000 or less thereof.
Is so small that it can be ignored.

As described above, by using the switching circuit as shown in FIG. 38, the current driving capability of the current driving transistor can be almost doubled as compared with the conventional one, so that the same current driving capability can be obtained. On the other hand, the transistor area can be reduced to about half and the miniaturization can be facilitated. Further, the potential of the substrate of each transistor can be electrically separated by the N well. Therefore, they can be easily provided on the same semiconductor substrate.
However, even if the transistors 31, 32, and 33 are constituted by individual transistors, the operation thereof functions without change.

FIG. 39 is a sectional view of a transistor of the charge / discharge control IC of the present invention. The transistor is formed using single-crystal silicon films 53, 54 and 55 formed on an insulating film 52 formed on a silicon substrate 51. Such a substrate having a single crystal silicon film provided over an insulating film is generally called an SOI substrate. S
A transistor having a cross-sectional view as shown in FIG. 39 is formed using the OI substrate. That is, an N-type source region 53 and an N-type drain region 55 are provided on both sides of the channel formation region 54, and a gate electrode 57 is provided on the channel formation region 54 via a gate insulating film 56. With the transistor having the structure illustrated in FIG. 39, the potential of the channel formation region 54 which is also a substrate of the transistor can be formed electrically independently of a transistor provided over the same substrate. That is, since the substrate potentials of the transistors can be electrically separated from each other, a charge / discharge control IC having a switch circuit can be easily realized.

FIG. 40 is a plan view of a transistor in which the potential of the channel formation region, which is the substrate, is made the same as the potential of the source region. An N-type source region 73, a drain region 72, and a channel formation region therebetween are formed in a single crystal silicon semiconductor film 71 provided on an insulation film, and a gate electrode 77 is formed on the channel formation region via a gate insulating film. Is provided. A P-type source region 74 is provided in a part of the source region 73, and the potential of the source region 73 and the potential of the channel formation region are set to the same potential by the source electrode 75.

FIG. 41 is a sectional view taken along line AA 'of FIG. A single crystal silicon semiconductor film 71 is provided over a silicon substrate 61 with an insulating film 68 interposed therebetween. In the single crystal silicon semiconductor film 71, a P-type source region 64, a P-type channel formation region 69, and an N-type drain region 62 are formed. A gate electrode 67 is provided on the channel formation region 69 with a gate insulating film 63 interposed therebetween. The P-type source region 64 and the N-type source region are connected to a source electrode 65. The N-type drain region 62 is the drain electrode 6
6 is connected.

FIG. 42 is a circuit diagram of a switch circuit of the charge / discharge control IC of the present invention constituted by using the transistor-structure MISFET as shown in FIG. External terminal-
N-type MISFETs 81 and 82 using an SOI substrate are connected in series between V and the minus terminal 80 of the secondary battery. The substrates of the transistors 81 and 82 are connected so that they have the same potential as the external terminal and the terminal of the secondary battery. By using an SOI substrate, the potentials of the substrates can be set to different potentials.

As described above, a charge / discharge control circuit in which the switch circuits are arranged on the same substrate can be realized.

[0121]

The charge / discharge control circuit of the present invention has a low current consumption due to a configuration in which the voltage dividing resistor of the overcharge and overdischarge detection circuit provided therein has a switching element for reducing the current consumption. It has the effect of achieving the conversion. Further, a power supply device having a long life can be supplied by the charge / discharge control circuit, the secondary battery, and the switch circuit.

Further, in the overdischarge state, the current consumption of the error amplifier of the overcharge detection circuit is cut, so that the power consumption of the battery in the overdischarge state can be reduced, and the deterioration of the battery can be prevented. This has the effect.
Further, since the current consumption of the error amplifier of the overcharge detection circuit is cut, the power consumption of the battery in the overdischarge state can be reduced, and the battery can be prevented from being deteriorated.

Further, since a plurality of comparator circuits can be integrated, there is an effect that an IC chip size can be reduced and current consumption can be reduced, and an inexpensive and high-performance battery charge / discharge control circuit can be realized. In addition, the current cut-off transistor is connected in series to the inter-cell voltage detection buffer circuit of the secondary battery provided therein, which has the effect of reducing current consumption. In particular,
This has the effect of reducing current consumption in an overdischarge state in which the capacity of the secondary battery is sharply reduced. Further, by inserting the current cutting transistor, it is possible to output a signal indicating overcharge / overdischarge and a normal state to a connected inter-battery voltage detection terminal which is an output terminal of the buffer circuit.

In addition, by using a configuration that also serves as a reference voltage source for detecting overcharge and overdischarge of the secondary battery provided therein, the charge / discharge control circuit can be configured with a reduced number of parts and can be manufactured at low cost. Rather, it has the effect of enabling a reduction in functionally important current consumption. The reduction of the current consumption of the charge / discharge control circuit has the effect of extending the life of the rechargeable power supply. Also, in the present invention, even when the secondary battery is formed by a plurality of batteries, since the reference voltage source for detecting the voltage of each battery is constituted by one circuit, the charge / discharge control circuit is similarly provided. Has the effect of reducing the current consumption and improving the life of the rechargeable power supply.

Further, the voltage dividing resistor for detecting the voltage of the secondary battery provided inside serves as both the overcharge voltage detection and the over-discharge voltage detection, so that the circuit is connected in parallel to the secondary battery. To reduce current consumption. Further, the present invention has an effect of improving the life of the secondary battery by reducing the current consumption of the charge / discharge control circuit. In addition, since the voltage dividing resistor is configured to be used for overcharging and overdischarging, the chip size is reduced when the charge / discharge control circuit is integrated.
There is an effect that can be provided cheaply.

According to the present invention, as described above, in the charge / discharge control circuit, as soon as the voltage detection circuit detects overcharge or overdischarge, the detection signal is fed back to further increase the overcharge or overdischarge detection level. Alternatively, resetting to detect overdischarge has an effect of eliminating a malfunction. Further, after resetting, by switching the switch circuit between the secondary battery and the charging power supply, there is an effect of preventing unstable oscillation of the voltage detection circuit due to voltage fluctuation of the secondary battery due to impedance change of the switch circuit.

Further, since a delay circuit is provided between the overcharge and overdischarge detection circuit and the control circuit provided therein, a malfunction at the time of detection can be prevented. Further, it has an effect of preventing a malfunction at the time of initial connection of the secondary battery. The charge / discharge control circuit, the secondary battery, and the switch circuit can supply a power supply device with stable operation.

The charge / discharge control circuit of the present invention is configured such that the voltage of the external terminal of the power supply device is input so that the voltage of the secondary battery serving as the power supply of the charge / discharge control circuit is the minimum voltage of the charge / discharge control circuit. When the charger is connected even when the voltage is lower than the operating voltage, the switch circuit can be controlled, and a power supply device capable of performing reliable charging regardless of the voltage of the secondary battery can be supplied.

Further, as described above, the present invention
In a charge / discharge control circuit composed of a MOSIC, when a voltage opposite to the normal voltage is applied to the charge / discharge control circuit, the output of the control circuit turns off the switch circuit, so that the charge to the secondary battery is reduced. It has the effect of preventing current runaway.

The charge / discharge control circuit of the present invention has an effect that the oscillation phenomenon at the time of overcurrent detection can be reliably prevented by providing the overcurrent detection circuit with a latch function. The charge / discharge control circuit of the present invention can supply a long-life power supply device by providing a voltage dividing resistor and a voltage detection circuit between terminals from which a sum voltage of two or more secondary batteries is output in series.

When two secondary batteries are connected in series and charged, even if one of the batteries becomes abnormal and the charging performance is significantly deteriorated, only the normal battery is charged and the difference between the voltage values of the two batteries is reduced. Can be prevented from increasing. Furthermore, since the rechargeable power supply and the charge / discharge control circuit of the present invention are configured as an integrated circuit including a switch circuit, the following effects can be obtained. (1) Assembly cost can be reduced. (2) The size can be reduced. (3) Improvement of reliability as a device.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a charge / discharge control circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit block diagram of a conventional rechargeable power supply device.

FIG. 3 is a circuit diagram of a voltage detector.

FIG. 4 is a circuit block diagram of another embodiment of the charge / discharge control circuit of the present invention.

FIG. 5 is a circuit block diagram of another embodiment of the charge / discharge control circuit of the present invention.

FIG. 6 is a battery charge / discharge control circuit diagram according to a second embodiment of the present invention.

FIG. 7 is a circuit example of an error amplifier having a power ON / OFF function.

FIG. 8 is a battery charge / discharge control circuit diagram showing another embodiment of the present invention.

FIG. 9 is a battery charge / discharge control circuit diagram showing another embodiment of the present invention.

FIG. 10 is a battery charge / discharge control circuit diagram showing another embodiment of the present invention. It is a circuit diagram of a voltage detector.

FIG. 11 is a circuit block diagram of a charge / discharge control circuit according to a third embodiment of the present invention.

FIG. 12 is a circuit diagram showing a buffer circuit.

FIG. 13 is a circuit block diagram of a charge / discharge control circuit according to a fourth embodiment of the present invention.

FIG. 14 is a circuit diagram of a reference voltage circuit.

FIG. 15 is a circuit block diagram of a charge / discharge control circuit when the number of secondary batteries is two.

FIG. 16 is a circuit diagram of VR1 and VR2 of FIG.

FIG. 17 is a circuit block diagram of a charge / discharge control circuit according to the first embodiment in the means 2 of the present invention.

FIG. 18 is a timing chart of the signals of the charge / discharge control circuit according to the first embodiment in the means 2 of the present invention.

FIG. 19 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment in the means 2 of the present invention.

FIG. 20 is a circuit diagram of a delay circuit according to a second embodiment in the means 2 of the present invention.

FIG. 21 is a circuit diagram of a delay circuit according to a second embodiment in the means 2 of the present invention.

FIG. 22 is a circuit diagram of a delay circuit according to a second embodiment in the means 2 of the present invention.

FIG. 23 is a circuit diagram of a delay circuit according to a second embodiment in the means 2 of the present invention.

FIG. 24 is a circuit block diagram of a rechargeable power supply device according to a third embodiment in the means 2 of the present invention.

FIG. 25 is a circuit block diagram of a charge / discharge control circuit according to a third embodiment in the means 2 of the present invention.

FIG. 26 is an example of a control circuit output unit of the present invention.

FIG. 27 is a circuit block diagram of a charge / discharge control circuit according to a fourth embodiment in the means 2 of the present invention.

FIG. 28 is a circuit diagram of a reference voltage circuit according to a fourth embodiment in the means 2 of the present invention.

FIG. 29 is a rechargeable control circuit diagram of Embodiment 5 in the means 2 of the present invention.

FIG. 30 is a diagram of a conventional rechargeable control circuit.

FIG. 31 is a circuit diagram of a comparator with a latch function according to the present invention.

FIG. 32 is a circuit block diagram of a charge / discharge control circuit according to the first embodiment in means 3 of the present invention.

FIG. 33 is a circuit block diagram of a charge / discharge control circuit according to a second embodiment in the means 3 of the present invention.

FIG. 34 is a circuit diagram of a voltage detector.

FIG. 35 is a circuit block diagram of another embodiment of the charge / discharge control circuit of Embodiment 2 in the means 3 of the present invention.

FIG. 36 is a circuit block diagram of a third embodiment of the rechargeable power supply device and means 3 of the charge / discharge control circuit according to the present invention.

FIG. 37 is a circuit block diagram of a conventional rechargeable power supply device.

FIG. 38 is a circuit diagram of a switch circuit of the charge / discharge control circuit in the means 3 of the present invention.

FIG. 39 is a cross-sectional view of a transistor used in the charge / discharge control circuit in Means 3 of the present invention.

FIG. 40 is a plan view of a transistor used in a charge / discharge control circuit in Means 3 of the present invention.

FIG. 41 is a cross-sectional view of the transistor of FIG. 35 taken along the line AA ′.

FIG. 42 is a circuit diagram of a switch circuit of a charge / discharge control circuit in the means 3 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Voltage division circuit 2, 3 Voltage detection circuit 4 Control circuit 5 Switch element 11 Reference voltage circuit 12 2 'Error amplifier of overdischarge detection circuit 13 3' Error amplifier of overcharge detection circuit 14 Battery connection terminal 15 Battery connection terminal 16 Over Output terminal of discharge detection circuit 17 Output terminal of overcharge detection circuit 18, 19 Battery 52, 53 Comparator circuit 21 Comparator 22 Comparator with latch function 23 Positive input terminal of comparator with latch function 24 Minus input terminal of comparator with latch function 25 With latch function Comparator output terminal 26 Latch release signal input terminal of comparator with latch function 101 Secondary battery 102 Charge / discharge control circuit 103 Switch circuit 104 Current sensing resistor 106 Reference voltage circuit 111, 112 Battery 113, 114 Voltage Split circuit 115, 116 Voltage detection circuit 117 Control circuit 118 Buffer circuit 175 Divided value control transistor 191, 192 Delay circuit 203 Pch transistor 204 Nch transistor 205 Capacity 226 Constant current circuit 266 Inverter circuit 267 Final output stage Pch transistor 268 Final output stage Nch transistor 269 Nch transistor for output control

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Minoru Sudo 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba F-term (reference) in Seiko Instruments Inc. EC03 5H030 AA03 AA06 AS14 BB01 BB21 FF43 FF44

Claims (2)

[Claims] 1. A secondary battery in which a first battery and a second battery are connected in series, and a first overcharge provided independently of the first battery and the second battery, respectively. An overdischarge detection circuit and a second overcharge / overdischarge detection circuit, and charging of the secondary battery from signals from the first overcharge / overdischarge detection circuit and the second overcharge / overdischarge detection circuit. A control circuit for outputting a signal for controlling discharge; and a charge / discharge balance state between the first battery and the second battery, with a potential between the first battery and the second battery as inputs. A buffer circuit whose operation is controlled by a signal from the control circuit, the control circuit comprising: Outputting a signal for stopping operation to the buffer circuit. Discharge control circuit. 2. A secondary battery in which a first battery and a second battery are connected in series, a switch circuit provided between the secondary battery and an external battery terminal, and controlling the switch circuit. And a charge / discharge control circuit connected in parallel with the secondary battery, wherein the charge / discharge control circuit is provided independently for the first battery and the second battery, respectively. A first overcharge / overdischarge detection circuit and a second overcharge / overdischarge detection circuit, and the first overcharge / overdischarge detection circuit and the second overcharge / overdischarge detection circuit.
A control circuit for logically converting a signal from the over-discharge detection circuit to a signal for controlling the switch circuit; and a first battery having a potential between the first battery and the second battery as an input. Outputting to the control circuit a signal that is information on the state of charge / discharge balance between the second batteries;
A buffer circuit whose operation is controlled by a signal from the control circuit, wherein the control circuit outputs a signal for stopping the operation of the buffer circuit to the buffer circuit when the power supply is in an overdischarged state. Rechargeable power supply.