JP2009232550A - Semiconductor integrated circuit for charging control - Google Patents

Abstract

[PROBLEMS] To change a set temperature for shutdown or a temperature range for current control by simply changing one place in a circuit, a plurality of set values can be adjusted in a desired direction, and the adjustment is easy. Provide charge control ICs that require little increase in chip size.
A temperature detection circuit (13) having a temperature detection element and generating a voltage corresponding to a chip temperature is provided, and a set temperature for shutdown and a temperature range for current control are determined based on the voltage of the temperature detection circuit. In a charge control IC with a function to control the charging current by setting a threshold value, a bias circuit (BIAS) that generates a predetermined bias voltage and a current source (CS) that sends current to the temperature sensing element (SNS) A current mirror circuit capable of changing the mirror ratio is provided between the two, and the current flowing through the temperature detection element is changed by changing the mirror ratio of the current mirror circuit, so that the set temperature for shutdown and the upper limit of the temperature range for current control are changed. The determination threshold value for the lower limit temperature can be adjusted at the same time.
[Selection] Figure 1

Description

  The present invention relates to a technique for suppressing a temperature rise in a charging device for a secondary battery, and more particularly to a technique that is effective when used for a charge control IC (semiconductor integrated circuit) C equipped with a charge control circuit.

  An IC equipped with a charging control circuit for controlling a charging current is used for a charging device for a secondary battery in order to suppress an abnormal temperature rise inside the battery or the device. As an invention related to such a charging device, there is an invention described in Patent Document 1, for example. The present invention includes a temperature detection unit in or near a heat-generating component having the highest temperature or a component having the smallest temperature margin, and charging the secondary battery when the output of the temperature detection unit exceeds a predetermined temperature. The current is lowered or stopped.

In addition, the charging device has a function of providing a temperature detection element on the chip to suppress the temperature rise in order to prevent a decrease in reliability due to heat generation of the charging control IC itself that controls the charging current and also a failure. Some are provided.
JP 2001-145274 A JP 2007-31519 A

  The conventional technology for suppressing the temperature rise of the charge control IC is a simple one in which when the chip temperature exceeds a predetermined temperature such as 150 ° C., the current control transistor is turned off to cut off the charge current. It wasn't too much. In this control method, the chip temperature can be prevented from exceeding the set temperature by repeating a cycle of temperature increase-charge current cut-off-temperature decrease-charge current restart-temperature increase.

  However, in order to completely cut off the charging current when the chip temperature exceeds a predetermined temperature such as 150 ° C., when the charging current is restarted next time, the current control transistor is abruptly caused by the response delay of the feedback control loop. A large current flows, and there is a possibility of causing a chattering phenomenon of current interruption-current resumption-current interruption-current resumption. Moreover, when a large current suddenly flows into the secondary battery when the current is resumed, there is a risk that the characteristics of the secondary battery will deteriorate, and the battery life will be shortened.

  Therefore, the inventors cut off (shut down) the charging current when the chip temperature rises to a predetermined set temperature (for example, 140 ° C.) or higher, and at the predetermined temperature lower than the current cut-off set temperature. Considering that a desirable result can be obtained if the charge control circuit is configured to reduce the charging current as the temperature increases when the temperature is in the temperature range (for example, 90 ° C. to 100 ° C.), a specific chip temperature detection circuit was examined.

  As a result, assuming a system in which the semiconductor chip to be used is determined, when the temperature range for controlling the charging current is determined according to the specific set temperature and temperature for shutdown, chip temperature detection with desired characteristics It came to devise the circuit form which can realize a circuit easily. However, if the semiconductor chip to be used changes, it is necessary to change the set temperature for shutdown and the temperature range for current control. In that case, the potential (resistance ratio) etc. at multiple points in the circuit must be changed. It became clear that there was a problem that the change was troublesome and caused an increase in chip size.

  Note that a technique is disclosed in Patent Document 2 in which a current flowing through a temperature detection diode, which is caused by process variations, can be adjusted with a resistor that can be trimmed. However, the present invention sets a plurality of locations. It is not disclosed until it is adjusted simultaneously.

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to a plurality of systems having different set temperatures for shutdown and temperature ranges for current control depending on semiconductor chips to be used and application systems. An object of the present invention is to provide a charge control IC that can be used and has a wide use range.

  Another object of the present invention is to adjust a plurality of set values in a desired direction by changing only one place in a circuit when it is desired to change a set temperature for shutdown or a temperature range for current control. It is an object of the present invention to provide a charge control IC that is easy to implement and requires little increase in chip size.

  In order to achieve the above object, the present invention comprises a temperature detection circuit having a PN junction element as a temperature detection element and generating a voltage corresponding to the chip temperature, and based on the voltage of the temperature detection circuit, In a semiconductor integrated circuit for charge control having a function of controlling a charging current supplied to a secondary battery by setting a determination threshold value of a temperature range for current control, by changing a current flowing through the temperature detection element, The shutdown set temperature judgment threshold value and the upper and lower limit temperature judgment threshold values of the current controlled temperature range can be adjusted simultaneously. Here, as a method of changing the current flowing through the temperature detection element, a current mirror circuit capable of changing the mirror ratio is provided between a bias circuit that generates a predetermined bias voltage and a current source that supplies current to the temperature detection element. A method of changing the current by changing the mirror ratio of the current mirror circuit is effective.

  Since the forward voltage VF differs depending on the current flowing in the PN junction diode, according to the configuration as described above, the determination threshold value in the temperature range also changes when the determination threshold value corresponding to the shutdown set temperature is changed. A plurality of set values can be adjusted in a desired direction only by changing one place in the circuit.

  More specifically, a temperature detection circuit that generates a voltage according to the chip temperature using an element having a PN junction as a temperature detection element, a current control transistor provided between the voltage input terminal and the output terminal, A control circuit for controlling a charging current supplied to a secondary battery by controlling the current control transistor based on an output voltage of the temperature detection circuit, wherein the control circuit includes the control circuit When the chip temperature is in a predetermined temperature range lower than the current cutoff set temperature, the charging current is reduced as the temperature increases, and when the chip temperature is lower than the lower limit temperature of the temperature range, the charging current having a predetermined current value is The current control transistor is controlled so that a charging current smaller than the predetermined current value flows from the upper limit temperature of the temperature range to the current cutoff set temperature. The temperature detection circuit includes: a bias circuit that generates a predetermined bias voltage; a first determination comparison circuit that determines whether shutdown is necessary; a current source circuit that supplies current to the temperature detection element; and the predetermined temperature A second determination comparison circuit for determining a range, a current mirror circuit capable of changing a mirror ratio is provided between the bias circuit and the current source circuit, and the mirror ratio of the current mirror circuit is changed. Thus, the current flowing through the temperature detection element is changed, and the determination threshold value for the current cutoff set temperature and the determination threshold value for the upper or lower temperature limit of the temperature range for current control can be adjusted simultaneously.

  As a method of changing the current flowing through the temperature detection element, there are a method of changing by a variable resistor as described in Patent Document 2 and a method of changing the number of resistors connected by a resistor circuit having a plurality of resistors. Since the resistance of the chip has a large variation and the area is larger than that of the transistor, it is advantageous to change the current passed through the temperature detection element by the current mirror circuit because the accuracy is high and the area can be reduced.

  Preferably, the bias circuit includes a current-voltage conversion transistor at an output unit, and the current-voltage conversion transistor and the current source transistor of the first determination comparison circuit constitute a current mirror circuit. By being connected in this manner, it also serves as a circuit for applying a bias to the first determination comparison circuit. As a result, an increase in circuit scale can be suppressed as compared with the case where separate bias circuits are provided.

  Preferably, a plurality of transistors of different sizes are provided in the output section of the bias circuit and the current source circuit, respectively, and a programmable element such as a fuse element is connected in series with the plurality of transistors. The corresponding transistors of the output circuit of the bias circuit and the transistors of the current source circuit are connected to form a current mirror circuit, and the mirror ratio is determined by setting the programmable element. To be configured. Thus, by setting a programmable element in the final process, it is possible to change the temperature at which shutdown is easily performed and the temperature range in which current is controlled.

  Further, preferably, the temperature detection circuit includes a subtraction circuit that subtracts a voltage generated by the temperature detection element from a predetermined voltage, an inverting amplification circuit that inverts and amplifies the output of the subtraction circuit, and an output of the inverting amplification circuit. A first comparator for comparing with a first voltage, and when the output of the inverting amplifier circuit is lower than the first voltage, the output of the inverting amplifier circuit is controlled by the output of the first comparator; When the output of the inverting amplifier circuit is higher than the first voltage, first selection means for selectively transmitting the first voltage to the subsequent stage, and the output of the inverting amplifier circuit and the first voltage are lower than the first voltage. A second comparator for comparing with the second voltage, and when the output of the inverting amplifier circuit is higher than the second voltage, the output of the inverting amplifier circuit is controlled by the output of the second comparator. When the output of the inverting amplifier circuit is lower than the second voltage is configured with a, a second selecting means for selectively transmitting to the subsequent stage of the second voltage. As a result, it is possible to relatively easily design a charging power control circuit that can charge the chip in a desired temperature range.

  Preferably, a constant current control amplifier is provided for controlling a control voltage so that a voltage according to an output charging current is fed back and a constant current flows through the current control transistor, and the output voltage of the temperature detection circuit is the constant voltage. The current control amplifier is configured to be supplied as a reference side voltage. Thereby, the secondary battery can be charged with a predetermined current within a range where the chip temperature does not exceed the predetermined temperature.

  Further preferably, a constant voltage control amplifier that receives the voltage of the output terminal and generates a voltage corresponding to a potential difference with a predetermined reference voltage and outputs a voltage for constant voltage control of the current control transistor; and the output terminal A voltage detection circuit that detects whether or not the voltage of the output terminal has reached a predetermined voltage, and before the voltage of the output terminal reaches the predetermined voltage, the current control transistor by the output of the constant current control amplifier After the voltage at the output terminal reaches a predetermined voltage, the current control transistor may be controlled by the output of the constant voltage control amplifier. Thus, when the chip temperature is higher than the temperature range, charging can be performed at a predetermined low voltage.

  According to the present invention, in a control IC having a function of controlling a charging current according to a chip temperature, it is possible to avoid a chattering phenomenon of current on / off due to a vertical movement of the chip temperature. Further, there is an effect that it is possible to prevent a large current from suddenly flowing into the secondary battery when the current is resumed and the characteristics of the secondary battery to deteriorate.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of an embodiment of a charge control IC for a secondary battery suitable to which the present invention is applied.

  As shown in FIG. 1, the charging control IC 10 of this embodiment includes a voltage input terminal VIN to which a DC voltage from a DC power source 20 such as an external AC adapter is input, and lithium ions to be charged. A battery terminal BAT to which a secondary battery 40 such as a battery is connected; a current control transistor Q1 provided between the voltage input terminal VIN and the battery terminal BAT; and a battery voltage Vbat for performing constant voltage control. A constant voltage control amplifier AMP1 that compares the reference voltage Vref1 and generates a gate control voltage of Q1 is provided.

  Further, in order to perform current control by detecting a current proportional to the current flowing through the transistor Q1, the source terminal is connected to the voltage input terminal VIN and has a magnitude 1 / N of Q1, and the same voltage as Q1. Is applied to the control terminal (gate terminal), the external terminal PROG to which the drain terminal of Q2 is connected and an external resistor Rp can be connected to the outside, and the terminal PROG for constant current control. A constant current control amplifier AMP2 that compares the voltage and the reference voltage Vcref to generate the gate control voltage of Q1 is provided.

  Further, the charge control IC 10 of this embodiment compares a reference voltage Vref2 such as 5.8V with Vin in order to protect the chip from a DC voltage Vin inputted to the voltage input terminal VIN from the outside. A comparator CMP1 for detecting an abnormal voltage, a comparator CMP2 for comparing the voltage of the battery terminal BAT and the reference voltage Vref3, and a voltage of an external terminal TH to which a temperature sensor 50 such as a thermistor for detecting the temperature in the vicinity of the battery is connected. The comparator CMP3 for comparing with the reference voltage Vref4, and whether or not the voltage to be monitored is an abnormal voltage is determined based on the outputs of these comparators CMP1 to CMP3. If the voltage is abnormal, the current control transistor An open-collector transistor whose drain is connected to the gate of Q1 to turn off Q1 An internal control circuit 11 for generating and outputting a voltage for controlling the gate of 3.

  In addition, a regulator 12 that generates a constant voltage Vreg that does not depend on temperature, and a signal that turns off the switch transistor Q3 when an abnormal temperature is detected by detecting the chip temperature, and according to the detected temperature A chip temperature detection circuit 13 for generating a reference voltage Vcref to be supplied to the constant current control amplifier AMP2 is provided.

  The reference voltage Vref4 is generated by dividing the constant voltage Vreg generated by the regulator 12 with resistors R1 and R2. The constant voltage Vreg is output to the external terminal VREG to which the other terminal of the external resistor Rt connected in series with the temperature sensor 50 is connected. Further, a timer circuit 14 including a counter for measuring time for managing the precharge time, the quick charge time, and the like, and an oscillation circuit 15 for generating an oscillation signal having a frequency of 64 kHz, for example, are provided.

  FIG. 3 shows a specific circuit configuration example of the chip temperature detection circuit 13.

  The chip temperature detection circuit 13 of this embodiment includes a chip temperature detection element SNS formed by connecting three diodes D1 to D3 having negative temperature characteristics formed on the chip in series, and a current to the diode array. A constant current source CS that flows, resistors R3 and R4 that divide the constant voltage Vreg, and a potential Va (= 3VF) of a connection node Na between the voltage V1 divided by R3 and R4, the constant current source CS, and the temperature detection element SNS. ) And a thermal shutdown detection circuit 31 including a comparator CMP0 having a hysteresis characteristic and a bias circuit BIAS common to the comparator CMP0 and the constant current source CS.

  The resistance ratio between the current I0 of the constant current source CS and the resistors R3 and R4 is set such that V1> 3VF when the chip temperature is higher than 140 ° C. VF is the forward voltage of the diode. Thus, when the chip temperature becomes higher than 140 ° C., the output TS of the comparator CMP0 changes to a high level, and the internal control circuit 11 detects this and outputs a voltage for turning off the transistor Q3. As a result, the current control transistor Q1 is turned off to cut off the charging current supplied to the secondary battery. The diodes D1 to D3 as the chip temperature detection element SNS are preferably formed in the vicinity of the current control transistor Q1 that generates the largest amount of heat.

  The chip temperature detection circuit 13 subtracts the voltage follower 32 that impedance-converts and outputs the potential Va of the node Na, the output potential of the voltage follower 32, and the potential determined by the resistance circuit of the resistors R11 to R14 as inputs. A circuit 33 and an inverting amplifier 34 for inverting and amplifying the output potential Vb of the subtraction circuit 33 are provided.

  Further, at the subsequent stage of the inverting amplifier 34, a comparator 35 for comparing the output Vc of the inverting amplifier 34 and the constant voltage Vreg, and the output of the inverting amplifier 34 or the constant voltage Vreg (2. 5V) to the subsequent stage, a comparator 37 for comparing the output Vc of the inverting amplifier 34 and the voltage Vd obtained by dividing the constant voltage Vreg by the resistors R21 and R22, and the output of the comparator 37 A selector 38 for outputting either the output of the selector 36 or the voltage Vd as a reference voltage Vcref is provided. The voltage Vd is set to a potential such as 0.5V.

  Next, the operation of the chip temperature detection circuit 13 configured as described above will be described with reference to FIG.

  In the chip temperature detection circuit of this embodiment, since the forward voltage VF of the diode as the temperature detection element has a negative temperature characteristic, the potential Va of the node Na is as shown by a broken line A in FIG. It changes along a straight line that decreases as the temperature increases. Va is determined to be, for example, 2.27 V when the chip temperature is 90 ° C. On the other hand, since the subtraction circuit 33 outputs a potential obtained by subtracting Va from the potential determined by the resistance circuit of the resistors R11 to R14, the output Vb increases as the temperature increases as shown by the solid line B in FIG. It changes along the increasing straight line. The resistance values of the resistors R11 to R14 are determined so that Vb determined by these resistance ratios is 2.5 V when the chip temperature is 90 ° C.

  Since the output potential Vb of the subtracting circuit 33 is inverted and amplified by the inverting amplifier 34, the output Vc of the inverting amplifier 34 is 2. when the chip temperature is 90 ° C., as indicated by a dashed line C in FIG. It changes along a straight line that goes through the point of 5V and becomes lower as the temperature becomes higher. The resistance ratio between the input resistor R31 and the feedback resistor R32 is set so that the output Vc of the inverting amplifier 34 is 0.5 V when the chip temperature is 100 ° C.

  In the subsequent selector 36, Vreg is 2.5V when the output Vc of the inverting amplifier 34 is higher than 2.5V, and inverting amplifier 34 when the output Vc of the inverting amplifier 34 is lower than 2.5V. Further, in the selector 38, when the output Vc of the inverting amplifier 34 is higher than 0.5V, the output Vc of the inverting amplifier 34 is 0.5V when the output Vc is lower than 0.5V. The voltage Vd is selected. Therefore, as shown in FIG. 4C, the output reference voltage Vcref changes along a straight line that is constant at 2.5V at 90 ° C. or lower and lower as the temperature increases at a range of 90 ° C. to 100 ° C. It changes so that it may become 0.5V constant at 100 degreeC or more.

  Further, when the temperature exceeds 140 ° C., as described above, the current control transistor Q1 is cut off based on the output of the thermal shutdown detection circuit 31, so that the charging current IBAT supplied to the secondary battery 40 by Q1 is As shown in FIG. 2, when the temperature is 90 ° C. or lower, the temperature is constant at 0.8C, and when the temperature is in the range of 90 ° C. to 100 ° C., the temperature is increased. Furthermore, it is controlled to be 0 at 140 ° C. or higher.

  Here, 0.8C charging means charging with a current value of 80% with respect to the rated current (1C) determined by the characteristics of the secondary battery. The reason why the temperature is set to 0.8 C instead of 1 C is because the deterioration of the battery due to repeated charging is taken into consideration. Further, when the charging current is small, the charging time becomes long. Therefore, in relation to the charging time, it is desirable to control to charge at an arbitrary constant current between 0.7 C and 1 C at 90 ° C. or less. Moreover, the temperature of 90 ° C. or 100 ° C. that gives the timing for switching the control is determined according to the characteristics of the IC to be used, the battery to be charged, etc., and is not limited to such a temperature. Not too long.

  As described above, in the charging operation by the charging control IC 10 of the present embodiment, when the chip temperature rises and exceeds 90 ° C., the charging current is reduced, so that the rise of the chip temperature is suppressed. Therefore, the fail-safe function by the thermal shutdown detection circuit rarely works, so that the chattering phenomenon of the interruption of the charging current due to the rise of the chip temperature-the sudden rise of the chip temperature due to the restart-the interruption of the charging current is avoided. Become. Therefore, it is possible to prevent a situation in which a large current suddenly flows into the secondary battery when the current is resumed and the characteristic deterioration of the secondary battery progresses.

  In addition, in the said Example, although the temperature range which changes a charging current is 90 to 100 degreeC, it is not limited to this. The lower limit temperature of the desirable temperature range is 80 ° C to 100 ° C, the upper limit temperature is 90 ° C to 120 ° C, the temperature difference of the temperature range is 5 ° C to 20 ° C, and the more desirable temperature difference is 8 ° C to 15 ° C. is there. Further, in the above embodiment, the charging current is changed from 0.8 C to 0.2 C while changing by 10 ° C., that is, the current change rate is 0.06 C / ° C., but is not limited to this. . A desirable rate of current change is in the range of 0.04 C / ° C to 0.08 C / ° C. By setting such conditions, the chip temperature during charging can be maintained in a desired range.

  By the way, in the chip temperature detection circuit 13, the determination threshold corresponding to the reference voltage of the comparator CMP0, that is, the shutdown temperature can be changed by changing the resistance ratio of the resistors R3 and R4 that divide the constant voltage Vreg. Further, by changing the resistance ratio of the resistors R11 and R12 that provide one input potential of the subtraction circuit 33, a determination threshold value corresponding to the lower limit temperature (90 ° C. in FIG. 4) of the temperature range for changing the charging current is obtained. Further, by changing the resistance ratio of the resistors R21 and R22 that provide one input potential of the comparator 37, the determination threshold corresponding to the upper limit temperature (100 ° C. in FIG. 4) of the temperature range for changing the charging current can be changed.

  However, it is troublesome to change the resistance ratio at the three locations as described above when changing the threshold values for the set temperature and the lower limit temperature and the upper limit temperature of the temperature range, and it can be changed at the final stage of the process. In addition, if an adjustment circuit including a plurality of resistors and fuses is provided at each location, there is a problem that the circuit scale greatly increases.

  In the charging control IC 10 of the present embodiment, the determination threshold value corresponding to the shutdown temperature and the charging are changed by changing the current passed through the temperature detection diodes D1 to D3 by the constant current source CS in the chip temperature detection circuit 13. The determination threshold value corresponding to the lower limit temperature and the upper limit temperature of the temperature range for changing the current can be adjusted simultaneously.

  FIG. 5 shows a specific circuit example of the thermal shutdown detection circuit 31.

  The thermal shutdown detection circuit 31 of this embodiment includes a current-voltage conversion transistor Q11 composed of an N-channel MOSFET (insulated gate field effect transistor; hereinafter referred to as MOS transistor) through which a reference current Iref flows. MOS transistors Q12 and Q13 constituting a current mirror circuit that is connected in common to the transistor Q11 and generates a return current, a P-channel type current-voltage conversion MOS transistor Q14 connected in series with Q12, and in series with Q13 Is provided with a bias circuit BIAS composed of a P-channel type current-voltage conversion MOS transistor Q15 and the like.

  The comparator CMP0 includes a source-commonly connected differential MOS transistors Q21 and Q22 to which a voltage V1 divided by the resistors R3 and R4 and a potential Va of a node Na to which the temperature detection element SNS is connected are input. Active load MOS transistors Q23, Q24 and resistors R41, R42; R43, R44 connected between the drain terminal of Q22 and the ground point, and a common source of the transistors Q21, Q22 and the power supply voltage VDD The output circuit includes a constant current transistor Q25, a MOS transistor Q31 connected to the transistor Q14 of the bias circuit BIAS, and a MOS transistor Q32 connected in series with the Q31.

  The constant current transistor Q25 and the transistor Q14 of the bias circuit BIAS are connected to form a current mirror so that a predetermined operating current proportional to the reference current Iref flows to the comparator CMP0. It is configured. Resistors R41 to R44 are provided to provide hysteresis characteristics to the comparator. The source terminal of the output stage MOS transistor Q32 having the gate terminal connected to the connection node between the differential transistor Q22 and the resistor R43 is connected to the resistors R43 and R44. By being coupled to the node, it operates as a hysteresis. The output voltage of the comparator CMP0 is output via a CMOS inverter INV connected to a connection node between the MOS transistors Q31 and Q32.

  In this embodiment, the constant current source CS connected in series with the temperature detection element SNS and supplying a bias current is a P-channel type MOS transistor Q41 connected to form a current mirror with the transistor Q15 of the bias circuit BIAS. Connected in parallel to the transistor Q41, the transistor Q42 whose element size is set to double Q41, the transistor Q43 set to 4 times, and the drain side of the transistors Q41 to Q43, respectively, connected in series. It comprises fuse elements F21, F22, F23 made of polysilicon or the like.

  The other ends of the fuse elements F21, F22, and F23 are commonly connected to each other, and a temperature detection element SNS is connected between the connection node and a ground point. The same voltage as the gate voltage of Q41 is applied to the gate terminals of the transistors Q42 and Q43, and the transistors Q42 and Q43 are configured to operate as a weighted current source in which a drain current twice and four times that of Q41 flows.

  Further, in the chip temperature detection circuit 13 of this embodiment, a transistor Q16 twice as large as the element size Q15 and a transistor Q17 twice as large as the element size Q15 are provided in parallel with the current-voltage conversion MOS transistor Q15 of the bias circuit BIAS. The gate terminals of Q16 and Q17 are connected so that the same voltage as the gate voltage of Q15 is applied.

  Further, fuse elements F11, F12, and F13 made of polysilicon are connected in series to the drain sides of the transistors Q15 to Q17, respectively. The element sizes of the transistors Q16 and Q17 are set to be twice or four times that of Q15, and the same voltage is applied to the gate terminal, so that the drain current twice and four times that of Q15 flows through Q16 and Q17. become. Therefore, if the current flowing through the transistor Q15 is I1, it is possible to adjust the current in seven stages I1, I1, 3I1,..., 7I1 in accordance with the setting states of the fuse elements F11 to F13.

  The fuse elements F11 to F13 and F21 to F23 can be blown by a laser beam or the like in the final step of the process, and the total drain current of Q15 to Q17 and the total drain current of Q15 to Q17 and Q41 to Q43 are determined depending on the combination of the fuse elements that remain without being blown. The total drain current ratio can be set to any one of 49 types.

  FIG. 6 shows the relationship between the forward voltage VF of the temperature detecting diode and the chip temperature. In FIG. 6, a solid line X indicates the temperature characteristics of VF when the ratio of the total drain current of Q15 to Q17 and the total drain current of Q41 to Q43 is set to 1: 1. The broken line Y shows the temperature characteristics of VF when the current ratio is set larger than 1: 1 and the current on the Q41 to Q43 side is increased by 10%, and the alternate long and short dash line Z shows the current ratio larger than 1: 1. The temperature characteristics of VF when the current on the Q41 to Q43 side is reduced by 10% with a small setting is shown.

  From FIG. 6, by changing the current by ± 10% as in T1 near the chip temperature of 90 ° C., it is the same as the VF at 90 ° C. at about 80 ° C. and 100 ° C., and T2 near the chip temperature of 100 ° C. By changing the current by ± 10%, the same as VF at 100 ° C at approximately 90 ° C and 110 ° C, and by changing the current by ± 10% as T3 near the chip temperature of 140 ° C. It turns out that it can adjust so that it may become the same as VF at about 130 degreeC and 150 degreeC at 140 degreeC.

  Then, by changing the current I0 flowing through the diode and shifting the temperature characteristic of VF as shown in FIG. 6, the subtractor circuit output Vb of the solid line B and the inverting amplifier output Vc of the alternate long and short dash line C of FIG. Can be shifted. That is, the threshold is determined by changing the voltage compared with the resistance ratio without changing the threshold voltage determined by the resistance ratio of the resistors R3 and R4, the resistance ratio of the resistors R11 and R12, and the resistance ratio of the resistors R21 and R22. You can make the same adjustments as changing the value.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention. For example, in the above embodiment, a diode is used as the chip temperature detection element, but a base-emitter PN junction of a bipolar transistor may be used as the chip temperature detection element.

  In the embodiment, the three-stage diodes D1 to D3 are used as the temperature detection element SNS. However, the number of diodes connected in series can be changed using a fuse element or the like. Also good. By changing the number of diode stages, the slope of the VF chip temperature characteristic line in FIG. 6 and the slope of the alternate long and short dash line C in FIG. 3B and the rate of change of the charging current in FIG. 2 can be changed. Therefore, various adjustments can be made by combining with the means for changing the current passed through the diode of the embodiment.

  In the above description, the example in which the present invention is applied to the secondary battery charge control IC has been described. However, the present invention is not limited thereto, and in addition to the secondary battery charge control circuit, the DC-DC Widely used in multi-function power supply control ICs such as power management ICs equipped with multiple power supply systems such as DC power supply circuits such as converters and LDOs (low-saturation series regulators) and WLED (white light-emitting diode) driver circuits can do.

It is explanatory drawing which shows schematic structure of IC for charge control as an example of suitable IC to which this invention is applied. It is a graph which shows the relationship between the chip | tip temperature by charging temperature control and charging current in embodiment of this invention. It is a circuit block diagram which shows the specific example of a chip | tip temperature detection circuit. 4 is a graph showing changes in voltages at various parts in the chip temperature detection circuit of FIG. 3. It is a circuit diagram which shows the specific example of the thermal shutdown detection circuit of an Example. It is a graph which shows the relationship between the forward voltage VF of the diode for temperature detection, and chip | tip temperature.

Explanation of symbols

10 Charge control IC
11 Internal control circuit 12 Regulator 13 Chip temperature detection circuit 14 Timer circuit 15 Oscillation circuit 31 Thermal shutdown detection circuit 32 Voltage follower 33 Subtraction circuit 34 Inverting amplifier 35, 37 Comparator 36, 38 Selector 20 DC power supply 40 Secondary battery 50 Battery temperature sensor (Thermistor)
SNS temperature sensing element

Claims (7)

A temperature detection circuit that generates a voltage according to the chip temperature using an element having a PN junction as a temperature detection element, and a threshold value for determining a set temperature for shutdown and a current range based on the voltage of the temperature detection circuit Is a semiconductor integrated circuit for charge control having a function of controlling the charging current supplied to the secondary battery,
The charging is characterized in that the current flowing through the temperature detection element is changed so that the judgment threshold value for the set temperature for shutdown and the judgment threshold values for the temperature range upper limit and lower limit temperature can be adjusted simultaneously. Control semiconductor integrated circuit.   A current mirror circuit capable of changing a mirror ratio is provided between a bias circuit that generates a predetermined bias voltage and a current source circuit that supplies current to the temperature detection element, and the mirror ratio of the current mirror circuit is changed to change the mirror ratio. The current flowing through the temperature detecting element is changed, and the judgment threshold value for the set temperature for shutdown and the judgment threshold values for the upper and lower temperature limits of the current control can be adjusted at the same time. 2. A semiconductor integrated circuit for charge control according to 1. A temperature detection circuit that generates a voltage corresponding to a chip temperature using an element having a PN junction as a temperature detection element, a current control transistor provided between a voltage input terminal and an output terminal, and an output of the temperature detection circuit A control circuit for controlling a charging current supplied to a secondary battery by controlling the current control transistor based on a voltage, and a charge control semiconductor integrated circuit comprising:
The control circuit reduces the charging current as the temperature increases when the chip temperature is in a predetermined temperature range lower than the current cutoff set temperature, and the predetermined current value when the chip temperature is lower than the lower limit temperature of the temperature range. And the current control transistor is controlled to flow a charging current smaller than the predetermined current value from the upper limit temperature of the temperature range to the current cutoff set temperature,
The temperature detection circuit includes: a bias circuit that generates a predetermined bias voltage; a first determination comparison circuit that determines whether shutdown is necessary; a current source circuit that supplies current to the temperature detection element; and the predetermined temperature range A second determination comparison circuit for determining
A current mirror circuit capable of changing a mirror ratio is provided between the bias circuit and the current source circuit, and by changing a mirror ratio of the current mirror circuit, a current flowing through the temperature detection element is changed, thereby providing a current. A semiconductor integrated circuit for charge control, wherein a judgment threshold value for a cut-off set temperature and a judgment threshold value for an upper limit or a lower limit temperature of a temperature range for current control can be adjusted simultaneously.   The bias circuit includes a current-voltage conversion transistor at an output unit, and the current-voltage conversion transistor and the current source transistor of the first determination comparison circuit are connected to form a current mirror circuit. 4. The charge control semiconductor integrated circuit according to claim 3, wherein the charge control semiconductor integrated circuit also serves as a circuit for applying a bias to the first determination comparison circuit.   A plurality of transistors of different sizes are provided in the output section of the bias circuit and the current source circuit, respectively, and a programmable element is connected in series with the plurality of transistors, and the plurality of transistors in the output section of the bias circuit And corresponding ones of the plurality of transistors of the current source circuit are connected to form a current mirror circuit, and a mirror ratio is determined by setting to the programmable element. The semiconductor integrated circuit for charge control according to claim 3 or 4. The temperature detection circuit includes:
A subtracting circuit for subtracting a voltage generated by the temperature sensing element from a predetermined voltage;
An inverting amplifier circuit for inverting and amplifying the output of the subtracting circuit;
A first comparator for comparing the output of the inverting amplifier circuit with a first voltage;
Controlled by the output of the first comparator, the output of the inverting amplifier circuit is lower when the output of the inverting amplifier circuit is lower than the first voltage, and the output of the inverting amplifier circuit is higher than the first voltage. First selection means for selectively transmitting the first voltage to a subsequent stage when it is high;
A second comparator for comparing the output of the inverting amplifier circuit with a second voltage lower than the first voltage;
Controlled by the output of the second comparator, the output of the inverting amplifier circuit is higher when the output of the inverting amplifier circuit is higher than the second voltage, and the output of the inverting amplifier circuit is higher than the second voltage. Second selection means for selectively transmitting the second voltage to a subsequent stage when the voltage is low;
The semiconductor integrated circuit for charge control according to claim 3, comprising: A constant current control amplifier that controls the control voltage so that a voltage according to the output charging current is fed back and a constant current flows through the current control transistor,
7. The semiconductor integrated circuit for charge control according to claim 3, wherein an output voltage of the temperature detection circuit is supplied as a reference voltage to the constant current control amplifier.

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