JP2002004991A - Semiconductor device for ignition - Google Patents

Abstract

(57) [Problem] For ignition for preventing an unnecessary high voltage from being generated in a secondary winding of an ignition coil when an output stage element is forcibly turned off after an input signal is continuously applied. It is an object to provide a semiconductor device. SOLUTION: When an input signal 19 is continuously applied, an IGBT 2
Circuit, a capacitor 11, a resistor 10
, And a main current gradually decreasing circuit composed of the FET 15.
When the timer circuit 14 that operates by application of the input signal 19 times out, the FET 15 turns on, and the capacitor 11 connected in parallel with the resistor 9 that generates the reference voltage of the current limiting circuit.
Is slowly discharged through the resistor 10 to gradually reduce the reference voltage. Along with this, the current limiting circuit gradually reduces the main current, and turns off the IGBT 2. By the low-speed OFF operation of the IGBT 2, no high voltage is generated in the ignition coil 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition semiconductor device, and more particularly to an ignition semiconductor device applied to an ignition system of an internal combustion engine for an automobile.

[0002]

2. Description of the Related Art As an ignition system for an internal combustion engine for a vehicle, a distributorless ignition system in which an ignition coil and an ignition semiconductor device are mounted for each cylinder of the internal combustion engine has become common. The ignition semiconductor device used in such a system includes a switching device for turning on / off the primary current of the ignition coil.

[0003] The ignition semiconductor device provided in each cylinder is:
The on / off control is individually performed by the engine control unit, but the on / off control may not be performed normally, for example, when the engine stalls. In particular, when a continuous drive signal is applied to the switching device, a continuous current flows to the primary side, so that the ignition coil is destroyed or burnt out, or only a specific cylinder explodes on its own. Abnormally vibrates.

A device coping with such an abnormal operation is described in, for example, Japanese Patent Application Laid-Open No. 8-28415.
According to the technology described in this publication, a continuous conduction prevention circuit is provided, and when a conduction state of a switching device continues for a predetermined time or more by a driving signal from an engine control unit, a driving signal input to the switching device is forcibly applied. The driving of the switching device is stopped by shutting off the switching device. This prevents the switching device and the ignition coil from being damaged by continuous energization.

In addition, such an ignition semiconductor device includes:
A current limiting circuit is provided, and when a switching device detects an overcurrent, a driving signal of the switching device is suppressed to prevent the switching device from being destroyed.

[0006]

However, in the conventional ignition semiconductor device, the current limiting circuit prevents an overcurrent in the output stage element, thereby preventing the ignition semiconductor device and the ignition coil from being thermally damaged. The continuous conduction preventing circuit turns off the drive signal when a continuous drive signal is applied for a predetermined time or more to turn off the output stage element of the ignition semiconductor device. Since the operation is performed at the same speed as during normal operation, the ignition coil
There is a problem in that a high voltage similar to that during normal operation is generated in the next winding, and the gasoline mixture remaining in the cylinder may ignite and give an abnormal rotational force to the engine.

The present invention has been made in view of such a point, and turns off an output stage element after a drive signal is continuously applied. However, during the off operation, there is no need for a secondary winding of an ignition coil. An object of the present invention is to provide an ignition semiconductor device that does not generate a high voltage.

[0008]

According to the present invention, in order to solve the above-mentioned problems, a switching device connected in series with an ignition coil for controlling on / off of a current flowing in the ignition coil, and a current flowing in the ignition coil, A current limiting circuit that controls the switching device so as to limit the voltage, and a voltage limiting circuit that clamps a voltage emitted from the ignition coil.
A timer circuit that starts operating in response to an input signal applied to the drive terminal of the switching device and outputs an output signal after a lapse of a predetermined time from the application of the input signal; and in response to an output signal of the timer circuit. And a main current gradually decreasing circuit for reducing a current flowing through the switching device regardless of continuous application of the input signal.

According to such an ignition semiconductor device, when an input signal for turning on the switching device is continuously applied, the timer circuit outputs an output signal, and in response to the output signal, The main current decreasing circuit controls to reduce the current flowing through the switching device. As a result, the switching device performs the off operation at a lower speed than the normal off operation, whereby the current flowing through the primary winding of the ignition coil is interrupted at a low speed, and thus a high voltage is generated in the secondary winding. Is suppressed.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration example of a first embodiment of an ignition semiconductor device according to the present invention. This ignition semiconductor device 1 has an IGBT (Insulated) as a switching device as an output stage element.
Gate Bipolar Transistor (Insulated Gate Bipolar Transistor) 2 is used. A Zener diode 3 for clamping a voltage released from the ignition coil is connected between the collector and the gate of the IGBT 2. The emitter of the IGBT 2 is grounded via a shunt resistor 4, and the gate is connected to an input terminal 7 via resistors 5 and 6. The connection point between the emitter of the IGBT 2 and the shunt resistor 4 is connected to the non-inverting input of the operational amplifier 8,
The inverting inputs of the operational amplifier 8 are resistors 9 and 10, a capacitor 1
1 and the constant current element 12 are connected to a common connection point, and the output of the operational amplifier 8 is connected to an FET (Field-Effect Transistor:
Field-effect transistor) 13. The drain of this FET 13 is connected to the common connection point of the resistors 5 and 6, and the source is grounded. Input terminal 7
Is connected to the power supply terminal of the operational amplifier 8, the constant current element 12, and the timer circuit 14. Timer circuit 14
Is connected to the gate of FET15. This F
The drain of the ET 15 is connected to the resistor 10, and the source is grounded. Further, the collector of the IGBT 2 is connected to the primary winding of the ignition coil 16, and the other end of the primary winding is connected to the battery 17. The secondary winding of the ignition coil 16 is grounded via the gap 18 of the ignition plug.

Here, a shunt resistor 4, an operational amplifier 8,
The FET 13, the resistor 5, the resistor 9, the constant current element 12, and the resistor 6 form a current limiting circuit for limiting the load current of the IGBT 2. Further, the constant current element 12 is an element for producing a reference voltage of the operational amplifier 8, and the reference voltage is a value determined by a product of a current flowing through the constant current element 12 and a resistance value of the resistor 9, and the IGBT 2 This corresponds to the terminal voltage when the limiting current value flows through the shunt resistor 4.

Further, a capacitor 11, a resistor 10, an FET 15, and a timer circuit 14 connected in parallel with the resistor 9
Constitutes a self-shutdown circuit that turns off the IGBT 2 when the input signal 19 is continuously applied to the input terminal 7. In particular, in the present invention, the self-shutdown circuit makes the turn-off operation of the IGBT 2 slow. And a main current gradually decreasing circuit. Timer circuit 14
Is a circuit for outputting a drive signal to the gate of the FET 15 after a certain period of time has elapsed since the input signal 19 was applied.

In the above configuration, when the input signal 19 is applied to the input terminal 7, the IGBT 2 performs a turn-on operation, and the primary winding of the ignition coil 16 and the IGBT 2
Current flows through BT2. Thereafter, the timer circuit 14
When the input signal 19 is turned off within a time range shorter than the operation time, the IGBT 2 performs a turn-off operation, and the current flowing through the primary winding of the ignition coil 16 is cut off. As a result, the energy stored in the primary winding of the ignition coil 16 is induced in the secondary winding, a high voltage is generated in the secondary winding, discharge occurs in the gap 18, and the air-fuel mixture in the cylinder Is ignited. The turn-off operation of the IGBT 2 in the normal operation is determined by the input capacitance of the IGBT 2 and the resistances of the resistors 5 and 6 and the resistance of the input signal circuit, and generally operates in 50 microseconds or less.

When an input signal 19 is applied to the input terminal 7, the potential of the input signal 19 becomes the power supply voltage of the operational amplifier 8, and a constant current is supplied to the resistor 9 by the constant current element 12. A reference voltage to the inverting input of. Thus, the current limiting circuit of the ignition semiconductor device 1 operates. When the IGBT 2 is turned on, a current flows through the shunt resistor 4. However, when this current abnormally increases and the terminal voltage of the shunt resistor 4 exceeds the reference voltage, the output potential of the operational amplifier 8 is inverted and the FET 13
Is turned on and the common connection point of the resistors 5 and 6 is connected to the ground, so that the input signal 1 to the gate of the IGBT 2 is
9 is shut off, and the IGBT 2 is forcibly turned off.

Next, the operation of the ignition semiconductor device when the input signal 19 is continuously applied to the input terminal 7 due to engine stall will be described with reference to FIG. 2A and 2B are diagrams showing the relationship between the secondary voltage of the ignition coil and the primary current / voltage, wherein FIG. 2A shows the periphery of the ignition coil, and FIG.
Indicates a change in the primary current / voltage of the ignition coil, and (C)
Indicates a change in the secondary voltage of the ignition coil. In FIG. 2A, the IGBT 2 is represented by a switch, the current flowing through the primary winding of the ignition coil 16 is I _L , the collector-emitter voltage of the IGBT 2 is V _SW , and the gap 18 generated in the secondary winding is _Is represented by V _C2 .

First, the normal operation of the ignition semiconductor device 1 will be described. When IGBT2 is turned on, as shown (B), the voltage V _SW drops to the ground potential from the voltage of the battery, the current I _L flowing through the primary winding of the ignition coil 16 gradually increases. Thereafter, when the current I _L is equal to or greater than a predetermined current value, it operates the current limit circuit, the current value is limited, the voltage V _SW rises slightly. When the IGBT 2 performs a turn-off operation, the current IL decreases to 0, and accordingly, the voltage V _L
SW soars. When this voltage V _SW is clamped by the Zener voltage determined by the Zener diode 3, 1
The energy of the secondary winding is induced on the secondary winding side and then decreases. The secondary winding side, by its induced energy,
A negative potential is generated, and the voltage V _{C2 of the} gap 18 increases in the negative direction as shown in FIG. The voltage generated in the secondary winding is fed back to the primary winding side with a certain phase delay, and the lowered voltage V _SW rises again. Then, the voltage of the secondary winding, that is, the gap 1
When it rises up to the voltage that there is a voltage V _C2 of 8, gap 18
, The voltage of the primary winding and the secondary winding of the ignition coil 16 decreases, the voltage V _SW becomes the battery voltage, and the voltage V _{C2 of the} gap 18 becomes zero.

Next, an engine stall occurs and the input signal 19
Is continuously applied. When the input signal 19 is applied for a predetermined time or more, the timer circuit 14
Outputs a drive signal to the gate of the FET 15. Then, FE
T15 turns on and discharges the electric charge stored in the capacitor 11 via the resistor 10. The discharging speed is determined by the time constant of the capacitor 11 and the resistor 10.

When the timer circuit 14 outputs a drive signal to the FET 15, the IGBT 2 is connected to the operational amplifier 8 and the FET 1
3 is in a state where the current is limited. When the capacitor 11 is discharged in this state, the reference voltage of the operational amplifier 8 gradually decreases. I
GBT 2 is connected to the terminal voltage of shunt resistor 4 and operational amplifier 8.
Since the current is controlled so that the reference voltage becomes the same as that of FIG.
In the (B) as indicated by the broken line, gradually decreasing the current I _L with a decrease in the reference voltage. As a result, the voltage V _SW also gradually increases from the potential at the time of current limitation, as indicated by the broken line, and accordingly, the voltage V _{C2 of the} gap 18 becomes ( It changes as shown by the broken line in C). Thus, I
By changing the current limit value of the GBT 2 to turn off the IGBT 2 at a low speed, the gap 18
Voltage V _C2 is not boosted to a voltage that leads to discharge, and therefore, unnecessary explosion does not occur.

The ignition semiconductor device 1 having the above-described current limiting circuit for limiting the load current of the IGBT 2 and the main current gradually decreasing circuit for performing the turn-off operation of the IGBT 2 at a low speed is a hybrid integrated circuit combining these components. Can be configured by For example, a silicon chip such as an IGBT 2, an operational amplifier 8, a constant current element 12, a timer circuit 14, and FETs 13 and 15 is mounted on a ceramic substrate, and a printed resistor or a resistor chip is used as the resistors 5, 6, 9, and 10, and a shunt resistor is used. By mounting a resistor chip as 4 and a capacitor chip as a capacitor 11, connecting them with wires and sealing them with resin, they can be housed in one package.

The ignition semiconductor device 1 is an IGBT.
2. It is also possible to use only a plurality of semiconductor chips (bare chips) for the current limiting circuit and the main current gradually decreasing circuit so as to be housed in one package.

Further, by forming all functions of the semiconductor device 1 for ignition on a single silicon substrate, the semiconductor device 1 for ignition can be constituted by one chip.
FIG. 3 is a circuit diagram showing a configuration example of a second embodiment of the semiconductor device for ignition. 3, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, the main current gradually decreasing circuit includes a timer circuit 14, an oscillation circuit 20, a shift circuit 21, n sets of resistors 22-1 to 22-n, and FET2.
3-1 to 23-n.

The timer circuit 14 is a circuit for outputting a main current gradual decrease start signal after a lapse of a certain time from when the input signal 19 is applied, and its output is connected to the oscillation circuit 20. The output of the oscillation circuit 20 is connected to the shift circuit 21,
The n outputs of the shift circuit 21 are connected to the FETs 23-1
To 23-n. Resistance 22-1
Each series circuit of 22-n and FETs 23-1 to 23-n is connected in parallel to a resistor 9 for generating a reference voltage of the operational amplifier 8. This resistor 9 and resistors 22-1 to 22-1
A circuit for reducing the reference voltage of the operational amplifier 8 in a stepwise manner is constituted by the parallel circuit with the line 22-n.

The oscillating circuit 20 determines the speed of the stepwise reduction, and the shift circuit 21 includes the FETs 23-1 and FET2.
This is a circuit for deciding which FET of 3-n or FET 23-n between FET 23-1 and FET 23-n is to be driven. When the resistances 22-1 to 22-n have the same resistance value, the first to n-th FETs 23-1 to 23-n
If drive signals are sequentially applied to 23-n, the resistance value at both ends of the resistor 9 becomes a parallel value of the resistor 9 and the n resistance values, and the resistance value gradually decreases. Then, the voltage across the resistor 9 becomes a voltage determined by Ohm's law (resistance × current = voltage). As a result, the collector current of the IGBT 2 can be reduced slowly. This leads to suppression of generation of a high voltage in the secondary winding of the ignition coil 16.

FIG. 4 is a circuit diagram showing a configuration example of a third embodiment of an ignition semiconductor device. In FIG. 4, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment,
The current limiting circuit is constituted by resistors 24 and 25 and a transistor 26, and the main current gradually decreasing circuit is constituted by a timer circuit 14, a resistor 27 and an FET 28.

That is, in the current limiting circuit, the IGBT 2
Is connected to the base of a transistor 26 via a resistor 24, the collector of the transistor 26 is connected to a common connection point between the resistors 5 and 6, and the emitter is connected via a resistor 25. Grounded.
In the main current gradually decreasing circuit, the output of the timer circuit 14 is FET2
8, the drain is connected to a common connection point of the resistors 5 and 6, and the source is grounded.

When the IGBT 2 is turned on by application of the input signal 19 to the input terminal 7 and the terminal voltage of the shunt resistor 4 generated by the main current exceeds the forward bias voltage of the transistor 26 while the main current is increasing. ,
The transistor 26 is turned on, pulling the potential at the common connection point of the resistors 5 and 6 in the direction of the ground potential,
By reducing the gate voltage of BT2, the main current is reduced, and the main current is limited to a predetermined value.

Next, the input signal 19 is continuously output to the input terminal 7.
, The timer circuit 14 outputs a drive signal a predetermined time after the application of the input signal 19. As a result, the FET 28 is turned on, and the input signal 19 is shunted to the resistor 27 to lower the gate voltage of the IGBT 2. The charge stored in the gate of the IGBT 2 is released via the resistor 5 and the resistor 27, and the IGBT 2 starts off operation. It is the resistor 5 and the resistor 27 that determine the turn-off speed of the IGBT 2. The turn-off speed of the IGBT 2 can be reduced by increasing the resistance value of the resistor 27. That is, the current flowing through the IGBT 2 and the primary winding of the ignition coil 16 can be reduced slowly, and the generation of a high voltage in the secondary winding of the ignition coil 16 can be suppressed.

FIG. 5 is a circuit diagram showing a configuration example of a fourth embodiment of the semiconductor device for ignition. 5, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment,
The main current gradually decreasing circuit includes a constant current element 12, a resistor 9, a diode 35, a capacitor 11, a timer circuit 14,
FETs 31, 32, and 33 are provided.

That is, in the main current gradually decreasing circuit, the capacitor 11 is connected so that a part of the current flowing from the constant current element 12 to the resistor 9 is charged through the diode 35, and is discharged such that the constant current is discharged. It is connected to the drain of FET32. The source of the FET 32 is grounded, the gate is connected to the gate and the drain of the FET 33, the drain of the FET 33 is connected to the constant current element 34, and the source is grounded. These FET32,
Reference numeral 33 denotes a current mirror circuit, and the capacitor 11 discharges a constant current at a current determined by the constant current element 34. The output of the timer circuit 14 is connected to the gate of the FET 31, the drain is connected to the common connection point of the resistor 5 and the diode 35, and the source is grounded.

The IGBT 2 is turned on by the application of the input signal 19 to the input terminal 7, and while the main current is increasing, the terminal voltage of the shunt resistor 4 generated by the main current is determined by the constant current element 12 and the resistor 9. When the reference voltage is exceeded, the FET 13 is turned on, and the resistors 5 and 6 are turned on.
With the potential of the common connection point with the earth potential,
By reducing the gate voltage of the IGBT 2, the main current is reduced, and the main current is limited to a predetermined value.

Next, the input signal 19 is continuously output to the input terminal 7.
, The timer circuit 14 outputs a drive signal a predetermined time after the application of the input signal 19,
1 is turned on, and the anode of the diode 35 is set to the ground potential. At this time, the diode 35 prevents the capacitor 11 from being charged and prevents the discharge current of the capacitor 11 from flowing into the resistor 9 and the FET 31. Thereby, the FET 32 discharges the electric charge stored in the capacitor 11 at a constant current.

When the timer circuit 14 issues a drive signal to the FET 31, the IGBT 2 is connected to the operational amplifier 8 and the FET 1
3 is in a state where the current is limited. When the capacitor 11 is discharged in this state, the FET 3
2 has an FET through which a constant current determined by the constant current element 34 flows.
Since a constant current determined by the ratio of 33 to FET 32 flows,
The capacitor 11 is gradually discharged, and the reference voltage of the operational amplifier 8 gradually decreases. This allows I
The current flowing through the GBT 2 and the primary winding of the ignition coil 16 will be reduced slowly,
Generation of a high voltage in the next winding is suppressed.

Incidentally, the battery voltage of a general automobile is 12
Although it is a V specification, it starts with two batteries connected in series in a cold region, or the engine is started using the power supply of another car in a situation where the battery deteriorates even in summer and it can not be restarted There are cases. Naturally, there is a case where a 12V vehicle uses a power source of a 24V battery voltage vehicle. In such a case, if the case where the input signal 19 is continuously applied to the input terminal 7 occurs, the voltage applied to the IGBT 2 which is a switching device during the current limiting operation becomes large, and the IGBT 2 is thermally damaged. There can be.

For example, a battery voltage of 12 V and a current limit value of 20
A, when the ignition coil resistance is 0.5Ω, the collector loss of the IGBT 2 is 20A × (12V−20A × 0.5Ω) =
40W. On the other hand, a battery voltage of 12 V and a current limit value of 20
A, when a 24V power supply is used for a circuit having an ignition coil resistance of 0.5Ω, 20A × (24V−20A × 0.5
Ω) = 280 W.

Therefore, it is necessary to prevent the IGBT 2 of the switching device from being thermally damaged even when the power supply voltage is higher than usual. Next, a description will be given of an ignition semiconductor device which has taken such measures.

FIG. 6 is a circuit diagram showing a configuration example of a fifth embodiment of an ignition semiconductor device. 6, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment,
In addition to the current limiting / main current gradually decreasing circuit 40 including the current limiting circuit and the main current gradually decreasing circuit, when the voltage of the battery 17 is equal to or higher than the specified voltage and there is a continuous input signal 19, the IG
A main current cutoff circuit for cutting off the main current of the BT2 at high speed is provided.

That is, the main current cutoff circuit is IGBT2
Voltage dividing resistors 41 and 42 for detecting the collector voltage of
A reference voltage source 43 for setting a specified voltage, an operational amplifier 44 having a non-inverting input connected to a common connection point of the resistors 41 and 42 and an inverting input connected to the reference voltage source 43, and an output of the operational amplifier 44 The connected resistor 45 and the drain are I
Two resistors 5a connected in series to the gate of GBT2,
5b, the source is grounded, and the gate is connected to the output of the operational amplifier 44 via the resistor 45.
ET46. The power supply terminal of the operational amplifier 44 is connected to the input terminal 7. Thereby, the input signal 19 and the collector voltage of the IGBT 2 are monitored, and when the collector voltage is equal to or higher than the specified voltage, the input signal 19 is monitored.
Are continuously applied, the gate voltage of the IGBT 2 is forcibly reduced to a drive voltage at which the IGBT 2 cannot maintain the ON state, and the main current is cut off.

In this configuration, when the input signal 19 is continuously applied, the IGBT 2 causes a constant main current to flow by the current limiting / main current gradually decreasing circuit 40, and then performs an operation of gradually reducing the main current. In this case, the collector voltage of the IGBT 2 during the current limiting operation is a voltage obtained by subtracting the product of the ignition coil resistance and the current limiting value from the voltage of the battery 17;
That is, V _CE = V _B -Rc × Icl is added. Here, V _CE is the collector-emitter voltage of IGBT2, V
_B is the battery voltage, Rc is the ignition coil resistance, and Icl is the current limit value.

In this case, even when the battery voltage is high, the current limit value hardly increases, so that the collector voltage of the IGBT 2 increases by the increase in the battery voltage. According to the above configuration, first, the resistors 41 and 42 and the reference voltage source 43
An output is generated in the operational amplifier 44 at the collector voltage value determined by the following equation, and the FET 46 is driven. Since the FET 46 is connected in parallel between the gate and the emitter of the IGBT 2, regardless of the operation of the current limiting / main current gradually decreasing circuit 40, the IGBT 2
Gate voltage of the IGBT2
Works at high altitude to turn off.

The partial voltage of the collector voltage applied to the non-inverting input of the operational amplifier 44 may be replaced by a Zener diode instead of the resistor 41. Further, a series configuration of a Zener diode and a resistor 41 may be used. Furthermore, a constant current element may be connected in series with the resistor 41, and the collector voltage higher than a certain voltage may be shared by the constant current element.

The current limiting / main current gradually decreasing circuit 40 can be composed of the current limiting circuit and the main current gradually decreasing circuit illustrated in FIG. 1, FIG. 4 or FIG. Next, as described above, the battery voltage of a general automobile is a 12V specification, but the battery voltage may drop when the engine is started in a cold region or when the battery is deteriorated. At this time, the input signal 19 for turning on / off the switching device may be controlled and input for a longer on-time than the normal battery voltage. Therefore, the above-mentioned main current gradually decreasing circuit which operates as a protection circuit when the input signal 19 for an abnormally long time is input is adjusted to an input signal which is controlled for a longer time than when the battery voltage is normal, and exceeds that time. It may be configured to operate when input is continued. However, with such a configuration, conversely, when the battery voltage increases, the switching device may be thermally damaged. In order to prevent this, when the battery voltage becomes equal to or higher than a certain voltage, it is necessary to shorten a time-out period until the timer circuit outputs an output signal for starting the gradual reduction operation of the main current gradual reduction circuit. For that purpose, the switching device needs to monitor the battery voltage.

Generally, in a circuit configuration in which one of the main current circuits of the switching device is connected to the battery via the primary winding of the ignition coil 16 as a load and the other is grounded, Cannot directly monitor the battery voltage. Therefore, when monitoring the battery voltage, another terminal for directly receiving the voltage signal from the battery is required. Hereinafter, an ignition semiconductor device having a function of monitoring battery voltage and preventing thermal destruction of a switching device without requiring such an additional terminal will be described.

FIG. 7 is a circuit diagram showing a configuration example of a semiconductor device for ignition according to a sixth embodiment. 7, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment,
As a circuit for monitoring the voltage of the battery 17, an off-time V _CE voltage holding circuit 47 for detecting and holding a voltage V _CE applied between the collector and the emitter of the IGBT 2 when the IGBT 2 is turned off, and whether the voltage of the battery 17 is high. An operational amplifier 48 for comparing whether or not the reference voltage source 4
9 to form a timer control circuit. In this figure, for the sake of explanation, the monitor circuit constituting the main current gradually decreasing circuit is made independent, and the monitor circuit 14a and the current limiting /
This is indicated by a main current gradually decreasing circuit 40a.

In the timer control circuit, the off-time V _CE voltage holding circuit 47 is connected to the collector of the IGBT 2 and
When the GBT 2 is turned off, the voltage applied to the collector (= voltage of the battery 17) is input, the voltage of the battery 17 is stored following the change, and the input signal 19 for turning on the IGBT 2 is input. When the voltage is applied to the terminal 7, the voltage value stored immediately before the application of the input signal 19 is retained and output. When the IGBT 2 is turned off, its collector-emitter voltage V
By monitoring _CE , the voltage value of the battery 17 can be accurately detected. The operational amplifier 48 operates when the input signal 19 at which the IGBT 2 is turned on is applied to the input terminal 7, and the voltage of the battery 17 held in the off-time V _CE voltage holding circuit 47 applied to the non-inverting input is compared with the voltage of the battery 17. The voltage of the reference voltage source 49 applied to the inverting input is compared, and the comparison result is supplied to the timer circuit 14a. The timer circuit 14a is provided with a current limiting / main current gradually decreasing circuit 40 after a certain period of time has passed since the input signal 19 was applied.
This circuit outputs a main current gradual decrease start signal to a. When a voltage comparison result indicating that the voltage of the battery 17 is high is received from the operational amplifier 48, for example, the time constant is switched to a small value, and the application of the input signal 19 starts. The time until the main current gradual decrease start signal is output is shortened.

According to such a circuit, before the input signal 19 is applied to the input terminal 7, the off-time V _CE voltage holding circuit 47 causes the V _CE voltage before the input signal 19 is applied, that is, the voltage of the battery 17. holding a voltage, operates the operational amplifier 48 is at the same time when the input signal 19 is applied, the result of the comparison between the voltage of V _CE voltage and the reference voltage source 49 that has been held by the off time V _CE voltage holding circuit 47 And the voltage comparison result signal is input to the timer circuit 14a. The timer circuit 14a to which the voltage comparison result signal has been input outputs the main current gradual decrease start signal at a time corresponding to the voltage comparison result signal. That is, as a result of the voltage comparison, the timer circuit 14a
, The main current gradual decrease start signal is output in a short time.

FIG. 8 is a circuit diagram more specifically showing the configuration of the semiconductor device for ignition according to the sixth embodiment. In this figure, the off-time V _CE voltage holding circuit 47 of the timer control circuit includes two depletion IGBTs 50 and 51.
, Resistors 52 to 55, and two MOSFETs (Metal-Ox
ide Semiconductor Field-Effect Transistor) 56,
57 and a capacitor 58.

The depletion IGBTs 50 and 51 have their collectors connected to the collector of the IGBT 2, their gates and emitters both connected, and their resistors 52 and 53.
And grounded via resistors 54 and 55. MOS
The gate of the FET 56 is connected to the common connection point of the resistors 54 and 55, the drain is connected to the common connection point of the resistors 52 and 53, and the source is connected to the capacitor and the non-inverting input of the operational amplifier 48. The gate of the MOSFET 57 is connected to the input terminal 7, and the drain is connected to the gate and emitter of the depletion IGBT 51 and the resistor 54.
And the source is grounded.
The operational amplifier 48 has a power supply terminal connected to the input terminal 7, a non-inverting input connected to the reference voltage source 49, and an output connected to the timer circuit 14a.

According to this circuit, the input signal 19 causes I
When the GBT 2 is performing a turn-off operation, the IGBT
2, a current proportional to the collector-emitter voltage V _CE flows through the depletion IGBT 50, and a divided voltage is generated at a common connection point between the resistors 52 and 53. At this time, since the MOSFET 56 is turned on by the voltage divided at the common connection point of the resistors 54 and 55 by the current flowing through the depletion IGBT 51 and the resistors 54 and 55, the voltage is divided at the common connection point of the resistors 52 and 53. Voltage
The capacitor 58 is charged via the MOSFET 56,
Will be retained.

Next, when the input signal 19 is applied to the input terminal 7, the MOSFET 57 is turned on and the gate voltage of the MOSFET 56 is pulled in the direction of the ground potential, so that the MOSFET 56 is turned off and the capacitor 58 is turned on. , The voltage corresponding to the voltage of the battery 17 immediately before the application of the input signal 19. At this time, simultaneously with the application of the input signal 19, the operational amplifier 48 using the input signal 19 as a power supply operates, and the voltage of the capacitor 58 is adjusted by the operational amplifier 48 to the reference voltage source 49.
And the comparison result is output to the timer circuit 14a. The timer circuit 14a, to which the signal from the operational amplifier 48 has been input, compares the voltage of the operational amplifier 48 with
When the voltage of the battery 17 is high, the main current gradual decrease start signal is output in a shorter time than when the voltage of the battery 17 is low.
Output to the main current gradually decreasing circuit 40a to prevent the switching device from being thermally damaged.

In the above example, one set of the operational amplifier 4
8 and the reference voltage source 49 to determine whether the voltage of the battery 17 is higher or lower than a certain specified voltage, and to output the main current gradual decrease start signal in a shorter time when the voltage is higher than when the voltage is lower. A plurality of such operational amplifiers and reference voltage sources may be provided to control the timer circuit 14a so as to sequentially shorten the time until the main current gradual decrease start signal is output according to the voltage level of the battery 17. Good.

The current limiting / main current gradually decreasing circuit 40a can be constituted by the current limiting circuit and the main current gradually decreasing circuit illustrated in FIG. 1, FIG. 4 or FIG. FIG. 9 is a diagram showing an example in which the semiconductor device for ignition is constituted by one chip. In FIG. 9, the same elements as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.
The ignition semiconductor device 1 includes an IGBT 2a as an output stage element for controlling a main current flowing through the ignition coil 16, an IGBT 2b for detecting a current of the main current, a current limiting circuit for limiting the main current, and an emission from the ignition coil. Diode 3 for limiting (clamping) voltage and a main current gradually decreasing circuit are formed on a single silicon substrate as a monolithic integrated circuit, and input terminals 7 and output terminals 59 are provided as external terminals.
And a ground terminal 60. In this circuit, since the shunt resistor 4 having a large power capacity cannot be formed on the silicon substrate, the IGBT for controlling the main current is not used.
An IGBT 2b for current detection is connected in parallel to 2a, a part of the main current is shunted to the IGBT 2b, and the shunt current is detected to detect the value of the main current.

In the illustrated example, the current limiting circuit and the main current gradually decreasing circuit illustrated in FIG. 4 are shown. Of course, the current limiting circuit and the main current gradually decreasing circuit shown in FIG. 1, FIG. 3 or FIG. You may comprise. At the same time, FIG.
Or the timer control circuit shown in FIG. 8 may be included.

[0053]

As described above, according to the present invention, when the input signal is continuously applied for a long time, the output stage element is used as a self-shutdown circuit which cuts off the ignition coil current regardless of the input signal. Is configured to be turned off at a low speed. As a result, at the time of the self-shutdown, the output stage element is turned off more slowly than the turn-off operation in the normal operation, so that a high voltage is prevented from being generated in the ignition coil, and an abnormal torque may be applied to the engine. Disappears. In addition, since an abnormal rotational force is not applied, an abnormal noise and an abnormal vibration from the engine are not generated, and a quiet vehicle can be provided.

Further, a circuit is provided which forcibly cuts off the main current of the switching device at high speed when the battery voltage is high and the drive signal is continuously applied. This makes it possible to prevent thermal destruction due to excessive voltage being applied to the switching device.

Further, a means for storing and holding the battery voltage applied to the switching device when the switching device is turned off, and a structure for controlling the time until the timer circuit outputs the main current gradual decrease start signal in accordance with the battery voltage. did. Thus, the ignition semiconductor device is configured without providing a terminal for monitoring the battery voltage, and with an existing three-terminal package including an input terminal, an output terminal for connecting an ignition coil, and a ground terminal for grounding. By controlling the time until the main current gradual decrease start signal is output according to the battery voltage, it is possible to prevent the switching device from being thermally destroyed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of a first embodiment of an ignition semiconductor device according to the present invention.

FIG. 2 is a diagram showing a relationship between a secondary voltage and a primary current / voltage of an ignition coil, wherein (A) shows a periphery of the ignition coil, and (B) shows a primary current / voltage of the ignition coil. (C) shows the change in the secondary voltage of the ignition coil.

FIG. 3 is a circuit diagram showing a configuration example of an ignition semiconductor device according to a second embodiment;

FIG. 4 is a circuit diagram showing a configuration example of a third embodiment of an ignition semiconductor device.

FIG. 5 is a circuit diagram showing a configuration example of a semiconductor device for ignition in a fourth embodiment.

FIG. 6 is a circuit diagram showing a configuration example of a fifth embodiment of an ignition semiconductor device.

FIG. 7 is a circuit diagram illustrating a configuration example of an ignition semiconductor device according to a sixth embodiment;

FIG. 8 is a circuit diagram more specifically showing a configuration of a sixth embodiment of an ignition semiconductor device.

FIG. 9 is a view showing an example in which the semiconductor device for ignition is constituted by one chip.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ignition semiconductor device 2 IGBT 3 Zener diode 4 Shunt resistor 5, 5a, 5b, 6 Resistance 7 Input terminal 8 Operational amplifier 9, 10 Resistance 11 Capacitor 12 Constant current element 13 FET 14, 14a Timer circuit 15 FET 16 Ignition coil 17 Battery 18 Gap 19 Input signal 20 Oscillation circuit 21 Shift circuit 22-1 to 22-n Resistance 23-1 to 23-n FET 24, 25 Resistance 26 Transistor 27 Resistance 28 FET 31, 32, 33 FET 34 Constant current element 35 Diode 40, 40a Current limiting / main current gradually decreasing circuit 41, 42 Resistance 43 Reference voltage source 44 Operational amplifier 45 Resistance 46 FET 47 _VCE voltage holding circuit at OFF 48 Operational amplifier 49 Reference voltage source 50, 51 Depletion IGBT 52 to 55 Resistance 56 , 57 MO SFET 58 Capacitor 59 Output terminal 60 Ground terminal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23Q 3/00 620 F23Q 3/00 620B

Claims (15)

[Claims] A switching device connected in series with the ignition coil for controlling on / off of a current flowing in the ignition coil; a current limiting circuit for controlling the switching device to limit the current flowing in the ignition coil; An ignition semiconductor device equipped with a voltage limiting circuit that clamps a voltage emitted from the ignition coil, wherein the operation starts in response to an input signal applied to a drive terminal of the switching device, and the application of the input signal A timer circuit that outputs an output signal after a lapse of a fixed time from a main current gradually decreasing circuit that reduces a current flowing through the switching device in response to an output signal of the timer circuit, regardless of continuous application of the input signal. A semiconductor device for ignition characterized by comprising: 2. The ignition semiconductor device according to claim 1, wherein said main current gradually decreasing circuit gradually turns off a current limit value of said current limiting circuit to turn off said switching device. 3. The current limiting circuit is connected in series with the switching device to detect a voltage value proportional to a current flowing through the switching device, and a reference voltage value corresponding to the current limit value. A reference voltage circuit to be generated, an operational amplifier that receives the voltage value of the shunt resistor and the reference voltage value, and a voltage of an input signal applied to a drive terminal of the switching device by an output of the operational amplifier. A first transistor, the main current decreasing circuit being connected in parallel to the reference voltage circuit, a second transistor turning on in response to an output signal of the timer circuit, the capacitor and the second The second transistor is connected in series and charges the capacitor when the second transistor is turned on. 3. The ignition semiconductor device according to claim 2, further comprising a resistor for discharging. 4. The current limiting circuit is connected in series with the switching device to detect a voltage value proportional to a current flowing through the switching device, and a reference voltage value corresponding to the current limit value. A reference voltage circuit to be generated, an operational amplifier that receives the voltage value of the shunt resistor and the reference voltage value, and a voltage of an input signal applied to a drive terminal of the switching device by an output of the operational amplifier. A first transistor, wherein the main current gradually decreasing circuit operates in response to an output signal of the timer circuit, a shift circuit receiving an oscillation output of the oscillation circuit, and an output signal of the shift circuit. A plurality of second transistors that perform a turn-on operation, one end of which is connected in series with the second transistor, and the other end of which is connected to the second transistor; 3. The ignition semiconductor device according to claim 2, further comprising a plurality of resistors connected in common to said reference voltage circuit to reduce said reference voltage value in a stepwise manner. 5. The transistor according to claim 1, wherein the main current gradually decreasing circuit is turned on in response to an output signal of the timer circuit.
When the transistor is connected in series and shunts the input signal during turn-on operation of the transistor, the voltage applied to the drive terminal of the switching device is reduced, and the switching is performed in parallel with the drive terminal of the switching device. 3. The ignition semiconductor device according to claim 2, further comprising: a resistor for discharging a charge stored in an input capacitance of the device. 6. The shunt resistor, which is connected in series with the switching device and detects a voltage value proportional to a current flowing through the switching device, and a reference voltage value corresponding to the current limit value. A reference voltage circuit to be generated, an operational amplifier that inputs the voltage value of the shunt resistor and inputs the reference voltage value via a diode, and an input signal applied to a drive terminal of the switching device by an output of the operational amplifier. A first transistor for controlling the voltage of the operational amplifier, wherein the main current gradually decreasing circuit is turned on in response to an output signal of the timer circuit, and a capacitor connected in parallel to an input terminal of the reference voltage value of the operational amplifier. A second transistor for disabling the output of the reference voltage circuit and a capacitor connected in parallel to the capacitor. 3. The ignition semiconductor device according to claim 2, further comprising a constant current discharge circuit for discharging the electric charge of the capacitor. 7. A main terminal voltage of the switching device and a voltage of an input signal applied to a drive terminal of the switching device are monitored, and the main terminal voltage is regulated during a current limiting operation of the current limiting circuit. 7. A circuit according to claim 3, further comprising a main current cutoff circuit for controlling the input signal when the voltage is equal to or higher than a voltage to cut off a main current irrespective of an operation of the main current gradually decreasing circuit. Item 14. An ignition semiconductor device according to Item 1. 8. The main current cutoff circuit inputs a voltage proportional to a voltage between main terminals of the switching device, inputs a second reference voltage corresponding to the specified voltage, and supplies a drive terminal of the switching device to a drive terminal of the switching device. A second operational amplifier powered by the voltage of the applied input signal, and a third transistor that controls the voltage of the input signal by the output of the second operational amplifier to turn off the switching device at high speed. The ignition semiconductor device according to claim 7, wherein the ignition semiconductor device is provided. 9. An off-main-terminal-voltage holding circuit for monitoring a voltage of a battery connected via the ignition coil by the switching device holding a main-terminal voltage during a turn-off operation; A reference voltage source for generating a reference voltage corresponding to a voltage equal to or higher than a specified voltage, and a voltage of an input signal applied to a drive terminal of the switching device as a power supply, which is held in the off-main-terminal voltage holding circuit. Comparing the voltage proportional to the voltage of the battery and the voltage of the reference voltage source, and when the voltage value held in the off-time main terminal voltage holding circuit exceeds the voltage of the reference voltage source. A second operational amplifier that outputs to the timer circuit a signal for reducing the time from when the input signal is applied to when the timer circuit outputs the output signal. The ignition semiconductor device according to any one of claims 3 to 6. 10. The off-state main terminal voltage holding circuit,
A first and a second voltage dividing circuit for dividing a voltage of a main terminal of the switching device connected to the ignition coil; a third transistor which is turned on by an output voltage of the second voltage dividing circuit; A second capacitor that charges an output voltage of the first voltage divider circuit by a turn-on operation of the third transistor; and a turn-on operation by a voltage of an input signal applied to a drive terminal of the switching device. The ignition semiconductor device according to claim 9, further comprising: a fourth transistor that turns off the third transistor. 11. A plurality of sets of the second operational amplifier and the reference voltage sources having different voltage values, and a time until the timer circuit outputs an output signal is changed according to a voltage of the battery. The ignition semiconductor device according to claim 9, wherein: 12. A hybrid integrated circuit comprising a plurality of components including the switching device, the current limiting circuit, the voltage limiting circuit, the timer circuit, and the main current gradually decreasing circuit. The ignition semiconductor device according to claim 1. 13. A monolithic integrated circuit in which the switching device, the current limiting circuit, the voltage limiting circuit, the timer circuit, and the main current gradually decreasing circuit are formed on one silicon substrate. 1
The semiconductor device for ignition according to claim 1. 14. A single package comprising only a plurality of semiconductor chips constituting said switching device, said current limiting circuit, said voltage limiting circuit, said timer circuit, and said main current gradual decrease circuit. The ignition semiconductor device according to claim 1. 15. A main terminal voltage of the switching device and a voltage of an input signal applied to a drive terminal of the switching device are monitored, and the main terminal voltage is regulated during a current limiting operation of the current limiting circuit. 15. A circuit according to claim 12, further comprising a main current cut-off circuit for controlling the input signal when the voltage is equal to or higher than a voltage to cut off the main current at high speed regardless of the operation of the main current gradually decreasing circuit. The ignition semiconductor device according to claim 1.