JP7725966B2 - Semiconductor device and ignition control device equipped with the same - Google Patents

Description

The present invention relates to a semiconductor device and the circuit configuration of an ignition control device equipped with the semiconductor device.

The igniter, which controls the current flowing through the ignition coil of an internal combustion engine, is equipped with power semiconductor elements such as insulated gate bipolar transistors (IGBTs), and controls the flow of primary current through the ignition coil by controlling the power semiconductor elements based on switching control signals from the engine control unit (ECU).

When the power semiconductor element is turned off, the voltage in the primary coil rises to several hundred volts, generating a high voltage of several tens of kV in the secondary coil depending on the winding ratio between the primary and secondary coils, causing the spark plug to discharge a spark.

In addition, as shown in Patent Document 1, for example, the igniter is equipped with a resistor connected between the gate signal input terminal of the igniter and the gate terminal of the power semiconductor element, and a resistor connected between the gate signal input terminal of the igniter and the ground terminal (or emitter terminal), and the gate charge is extracted through these resistors when the power semiconductor is turned off.

Furthermore, as shown in Patent Document 1, for example, there is a technology that provides a speed-up diode from the gate terminal of the power semiconductor to the signal input terminal of the igniter, thereby quickly extracting the gate charge of the power semiconductor element when the power semiconductor element is turned off, thereby quickly turning off the power semiconductor element.

JP 2018-7539 A

The sudden change in current when the power semiconductor element is turned off and the electromotive force caused by the parasitic inductance of the ground wiring cause the emitter potential of the igniter to drop relative to the ECU ground, causing the potential difference between the signal input terminal and the emitter terminal of the igniter to increase.
This causes problems such as the power semiconductor elements not being able to turn off properly, lengthening the turn-off time, or causing the collector current, which is equivalent to the primary coil current, to oscillate during the turn-off period, affecting the timing of the ignition coil discharge and generating noise that can affect other equipment inside the vehicle.
The present invention has been made in consideration of the above-mentioned problems, and aims to provide a semiconductor device that can suppress the adverse effects caused by oscillations in the collector current of a power semiconductor element, and an ignition control device equipped with the same.

To solve the above problem, the present invention provides a semiconductor device and an ignition control device equipped with the semiconductor device, which includes: a power semiconductor element connected between a first terminal on the high potential side and a second terminal on the low potential side; a control terminal to which a switching control signal is input; a gate resistor connected between the gate of the power semiconductor element and the control terminal; a cutoff unit connected between the gate of the power semiconductor element and the second terminal; an input determination circuit that determines whether the potential difference between the control terminal potential and the second terminal potential is higher than a predetermined potential and outputs this determination result as an input determination signal; and a delay circuit that receives the input determination signal and whose output is connected to the input of the cutoff unit, and that, when the potential difference is higher than the predetermined potential (an ON determination signal), outputs the input determination signal with a predetermined delay from when the potential difference exceeds the predetermined potential.

The present invention provides a semiconductor device that can suppress the adverse effects of oscillations in the collector current of a power semiconductor element, and an ignition control device equipped with the same.

1 is a diagram illustrating a configuration example of a first embodiment of a semiconductor device according to the present invention and an ignition control device including the semiconductor device; FIG. 2 is a diagram illustrating a configuration example of an input determination circuit. FIG. 2 is a diagram illustrating an example of the configuration of a delay circuit. 1 is a diagram illustrating an example of the configuration of a semiconductor device and an ignition control device including the semiconductor device according to a conventional technology; FIG. 1 is a diagram of operational waveforms of an embodiment of the prior art. FIG. 4 is a diagram showing operational waveforms according to the first embodiment; FIG. 2 is a diagram illustrating an example of the configuration of a control signal generating unit. FIG. 10 is a diagram illustrating a configuration example of a second embodiment of a semiconductor device according to the present invention and an ignition control device including the semiconductor device. FIG. 10 is a diagram illustrating a configuration example of a third embodiment of a semiconductor device according to the present invention and an ignition control device including the semiconductor device. FIG. 10 is a diagram showing operational waveforms of the first embodiment in a state where the parasitic inductance of the emitter wiring is high. FIG. 10 is a diagram showing operational waveforms of the third embodiment in a state where the parasitic inductance of the emitter wiring is high. FIG. 10 is a diagram illustrating a configuration example of a fourth embodiment of a semiconductor device according to the present invention and an ignition control device including the semiconductor device. FIG. 10 is a diagram illustrating a configuration example of a fifth embodiment of a semiconductor device according to the present invention and an ignition control device including the semiconductor device.

Figures 1 to 3 show an example configuration of a first embodiment of a semiconductor device and an ignition control device equipped with the semiconductor device according to the present invention. Here, the semiconductor device of the present application may be a load driving device having inductance, such as an igniter.

The ignition control device 1000 for an internal combustion engine of an automobile or the like comprises a control signal generating unit 10, an ignition plug 20, an ignition coil 30, a power supply 40, and a semiconductor device 100 according to the present invention.

The control signal generating unit 10 generates a switching control signal Vin that controls the on/off switching of the power semiconductor element 110 built into the semiconductor device 100.

The control signal generating unit 10 is, for example, part or all of the ECU of a vehicle.

When the control signal generating unit 10 supplies the switching control signal Vin to the semiconductor device 100, the internal combustion engine ignition control device 1000 initiates the ignition operation of the spark plug 20.

The spark plug 20 generates an electrical spark by discharging. The spark plug 20 discharges when an applied voltage of, for example, approximately 10 kV or more is applied.

The spark plug 20 is installed, for example, in an internal combustion engine, and in this case ignites combustion gases such as an air-fuel mixture in the combustion chamber.

The spark plug 20 is installed, for example, in a through hole that extends from the outside of the cylinder to the combustion chamber inside the cylinder, and is fixed so as to seal the through hole. In this case, one end of the spark plug 20 is exposed inside the combustion chamber, and the other end receives an electrical signal from outside the cylinder.

The ignition coil 30 supplies a high voltage electrical signal that causes the spark plug 20 to discharge.

The ignition coil 30 may function as a transformer, for example, an ignition coil having a primary coil 32 and a secondary coil 34.

One end of the primary coil 32 and one end of the secondary coil 34 are electrically connected.

The primary coil 32 of the ignition coil 30 has fewer windings than the secondary coil 34 and shares a core with the secondary coil 34. The secondary coil 34 generates an electromotive force (mutually induced electromotive force) in response to the electromotive force generated in the primary coil 32.

The other end of the secondary coil 34 is connected to the spark plug 20, and the generated electromotive force is supplied to the spark plug 20, causing it to discharge.

The power supply 40 supplies voltage to the ignition coil 30. The power supply 40 supplies, for example, a predetermined constant voltage Vb (for example, 14 V) to one end of the primary coil 32 and the secondary coil 34. For example, the power supply 40 is a car battery.

The semiconductor device 100 switches between conduction and non-conduction between the other end of the primary coil 32 of the ignition coil 30 and the reference potential in response to the switching control signal Vin supplied from the control signal generating unit 10.

For example, the semiconductor device 100 establishes conduction between the primary coil 32 and the reference potential when the switching control signal Vin is at a high potential (on potential), and establishes non-conduction between the primary coil 32 and the reference potential when the switching control signal Vin is at a low potential (off potential).

Here, the reference potential may be the reference potential in the vehicle's control system, or may be the reference potential corresponding to the semiconductor device 100 inside the vehicle. The reference potential may be a low potential that turns off the semiconductor device 100, such as 0 V, for example.

The semiconductor device 100 includes a control terminal 102, a first terminal 104, a second terminal 106, a power semiconductor element 110, a cutoff unit 120, an input determination circuit 130, a delay circuit 140, a logic circuit 150, a gate resistor 170, a speed-up diode 180, and a pull-down resistor 190. The semiconductor device 100 has these elements integrated on a single semiconductor substrate.

In addition, the power supply voltage that operates the input determination circuit 130 and the delay circuit 140 is also the switching control signal Vin input from the control terminal 102, and the input determination circuit 130 and the delay circuit 140 operate only when the switching control signal Vin is at a high potential.

The control terminal 102 is connected to the control signal generating unit 10 and receives the switching control signal Vin that controls the power semiconductor element 110. The first terminal 104 is connected to the power supply 40 via the ignition coil 30.

The second terminal 106 is connected to a reference potential. That is, the first terminal 104 is a terminal on the higher potential side compared to the second terminal 106, and the second terminal 106 is a terminal on the lower potential side compared to the first terminal 104.

The power semiconductor element 110 includes a gate terminal, a collector terminal, and an emitter terminal, and the gate is controlled in response to a switching control signal Vin input to the gate terminal, electrically connecting or disconnecting the collector terminal and the emitter terminal.

The power semiconductor element 110 is connected between the first terminal 104 on the high potential side and the second terminal 106 on the low potential side, and is controlled to be on or off depending on the gate potential.

The power semiconductor element 110 is, for example, an IGBT, or may be a metal oxide semiconductor field effect transistor (MOSFET).
In the case of a MOSFET, the collector terminal may be read as a drain terminal, and the emitter terminal as a source terminal.

The emitter terminal of the power semiconductor element 110 is connected to the second terminal 106. The collector terminal is connected to the first terminal 104.

In this embodiment, an example will be described in which the power semiconductor element 110 is an IGBT that electrically connects the collector terminal and the emitter terminal in response to the switching control signal Vin becoming high potential.

First, the basic operation of the semiconductor device 100 will be described. In the turn-on operation, which turns on the power semiconductor element 110 and conducts the primary coil current, when a high potential is input to the switching control signal Vin, a high potential equal to or greater than the threshold voltage of the power semiconductor element 110 is applied to the gate terminal of the power semiconductor element 110 via the gate resistor 170, turning on the power semiconductor element 110 and causing the primary coil current to begin flowing.

On the other hand, when a low potential is input to the switching control signal Vin, the charge at the gate terminal of the power semiconductor element 110 is discharged to the reference potential via the gate resistor 170, the speed-up diode 180, and the pull-down resistor 190. As a result, the gate potential of the power semiconductor element 110 drops to a low potential below the threshold voltage of the power semiconductor element, turning the power semiconductor element 110 off and cutting off the primary coil current.

In addition to the basic operation described above, the semiconductor device 100 of FIG. 1 includes an input determination circuit 130, a delay circuit 140, a logic circuit 150, and a cutoff unit 120.
The cutoff unit 120 is connected between the gate terminal of the power semiconductor element 110 and a reference potential. As an example, the cutoff unit 120 is an n-channel MOSFET that is controlled to turn on or off between the drain terminal and the source terminal in response to a cutoff unit input signal Vmos, which is the gate potential.

As an example, the cutoff unit 120 is a normally-off switch element that electrically connects the drain terminal and source terminal when the cutoff unit input signal Vmos, which is the gate potential, becomes high potential.

The cutoff unit 120 has a drain terminal connected to the gate terminal of the power semiconductor element 110 and a source terminal connected to a reference potential. Depending on whether the cutoff unit input signal Vmos input to the gate terminal is high or low, the cutoff unit 120 switches whether to supply the switching control signal Vin input from the control terminal 102 to the gate terminal of the power semiconductor element 110.

The gate resistor 170 is connected between the control terminal 102 and the gate terminal of the power semiconductor element 110.

When the cutoff unit 120 is in the off state, the gate resistor 170 supplies the switching control signal Vin to the gate terminal of the power semiconductor element 110. When the cutoff unit 120 is in the on state, the switching control signal Vin flowing in through the gate resistor 170 flows to the reference potential via the cutoff unit 120, and a low potential is applied to the gate terminal of the power semiconductor element 110.

Furthermore, when the cutoff unit 120 is in the ON state, the gate voltage of the power semiconductor element 110 is discharged to the reference potential via the cutoff unit 120. In other words, the power semiconductor element 110 is in the OFF state.

The input determination circuit 130 is connected between the control terminal 102 and the delay circuit 140.

The input determination circuit 130 receives the control terminal potential Vg and emitter potential Ve from the control signal generating unit 10 and makes a determination. If the difference between the control terminal potential Vg and the emitter potential Ve is equal to or greater than a predetermined potential, it determines that the signal is an on signal for the power semiconductor element and outputs an on determination signal Vj as the input determination signal. If the difference between the control terminal potential Vg and the emitter potential Ve is lower than the predetermined potential, it determines that the signal is an off signal for the power semiconductor element and outputs an off determination signal Vj as the input determination signal. The input determination signal Vj is sent to the cutoff unit 120 via the delay circuit 140 and the logic circuit 150. Here, the predetermined potential is, for example, the threshold potential of the power semiconductor element. In this example, the on determination signal is a high-level signal, and the off determination signal is a low-level signal.

An example configuration of the input determination circuit 130 is shown in Figure 2.

The input determination circuit 130 includes resistors 131 and 132 connected in series between the control terminal 102 and the second terminal 106, and a resistor 133 and a MOSFET 134 arranged in series with each other and in parallel with the resistors 131 and 132. The input determination circuit 130 further includes multiple inverters 135 whose inputs and outputs are connected in series between one end of the resistor 133 and the collector of the MOSFET 134.

The wiring extending from the connection point between resistors 131 and 132 is connected to the gate of MOSFET 134.

Furthermore, the input of one of the multiple inverters 135 is connected to the connection point between one end of resistor 133 and the drain of MOSFET 134, and the output of one of the inverters is connected to the input terminal of delay circuit 140.

Generally, the semiconductor device 100 is integrated with the ignition coil 30, and the control terminal 102, second terminal 106, and terminals corresponding to the power supply 40 connection terminal of the ignition coil 30 are connected to the ECU's signal output terminal, reference potential, and battery terminal, or to the corresponding connection terminals, via a harness. Depending on the length of this harness, the parasitic inductance between the second terminal 106 and the reference potential is expected to be a maximum of approximately 5 μH.

When the switching control signal Vin input to the control terminal 102 becomes an OFF signal and the IGBT, which is the power semiconductor element 110, turns OFF, the potential of the second terminal 106 drops by a voltage value determined by the slope of the collector current Ic and the parasitic inductance value of the harness. As a result, the potential difference between the control terminal 102 and the second terminal 106 rises, and depending on the rising potential, it becomes an input signal equivalent to when an ON signal is input from the switching control signal Vin. If the semiconductor device 100 operates in response to this signal, it will prevent the turn-off operation. The rise time is approximately several microseconds.

The multiple inverters 135 in the input determination circuit 130 also have a delay effect on the input signal, but they do not have the ability to mask the ON determination signal for several microseconds.

The delay circuit 140 receives the input judgment signal Vj output from the input judgment circuit 130, has its output connected to the input of the logic circuit 150, and outputs the delay circuit output signal Vd.

If the input judgment signal Vj output by the input judgment circuit 130 to the logic circuit 150 is an ON judgment signal, the delay circuit 140 can delay it by 10 μsec to 20 μsec from the time the ON judgment signal is received.

An example configuration of the delay circuit 140 is shown in Figure 3.

The delay circuit 140 includes a resistor 141 connected to the output of the input determination circuit 130, a capacitor 142 to which current is supplied via the resistor 141, and multiple inverters 143 connected to the junction of the resistor 141 and the capacitor 142, with their inputs and outputs connected in series.

One end of resistor 141 is connected to the output of the input judgment circuit 130, and the other end is connected to the capacitor.

The input of one of the multiple inverters 143 is connected to the junction of resistor 141 and capacitor 142, and the output of one of the multiple inverters 143 is connected to the input terminal of the cutoff unit 120.

The delay circuit 140 smooths out temporary increases and decreases in the input potential by using the charging and discharging effect of the capacitor 142, and the delay time can also be adjusted by adjusting the capacitance of the capacitor 142.

The logic circuit 150 is a device that converts the delay circuit output signal Vd output from the delay circuit 140 into the cutoff unit input signal Vmos, and in this embodiment uses an inverter circuit.

In the semiconductor device 100 according to this embodiment, when the power semiconductor element 110 is in a normal state and the switching control signal Vin changes from a high potential to a low potential, the power semiconductor element 110 changes from an on state to an off state.

As a result, the collector current Ic flowing from the power supply 40 through the primary coil 32 of the ignition coil 30 suddenly decreases.

When the switching control signal Vin is applied at a high potential to the control terminal 102, the time change dIc/dt of the collector current Ic is determined according to the inductance of the primary coil 32 and the supply voltage of the power supply 40, and the collector current Ic maintains a predetermined (or set) current value according to the on-time.

For example, the collector current Ic is several amperes, several tens of amperes, or several tens of amperes in the on state.

Due to the sudden decrease in collector current in the off state, the voltage across the primary coil 32 increases rapidly due to self-induced electromotive force, generating an induced electromotive force of up to several tens of kV across the voltage across the secondary coil 34.

The ignition control device 1000 supplies the voltage of this secondary coil 34 to the spark plug 20, causing the spark plug 20 to discharge and ignite the combustion gas.

FIG. 5b shows the operational waveforms of the various parts of the semiconductor device 100 when the power semiconductor element 110 changes from the ON state to the OFF state.
The operation waveforms will be explained with reference to FIG. 6, which shows an example of the output circuit configuration of the control signal generating section 10 of FIG.

At time T4, the command signal (CPU output signal) CPUout from the CPU 710 in the control signal generating unit 10 changes from high to low, turning off transistor 720, and the switching control signal Vin discharges capacitor 730, causing the potential to gradually decrease.

Because this switching control signal Vin also serves as the power supply voltage for the input determination circuit 130, the input determination signal Vj, which is the output voltage of the input determination circuit 130, also drops in response to the switching control signal Vin. When the switching control signal Vin falls below the determination voltage of the input determination circuit 130, the input determination signal Vj outputs a low potential as an off determination signal.

Furthermore, when the switching control signal Vin begins to decrease, the gate charge of the power semiconductor element 110 begins to discharge to the pull-down resistor 190 via the speed-up diode 180.

When the input determination signal Vj outputs an OFF determination signal, the delay circuit output voltage Vd also outputs a low potential, the cutoff unit input signal Vmos, which is the output voltage of the logic circuit 150, becomes a high potential, and the cutoff unit 120 becomes conductive. The gate charge of the power semiconductor element 110 also begins to discharge via the cutoff unit 120, accelerating gate charge discharge.

From time T5, when the gate potential of the power semiconductor element 110 drops to near the threshold voltage of the power semiconductor element 110, the collector current Ic begins to drop, and the emitter potential Ve drops sharply due to -dIc/dt and parasitic inductance. As a result, the voltage between the control terminal 102 and the emitter potential Ve rises, and the input determination circuit 130 mistakenly recognizes that a high potential has been input from the switching control signal Vin, outputs an ON determination signal, and the conduction of the cutoff unit 120 is cut off.

As a result, the magnitude relationship between the control terminal 102 side and the gate potential of the power semiconductor element 110 changes, the discharge rate slows, or the gate of the power semiconductor element 110 is charged again, the decrease in collector current Ic slows, and the decrease in emitter potential Ve begins to increase. The voltage between the control terminal 102 and the emitter potential Ve decreases again, and the input determination circuit 130 again outputs an OFF determination signal, causing the cutoff unit 120 to become conductive and accelerating the turning off of the power semiconductor element 110.

As this operation is repeated, the power semiconductor element repeatedly turns on and off between periods T5 and T6, as shown in Figure 5b, causing the collector voltage Vc and collector current Ic to oscillate in a cycle of several microseconds.

In the present invention, by including the delay circuit 140, as shown in Figure 5b, even if the input judgment signal Vj, which is the input signal to the delay circuit, begins to rise due to a drop in the emitter potential Ve, the delay circuit 140 delays it by 10 to 20 μsec, attempting to maintain the conductive state of the cutoff unit 120. As a result, the power semiconductor element 110 also continues to maintain gate discharge, thereby suppressing oscillations in the collector voltage Vc and collector current Ic.

As described above, the role of the pull-down resistor 190 in this application is to draw out the gate charge of the power semiconductor element 110 and the charge of the capacitor 730. Therefore, if the gate charge of the power semiconductor element 110 can be completely drawn out by the cut-off unit 120 and the control signal generating unit 10 does not have a capacitor 730, the pull-down resistor 190 is not necessary.

Figure 4 shows an example 10000 of an ignition control device for an internal combustion engine according to a reference example, and an ignition control device equipped with the same. The semiconductor device 900 constituting the ignition control device 10000 includes a power semiconductor element 910, a gate pull-down circuit (shutoff unit) 920 connected to its gate terminal, gate resistors 912 and 970 connected between the control terminal 902 and the gate terminal of the power semiconductor element 910, a pull-down resistor 990, and a speed-up diode 980.

The semiconductor device 900 is composed of two chips: a power semiconductor chip 911 including a power semiconductor element 910 and a gate resistor 912, and a control semiconductor chip 921 including a cutoff unit 920, an input determination circuit 930, a gate control circuit 950, and the like.

When the signal input to the control terminal 902 is an off-determination signal, the charge on the gate capacitance of the power semiconductor element 910 is extracted via the speed-up diode 980 and pull-down resistor 990. The cutoff unit 920 also establishes electrical continuity between the gate and emitter of the power semiconductor element 910. This extracts charge from the gate capacitance of the power semiconductor element 910, rapidly lowering the gate potential and cutting off the collector current.

By extracting the gate charge using the cutoff section 920, the power semiconductor element 910 can be rapidly turned off.

The faster the power semiconductor element 910 turns off, the more rapidly the emitter potential Ve drops, causing the input determination circuit 930 to mistakenly recognize it as on, turning the power semiconductor element 910 back on. When the power semiconductor element 910 turns on, the potential difference Vge between the control terminal and the second terminal drops, and when the input determination circuit 930 recognizes an off signal, the power semiconductor element 910 turns off. Repeating this cycle causes the collector current to oscillate.

This vibration can have adverse effects such as affecting the timing of discharge in the secondary coil 834 of the ignition coil 830, causing noise that affects other devices, and increasing losses.

Figure 5a shows the operating waveforms of each part of the semiconductor device 900 as the power semiconductor element 910 transitions from the on state to the off state.

At time T1, the switching control signal Vin changes from high to low, causing the input determination circuit 930 to stop operating and the input determination signal Vj to drop. As a result, at time T2, the cutoff unit input signal Vmos rises, the cutoff unit 920 becomes conductive, and the collector current Ic begins to drop. During the period T2 to T3, -dIc/dt and parasitic inductance cause the emitter potential Ve to oscillate with a period of several microseconds. Similarly, the potential difference Vge between the control terminal and the second terminal oscillates, causing the input determination circuit 930 to mistakenly recognize this as an ON signal for the power semiconductor element 910. As a result, the output input determination signal Vj also oscillates, the cutoff unit 920 is cut off, and the power semiconductor element 910 is turned ON. After this, the power semiconductor element 910 repeatedly turns ON and OFF, causing the collector voltage Vc to oscillate, and the collector current Ic to oscillate slightly.

Figure 7 shows an example configuration of a second embodiment 1001 of a semiconductor device and an ignition control device equipped with the semiconductor device according to the present invention.

The difference between the ignition control device 1001 and the ignition control device 1000 of the first embodiment is that the semiconductor device 200 is configured from two chips: a control semiconductor chip 101 and a power semiconductor chip 111. This configuration also achieves the same effects as the first embodiment.

In the following embodiments, the semiconductor devices 300, 400, and 500 can also be configured as two chips.

Figure 8 shows an example configuration of a third embodiment 1003 of a semiconductor device and an ignition control device equipped with the semiconductor device according to the present invention.

The difference between the ignition control device 1003 and the ignition control device 1000 of the first embodiment is that the speed-up diode 180 inside the semiconductor device 300 has been removed and a backflow prevention diode 181 has been added. The rest of the configuration is the same as that of the semiconductor device 100.

Diode 181 is connected between the control signal generating unit 10 and the gate of the power semiconductor element 110, with the anode connected to the control signal generating unit 10 side and the cathode connected to the power semiconductor element 110 side.

The pull-down resistor 190 can also serve as a path for extracting gate charge when the power semiconductor element 110 is off. Therefore, to ensure that the gate charge is extracted from the cutoff section 120, a diode 181 is installed to prevent the gate charge of the power semiconductor element 110 from flowing back into the pull-down resistor 190.

Figure 9b shows the operating waveforms of each part of semiconductor device 300 as power semiconductor element 110 transitions from the on state to the off state. For comparison, Figure 9a shows the operating waveforms of semiconductor device 100. Here, to illustrate the difference between the two, the case is shown where the parasitic inductance of the emitter wiring is higher than in Figures 5a and 5b.

The phenomenon occurring between times T1 and T6 is similar to that shown in Figures 5a and 5b. However, due to the large parasitic inductance of the emitter wiring, the drop in emitter potential Ve at turn-off is large, and the rise in switching control signal Vin is also large. In Figure 9a, which corresponds to the operational waveform diagram of semiconductor device 100, the input determination circuit 130 and delay circuit are unable to suppress the oscillations, the cutoff unit 120 is unable to maintain a conductive state, the discharge rate of the gate charge of power semiconductor element 110 slows down temporarily, causing a drop in collector voltage Vc and slight oscillations in collector current Ic.

In contrast, in Figure 9b, which corresponds to the operating waveform diagram of semiconductor device 300, the presence of diode 181 increases the impedance from the gate terminal of power semiconductor element 110 to control terminal 102, so even when a turn-off signal is input, the gate charge of power semiconductor element 110 is not discharged to the pull-down resistor. Instead, when the switching control signal Vin drops sufficiently and the input determination circuit detects off, cutoff unit 120 becomes conductive and begins to draw the gate charge of the power semiconductor element. During this period, the switching control signal Vin continues to fall, and at time T5 when the gate voltage falls below the threshold voltage of power semiconductor element 110, collector current Ic begins to fall.

At this time, the slope of the collector current Ic and parasitic inductance cause the Ve voltage to drop and the switching control signal Vin to rise, but because the switching control signal Vin at the start of current interruption is lower than at timing T2 in Figure 9a and does not exceed the judgment voltage of the input judgment circuit, it does not result in a false detection of an on signal, the interrupter unit 120 maintains conduction, and the power semiconductor element 110 is able to interrupt the current without vibrating.

Figure 10 shows an example configuration of a fourth embodiment of a semiconductor device and an ignition control device equipped with the semiconductor device according to the present invention.

The difference between the semiconductor device 400 and the semiconductor device 300 of the ignition control device 1004 of this embodiment is that the semiconductor device 400 does not have a diode 181 and the resistance value of the gate resistor 170 is very large. The rest of the configuration is the same as the semiconductor device 300.

The cutoff section 120 has an impedance, and it is desirable that the resistance value of the gate resistor 170 be at least five times the impedance of the cutoff section 120.

By setting the resistance value of the gate resistor 170 sufficiently large, the impedance from the gate terminal of the power semiconductor element 110 to the control terminal 102 is increased, as in the third embodiment, thereby suppressing the pull-down resistor from extracting the gate charge from the power semiconductor element 110, and once the Vin voltage has dropped sufficiently, the cutoff unit 120 extracts the charge.

Figure 11 shows an example configuration of a fifth embodiment of a semiconductor device and an ignition control device equipped with the semiconductor device according to the present invention.

The difference between semiconductor device 500 and semiconductor device 300 of ignition control device 1005 is that semiconductor device 500 has a series circuit of gate resistor 170 and backflow prevention diode 181 in parallel with second gate resistor 171 between control terminal 102 and the gate of power semiconductor element 110. Here, the resistance value of second gate resistor 171 is preferably at least five times the impedance of cutoff section 120. The rest of the configuration is the same as semiconductor device 300.

The gate resistor 170 of the fourth embodiment and the second gate resistor 171 shown in the fifth embodiment increase the impedance from the gate terminal of the power semiconductor element 110 to the control terminal 102 when turned off, thereby suppressing the pull-down resistor 190 from extracting the gate charge of the power semiconductor element 110, and allowing the cutoff unit 120 to extract the charge once the Vin voltage has dropped sufficiently.

In the fourth embodiment shown in Figure 10, if the resistance value of the gate resistor 170 is made too large, the delay time when turning on the power semiconductor element 110 becomes too long. In contrast, in the fifth embodiment shown in Figure 11, the gate of the power semiconductor element 110 is charged via the gate resistor 170 and diode 181 during the on period, and by providing a second gate resistor 171 during the off period, most of the gate charge of the power semiconductor element 110 is extracted from the cutoff section 120, thereby reducing the increase in delay time when turning on the power semiconductor element 110.

As described above, in this embodiment, even if the emitter potential drops with respect to the ECU ground when the power semiconductor element is rapidly turned off and the gate-emitter potential difference increases, the provision of a delay circuit prevents malfunction of the power semiconductor element.
This makes it possible to suppress the adverse effects of oscillations in the collector current of the power semiconductor element.

Embodiments of the present application are not limited to this; for example, the blocking unit 120 may be a p-type MOSFET, and the inverter of the logic circuit 150 may be eliminated. Furthermore, the semiconductor device 100 does not have to be configured on the same semiconductor substrate.

10... Control signal generating unit 20... Spark plug 30... Ignition coil 32... Primary coil 34... Secondary coil 40... Power supply 100... Semiconductor device (first embodiment)
102... Control terminal 104... First terminal 106... Second terminal 110... Power semiconductor element 120... Cutoff section 130... Input determination circuit 131, 132, 133... Resistor 134... MOSFET
135... inverter 140... delay circuit 141... constant current source 142... capacitor 143... inverter 150... logic circuit 170... gate resistor 171... second gate resistor 180... speed-up diode 181... diode 190... pull-down resistor 1000... ignition control device 101 including the semiconductor device of the first embodiment... control semiconductor chip of the semiconductor device (second embodiment)
111...power semiconductor chip of semiconductor device (second embodiment)
1001... Ignition control device 200 including the semiconductor device of the second embodiment... Semiconductor device (second embodiment)
300...Semiconductor device (third embodiment)
1003... Ignition control device 400 including the semiconductor device of the third embodiment... Semiconductor device (fourth embodiment)
1004... Ignition control device 500 including the semiconductor device of the fourth embodiment... Semiconductor device (fifth example)
1005... Ignition control device 710 including the semiconductor device of the fifth embodiment... CPU
720... PNP transistor 730... capacitor 820... spark plug (prior art example)
830...Ignition coil (prior art example)
832: Primary coil (prior art example)
834: Secondary coil (prior art example)
840...Power supply (prior art example)
900...Semiconductor device (prior art example)
902: Control terminal (prior art example)
904: Collector terminal (prior art example)
910...Power semiconductor element (prior art example)
911...Power semiconductor chip (prior art example)
912...Gate resistor (prior art example)
920: Interrupter (prior art example)
921...Control semiconductor chip (prior art example)
930...input determination circuit (prior art example)
950...Gate control circuit (prior art example)
970...Resistor (prior art example)
980...Speed-up diode (prior art example)
990...Pull-down resistor (prior art example)
10000...Example of ignition control device (prior art example)
CPUout...CPU output signal Vg...control terminal potential Ve...emitter potential Vin...switching control signal Vj...input determination signal Vd...delay circuit output signal Vmos...cutoff unit input signal Ic...collector current

Claims (8)

a power semiconductor element connected between a first terminal on a high potential side and a second terminal on a low potential side;
a pull-down resistor connected between a control terminal to which a switching control signal is input and the second terminal;
a gate resistor and a reverse current prevention diode are connected between the control terminal and the gate of the power semiconductor element to form a series circuit, and a second gate resistor is connected in parallel to the series circuit;
the anode of the reverse current prevention diode is connected to the control terminal side and the cathode is connected to the gate side of the power semiconductor element,
a cutoff portion connected between the gate of the power semiconductor element and the second terminal;
an input determination circuit that determines whether a potential difference between the potential of the control terminal and the potential of the second terminal is higher than a predetermined potential and outputs the determination result as an input determination signal, wherein the input determination circuit outputs an ON determination signal as the input determination signal when the potential difference is higher than the predetermined potential, and further comprises a delay circuit that receives the input of the input determination signal, has an output connected to the input of the cutoff unit, and outputs the ON determination signal with a predetermined delay time from the time of input;
Semiconductor device. The resistance value of the gate resistor is 5 times or more the impedance of the cutoff section.
The semiconductor device according to claim 1 . The resistance value of the second gate resistor is five times or more the impedance of the cutoff section.
The semiconductor device according to claim 1 . the delay circuit includes a resistor and a capacitor connected in series between the output of the input determination circuit and the second terminal.
The semiconductor device according to claim 1 . the delay time in the delay circuit is 10 μsec to 20 μsec from the time when the ON determination signal of the input determination signal is received;
The semiconductor device according to claim 1 . the power semiconductor element, the pull-down resistor, the first gate resistor, the second gate resistor, the reverse current prevention diode, the cutoff unit, and the delay circuit are formed within the same chip .
The semiconductor device according to claim 1 . The semiconductor device is an igniter of an ignition control device of an internal combustion engine.
The semiconductor device according to claim 1 . 7. An ignition control device for an internal combustion engine, comprising the semiconductor device according to claim 1 as an igniter.