JP6677034B2 - Gate drive circuit, semiconductor device - Google Patents

Description

  The present invention relates to a gate drive circuit for supplying a gate drive signal to a switching element, and a semiconductor device including the gate drive circuit.

  Japanese Patent Application Laid-Open No. H11-163873 discloses that a drive voltage level of a power MOSFET is increased in response to a temperature rise due to heat generation of a chip during a large current operation, thereby preventing conduction loss due to an increase in on-resistance Ron and improving efficiency. Possible techniques are disclosed.

JP 2008-017625 A

  Despite the need for a power module with reduced power loss, the amount of reduction in DC loss for each generation of IGBT tends to saturate. Therefore, the gate resistance of the power device may be reduced in order to reduce the switching loss. However, the gate resistance has a "positive temperature characteristic" in which the resistance value increases as the temperature rises. Therefore, at a high temperature, the gate resistance increases and the current charged in the gate decreases. Then, the switching speed of the power device decreases, and the power loss during switching increases.

  If the supply current is increased by further reducing the gate resistance in order to improve this problem, the gate resistance at low temperatures becomes insufficient, and the dV / dt during switching of the power device becomes steep. Then, a dV / dt current flows into the gate of the power device in the off state through the feedback capacitance, and the power device may be turned on by raising the gate voltage. In addition, when the switching speed is increased by lowering the gate resistance, the voltage change and the current change become steep, and the emission noise of the power device increases.

  As described above, simply lowering the resistance value of the gate resistor causes various adverse effects. At a high temperature, it is necessary to increase the driving capability of the power device to reduce switching loss, and at a low temperature, to reduce the driving capability, suppress the speeding up of dV / dt, and suppress the gate floating and the increase in noise.

  SUMMARY An advantage of some aspects of the invention is to provide a gate drive circuit and a semiconductor device that can reduce switching loss without any adverse effect.

  The gate drive circuit according to the present invention includes a first switching element having a drain connected to a power supply terminal, a second switching element having a drain connected to a source of the first switching element, and a first switching element having a drain connected to a source of the first switching element. An input terminal connected to the gate and the gate of the second switching element; an output terminal connected to the connection between the first switching element and the second switching element; and an analog temperature output for outputting a voltage proportional to temperature. Circuit, and a current increasing switching element for increasing a supply current to the output terminal in proportion to an output of the analog temperature output circuit in synchronization with a signal for turning on the first switching element. And

  Another gate drive circuit according to the present invention includes a first switching element having a drain connected to a power supply terminal, a second switching element having a drain connected to a source of the first switching element, and a first switching element having a drain connected to a source of the first switching element. An input terminal connected to the gate of the element and the gate of the second switching element; an output terminal connected to the connection between the first switching element and the second switching element; and an analog that outputs a voltage proportional to temperature. A temperature output circuit, and a current sink switching element for increasing a sink current from the output terminal in proportion to an output of the analog temperature output circuit in synchronization with a signal for turning on the second switching element. It is characterized by.

A semiconductor device according to the present invention includes a first chip on which a gate drive circuit is formed, a second chip on which a gate drive circuit different from the gate drive circuit is formed, and a power supply for supplying power to the second chip. A bootstrap circuit for boosting the voltage of the power supply and supplying the boosted voltage to the first chip, an analog temperature output circuit for outputting a voltage proportional to the temperature , and A switching element whose ON / OFF is controlled by an output voltage of the temperature output circuit , wherein a current flowing through the bootstrap circuit is made proportional to an output voltage of the analog temperature output circuit.

  According to the present invention, since a current proportional to the temperature is added to the gate of the power device in synchronization with the signal for turning on the power device output from the microcomputer, the switching loss can be reduced without any adverse effect.

FIG. 2 is a diagram illustrating a system including a gate drive circuit. FIG. 2 is a circuit diagram of the gate drive circuit according to the first embodiment. FIG. 3 is a diagram illustrating temperature characteristics of an analog temperature output circuit. FIG. 4 is a diagram illustrating characteristics of a current increasing switching element. FIG. 9 is a circuit diagram of a gate drive circuit according to a second embodiment. It is a circuit diagram of a gate drive circuit according to a modification. FIG. 3 is a diagram illustrating an operating temperature range of the analog temperature output circuit. FIG. 9 is a circuit diagram of a gate drive circuit according to a third embodiment. It is a circuit diagram of a gate drive circuit according to a modification. FIG. 9 is a circuit diagram of a gate drive circuit according to a fourth embodiment. FIG. 13 is a circuit diagram of a gate drive circuit according to a fifth embodiment. FIG. 15 is a circuit diagram of a gate drive circuit according to a sixth embodiment. FIG. 17 is a circuit diagram of a semiconductor device according to a seventh embodiment. FIG. 15 is a circuit diagram of a gate drive circuit according to an eighth embodiment. FIG. 21 is a circuit diagram of a semiconductor device according to a ninth embodiment. FIG. 9 is a circuit diagram of a semiconductor device according to a modification.

  A gate drive circuit and a semiconductor device according to an embodiment of the present invention will be described with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and description thereof may not be repeated.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a system including the gate drive circuit 12 according to the first embodiment. A signal for turning on / off the power device 14 is output from the microcomputer 10 to the gate drive circuit 12. This signal is converted into a voltage output by the gate drive circuit 12 and transmitted to the power device 14 via the gate resistor 13. The sense current of power device 14 is transmitted to gate drive circuit 12 as signal 16.

  FIG. 2 is a circuit diagram of the gate drive circuit 12. The gate drive circuit 12 includes a CMOS inverter including a first switching element 20 and a second switching element 22. The drain of the first switching element 20 is connected to the power supply terminal 25. The drain of the second switching element 22 is connected to the source of the first switching element 20. The first switching element 20 is a p-channel MOSFET, and the second switching element 22 is an n-channel MOSFET.

  The input terminal 23 is connected to the gate of the first switching element 20 and the gate of the second switching element 22. An output terminal 24 is connected to a connection between the first switching element 20 and the second switching element 22. An input signal from the microcomputer 10 is input to the input terminal 23, and an output from the output terminal 24 is output to the power device 14. When the power device 14 is turned on, the first switching element 20 is turned on by an input signal from the microcomputer 10, and the gate of the power device 14 is charged with a current from the driving power supply Vcc. On the other hand, when the power device 14 is turned off, the second switching element 22 is turned on by the input signal from the microcomputer 10 to discharge the gate of the power device 14. The value of the current for performing charging and discharging depends on the gate resistance 13. Therefore, the gate resistor 13 is designed to have an appropriate value according to the specifications and the like.

  The gate drive circuit 12 includes an analog temperature output circuit 30 that outputs a voltage proportional to the temperature of the gate drive circuit 12. FIG. 3 is a diagram showing characteristics of the analog temperature output circuit 30. The analog temperature output circuit 30 outputs a higher voltage as the temperature is higher.

  Returning to the description of FIG. An analog switch 32 is connected to the analog temperature output circuit 30. The output of the NOT circuit 31 for inverting the input signal applied to the input terminal 23 is connected to the analog switch 32. The output of the analog temperature output circuit 30 and the output of the NOT circuit 31 are input to the analog switch 32. The analog switch 32 outputs an output voltage of the analog temperature output circuit 30 when a signal for turning on the first switching element 20 is input to the NOT circuit 31.

  An amplifier 34 is connected to the output of the analog switch 32. The output of the amplifier 34 is connected to the gate of the switching element 36. The drain of the switching element 36 is connected to the power supply terminal 25 via a resistor, and the source of the switching element 36 is connected to GND.

  The gate drive circuit 12 includes a current increasing switching element 38 formed by a p-channel MOSFET. The drain of the current increasing switching element 38 is connected to the power supply terminal 25, and the source of the current increasing switching element 38 is connected to the output terminal 24. The current increasing switching element 38 is connected in parallel with the first switching element 20. The gate of the current increasing switching element 38 is connected to the drain of the switching element 36.

  The operation of the gate drive circuit 12 will be described. When the power device 14 is turned on, a signal for turning on the first switching element 20 (hereinafter, sometimes referred to as a first on signal) is applied from the input terminal 23 to the first switching element 20. As a result, the current from the drive power supply Vcc is applied to the gate of the power device 14 via the output terminal 24.

  At this time, the first ON signal is transmitted to the analog switch 32 via the NOT circuit 31. Then, the analog switch 32 transmits the output voltage of the analog temperature output circuit 30 to the amplifier 34. When the voltage amplified by the amplifier 34 is applied to the switching element 36, the current increasing switching element 38 is turned on. That is, a voltage proportional to the output of the analog temperature output circuit 30 is applied to the gate of the current increasing switching element 38.

  FIG. 4 is a diagram illustrating characteristics of the current increasing switching element 38. As the voltage (Vgs) applied to the gate of the current increasing switching element 38 increases, the current (Ids) of the current increasing switching element 38 increases. Since Vgs increases as the temperature increases, Ids increases when the temperature is high, and Ids decreases when the temperature is low. This Ids is added to the current flowing through the first switching element 20 to the output terminal 24.

  Therefore, when the power device 14 is turned on at a high temperature, a large current can be supplied to the gate of the power device 14, so that the on-loss can be reduced. As a result, the adverse effects caused by the gate resistance 13 increasing at a high temperature can be eliminated. Further, when the power device 14 is turned on at a low temperature, the output capability of the power device 14 is reduced because the current Ids of the current increasing switching element 38 is small. As a result, it is possible to suppress an increase in dV / dt of switching of the power device 14 and suppress occurrence of gate floating and an increase in emission noise of the device.

  Further, the analog switch 32 transmits the output of the analog temperature output circuit 30 to the amplifier 34 only when the first ON signal for turning on the first switching element 20 is transmitted to the input terminal 23. By turning on the current increasing switching element 38 in synchronization with the signal for turning on the first switching element 20 in this manner, the current is supplied from the current increasing switching element 38 to the output terminal 24 during the period in which the first switching element 20 is off. Can be prevented from flowing.

  An important feature of the gate drive circuit 12 according to the first embodiment of the present invention is that the gate drive circuit 12 includes the current increasing switching element 38 that increases the supply current to the output terminal 24 in proportion to the output of the analog temperature output circuit 30. is there. The configuration of the gate drive circuit 12 can be modified as long as the characteristics are not lost. For example, the analog temperature output circuit 30 may output a voltage proportional to the temperature of a portion other than the gate drive circuit 12. For example, it is preferable to output a voltage proportional to the temperature of the gate resistor 13. The type of the switching element can be appropriately changed. The method of transmitting a signal from the analog temperature output circuit 30 to the current increasing switching element 38 can be appropriately changed.

  These modifications can be appropriately applied to the gate drive circuit and the semiconductor device according to the following embodiments. Note that the gate driver circuit and the semiconductor device according to the following embodiments have many points in common with the first embodiment, and therefore, the description will focus on the differences from the first embodiment.

Embodiment 2 FIG.
FIG. 5 is a circuit diagram of the gate drive circuit according to the second embodiment. This gate drive circuit includes a comparator 40 and an AND circuit 42. The output voltage of the analog temperature output circuit 30 and a predetermined reference voltage Vref are input to the comparator 40. Then, the comparator 40 outputs a signal only when the output voltage is higher than the reference voltage. The output signal is a digital signal.

  The output of the comparator 40 and the output of the NOT circuit 31 are input to the AND circuit 42. The AND circuit 42 outputs the logical product of these. The output from the AND circuit 42 occurs only when the output voltage of the analog temperature output circuit 30 is higher than the reference voltage Vref and a first ON signal for turning on the first switching element 20 is output. When an output signal is output from the AND circuit 42 to the analog switch 32, the analog switch 32 transmits the output voltage of the analog temperature output circuit 30 to the amplifier 34.

  As described above, the current supplied to the output terminal 24 is increased by the current increasing switching element 38 only when the comparator 40 outputs a signal. Therefore, only when a voltage higher than the reference voltage Vref is generated by the analog temperature output circuit 30, the current increasing switching element 38 can be turned on. As a result, the range of design freedom can be expanded.

  FIG. 6 is a circuit diagram of a gate drive circuit according to a modification. A comparator 50 is provided which receives an output voltage of the analog temperature output circuit 30 and a predetermined reference voltage Vref1 as inputs. The output of the comparator 50 becomes High when the output of the analog temperature output circuit 30 is higher than the reference voltage Vref1. The output of the comparator 50 becomes High when, for example, the temperature is higher than 70 ° C.

  A comparator 52 is provided which receives an output voltage of the analog temperature output circuit 30 and a predetermined reference voltage Vref2 as inputs. The output of the comparator 52 is inverted by the NOT circuit 54. The output of the NOT circuit 54 becomes High when the output of the analog temperature output circuit 30 is smaller than the reference voltage Vref2. The output of the NOT circuit 54 becomes High when the temperature is lower than 150 ° C., for example.

  The output of the comparator 50 and the output of the NOT circuit 54 are input to an AND circuit 56, and their logical product is output to an AND circuit 58. When the temperature of the gate drive circuit 12 is higher than 70 ° C. and lower than 150 ° C., the output of the AND circuit 56 becomes High. Therefore, the AND circuit 58 outputs a high signal to the analog switch 32 when the temperature of the gate drive circuit is higher than 70 ° C. and lower than 150 ° C. and the first ON signal is output.

  With this configuration, when the temperature of the gate drive circuit is higher than 70 ° C. and lower than 150 ° C., the current increasing switching element 38 can be turned on. Thus, it is possible to suppress an increase in emission noise by suppressing an increase in dV / dt during switching. FIG. 7 is a diagram showing that the current increasing switching element 38 is turned on only when the gate voltage of the current increasing switching element is between Vgs1 and Vgs2. Vgs1 is, for example, Vgs when the temperature is 70 ° C., and Vgs2 is, for example, Vgs when the temperature is 150 ° C.

  As described above, the gate drive circuit according to the modified example is configured such that the current increasing switching element 38 outputs only when the output voltage of the analog temperature output circuit 30 is between the predetermined lower limit value and the predetermined upper limit value. This is to increase the supply current to the terminal 24. The gate drive circuit according to the modification can be modified within a range not losing this feature. For example, the above-mentioned temperature range is an example, and for example, the current increasing switching element 38 may be turned on when the detected temperature is in a range of −40 ° C. to 0 ° C.

Embodiment 3 FIG.
FIG. 8 is a circuit diagram of the gate drive circuit according to the third embodiment. FIG. 8 illustrates the power device 14 for convenience of explanation. This circuit is obtained by adding a comparator 60 and an AND circuit 62 to the circuit of FIG. The current flowing through the power device 14 and the reference current Iref are input to the comparator 60. The comparator 60 outputs a High signal only when the current of the power device 14 is larger than the reference current Iref.

  The logical product of the output of the comparator 60 and the output of the comparator 40 is output from the AND circuit 62 to the AND circuit 42. Therefore, the current increasing switching element 38 can be turned on only when a certain or more current flows through the power device 14. The current increasing switching element 38 increases the current flowing to the output terminal 24 only when the current of the power device 14 is larger than a predetermined value.

  The gate drive circuit according to the third embodiment controls on / off of the current increasing switching element 38 according to the temperature and the current of the power device 14. Thereby, design flexibility can be improved.

  FIG. 9 is a circuit diagram of a gate drive circuit according to a modification. The current of the power device 14 is applied to the current signal output circuit 70. The current signal output circuit 70 adds the current of the power device 14 to the output of the analog temperature output circuit 30 as an analog signal. By doing so, the current increasing switching element 38 increases the current flowing to the output terminal 24 in proportion to the sum of the output of the analog temperature output circuit 30 and the voltage proportional to the current of the power device 14. As the main current of the power device 14 increases, the loss of the power device 14 increases. Therefore, as in this modification, the loss can be suppressed by increasing the output capability of the gate drive circuit 12 when the main current flowing through the power device 14 is high.

Embodiment 4 FIG.
FIG. 10 is a circuit diagram of the gate drive circuit according to the fourth embodiment. This gate drive circuit includes a current sink switching element 80. The output of the analog temperature output circuit 30 is transmitted to the gate of the current sink switching element 80 via the analog switch 82 and the amplifier 84. The drain of the current sink switching element 80 is connected to the output terminal 24, and the source is connected to GND. The current sinking switching element 80 is connected in parallel with the second switching element 22.

  The analog switch 82 transmits the output of the analog temperature output circuit 30 to the amplifier 84 when a signal for turning on the second switching element 22 (referred to as a second ON signal) is transmitted to the input terminal 23. The signal transmitted from the analog temperature output circuit 30 to the amplifier 84 turns on the current sink switching element 80. Therefore, in synchronization with the signal for turning on the second switching element 22, the current drawn from the output terminal 24 can be increased in proportion to the output of the analog temperature output circuit 30. By providing the current sinking switching element 80 that operates as described above, the sinking current from the output terminal 24 increases at a high temperature, so that the switching speed of the power device 14 when the power device 14 is turned off increases, and the loss at the time of turning off the power device 14 can be reduced. On the other hand, when the temperature is low, the current drawn from the output terminal 24 becomes small, so that it is possible to suppress the increase in the speed of di / dt and the off-surge.

Embodiment 5 FIG.
FIG. 11 is a circuit diagram of the gate drive circuit according to the fifth embodiment. This gate drive circuit is obtained by incorporating the configuration including the current increasing switching element 38 described in the first embodiment into the configuration including the current sinking switching element 80 described in the fourth embodiment. The current increasing switching element 38 is turned on in synchronization with the signal for turning on the first switching element 20, and the current sinking switching element 80 is turned on in synchronization with the signal for turning on the second switching element 22.

  As described above, by linking the gate current at the time of turning on and off the power device 14 with the temperature, the driving capability of the power device 14 is reduced at low temperatures, so that gate floating and noise can be suppressed. The total switching loss can be improved. Further, by providing both the current increasing switching element 38 and the current sinking switching element 80, it is possible to suppress a decrease in the dead time margin.

Embodiment 6 FIG.
FIG. 12 is a circuit diagram of the gate drive circuit according to the sixth embodiment. This gate drive circuit has a switch 90. The switch 90 is connected to the input terminal 23. The switch 90 is connected to the gate of the current increasing switching element 38, the output terminal 24, and the drain of the current sinking switching element 80.

  The switch 90 turns on one of the current increasing switching element 38 and the current sinking switching element 80 according to the voltage of the input terminal 23. Specifically, when a first ON signal for turning on the first switching element 20 is transmitted to the input terminal 23, the switch 90 connects the gate of the current increasing switching element 38 and the current sinking switching element 80. Then, since the current sinking switching element 80 functions in the same manner as the switching element 36 of FIG. 2, the current increasing switching element 38 can be turned on. On the other hand, when a second ON signal for turning on the second switching element 22 is transmitted to the input terminal 23, the switch 90 connects the current sinking switching element 80 to the output terminal 24.

  Functionally, the switch 90 is a combination of the analog switches 32 and 82 of FIG. Therefore, the same effects as those of the gate drive circuit of FIG. 11 can be obtained with a simple circuit configuration.

Embodiment 7 FIG.
FIG. 13 is a diagram illustrating a gate drive circuit and the like according to the seventh embodiment. Power devices 14a and 14b are totem pole connected. The power device 14a is controlled by a first chip 102 on which a gate drive circuit is formed, and the power device 14b is controlled by a second chip 103 on which a gate drive circuit is formed. The first chip 102 is configured as one chip in which elements obtained by removing the analog temperature output circuit 30 from the gate drive circuit described in the above embodiments are incorporated. The same applies to the second chip 103. The analog temperature output circuit 30 is provided outside the chip.

  For example, the analog temperature output circuit 30 is provided on the second chip 103. In this case, pads are provided on the second chip 103. Then, the pad and the output of the analog temperature output circuit 30 are connected using a frame or a gold wire. According to the configuration of the seventh embodiment, it is not necessary to incorporate the analog temperature output circuit 30 into the chip on which the gate drive circuit is formed, so that the chip can be prevented from increasing in size.

Embodiment 8 FIG.
FIG. 14 is a diagram illustrating a gate drive circuit and the like according to the eighth embodiment. The output of the analog temperature output circuit 30 that outputs a voltage proportional to the temperature of the gate drive circuit is connected to the drain of the first switching element 20 via the amplifier 110. The drain of the second switching element 22 is connected to the source of the first switching element 20.

  The output of the analog temperature output circuit 30 amplified by the amplifier 110 is used as a power supply of a CMOS inverter including the first switching element 20 and the second switching element 22. Therefore, if the gate drive circuit is high in temperature, the gate voltage of the power device 14 is increased and the loss at the time of switching can be improved. If the gate drive circuit is low in temperature, the gate voltage of the power device 14 is reduced and the gate floating and noise are suppressed. Can be.

Embodiment 9 FIG.
FIG. 15 is a circuit diagram of a semiconductor device according to the ninth embodiment. A first chip 102 provided with a gate drive circuit for driving the power device 14a and a second chip 103 provided with a gate drive circuit for driving the power device 14b are provided. A power supply 120 for supplying power to the first chip 102 and the second chip 103 is provided. A bootstrap diode BSD and a bootstrap capacitor BSC are provided as a bootstrap circuit that boosts the voltage of the power supply 120 and supplies the boosted voltage to the first chip 102.

  A switching element 124 is provided between the power supply 120 and the bootstrap diode BSD. The switching element 124 is, for example, a pMOS. The on / off of the switching element 124 is controlled by the output voltage of the analog temperature output circuit 30 that outputs a voltage proportional to the temperature. Therefore, when the temperature is high, the current supplied to the bootstrap diode BSD increases, and when the temperature is low, the current supplied to the bootstrap diode BSD decreases. The current flowing through the bootstrap diode BSD is proportional to the output voltage of the analog temperature output circuit 30. Therefore, the voltage supplied to the first chip 102 can be made dependent on the temperature.

  With this circuit configuration, the loss can be reduced by increasing the current supply capability to the power device 14a and increasing the switching speed at high temperatures. On the other hand, at a low temperature, the power supply capability to the power device 14a is reduced to suppress the increase in dV / dt during switching of the power device 14a, and it is possible to suppress the gate floating and the increase in noise.

  FIG. 16 is a circuit diagram of a semiconductor device according to a modification. Switching elements 122 and 124 are provided in the second chip 103. This can prevent an increase in the number of components due to the provision of the switching elements 122 and 124. Only one of the switching elements 122 and 124 may be incorporated in the second chip 103.

  In the present embodiment, a semiconductor device having a bootstrap circuit has been described. However, the above technique can be widely applied to a circuit that boosts or steps down a power supply voltage and supplies it to a chip.

  The gate drive circuit or the semiconductor device described in each of the embodiments described above can be used for driving a power device forming a three-phase bridge inverter. Thereby, the loss of the inverter system can be reduced. Note that the features of the gate drive circuit and the semiconductor device according to each embodiment described above may be combined as appropriate.

  12 gate drive circuit, 13 gate resistance, 14 power device, 20 first switching element, 22 second switching element, 23 input terminal, 24 output terminal, 25 power supply terminal, 30 analog temperature output circuit, 38 current increasing switching element, 40 comparator, 80 current sink switching element

Claims (13)

A first switching element having a drain connected to the power supply terminal,
A second switching element having a drain connected to a source of the first switching element;
An input terminal connected to the gate of the first switching element and the gate of the second switching element;
An output terminal connected to a connection portion between the first switching element and the second switching element;
An analog temperature output circuit that outputs a voltage proportional to temperature,
A current increasing switching element for increasing a supply current to the output terminal in proportion to an output of the analog temperature output circuit in synchronization with a signal for turning on the first switching element. Drive circuit.   The gate drive circuit according to claim 1, wherein a drain of the current increasing switching element is connected to the power supply terminal, and a source of the current increasing switching element is connected to the output terminal. An output voltage of the analog temperature output circuit, and a predetermined reference voltage as an input, comprising a comparator that outputs a signal only when the output voltage is greater than the reference voltage,
3. The gate drive circuit according to claim 2, wherein the current increasing switching element increases a supply current to the output terminal only when the comparator outputs a signal. An output voltage of the analog temperature output circuit and two comparators that receive a predetermined reference voltage as input,
The two comparators may be configured such that the current increasing switching element increases a supply current to the output terminal only when the output voltage is between a predetermined lower limit and a predetermined upper limit. The gate drive circuit according to claim 2, wherein   The current increasing switching element increases a supply current to the output terminal only when a current of an element driven by a current output from the output terminal is larger than a predetermined value. The gate drive circuit according to any one of claims 1 to 4.   The current increasing switching element, in proportion to the sum of the output of the analog temperature output circuit and the voltage proportional to the current of the element driven by the current output from the output terminal, the supply current to the output terminal The gate drive circuit according to claim 1, wherein the number of the gate drive circuits is increased. The first switching element, the second switching element, the input terminal, the output terminal, and the current increasing switching element are formed in one chip,
7. The gate drive circuit according to claim 1, wherein the analog temperature output circuit is provided outside the chip. A first switching element having a drain connected to the power supply terminal,
A second switching element having a drain connected to a source of the first switching element;
An input terminal connected to the gate of the first switching element and the gate of the second switching element;
An output terminal connected to a connection portion between the first switching element and the second switching element;
An analog temperature output circuit that outputs a voltage proportional to temperature,
A current sink switching element for increasing a sink current from the output terminal in proportion to an output of the analog temperature output circuit in synchronization with a signal for turning on the second switching element. Drive circuit.   9. A current increasing switching element for increasing a supply current to the output terminal in proportion to an output of the analog temperature output circuit in synchronization with a signal for turning on the first switching element. A gate drive circuit as described.   10. The gate drive circuit according to claim 9, further comprising a switch for turning on one of the current increasing switching element and the current sinking switching element according to a voltage of the input terminal. The first switching element, the second switching element, the input terminal, the output terminal, and the current sink switching element are formed in one chip,
9. The gate drive circuit according to claim 8, wherein the analog temperature output circuit is provided outside the chip.   A first chip on which a gate drive circuit is formed;
  A second chip on which a gate drive circuit different from the gate drive circuit is formed;
  A power supply for supplying power to the second chip;
  A bootstrap circuit that boosts the voltage of the power supply and supplies the boosted voltage to the first chip;
  An analog temperature output circuit that outputs a voltage proportional to temperature,
  A switching element that is provided between the power supply and the bootstrap circuit and that is turned on and off by an output voltage of the analog temperature output circuit;
  A semiconductor device, wherein a current flowing through the bootstrap circuit is made proportional to an output voltage of the analog temperature output circuit.   The semiconductor device according to claim 12, wherein the switching element is provided in the second chip.

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