JP2011015136A - Semiconductor circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit for driving a high voltage side power transistor in a low current consumption, the noise durability of which is excellent.SOLUTION: A one-shot trigger circuit (11) for producing a one-shot pulse (ON_B) which becomes to be an activated state within a short time period in accordance with a low voltage side input signal (HIN) is provided. A current is supplied to an internal node (15) in accordance with an input signal and a one-shot pulse signal for producing the one-shot pulse by first and second current supplying units (14, 16). A current flowing through a first internal node is received by a Wilson current mirror circuit (20), then converted into a voltage signal by a current detecting unit (R3). Then a driving signal of the switching power transistor is produced by a gate driver (DRV).

Description

  The present invention relates to a semiconductor circuit for driving a power transistor, and more particularly to a circuit for performing on / off driving of a power transistor disposed on a high potential side by performing level shift of an input signal from the low potential side.

  In an electric power device that drives an actuator or a motor, an inverter device that uses a DC voltage of several hundred volts obtained by rectifying an AC voltage as a power source is often used. In such a high-voltage power device, a totem pole type circuit in which the same power switching transistors are arranged on the high-voltage side and the low-voltage side and are alternately set to the on and off states is used as the unit circuit.

  In order to turn on / off the switching power transistor (high voltage transistor) in the output stage, an on / off command signal is given to the switching power transistor, and the switching power transistor is turned on / off in the correct order. This on / off command signal is given from a circuit operating at a low voltage such as a drive control circuit, and is a low voltage signal of several volts to 10 volts. Such a low voltage command signal can be applied to the switching power transistor arranged on the low voltage side of the power device without level conversion. However, for on / off control of the switching power transistor arranged on the high voltage side, it is necessary to shift the level of the on / off command signal to the high voltage side power supply voltage. For this reason, the input signal on the low voltage side is level-shifted and transmitted to the switching power transistor on the high voltage side.

  Various configurations of level shift circuits for driving switching power transistors in such power devices have been proposed.

  In Patent Document 1 (Japanese Patent Laid-Open No. 11-74779), a mirror signal of a current mirror circuit is converted into a voltage by a resistance element to generate a level-shifted command signal. A drive transistor is arranged in series with the master transistor of the current mirror circuit, and the drive transistor is selectively driven to an on / off state in accordance with an input signal on the low voltage side, and a current flows through the current mirror circuit accordingly.

  In this patent document 1, a soft switch circuit is provided for the gate of the drive transistor to slow down the rising speed of the gate voltage of the drive transistor. This prevents element destruction when the level shift current flowing through the master stage of the current mirror circuit changes abruptly and prevents malfunction due to noise.

  Patent Document 2 (Japanese Patent Laid-Open No. 2002-300018) similarly discloses a level shift circuit having a current mirror circuit and a drive transistor. A floating power supply is provided for the level shift circuit and the command signal generation driver, and the voltage of the output node (the connection node of the high-voltage side and low-voltage side switching transistors) is used as the low-side power supply voltage of the driver.

  This patent branch n2 uses the following configuration in order to prevent malfunction due to fluctuations in the floating power supply voltage when the voltage level of the output node changes. The mirror ratio of the current mirror circuit is made smaller than 1. The mirror current is converted into a voltage signal by a resistance element to generate an on / off command signal. The ratio, Ic / Ie, between the normal control current Ic in the current on the master side of the current mirror circuit and the mirror current on the slave side and the error current Ie accompanying the fluctuation of this floating power supply is the same. The input logic threshold value of the driver is set to a level at which the driver output signal does not change when an error current flows.

  In Patent Document 3 (Japanese Patent Laid-Open No. 7-297698), a level shift circuit is configured by a serial body of a resistance element and a drive transistor. Two source elements are connected in series as the source resistance of the drive transistor, and the source resistance value of the drive transistor is adjusted according to the on / off command value of the switching power transistor. Specifically, the drive transistor is operated in a source follower mode, and the source voltage of the drive transistor with respect to the source resistance is made constant. Thus, the equivalent voltage level generated by the resistance element for current / voltage conversion is changed, and an on / off command signal is generated.

  In Patent Document 3, the number of transistors in the level shift circuit is reduced, and the drive transistor is driven with a one-shot pulse to reduce current consumption. In this case, the flip-flop is set or reset in accordance with the pulse-like signal generated by the current / voltage conversion resistance element to generate an on / off control signal for the switching power transistor.

  Japanese Patent Laid-Open No. 9-200020 discloses a latch type level shift circuit having a transistor whose gate and drain are cross-coupled. A drive transistor is provided for each of the cross-coupled transistors. A CR series circuit in which a resistor and a capacitor element are connected in series is connected to the gate of the drive transistor in parallel with the resistor element (source resistor). A drive circuit that generates an on / off command signal in accordance with the level-shifted signal uses a floating power supply coupled to a high-voltage side reference voltage (VH). The low-side electrode of the floating power supply is separated from the output node of the power device. When the output voltage level of the cross-coupled latch type level shift circuit changes, a large peak current flows and charges the capacitive element of the CR series circuit. When the charging potential of this capacitive element becomes higher than the difference between the gate input voltage and the threshold voltage of the corresponding drive transistor, the drive transistor is turned off.

  In Patent Document 4, a drive transistor is operated in a source follower mode, and after a peak current flows, a minute current is supplied to a bias resistor (source resistor) by a source follower mode operation of the bias transistor. As a result, the current consumption of the latch type level shift circuit is reduced, and the latch state of the latch type level shift circuit is inverted at a high speed to ensure a high speed switching operation.

JP 11-74779 A JP 2002-300018 A Japanese Unexamined Patent Publication No. 7-297698 Japanese Patent Laid-Open No. 9-200020

  In the configuration disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 11-74779), the rising speed of the gate voltage of the drive transistor is slowed down. Therefore, it is possible to suppress noise caused by the peak current of the current mirror circuit by suppressing overcurrent at the time of transition of the operation state of the current mirror circuit. However, the drive transistor is composed of a MOS transistor (insulated gate field effect transistor), and a parasitic capacitance exists between the drain and the source. Therefore, a peak current flows through this parasitic capacitance, and it becomes difficult to sufficiently suppress the peak current. In addition, a current always flows from the current mirror circuit while the drive transistor is in an on state, so that the current consumption cannot be reduced and cannot be applied to a low power consumption application.

  Further, the gate voltage of the drive transistor is suppressed, and the current of the current mirror circuit is limited. Therefore, when a level shift signal is generated using a resistance element by the mirror current of this current mirror circuit, the level shift signal cannot be changed at high speed, and the switching transistor in the output stage is switched at high speed. The problem arises that it becomes impossible.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2002-300018), the mirror ratio of the current mirror circuit for level shift is made smaller than 1, so that loss due to the current flowing through the resistance element for generating the command signal is suppressed and high voltage is applied. It is intended to prevent a malfunction due to an error current due to a fluctuation of the side floating source offset voltage (voltage of the output node). However, in the configuration of Patent Document 2, only the drive transistor is arranged between the master stage of the current mirror circuit and the common power source (COM), and the peak current flowing from the current mirror circuit can be suppressed. Can not. In particular, the mirror ratio is made smaller than 1, the current from the master transistor is increased, the influence of the peak current is increased, and it is difficult to reduce the current consumption.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 7-297698) discloses that the source resistance of a high-breakdown-voltage input transistor is configured by a series body of first and second resistance elements, and the source resistance is reduced when the high-breakdown-voltage input transistor is turned on and off. Change the resistance value. This change in the source resistance selectively sets the short-circuit transistor connected in parallel with the second resistance element to the on state.

  In this Patent Document 3, two pulse generation circuits for generating a one-shot pulse signal at each of a rising edge and a falling edge of an input signal are provided for controlling the gate voltage of a high-voltage input transistor and a short-circuit transistor, The gate voltage of the high withstand voltage input transistor is generated by the OR signal of these two pulse signals, while the gate of the shorting transistor is driven by the pulse from one pulse generation circuit. In this configuration, it is difficult to accurately set the on-state timing of the high-voltage input transistor and the short-circuit transistor. In order to generate an on / off command voltage having a sufficient voltage level difference by a resistance element for current / voltage conversion, it is necessary to ensure a sufficient timing margin for the on state of these transistors, and output at high speed It becomes difficult to switch the stage transistors.

  In Patent Document 4 (Japanese Patent Laid-Open No. 9-200020), the input transistor is operated in the source follower mode, and the capacitor of the CR series circuit is charged with the peak current of the latch type level shift circuit to suppress this charging current. At the same time, a small current is passed through the source resistance during the ON command duration of the input signal, thereby reducing the overall power consumption. While the input transistor is in the OFF state, the charging current of the capacitive element of the CR circuit is discharged through the resistance element of the CR series circuit and the corresponding source resistance (bias resistance). Therefore, a period determined by the RC time constant is required to keep the corresponding input transistor off. When the input signal changes at high speed during high-speed operation, the charge charge of the capacitive element of this CR series circuit cannot be completely discharged, the timing at which the corresponding input transistor shifts from the off state to the on state is delayed, and the output switching transistor This makes it difficult to perform switching operation at high speed.

  As a level shift circuit configuration, the low-side electrode of the floating power supply is often connected to an output node (floating node). In this case, when a current flows through the latch-type level shift circuit due to a change in the floating voltage (voltage of the output node), a current flows through the drain-source parasitic capacitance of the input transistor. The capacitive element is charged. When the charge potential of this capacitive element increases, it is conceivable that the input transistor cannot operate in the source follower mode and goes into a deeper off state. In this case, the input transistor cannot be turned on until the charge of the capacitive element of the CR series circuit is discharged through the bias resistor, and it is more difficult to realize a high-speed switching operation. Occurs.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor circuit capable of generating a level shift signal excellent in noise resistance capable of generating a switching command signal with low current consumption and high speed.

  The semiconductor circuit according to the present invention generates a one-shot pulse signal having a shorter pulse width than the period of the first logic state of the first input signal in response to the transition of the input signal to the first logic state. One-shot pulse generation circuit, a first current supply unit that supplies current to the first internal node according to the input signal, and a second current supply unit that supplies current to the first internal node according to the one-shot pulse signal And a shift current generating circuit for passing a current corresponding to a current flowing through the first internal node to the second internal node, and a second internal node coupled between the high potential side reference power source and the second internal node. Current detection means for generating a signal corresponding to the current flowing through the node, and a switch drive circuit for selectively setting the semiconductor switching transistor to an on state in accordance with an output signal of the current detection means.

  First and second current supply units are provided for the first internal node, and the second current supply unit is driven one-shot. Therefore, it is possible to generate a control signal for turning on / off the output transistor by causing a current change at a high speed. Further, since it is one-shot driving, an increase in current consumption is suppressed.

It is a figure which shows the structure of the semiconductor circuit according to Embodiment 1 of this invention. FIG. 2 is a timing diagram illustrating an operation of the semiconductor circuit illustrated in FIG. 1. It is a figure which shows the structure of the semiconductor circuit according to Embodiment 2 of this invention.

[Embodiment 1]
FIG. 1 shows an overall configuration of a semiconductor circuit according to the first embodiment of the present invention. In FIG. 1, the semiconductor circuit according to the first embodiment of the present invention is a high-voltage gate drive circuit HVIC that drives output power transistors Q1 and Q2 according to low-voltage (low-potential) input signals HIN and LIN. Output power transistors Q1 and Q2 are formed of IGBTs (insulated gate bipolar transistors), for example, and supply positive and negative currents to load circuit 30 connected to output node 27. That is, the output power transistor Q1 supplies a positive current to the load circuit 30 from the high-voltage power supply node VM via the output node 27 when conducting. The output power transistor Q2 supplies a negative current to the load circuit 30 by flowing a current from the output node 27 to the common power supply node COM when conducting.

  The high voltage gate drive circuit HVIC includes a high potential side drive circuit 1 that drives the output power transistor Q1 according to the low voltage side input signal HIN, and a low potential side drive circuit 2 that drives the output power transistor Q2 according to the low voltage side input signal LIN. . The low voltage side input signals HIN and LIN are low voltage input signals having the amplitude of the low voltage side power supply voltage VCC. The low-voltage side input signals HIN and LIN are pulsed command signals that are generated from a control circuit (not shown) and command on and off of the output power transistors Q1 and Q2, respectively.

  The low potential side drive circuit 2 receives the low voltage side power supply voltage VCC and the voltage of the common power supply COM as both operation power supply voltages, generates a gate drive signal OUTL having an amplitude of the voltage VCC according to the low voltage side input signal LIN, and outputs power Apply to the gate of transistor Q2. The internal configuration of the low-potential side drive circuit 2 has a configuration in which the gate drive signal OUTL is generated in response to the rise and fall of the low-voltage side input signal LIN in consideration of the dead time of the output power transistors Q1 and Q2. However, the level shift operation is not performed. The low potential side drive circuit 2 has a delay circuit and a buffer circuit therein, and the internal configuration thereof will not be described here.

  The high-potential side drive circuit 1 includes an inverter 10 that receives the low-voltage side input signal HIN as an on / off command signal ON_A, and a one-shot circuit 11 that generates a one-shot pulse signal ON_B in response to the rising of the low-voltage side input signal HIN. Inverter 12 that receives this one-shot pulse signal ON_B, first current supply unit 14 that supplies current to internal node 15 according to the output signal of inverter 10, and current to internal node 15 according to the output signal of inverter 12 And a second current supply unit 16.

  The first current supply unit 14 includes a P-channel MOS transistor (insulated gate field effect transistor) PT1 connected in series between the power supply node VCC that supplies the low-voltage power supply voltage VCC and the internal node 15, and a resistance element R1. Including. Here, the node and the voltage thereon are denoted by the same reference numerals.

  Second current supply unit 16 includes a P-channel MOS transistor PT2 and a resistance element R2 connected in series between power supply node VCC and internal node 15. The current I1 supplied by the first current supply unit 14 is made smaller than the current I2 supplied by the second current supply unit 16. Further, the relationship of I1 · R1 = I2 · R2 is satisfied. Here, resistance elements R1 and R2 have resistance values R1 and R2, respectively.

  High potential side driving circuit 1 further corresponds to an N channel MOS transistor NT1 connected between internal node 15 and common power supply COM, and a current supplied from first and second current supply units 14 and 16. A Wilson current mirror circuit 20 for passing current and a high potential side floating unit 22 for generating a voltage signal corresponding to the current (shift current) flowing through the Wilson current mirror circuit 20 and generating the high-voltage side gate drive signal OUT1 are included.

  N channel MOS transistor NT1 conducts when an inverted signal of on / off command signal ON_A applied from inverter 10 is at H level (logic high level), and electrically couples internal node 15 and common power supply COM.

  Wilson current mirror circuit 20 functions as a shift current generating circuit for generating a current required for level shift, and includes a high breakdown voltage N-channel MOS transistor HNT1 and two NPN bipolar transistors BP1 and BP2. High voltage MOS transistor HNT 1 has its gate connected to internal node 15 and its drain connected to internal node 21. Bipolar transistor BP1 has its base and collector connected to the source of high voltage MOS transistor HNT1, and its emitter coupled to common power supply COM. Bipolar transistor BP2 has its collector connected to internal node 15, its base connected to the base of bipolar transistor BP1, and its emitter connected to common power supply COM. Bipolar transistors BP1 and BP2 form a current mirror circuit, and bipolar transistor BP1 functions as a master.

  High potential side floating portion 22 includes a resistance element R 3 connected between floating power supply node VB and internal node 21, a diode element DD connected between output node 27 and internal node 21, and internal node 21. A gate driver DRV that generates a high-voltage side gate drive signal OUTH according to the signal is included.

  The resistance element R3 functions as a current detection unit that causes a voltage drop when the shift current Io flows and generates a voltage signal corresponding to the shift current at the internal node 21.

  Diode element DD has its cathode connected to internal node 21 and its anode connected to output node 27. The diode DD prevents current from flowing from the internal node 21 to the output node 27 when the output node 27 is driven to the voltage level of the common power supply COM, and adversely affecting the potential change of the output node 27.

  The gate driver DRV is composed of an inverter circuit, and drives the gate drive signal OUTH to H level when the voltage of the internal node 21 becomes lower than its own input logic threshold value.

  A floating power supply 25 is connected between output node 27 and floating power supply node VB. Floating power supply 25 has a positive electrode connected to floating power supply node VB and a negative electrode connected to output node 27, and generates voltage EV between floating power supply node VB and output node 27. The difference between the voltage (floating voltage) VS of the floating power supply node VB and the output node 27 is maintained at a constant value by the floating power supply 25.

  FIG. 2 is a timing chart showing the operation of the high potential side drive circuit 1 of the semiconductor circuit HVIC shown in FIG. Hereinafter, the operation of the high potential side drive circuit 1 of the high voltage drive circuit HVIC shown in FIG. 1 will be described with reference to FIG.

  When the on / off command signal ON_A rises to the H level in response to the low-voltage side input signal HIN, the one-shot circuit 11 generates a one-shot pulse one-shot on / off command signal ON_B. The one-shot on / off command signal ON_B is a signal that is at the H level for a period shorter than the H level period of the low-voltage side input signal HIN (on / off command signal ON_A).

  When both on / off command signals ON_A and ON_B are at H level, the output signals of inverters 10 and 12 are at L level, MOS transistors PT1 and PT2 are on, MOS transistor NT1 is off, and low voltage side power supply node VCC Currents I1 and I2 are supplied to internal node 15 via current supply units 14 and 16, respectively. MOS transistor NT1 is in an off state, and a combined current I1 + I2 of currents I1 and I2 is supplied to Wilson current mirror circuit 20.

  In Wilson current mirror circuit 20, high voltage MOS transistor HNT1 is turned on in response to a rise in voltage level due to current supply to internal node 15, and current is supplied from floating power supply 25 through floating power supply node VB and resistance element R3. Io flows through the high voltage MOS transistor HNT1. The high voltage MOS transistor HNT1 has a gate driven by a voltage, and a current Ir flows through the bipolar transistor BP2.

The current Io from the high potential side floating portion 22 is supplied to the bases of the bipolar transistors BP1 and BP2 through the MOS transistor HNT1, and discharged to the common power supply COM as an emitter current through the bipolar transistor BP1. The bipolar transistors BP1 and BP2 have the same size. Therefore, the base current Ibe (BP1) of the bipolar transistor BP1 is equal to the base current Ibe (BP2) of the bipolar transistor BP2, and the emitter currents Ie (BP1) and Ie (BP2) of the bipolar transistors BP1 and BP2 are also equal. Become. In this case, the following equation holds:
Ie (BP1) = Ibe (BP1) + Io,
Ie (BP2) = Ibe (BP2) + Ir,
Therefore, Io = Ir
That is, in the Wilson current mirror circuit 20, the current Io supplied from the high potential side floating unit 22 is equal to the current Ir supplied by the current supply units 14 and 16. As a result, in the high potential side floating portion 22, the voltage level of the internal node 21 becomes lower than the input logic threshold value Vth of the gate driver DRV due to the voltage drop in the resistance element R3, and the gate driver DRV outputs it. The high-side gate drive signal OUTH shifts to the ON state (ON) at the H level at high speed. In response, output power transistor Q1 is turned on, and current is supplied to output node 27 from high voltage source VM.

  At this time, the output node 27 is coupled to the internal node 21 of the high potential side floating portion 22 via the diode element DD, and the internal node 21 rises to the high voltage side power supply voltage VM level. However, the floating power supply 25 drives the voltage of the floating power supply node VD to a voltage level higher than the voltage of the output node 27 by the voltage EV of the floating power supply 25, and the output signal OUTH of the gate driver DRV is maintained at the H level. The

  High breakdown voltage MOS transistor HNT1 has a drain voltage higher than its gate voltage, operates in a source follower mode, prevents high voltage VM from being supplied to bipolar transistors BP1 and BP2, and supplies current source 14 and A current equal to the current Ir supplied from 16 is extracted from the high potential side floating portion 22.

  When the one-shot on / off command signal ON_B from the one-shot circuit 11 falls to the L level, the MOS transistor PT2 in the second current supply unit 16 is turned off. Accordingly, the supply of the current I2 from the second current supply unit 16 is stopped, and the current I1 is supplied from the first current supply unit 14 to the Wilson current mirror circuit 20 via the MOS transistor PT1.

  A current equal to the current I1 flows through the resistance element R3 via the Wilson current mirror circuit 20. Even in this state, the voltage VB-I1 · R3 of the internal node 21 is lower than the input logic threshold value Vth + Vs of the gate driver DRV, and the output signal OUTH of the gate driver DRV is maintained at the H level. Here, the low-side power supply voltage of the gate driver DRV is the floating voltage VS.

  When the output power transistor Q1 is driven to the on state, only a large current flows for a short period of time, and the current consumption when the high voltage side output power transistor Q1 is in the on state can be reduced. In this case, the current I1 is smaller than the current I2, and the current consumption can be further reduced. The condition that the current I1 satisfies is expressed by the following equation.

VB−I1 · R3 <Vth + Vs,
EV-I1 · R3 <Vth,
Therefore, I1> (EV−Vth) / R3.
When the on / off command signal ON_A shifts to the off state (OFF), the MOS transistor PT1 is turned off and the MOS transistor NT1 is turned on. At this time, the one-shot on / off command signal ON_B from the one-shot circuit 11 is maintained in the off state (L level), and the MOS transistor PT2 is in the off state. Therefore, the internal node 15 is shifted to the voltage level of the common power supply COM by the MOS transistor NT1, and the high voltage MOS transistor HNT1 is turned off. Accordingly, the voltage of internal node 21 rises above the input logic threshold value of gate driver DRV, gate drive signal OUTH from gate driver DRV goes to L level, and output power transistor Q1 is turned off.

  The current supplied from the high voltage MOS transistor HNT1 is discharged to the common power supply COM by the bipolar transistor BP1. Therefore, when the high voltage MOS transistor HNT1 is in the off state, voltage fluctuation occurs in the floating power supply node VB, and even if a noise current flows through the drain-source parasitic capacitance of the high voltage MOS transistor HNT1, the bipolar transistor BP1 It is prevented that the source voltage of the high voltage MOS transistor HNT1 is discharged and its voltage level is greatly increased due to noise or power supply fluctuation. Thereby, high voltage MOS transistor HNT1 can be turned on at high speed in accordance with the current supply from current supply units 14 and 16.

  The high breakdown voltage MOS transistor HNT1 has a gate coupled to the common power supply COM via the MOS transistor NT1, and at the time of transition to the off state, all the charge accumulated in the gate capacitance is discharged by the MOS transistor NT1 and is turned on at high speed. To the off state.

  Further, since only the Wilson current mirror circuit 20 is used and a logic state storage circuit such as a flip-flop is not used, even if noise occurs, the influence of the noise can be reliably suppressed. .

  As described above, according to the first embodiment of the present invention, the gate drive signal is set to the on state in accordance with the one-shot pulse on command signal from the one-shot circuit. For this reason, the period during which a large current flows when the output power transistor is driven can be shortened, and the current consumption can be reduced. In addition, the Wilson current mirror circuit can generate a gate drive signal that is accurately and constantly flowing, suppresses the influence of noise, and is level-shifted at a high speed with low current consumption for the gate driver. it can.

[Embodiment 2]
FIG. 3 schematically shows a structure of a semiconductor circuit according to the second embodiment of the present invention. The semiconductor circuit shown in FIG. 3 differs from the semiconductor circuit shown in FIG. 1 in the following points. That is, in the high potential side floating unit 22, a current mirror circuit that generates a mirror current of the current Io supplied to the Wilson current mirror circuit 20 is provided. This current mirror circuit includes P channel MOS transistors PT3 and PT4. MOS transistor PT3 has its gate and drain interconnected and its source connected to floating power supply node VB. MOS transistor PT4 is connected between floating power supply node VB and internal node 30, and its gate is connected to the gate of MOS transistor PT3. The ratio of the sizes (ratio of gate width to gate length) of the MOS transistors PT3 and PT4 is set to n: 1. Therefore, the current Io / n flows through the MOS transistor PT4.

  Resistive element R 4 is connected between internal node 30 and output node 27. The gate driver ZDRV is configured by a buffer that drives the gate drive signal OUTH to H level when the voltage level of the internal node 30 becomes H level.

  The other configuration of the semiconductor circuit shown in FIG. 3 is the same as that of the semiconductor circuit shown in FIG. 1, and corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  The operation timing of the semiconductor circuit shown in FIG. 3 is the same as the timing diagram shown in FIG. When the on / off command signals ON_A and ON_B are at the H level, the current Io flows through the Wilson current mirror circuit 20, and accordingly, the current Io / n flows through the resistance element R4 by the current mirror operation of the MOS transistors PT3 and PT4. When voltage Io · R4 (= (I1 + I2)) of internal node 30 becomes higher than input logic threshold value VTH of gate driver ZDRV, gate drive signal OUTH from gate driver ZDRV becomes H level. Here, the resistance value of the resistance element R4 is R4.

When the one-shot on / off command signal ON_B from the one-shot circuit 11 becomes L level, the current flowing through the resistance element R4 becomes I1 / n. At this time, the voltage applied to the resistance element R4 is such that I1 · R4 / n is higher than the input logic threshold value VTH of the gate driver ZDRV, and the gate drive signal OUTH is maintained at the H level. Therefore, in this case, the current I1 needs to satisfy the following relationship:
I1 · R4 / n> VTH,
Therefore, I1> n · VTH / R4.
An error current may flow from the floating power supply node due to fluctuations in the floating power supply node VB or noise. In this case, the ratio between the normal current Io flowing through the MOS transistor PT3 and the error current Ier, Io / Ier, is maintained even in the current flowing through the MOS transistor PT4. When the error current Ier flows through the MOS transistor PT3, the voltage drop of the resistance element R4 is Ier · R4 / n, which is a voltage level sufficiently lower than the input logic threshold value VTH of the gate driver ZDRV. Therefore, even if the error current Ier flows, the gate driver ZDRV can determine that the input signal due to the error current is at the L level, and can prevent malfunction due to the error current. Therefore, the input logic threshold value VTH, the resistance value R4 of the resistance element R4, the currents I1 and Ier satisfy the following relationship:
I1 · R4 / n> VTH and Ier · R4 / n <VTH.
The input logic threshold value of the gate driver ZDRV, the current I1, and the resistance value of the resistance element R4 are set so as to satisfy the above relationship.

  When no current flows in the Wilson current mirror circuit 20, the MOS transistors PT3 and PT4 are also off in the high potential side floating portion 22, and the potential of the internal node 30 is set to the voltage (floating voltage) VS of the output node 27. Equally, the gate driver ZDRV determines the L level, and the output gate drive signal OUTH is maintained at the L level.

  As described above, according to the second embodiment of the present invention, the current mirror circuit is arranged in the high-potential side floating unit 22, and an input signal to the gate driver is generated by a current smaller than the current flowing through the Wilson current mirror circuit. ing. Accordingly, the current flowing through the resistance element R4 for current / voltage conversion is small, and power loss in the resistance element R4 can be reduced. Even if noise such as power fluctuation occurs and error current flows, the normal control signal and error signal due to noise can be identified by the gate driver input logic threshold value, and malfunction due to noise is surely prevented. be able to.

  The semiconductor circuit according to the present invention is applied to a circuit configured to control the on / off of the high-voltage side switching transistor by level-shifting the low-voltage side input signal. A circuit for driving the high-voltage side switching power transistor can be realized.

  The transistor of the output unit is not limited to the IGBT but may be a power MOS transistor. Further, the power transistors Q1 and Q2 of the output unit are shown as being connected in a half-bridge configuration in FIGS. 1 and 3, but may be output transistors connected in a full-bridge configuration. Further, the load circuit 30 may be either an actuator or a motor.

  DESCRIPTION OF SYMBOLS 1 High potential side drive circuit, 2 Low potential side drive circuit, 11 One shot circuit, 14 1st current supply part, 16 2nd current supply part, 20 Wilson current mirror circuit, 22 High potential side floating part, R1- R4 resistance element, HNT1 high voltage MOS transistor, BP1, BP2 bipolar transistor, DRV, ZDRV gate driver, Q1, Q2 output power transistor.

Claims (4)

A semiconductor circuit for controlling on and off of a semiconductor switching transistor for driving an output node to a voltage level higher than a voltage on the low voltage side according to an input signal from the low voltage side;
A one-shot pulse generation circuit for generating a one-shot pulse signal having a pulse width shorter than a period of a first logic state of the first input signal in response to a transition of the input signal to a first state;
A first current supply unit for supplying a current to a first internal node according to the input signal;
A second current supply unit for supplying a current to the first internal node according to the one-shot pulse signal;
A shift current generating circuit for causing a current corresponding to a current flowing through the first internal node to flow through the second internal node;
A current detection unit coupled between a high-potential-side reference power supply and the second internal node, and generating a voltage signal having a level corresponding to a current flowing through the second internal node; and according to an output signal of the current detection unit A semiconductor circuit comprising a switch drive circuit that selectively sets the semiconductor switching transistor to an on state. The shift current generation circuit includes:
An insulated gate field effect transistor having a gate coupled to the first internal node and selectively allowing a current to flow from the second internal node in accordance with a voltage of the first internal node;
A first bipolar transistor connected between the first internal node and a common power source;
A second bipolar transistor connected between the insulated gate field effect transistor and the common power source and having a base connected to a base of the first bipolar transistor and receiving a current from the insulated gate field effect transistor The semiconductor circuit according to claim 1, comprising:   2. The semiconductor circuit according to claim 1, wherein a current flowing through the second current supply unit is larger than a current flowing through the first current supply unit. The current detection means includes
a current mirror circuit that generates a mirror current having a mirror ratio of n: 1, where n is a real number greater than 1, and a resistance element that converts the mirror current of the current mirror circuit into a voltage signal, The semiconductor circuit according to claim 1, wherein a voltage corresponding to a current that is 1 / n times the current flowing through the node is generated as a current detection signal.

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