JP5466124B2 - Pre-driver circuit and drive circuit - Google Patents

Description

  The present invention relates to a pre-driver circuit, and more particularly to a pre-driver circuit for a drive circuit that controls the voltage of a load such as a motor.

  FIG. 5 shows a configuration example of a driving circuit 1 for driving a conventional motor or the like.

  The drive circuit 1 includes a high-side pre-driver circuit 2 and a bridge circuit 3 connected to a load 4 such as a motor. The pre-driver circuit 2 includes a push-pull circuit 5 that is controlled based on the output voltage of the drive circuit 1, an internal supply voltage that is output via the push-pull circuit 5, and a drive voltage that is based on the output voltage. A circuit including a buffer circuit 6 for outputting is known (see Patent Document 1). Reference numeral 7 denotes a low-side pre-driver circuit.

US Pat. No. 7,635,998

  6 and 7 show configuration examples of the bridge circuit 3. The bridge circuit 3 in FIG. 6 includes two drive transistors 3a and 3b, and the bridge circuit 3 in FIG. 7 includes four drive transistors 3a, 3b, 3c, and 3d.

  In the bridge circuit 3 of FIG. 6, an excessive voltage is applied to the gate of the drive transistor 3a, and in the bridge circuit 3 of FIG. 7, an excessive voltage is applied to the gates of the drive transistors 3a and 3c. This is protected by the pre-driver circuit 2.

  However, as shown in FIG. 5, since the push-pull circuit 5 and the buffer circuit 6 are directly connected to the output voltage, the regenerative current flowing from the load 4 such as a motor to the pre-driver circuit 2 side is the push-pull circuit. 5 and the internal circuit of the pre-driver circuit 2 including the buffer circuit 6, and as a result, adversely affects the control of the drive circuit 1 (for example, malfunction or element destruction of the internal circuit).

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pre-driver circuit that does not affect the control of a drive circuit even when a regenerative current flows from a load such as a motor to the pre-driver circuit side.

The present invention is connected to a bridge circuit whose output terminal is a connection node connected to a load between a first drive transistor connected to a first power supply voltage and a second drive transistor connected to ground. A pre-driver circuit having an output monitor circuit connected to the output terminal as the connection node, and using the output monitor circuit to feed back only the voltage based on the voltage appearing at the output terminal a first feedback signal generating means for generating a first feedback signal, a first feedback signal the generated is inputted, first generates a second feedback signal for controlling driving of the pre-Symbol first driving transistor Two feedback signal generating means, one end of which is connected to a voltage higher than the first power supply voltage, and the other end of the second feedback signal. A first switching means connected to the generating means for turning on and off by an input signal, and the driving signal generating means configured by the first switching means and the second feedback signal generating means to the first switching means. The second feedback signal is output to the gate of the first driving transistor as a driving signal , and the second feedback signal generating means has a drain connected to the other end of the first switching means, and a source connected to the first switching transistor. It is an N-type transistor connected to one drive transistor and having a first feedback signal input to the gate .

The present invention is connected to a bridge circuit whose output terminal is a connection node connected to a load between a first drive transistor connected to a first power supply voltage and a second drive transistor connected to ground. A pre-driver circuit having an output monitor circuit connected to the output terminal as the connection node, and using the output monitor circuit to feed back only the voltage based on the voltage appearing at the output terminal First feedback signal generation means for generating a first feedback signal, and a second feedback signal that receives the generated first feedback signal and generates a second feedback signal for driving and controlling the first driving transistor. Feedback signal generating means, one end of which is connected to a voltage higher than the first power supply voltage, and the other end of the second feedback signal. A first switching unit connected to the generation unit and turned on / off by an input signal, and the second switching signal generating unit includes the first switching unit and the second feedback signal generating unit. A feedback signal is output as a drive signal to the gate of the first drive transistor, and the first feedback signal generation means outputs a signal obtained by shifting a voltage appearing at the output node of the output monitor circuit by a predetermined amount. And a voltage shift circuit that outputs the feedback signal as one feedback signal .

The present invention is connected to a bridge circuit whose output terminal is a connection node connected to a load between a first drive transistor connected to a first power supply voltage and a second drive transistor connected to ground. A pre-driver circuit having an output monitor circuit connected to the output terminal as the connection node, and using the output monitor circuit to feed back only the voltage based on the voltage appearing at the output terminal First feedback signal generation means for generating a first feedback signal, and a second feedback signal that receives the generated first feedback signal and generates a second feedback signal for driving and controlling the first driving transistor. Feedback signal generating means, one end of which is connected to a voltage higher than the first power supply voltage, and the other end of the second feedback signal. A first switching unit connected to the generation unit and turned on / off by an input signal, and the second switching signal generating unit includes the first switching unit and the second feedback signal generating unit. A feedback signal is output as a drive signal to the gate of the first drive transistor, and the drive signal generation means detects that the voltage appearing at the output terminal is close to the first power supply voltage, and The second switching means for short-circuiting the other end of the first switching means and the gate of the first driving transistor is further provided .

The output monitor circuit includes a first N-type transistor having a drain connected to a voltage higher than the first power supply voltage, a gate connected to the output terminal, and a drain connected to a voltage lower than the first power supply voltage. And a first P-type transistor having a gate connected to the output terminal and a source connected to a source of the first N-type transistor, wherein the first feedback signal generation means includes the output monitor circuit The first feedback signal is generated based on a voltage appearing at a connection node between the first N-type transistor and the first P-type transistor .

The voltage shift circuit includes an input terminal to which a voltage appearing at an output node of the output monitor circuit is input, an output terminal connected to a voltage higher than the first power supply voltage and outputting the first feedback signal; And a plurality of P-type transistors connected in series as diodes and connected between the output terminal and the output terminal .

  The present invention includes a bridge circuit having at least a first drive transistor connected to a first power supply voltage and a second drive transistor connected to ground, the first drive transistor, and a second drive. A drive circuit is configured by including a pre-driver circuit connected between a connection node between the transistor and a gate of the first drive transistor.

  According to the present invention, the connection node (N1) connected to the load between the first drive transistor connected to the first power supply voltage (VM) and the second drive transistor connected to the ground is provided. The pre-driver circuit connected to the bridge circuit serving as the output terminal has an output monitor circuit connected to the output terminal which is the connection node (N1), and the voltage (Vout) appearing at the output terminal using the output monitor circuit. ) To generate a first feedback signal (S1) that feeds back only the voltage, generates a second feedback signal (S2) based on the first feedback signal (S1), and appears on the output terminal. Since the first drive transistor is driven and controlled so that (Vout) approaches the first power supply voltage (VM), the regenerative current is generated from a load such as a motor. Also it flows to the pre-driver circuit side which constitutes the dynamic circuit, it becomes possible so as not to affect the control of the drive circuit.

1 is a circuit diagram illustrating a configuration example of a pre-driver circuit according to a first embodiment of the present invention. FIG. It is a circuit diagram which shows the structural example of the predriver circuit which is the 2nd Embodiment of this invention. It is a circuit diagram which shows the structural example of the predriver circuit which is the 3rd Embodiment of this invention. It is a circuit diagram which shows the structural example of the predriver circuit which is the 4th Embodiment of this invention. It is a circuit diagram which shows the structural example of the conventional predriver circuit. It is a circuit diagram which shows the structural example of the bridge circuit connected to the conventional predriver circuit. It is a circuit diagram which shows the structural example of the bridge circuit connected to the conventional predriver circuit.

[First example]
A first embodiment of the present invention will be described with reference to FIG.

<Circuit configuration>
FIG. 1 shows a configuration example of the drive circuit 300.

  The drive circuit 300 includes a bridge circuit 100 and a pre-driver circuit 200.

  The bridge circuit 100 includes at least a first drive transistor 101 connected to the first power supply voltage (VM) and a second drive transistor 102 connected to the ground.

  The pre-driver circuit 200 is connected between a connection node (N1) between the first drive transistor 101 and the second drive transistor 102 and the gate of the first drive transistor 101. The connection node (N1) is an output terminal 10 and is connected to a load 400 such as a motor.

(Pre-driver circuit)
Hereinafter, a specific configuration of the pre-driver circuit 200 will be described.

  The pre-driver circuit 200 includes a first feedback signal generation circuit 210, a second feedback signal generation circuit 222, and a first switching circuit 221. The second feedback signal generation circuit 222 and the first switching circuit 221 are configured as a drive signal generation circuit 220.

  The first feedback signal generation circuit 210 includes an output monitor circuit 213 connected to the output terminal 10 which is a connection node (N1). Using this output monitor circuit 213, a first feedback signal (S1) for feeding back only the voltage based on the voltage (Vout) appearing at the output terminal 10 is generated.

  Based on the input first feedback signal (S1), the second feedback signal generation circuit 222 performs the first feedback so that the voltage (Vout) appearing at the output terminal 10 approaches the first power supply voltage (VM). A second feedback signal (S2) that can drive and control the driving transistor 101 is generated. Specifically, it is only necessary that the gate-source voltage of the first driving transistor 101 becomes approximately equal to or higher than the threshold voltage of the first driving transistor 101 by the second feedback signal (S2).

  The first switching circuit 221 has one end connected to a voltage (VG) higher than the first power supply voltage (VM), the other end connected to the second feedback signal generation circuit 222, and an input signal (SIN). Turn on and off with.

  The first switching circuit 221 can be composed of a PMOS and is digitally turned on / off by an input signal SIN. Note that the first switching circuit 221 can also be configured as bipolar.

  The pre-driver circuit 200 receives the second feedback signal (S2) from the drive signal generation circuit 220 configured by the first switching circuit 221 and the second feedback signal generation circuit 222, and the first drive transistor. The drive signal (S3) is output to the gate 101. If the second feedback signal generation circuit 222 and the gate of the first driving transistor are directly connected, S2 = S3.

(Output monitor circuit)
The configuration of the output monitor circuit 213 will be described.

  The output monitor circuit 213 includes a first N-type transistor 211 and a first P-type transistor 212.

  The first N-type transistor 211 has a drain connected to a voltage (V2) higher than the first power supply voltage (VM), and a gate connected to the output terminal (10).

  The first P-type transistor 212 has a drain connected to a voltage (V3) lower than the first power supply voltage (VM), a gate connected to the output terminal 10, and a source connected to the source of the first N-type transistor 211. It is connected.

Then, the first feedback signal generation circuit 210 performs the first feedback based on the voltage appearing at the connection node (N2) between the first N-type transistor 211 and the first P-type transistor 212 of the output monitor circuit 213. The feedback signal (S1) is generated.
(Bridge circuit)
The bridge circuit 100 outputs at least a connection node (N1) between the first drive transistor 101 connected to the first power supply voltage (VM) and the second drive transistor 102 connected to the ground. 10 is assumed. Then, the voltage of the output terminal 10 is controlled by turning on the first drive transistor 101 after turning off the second drive transistor 102 and turning on the second drive transistor 102 after turning off the first drive transistor 101. Any circuit that operates the load 400 such as a motor connected to the output terminal 10 is not particularly limited.

  The bridge circuit 100 may be a half bridge circuit as shown in FIG. 2 or a full bridge circuit as shown in FIG. When the bridge circuit 100 is a full bridge circuit, the pre-driver circuit 200 according to the present invention can output a drive signal (S3) to at least one drive transistor connected to the first power supply voltage (VM). The drive signal (S3) is preferably output to both drive transistors connected to the first power supply voltage (VM).

(Voltage)
The voltage VG is not particularly limited as long as it is higher than the first power supply voltage (VM). From the viewpoint of not applying an excessive load to the first drive transistor 101, the first drive transistor 101 is It is preferable that VG is approximately VM + VGSmax, where VGSmax is the maximum allowable gate-source voltage.

  The voltage V2 is not particularly limited as long as it is higher than the first power supply voltage (VM). However, the voltage V2 is preferably the same as the voltage VG from the viewpoint of easily configuring the circuit.

  The voltage V3 is not particularly limited as long as it is lower than the first power supply voltage (VM), but the voltage V3 is preferably grounded from the viewpoint of easily configuring the circuit.

(input signal)
The input signal SIN is not particularly limited as long as it is a signal that can turn the first switching circuit 221 on and off. For example, when a signal that instructs on / off of the high-side driver is used as the input signal SIN, the digital signal (square wave) of 0V and 5V is level-shifted to a square wave that amplitudes between VG and VG-5V. Can be used.

  As a specific example, in order to generate an input signal SIN for turning on / off a P-type MOSFET having a VGS allowable voltage of 5 V as the first switching circuit 221 based on a square wave with LOW of 0 V and HIGH of 1.8 V In this case, a square wave can be used as the input signal SIN by using a level shifter so that LOW becomes VG-5V and HIGH becomes VG, but the present invention is not limited to this.

  Reference numeral 500 denotes a low-side pre-driver circuit for the second drive transistor 102, which is a well-known NMOS pre-driver circuit. The low-side pre-driver circuit 500 can be configured as a buffer that outputs an analog waveform with an amplitude below MaxVgs.

<Circuit operation>
An operation of the pre-driver circuit 200 in FIG. 1 will be described.

  In the description of the operation, the threshold voltages of the first drive transistor 101 and the first N-type transistor 211 are assumed to be substantially equal to simplify the description. Further, it is assumed that the second feedback signal generation circuit 222 adds 2 × VT to the first feedback signal (S1) and outputs the result.

(1) First, the first switching means 221 is turned on by the input signal SIN, and the gate of the first drive transistor 101 is driven via the second feedback signal generation circuit 222.

(2) Since the output monitor circuit 213 includes two source followers, the first N-type transistor 211 and the first P-type transistor 212, the first N-type transistor 211 and the first P-type transistor A voltage Vout−VT is output to a connection node (N2) between the terminal 212 and the terminal 212.

  In this example, the voltage of Vout−VT is the first feedback signal (S1). Note that VT is a threshold voltage of the first N-type transistor 211.

(3) The second feedback signal generation circuit 222 outputs a second feedback signal (S2) based on the first feedback signal (S1).

(4) Since the voltage of Vout + VT is applied to the gate of the first driving transistor 101, VGS = VG−VS = (Vout + VT) −Vout = VT of the first driving transistor 101, and the voltage of the output terminal 10 is further increased. The power supply voltage (VM) is controlled to be close to 1.

  In the pre-driver circuit 200 of FIG. 1, even if a current (a regenerative current when the load 400 is a motor) flows from the output terminal 10 to the output monitor circuit 213, the output monitor circuit 213 feeds back only the voltage. Therefore, it is possible to suppress the influence on the control of the drive circuit 300 without being affected by the current. Thereby, for example, in the drive circuit 300, malfunction or destruction of elements in the internal circuit can be prevented.

  Since the output monitor circuit 213 of the pre-driver circuit 210 is configured as a source follower, a high-speed response to an input signal is possible, whereby a current flowing from the output terminal 10 to the output monitor circuit 213 is driven. It is possible to suppress the influence of the delay due to the feedback on the control of the drive circuit 300 while suppressing the influence on the 300.

  In this example, in order to simplify the description, the threshold voltages of the first drive transistor 101 and the first N-type transistor 211 are substantially equal, and the second feedback signal generation circuit 222 is It is assumed that 2 × VT is added to the feedback signal (S1) of 1 and output. However, the present invention is not limited to this. Even if the threshold voltages of the transistors are different, the second feedback signal is not limited. Similar control is possible by appropriately setting how much the first feedback signal (S1) is shifted by the generation circuit 222.

[Second example]
A second embodiment of the present invention will be described with reference to FIG. In addition, about the same part as the 1st example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

<Circuit configuration>
In FIG. 2, the first feedback signal generation circuit 210 includes a voltage shift circuit 214. The voltage shift circuit 214 outputs a signal obtained by shifting a voltage appearing at a connection node (N2) between the first N-type transistor 211 and the first P-type transistor 212 of the output monitor circuit 213 by a predetermined amount. As a feedback signal (S1).

  The second feedback signal generation circuit 222 is configured by a second N-type transistor 223. The second N-type transistor 223 has a drain connected to the other end of the first switching circuit 221, a source connected to the first driving transistor 101, and a gate to which the first feedback signal (S1) is input. The

<Circuit operation>
The operation of the pre-driver circuit 200 in FIG. 2 will be described.

  In the following description of the operation, the threshold voltages of the first N-type transistor 211 and the second N-type transistor 223 are substantially the same (= VT). The voltage shift circuit 214 outputs a signal obtained by shifting the voltage of the connection node (N2) between the first N-type transistor 211 and the first P-type transistor 212 by 3 × VT as the first feedback signal ( Consider the case of outputting as S1).

(1) First, the first switching circuit 221 is turned on by the input signal SIN, and the drain terminal of the second N-type transistor 223 is pulled up to VG. The N-type transistor 223 is a circuit that clamps the source terminal with the signal S2-VT.

(2) Since the output monitor circuit 213 includes two source followers, the first N-type transistor 211 and the first P-type transistor 212, the first N-type transistor 211 and the first P-type transistor A voltage Vout−VT is output to a connection node (N2) between the terminal 212 and the terminal 212. Accordingly, the voltage shift circuit 214 outputs the first feedback signal (S1) of Vout−VT + 3 × VT = Vout + 2VT to the second N-type transistor 223.

(3) Since the second N-type transistor 223 is a source follower, it is a signal obtained by subtracting the first feedback signal (S1) (= Vout + 2VT) by the threshold voltage VT of the second N-type transistor 223. A certain Vout + VT is output as the second feedback signal S2.

(4) When the voltage of S2 is applied to the gate of the first drive transistor 101, the first drive transistor 101 is turned on and the voltage Vout at the output terminal rises.

(5) Since the voltage of Vout + VT is applied to the gate of the first drive transistor 101, VGS = VG−VS = (Vout + VT) −Vout = VT of the first drive transistor 101, and the voltage of the output terminal is further increased to the first voltage. It is controlled so as to be close to the power supply voltage VM.

  In this example, the threshold voltages of the first N-type transistor 211 and the second N-type transistor 223 are substantially the same (= VT), and the voltage shift circuit 214 is connected to the first N-type transistor 211 and the first P-type. The case where the signal obtained by shifting the voltage of the connection node (N2) between the transistor 212 and the transistor 212 by 3 × VT has been output as the first feedback signal (S1). However, the present invention is not limited to this. Similar control can be performed by appropriately setting a predetermined amount to be shifted by the voltage shift circuit 214 according to the threshold voltages of the N-type transistor 211 and the second N-type transistor 223.

[Third example]
A third embodiment of the present invention will be described with reference to FIG. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

<Circuit configuration>
The voltage shift circuit 214 includes a second P-type transistor 215, a third P-type transistor 216, and a fourth P-type transistor 217.

  The second P-type transistor 215 has a drain connected to a connection node (N2) between the first N-type transistor 211 and the first P-type transistor 212, and a gate connected to the drain.

  The third P-type transistor 216 has a drain connected to the source of the second P-type transistor 215 and a gate connected to the drain.

  The fourth P-type transistor 217 has a drain connected to the source of the third P-type transistor 216, a gate connected to the drain, and a source connected to a voltage (V5) higher than the first power supply voltage (VM). The first feedback signal (S1) is output from the source.

  The threshold voltages (VT) of the first N-type transistor 211 and the second N-type transistor 223, the first to fourth P-type transistors 212, 215, 216, and 217, and the first drive transistor 101 are substantially the same. Is set to

  Since the second to fourth P-type transistors 215, 216, and 217 have three diode-connected P-type transistors connected in series, a signal obtained by adding 3 × VT to the input voltage (voltage) Value) as a first feedback signal (S1).

<Circuit operation>
An operation of the pre-driver circuit 200 in FIG. 3 will be described.

(1) First, the first switching circuit 221 is turned on by the input signal SIN, and the drain terminal of the second N-type transistor 223 is pulled up to VG. The second N-type transistor 223 is a circuit that clamps the source terminal with the signal S2-VT.

(2) Since the output monitor circuit 213 is a source follower composed of the first N-type transistor 211 and the first P-type transistor 212, the first N-type transistor 211 and the first P-type transistor A voltage of VOUT−VT is output to a connection node (N2) between the transistor 212 and the transistor 212. The voltage shift circuit 214 outputs a first feedback signal (S1) of VOUT−VT + 3 × VT = VOUT + 2VT to the second N-type transistor 223.

(3) Since the second N-type transistor 223 is a source follower, VOUT + VT, which is a signal obtained by subtracting the first feedback signal S1 (= VOUT + 2VT) by the threshold voltage VT of the second N-type transistor 223, is obtained. It outputs as a 2nd feedback signal (S2).

(4) When the voltage of the second feedback signal (S2) is applied to the gate of the first drive transistor 101, the first drive transistor 101 is turned on and the voltage Vout of the output terminal 10 increases.

(5) Since the voltage of Vout + VT is applied to the gate of the first drive transistor 101, VGS = VG−VS = (Vout + VT) −Vout = VT of the first drive transistor 101, and the voltage of the output terminal 10 is further increased. Control is performed to approach the first power supply voltage (VM).

  In this example, the second feedback signal (S2) can be controlled to Vout + VT passively and at high speed according to the voltage of the output terminal 10.

[Fourth example]
A fourth embodiment of the present invention will be described with reference to FIG. In addition, about the same part as each example mentioned above, the description is abbreviate | omitted and the same code | symbol is attached | subjected.

  The drive signal generation circuit 220 includes a second switching circuit 224 connected between the other end of the first switching circuit 221 and the gate of the first drive transistor 101.

  The second switching circuit 224 is configured by a PMOS. The gate of this PMOS is controlled by the output of a comparator that compares the output voltage of N1 and VM so that the gate is turned on when the output voltage of the connection node (N1) approaches the first power supply voltage (VM).

  The second switching circuit 224 detects that the voltage (Vout) appearing at the output terminal 10 is close to the first power supply voltage (VM), and detects the other end of the first switching circuit 221 and the first switching circuit 221. The gate of the driving transistor 101 is short-circuited.

  By having the second switching circuit 224, if the second switching circuit 224 is turned on, the drive signal (S3) becomes VG, and the first and second feedback signals (S1, S2) do not depend on the first. It becomes possible to control the drive transistor 101 of the full-on.

DESCRIPTION OF SYMBOLS 1 Driver circuit 2 High-side pre-driver circuit 3 Bridge circuit 4 Load 5 Push-pull circuit 6 Buffer circuit 7 Low-side pre-driver circuit 10 Output terminal 100 Bridge circuit 101 1st drive transistor 102 2nd drive transistor 200 Pre-driver circuit 210 First feedback signal generation circuit 211 First N-type transistor 212 First P-type transistor 213 Output monitor circuit 214 Voltage shift circuit 220 Drive signal generation circuit 221 First switching circuit 222 Second feedback signal generation circuit 223 Second N-type transistor 224 Second switching circuit 300 Drive circuit 400 Load 500 Second driver transistor pre-driver circuit S1 First feedback signal S2 Second feedback signal

Claims (6)

A pre-driver connected to a bridge circuit whose output terminal is a connection node connected to a load between the first drive transistor connected to the first power supply voltage and the second drive transistor connected to the ground A circuit,
An output monitor circuit connected to the output terminal, which is the connection node, and generates a first feedback signal that feeds back only the voltage based on the voltage appearing at the output terminal using the output monitor circuit; 1 feedback signal generating means;
First feedback signal the generated is input, and a second feedback signal generating means for generating a second feedback signal for controlling driving of the pre-Symbol first driving transistor,
A first switching means that has one end connected to a voltage higher than the first power supply voltage and the other end connected to the second feedback signal generating means;
The second feedback signal is output as a drive signal to the gate of the first drive transistor from the drive signal generation means constituted by the first switching means and the second feedback signal generation means ,
The second feedback signal generating means includes
A predriver characterized in that a drain is connected to the other end of the first switching means, a source is connected to the first driving transistor, and a first feedback signal is input to the gate. circuit. A pre-driver connected to a bridge circuit whose output terminal is a connection node connected to a load between the first drive transistor connected to the first power supply voltage and the second drive transistor connected to the ground A circuit,
An output monitor circuit connected to the output terminal, which is the connection node, and generates a first feedback signal that feeds back only the voltage based on the voltage appearing at the output terminal using the output monitor circuit; 1 feedback signal generating means;
Second feedback signal generating means for receiving the generated first feedback signal and generating a second feedback signal for driving and controlling the first driving transistor;
A first switching unit that has one end connected to a voltage higher than the first power supply voltage and the other end connected to the second feedback signal generating unit;
With
The second feedback signal is output as a drive signal to the gate of the first drive transistor from the drive signal generation means constituted by the first switching means and the second feedback signal generation means,
The first feedback signal generating means includes
A pre-driver circuit , further comprising a voltage shift circuit that outputs a signal obtained by shifting a voltage appearing at an output node of the output monitor circuit by a predetermined amount as the first feedback signal . A pre-driver connected to a bridge circuit whose output terminal is a connection node connected to a load between the first drive transistor connected to the first power supply voltage and the second drive transistor connected to the ground A circuit,
An output monitor circuit connected to the output terminal, which is the connection node, and generates a first feedback signal that feeds back only the voltage based on the voltage appearing at the output terminal using the output monitor circuit; 1 feedback signal generating means;
Second feedback signal generating means for receiving the generated first feedback signal and generating a second feedback signal for driving and controlling the first driving transistor;
A first switching unit that has one end connected to a voltage higher than the first power supply voltage and the other end connected to the second feedback signal generating unit;
With
The second feedback signal is output as a drive signal to the gate of the first drive transistor from the drive signal generation means constituted by the first switching means and the second feedback signal generation means,
The drive signal generation means includes
Second switching means for detecting that the voltage appearing at the output terminal is close to the first power supply voltage and short-circuiting the other end of the first switching means and the gate of the first driving transistor. A pre-driver circuit characterized by further comprising: The output monitor circuit includes:
A first N-type transistor having a drain connected to a voltage higher than the first power supply voltage and a gate connected to the output terminal;
A first P-type transistor having a drain connected to a voltage lower than the first power supply voltage, a gate connected to the output terminal, and a source connected to a source of the first N-type transistor;
The first feedback signal generation means generates the first feedback signal based on a voltage appearing at a connection node between the first N-type transistor and the first P-type transistor of the output monitor circuit. predriver circuit according to any one of claims 1 to 3, characterized in that. The voltage shift circuit includes:
An input terminal to which a voltage appearing at an output node of the output monitor circuit is input;
An output terminal connected to a voltage higher than the first power supply voltage and outputting the first feedback signal;
A plurality of P-type transistors connected in series as diodes and connected between the input terminal and the output terminal;
The pre-driver circuit according to claim 2 , comprising: A bridge circuit having at least a first drive transistor connected to a first power supply voltage and a second drive transistor connected to ground;
A connection node between said first driving transistor and second driving transistor, and a pre-driver circuit according to any one of claims 1 to 5 is connected between the gate of said first driver transistor A drive circuit characterized by comprising:

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