Gate drive circuit

Abstract

The present invention relates to a gate drive circuit. The present invention provides a high-side driver of a gate drive circuit with a simpler circuit structure and using an N-channel MOSFET. A high-side driver circuit for driving a power semiconductor switch comprises: a main switch N-channel MOSFET, a drain terminal connected to the positive side Vdc of a power supply, and a source terminal connected to the OUT terminal of a signal for driving the power semiconductor switch; a charge storage circuit for storing charge from Vdc; a switch with a voltage detection function for detecting a voltage difference between an output terminal of the charge storage circuit and Vdc, and applying a part or all of the output voltage of the charge storage circuit to the gate terminal of the main switch N-channel MOSFET when it is detected that the output terminal voltage of the charge storage circuit is higher than the voltage of the positive side Vcc of the power supply by a certain voltage or more.

Description

Technical Field

[0001] The present invention relates to a gate drive circuit for driving a power semiconductor switch such as an IGBT. Background Art

[0002] For power devices such as high-power inverters or DCDC converters, high-frequency high-power switching elements are often used. As high-frequency high-power switching elements, IGBT (Insulated Gate Bipolar Transistor) or MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is often used. In many cases, the input characteristics of the driving terminal (for example, the gate terminal) of such elements are capacitive, and a large current must flow when driving.

[0003] Therefore, various circuits have been proposed for driving these high-frequency high-power switching elements. Such circuits are often referred to as gate drive circuits. The present invention relates to an improved high-side driver used in such a gate drive circuit.

[0004] Existing technologies and their problems

[0005] exist Figure 7 , Figure 8 An example of a conventional gate drive circuit for driving the high-frequency high-power switching element as described above is shown in FIG.

[0006] Figure 7 The gate drive circuit 3 shown is a circuit using a P-channel MOSFET 1 (hereinafter referred to as Q1) as an element for driving the IGBT 2 to turn on. Q1 performs an ON operation by making its gate voltage lower than the source voltage. As a result, Q1 is turned on and a Vcc voltage appears at the drain terminal. This Vcc voltage is applied to the gate terminal of the IGBT 2 via the resistor 11 and the output terminal 7.

[0007] Therefore, by making Figure 7 The IN terminal 5 of Q1 is at a low level (LOW), so that Q1 can be turned on. Then, when Q1 is turned on, IGBT2 can be turned on as described above.

[0008] Like this, according to Figure 7 The gate drive circuit 3 having the circuit configuration shown can turn on (or turn off) the IGBT 2 using the input potential of the IN terminal 5 .

[0009] However, generally, P-channel MOSFETs tend to have fewer varieties and larger ON resistance than N-channel MOSFETs. Figure 7 Q1 in the circuit is a circuit that uses an N-channel MOSFET to turn on the IGBT2, and thus improvement in performance can be expected.

[0010] According to this situation, Figure 8 The gate drive circuit of the circuit structure shown is also used. Figure 8 The gate drive circuit 3a is constructed by using an N-channel MOSFET for Q1a in the circuit. In order to turn on the N-channel MOSFET, its gate potential must be higher than the source potential. On the other hand, Figure 8 The source voltage of Q1a in the gate drive circuit 3a rises to the vicinity of the positive side voltage Vcc of the power supply. Figure 8 is supplied to the positive voltage terminal 4, Figure 7 Similarly, the positive side voltage Vcc is supplied to the positive side voltage terminal 4.

[0011] Therefore, a bootstrap circuit and a level shift circuit as described below are constructed to produce a circuit for making Figure 8 The gate potential of Q1a in the circuit rises to a high potential which is a voltage higher than the source potential.

[0012] exist Figure 8 In the example of the circuit configuration shown in FIG. 1 , a series circuit of a diode 12 (hereinafter referred to as D1) and a capacitor 13 (hereinafter referred to as C1) is formed as follows. Figure 8 Then, when the OUT terminal 7 is at the GND potential, the charge is accumulated in C1, and when the IN terminal 5 is set to the high level (High) and Q1a is turned on, the output side transistor of the photocoupler 10 for level shifting (hereinafter referred to as PC1) is turned on, and the charge charged in C1 is applied to the gate terminal of Q1a. Thus, when Q1a is turned on and the voltage of the OUT terminal 7 rises, the terminal voltage at the point where C1 is connected to the cathode side of D1 is higher than Vcc, and a voltage higher than Vcc can be applied to the gate terminal of Q1a.

[0013] According to this method, a power supply at a high potential that drives Q1a can be made relatively easily using D1 and C1. However, in order to use this high voltage power supply to turn Q1a on, it is necessary to study the circuit. For example, using a photocoupler ( Figure 8There are studies such as using an insulating element such as PC1 in the circuit to insulate the high voltage power supply from the input potential of the IN terminal 5 or using a level shift circuit to set a switch to shift the voltage level from the high voltage power supply. If such studies are not carried out, it is difficult to make a circuit that uses the input potential of the IN terminal 5 to turn Q1a on and off.

[0014] Existing patented technology

[0015] For example, Patent Document 1 (Japanese Patent No. 6303060) described later discloses a gate drive circuit using a P-channel MOSFET and an N-channel MOSFET, and particularly discloses a circuit configuration characterized in that an input signal is supplied to the P-channel MOSFET via a level shift circuit.

[0016] Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-270382) described later discloses a circuit configuration for supplying power from a floating power supply to a high-side driver, which is characterized by utilizing a level shift circuit capable of high-speed operation.

[0017] Patent Document 3 (Japanese Patent Application Laid-Open No. 2000-286687) described later discloses a circuit configuration for supplying power from a floating power supply to a high-side driver, which is characterized by using a level shift circuit that can prevent malfunction without increasing chip area or power consumption.

[0018] Prior art literature

[0019] Patent Literature

[0020] Patent document 1: Japanese Patent No. 6303060;

[0021] Patent document 2: Japanese Patent Application Publication No. 2006-270382;

[0022] Patent document 3: Japanese Patent Application Publication No. 2000-286687. Summary of the invention

[0023] Problems to be solved by the invention

[0024] As described above, in the gate drive circuit, when a P-channel MOSFET is used as a main switch, the performance is insufficient, so N-channel MOSFET is often used, and a high-potential power supply for driving the N-channel MOSFET can be made relatively simply. However, in order to use this high-voltage power supply to drive the N-channel MOSFET, an insulating component or a voltage shift circuit for eliminating the voltage difference with the input signal is required, and the circuit is complicated and expensive, and it is also considered that the sufficient improvement effect brought by the use of the N-channel MOSFET cannot be obtained.

[0025] The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-side driver having a simpler circuit structure and a gate drive circuit using an N-channel MOSFET.

[0026] Solutions to Solve Problems

[0027] (1) To solve the above-mentioned problems, the present invention provides a high-side driver, which is a circuit for driving a power semiconductor switch, wherein the high-side driver comprises: a main switch N-channel MOSFET, a drain terminal of which is connected to a positive side Vdc of a power supply of the circuit, and a source terminal of which is connected to an OUT terminal, the OUT terminal being a terminal for outputting a signal for driving the power semiconductor switch; a charge storage circuit for storing charge by injecting a current from the positive side Vdc of the power supply of the circuit; and a switch with a voltage detection function for operating by detecting a voltage difference between an output terminal of the charge storage circuit and the positive side Vdc of the power supply of the circuit, wherein, when the switch with the voltage detection function detects that a voltage at the output terminal of the charge storage circuit is higher than a voltage at the positive side Vdc of the power supply of the circuit by a certain voltage or more, the switch with the voltage detection function applies a part or all of the output voltage of the charge storage circuit to a gate terminal of the main switch N-channel MOSFET, thereby turning on the main switch N-channel MOSFET.

[0028] (2) In addition, the present invention is a high-side driver as described in (1), comprising: a startup P-channel MOSFET connected in parallel with the main switch N-channel MOSFET, having a source terminal connected to the positive side Vdc of the power supply and a drain terminal connected to the OUT terminal; and an ON signal input terminal to which a signal for turning on the power semiconductor switch is input and connected to the gate terminal of the startup P-channel MOSFET, wherein when the signal for turning on the power semiconductor switch is input to the ON signal input terminal, the startup P-channel MOSFET turns on. When the startup P-channel MOSFET turns on, the voltage of the OUT terminal rises, the switch with a voltage detection function detects that the output terminal voltage of the charge storage circuit is higher than the positive side Vdc voltage of the power supply of the circuit by a certain voltage or more, and applies a part or all of the output voltage of the charge storage circuit to the gate terminal of the main switch N-channel MOSFET, thereby turning on the main switch N-channel MOSFET.

[0029] (3) In addition, the present invention is a high-side driver described in (1) or (2) above, wherein the switch with voltage detection function has an internal switch, and when the switch with voltage detection function detects that the output terminal voltage of the charge storage circuit is higher than the voltage of the positive side Vdc of the power supply of the circuit by a certain voltage or more, the internal switch is turned on and a part or all of the output voltage of the charge storage circuit is applied to the gate terminal of the main switch N-channel MOSFET.

[0030] (4) In addition, the present invention is a high-side driver as described in any one of the above (1) to (3), wherein the high-side driver comprises: an OFF signal input terminal for inputting a signal for causing the power semiconductor switch to perform an OFF operation; a voltage conversion circuit connected between the positive side Vdc of the power supply of the circuit and the OFF signal input terminal, and performing voltage conversion by dividing the voltage between the positive side Vdc of the power supply of the circuit and the OFF signal input terminal and / or subtracting a certain value; a backflow prevention circuit provided between the gate terminal of the main switch N-channel MOSFET and the gate charge extraction MOSFET, and allowing current to flow only in a direction from the gate terminal of the main switch N-channel MOSFET toward the gate charge extraction MOSFET; and the gate charge extraction MOSFET SFET, the drain terminal is connected to the backflow prevention circuit, the source terminal is connected to the OFF signal input terminal, and the gate terminal is connected to the output terminal that outputs the voltage converted by the voltage conversion circuit. The drain terminal of the gate charge extraction MOSFET is connected to the gate terminal of the main switch N-channel MOSFET via the backflow prevention circuit, and a signal for turning off the power semiconductor switch is input to the OFF signal input terminal. When the voltage of the OFF signal input terminal drops from the positive side Vdc of the power supply of the circuit, the output voltage of the output terminal that outputs the voltage converted by the voltage conversion circuit rises, the charge extraction MOSFET turns on, and the main switch N-channel MOSFET turns off.

[0031] Effects of the Invention

[0032] According to the present invention, it is possible to provide a high side driver having a simpler structure than conventional ones without using an insulating element or the like, and further, it is possible to configure a gate driving circuit using the high side driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1A This is an explanatory diagram showing a circuit configuration of Principle 1 in this embodiment.

[0034] Figure 1B This is an explanatory diagram showing a circuit configuration of a modified example of Principle 1 in this embodiment.

[0035] Figure 2 This is an explanatory diagram showing a circuit configuration according to Principle 2 in this embodiment.

[0036] Figure 3 This is a graph showing changes in gate voltage when an IGBT or the like transitions to an ON operation.

[0037] Figure 4 This is an explanatory diagram showing a circuit configuration according to Principle 3 in this embodiment.

[0038] Figure 5A It is a diagram showing a specific example of a charge storage circuit.

[0039] Figure 5B It is a diagram showing a specific example of a charge storage circuit.

[0040] Fig. 6A This is a circuit diagram showing an example of a specific circuit configuration of a gate driving circuit in this embodiment.

[0041] Figure 6B This is a circuit diagram showing an example of a specific circuit configuration of a gate driving circuit when a modification example of Principle 1 is used in this embodiment.

[0042] Figure 7 This is a circuit diagram of a conventional gate drive circuit using a P-channel MOSFET.

[0043] Figure 8 This is a circuit diagram of a conventional gate drive circuit using an N-channel MOSFET instead of a P-channel MOSFET. DETAILED DESCRIPTION

[0044] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

[0045] First, after explaining three principles of the present invention, a high side driver of a gate drive circuit as a specific embodiment of the present invention will be explained.

[0046] 1. Principle 1

[0047] Figure 1A 1 is a block diagram for explaining the principle 1 for solving the above-mentioned problems in this embodiment. Figure 1AIn the figure, the gate drive circuit 26 involved in the present principle 1 is depicted, and the IGBT 27 driven by the gate drive circuit 26 is also depicted. In addition, in order to make the description easy to understand, the high-side driver as a characteristic structure is depicted in the center, and the circuit structure parts of the gate drive circuit that are the same as before are omitted and not shown because they have the same functions as before.

[0048] like Figure 1A As shown in the illustration of the present principle 1 ( Figure 1A ) in the gate drive circuit 26, in addition to the N-channel MOSFET 21 (hereinafter referred to as Q21) as the main switch, it also includes a charge storage circuit 23 and a switch 22 with a voltage detection function. Q21 literally corresponds to a preferred example of the main switch N-channel MOSFET in the technical solution.

[0049] First, in Figure 1A In FIG. 1 , the OUT terminal 25 is an output terminal, and its output voltage swings between a voltage lower than GND and a positive voltage Vdc. Figure 1A The source terminal of Q21, the main switch of the gate drive circuit 26, is connected to the OUT terminal 25, and the drain terminal thereof is connected to the positive voltage Vdc. When the gate voltage of Q21 is higher than the OUT terminal 25 (i.e., the source terminal) by Vgson (a certain value), Q21 turns on and outputs a high voltage (=approximately Vdc voltage) to the OUT terminal 25. Here, Vgson refers to the gate threshold voltage of Q21.

[0050] The charge accumulation circuit 23 accumulates charge, but the pin for accumulating charge is different from the pin for discharging charge.

[0051] First, when the OUT terminal 25 (connected to the c pin) is at a low potential (= approximately GND or a voltage lower than GND), the charge is accumulated by receiving a current supply from the a pin connected to the positive side voltage Vdc. Then, the accumulated charge is superimposed on the potential of the OUT terminal 25 and is output from the b pin without flowing back to Vdc. Therefore, with respect to the potential of the b pin, the potential is higher than the potential of the OUT terminal 25 (the source potential of Q1) by the amount of voltage corresponding to the accumulated charge. The b pin is connected to the e pin of the switch 22 with a voltage detection function described next. Specific examples of the charge accumulation circuit 23 are shown in Figures 5a and 5b, which will be described in detail later. Representative examples are given in these specific examples, and other circuit structures may also be used.

[0052] then, Figure 1AThe d pin of the switch 22 with voltage detection function is connected to the positive voltage terminal 24 (Vdc), the e pin is connected to the b pin of the charge storage circuit 23, and the f pin is connected to the gate terminal of Q21. Under such a connection relationship, the switch 22 with voltage detection function monitors the voltage between the d pin (that is, the positive voltage Vdc) and the e pin. As a result of the monitoring, when the voltage of the e pin is higher than the voltage of the d pin by a predetermined value or more, that is, when the voltage of the e pin is higher than Vdc by a predetermined voltage, the switch built in itself is turned on and the voltage of the e pin is supplied to the f pin. Since the voltage corresponding to the charge accumulated in the charge storage circuit 23 is supplied from the b pin to the e pin, the switch built in the switch 22 with voltage detection function is turned on, thereby, part or all of the voltage corresponding to the accumulated charge can be applied between the gate and the source of Q21. As a result, a voltage higher than Vdc is applied to the gate (source) of Q21, and when the gate-source voltage of Q21 is equal to or higher than Vgson, Q21 turns on.

[0053] When the OUT terminal 25 rises from a low potential to Vdc, the charge storage circuit 23 uses the accumulated charge to superimpose the voltage between the b pin and the c pin on the voltage of the OUT terminal 25 and output it from the b pin. This is because the c pin is connected to the OUT terminal 25. The voltage output in this way is superimposed on the voltage of the OUT terminal 25, so if the potential of the OUT terminal 25 rises, the voltage of the b pin also rises with it. When the voltage of the OUT terminal 25 is closer to Vdc, the voltage of the e pin of the switch 22 with a voltage detection function exceeds the voltage of the d pin (that is, the positive side voltage Vdc) and rises. When the voltage difference exceeds the specified value, the switch built into the switch 22 with a voltage detection function turns on, and a part or all of the output voltage of the charge storage circuit 23 is applied to the gate terminal of Q21. That is, the built-in switch is a switch that functionally connects the e pin and the f pin, and when the built-in switch is turned on, all or part of the output voltage of the charge storage circuit 23 (b pin = e pin) is supplied to the f pin (= gate terminal of Q21). The built-in switch mentioned here corresponds to a preferred example of an internal switch in the technical solution.

[0054] Here, the voltage output to the b pin (the voltage between the b pin and the c pin) by the charge accumulated in the charge accumulation circuit 23 is represented by V CH , a predetermined value (threshold voltage) of a voltage difference exceeding Vdc set in the switch 22 with a voltage detection function is set to V DET .

[0055] Then, the voltage VO of the OUT terminal 25 when the switch built in the switch with voltage detection function 22 is turned on is ON It is expressed by the following formula (1). When Q21 is turned on, the output voltage of the OUT terminal 25 rises rapidly due to the turning on of Q21 and finally reaches approximately Vdc.

[0056] VO ON =V DET -V CH +Vdc (1)

[0057] Here, the voltage between the gate terminal and the source terminal for turning on Q21 is Vgson, and k is a constant, and the following equation (2) holds.

[0058] V CH ≥k×Vgson (2)

[0059] Here, k is a constant indicating the ratio of the output voltage of the charge storage circuit 23 applied to the gate terminal of Q21. k is a constant equal to or less than 1. When the entire output voltage of the charge storage circuit 23 is applied to the gate terminal of Q21, k=1. When 1 / 2 of the output voltage of the charge storage circuit 23 is applied to the gate terminal of Q21, k=1 / 2. In this way, a part or all of the output voltage of the charge storage circuit 23 is applied to the gate terminal of Q21.

[0060] For example, when the voltage V of the b pin of the charge storage circuit 23 is set according to the stored charge CH V CH = Vdc and the threshold voltage of the switch 22 with voltage detection function is V DET = Vdc / 2, according to equation (1), the voltage VO at the OUT terminal 25 when Q21 turns on ON For VO ON = Vdc / 2. When the output voltage of OUT terminal 25 reaches VO ON = Vdc / 2, the built-in switch of the switch 22 with voltage detection function turns on, and becomes (1 / k)×V CH A voltage of is applied between the gate terminal and the source terminal of Q21. Therefore, if the above equation (2) holds, Q21 performs an ON operation.

[0061] As explained above, Figure 1A The high-side driver of the structure shown has the following function: when its own output voltage, that is, the voltage of the OUT terminal 25 is above a certain level, it autonomously performs an ON operation and maintains the ON operation state without using an insulating element such as a voltage shift circuit or a photocoupler.

[0062] Furthermore, if Figure 1A As shown, the f pin is connected to the gate terminal of Q21. However, a resistor 29 may be provided between the gate terminal and the source terminal, but this is not an essential structure.

[0063] 1.2 Variations of Principle 1

[0064] In the above-mentioned principle 1, the terminal c of the charge storage circuit 12 is connected to the OUT terminal 25. Therefore, the increase in the voltage at the OUT terminal 25 is applied to the terminal c. Figure 1B As shown in FIG. 1 , the c terminal of the charge storage circuit 12 may be connected to the OFF signal input terminal 34 instead of the OUT terminal 25. Figure 4 , Details of the OFF signal input terminal 34 and the signal input thereto are described in the description of Principle 3.

[0065] In using Figure 1A In the case of the circuit of principle 1 described in the above, as described later Figure 2 As shown, it is preferable to combine a startup P-channel MOSFET for startup. With such a structure, the IGBT can be driven more rationally. The details will be described later in 2. Principle 2.

[0066] In contrast, according to Figure 1B A modification of the principle 1 shown in FIG. Figure 1B ),and Figure 1A The circuit structure shown is different, and it is not necessary to combine a P-channel MOSFET, and a simpler circuit structure can be made. However, the case where the IGBT to be driven must be continuously turned on is excluded.

[0067] 2. Principle 2

[0068] Figure 2 This is a diagram for explaining another principle 2 of this embodiment, which is to combine a semiconductor switch with a small capacitance (a P-channel MOSFET for startup) with the above Figure 1A Thus, a high-side driver capable of more reasonably driving the gate drive circuit of the IGBT can be provided.

[0069] IGBT Operation

[0070] The gate circuit of a semiconductor switch such as an IGBT goes through roughly three states when switching from OFF to ON. Figure 3 A graph schematically showing this process is shown in . This graph is a graph showing the increase of the gate voltage over time. First, in region A, the IGBT is in the OFF state, and this is a region where only the gate voltage increases.

[0071] Region B is the time period when the IGBT transitions from OFF action to ON action. In this region, the rise of the gate voltage is temporarily eased. In this region B is the time period when the transition to ON action is in progress and the collector potential of the IGBT decreases. In this region B is the time period when the discharge current of the charge of the feedback capacitor of the IGBT needs to be provided, so region B is the time period when a large drive current is required. Generally, the output current of the gate drive circuit of the IGBT is limited, so a certain amount of time is required before the charge of the feedback capacitor is discharged. This time period can also be considered as region B.

[0072] Region C is a state where the voltage between the collector terminal and the emitter terminal of the IGBT is substantially saturated (collector potential is sufficiently reduced). This region C is a region where the ON operation of the IGBT is more reliable only if the gate voltage is further increased.

[0073] Figure 2 (Principle 2) Viewpoint

[0074] In order to quickly switch the IGBT from the OFF state to the ON state, a sufficiently large drive current is required in region B compared to region A or region C. Figure 2 The high-side driver of the gate drive circuit of the principle shown in FIG. 1 is a circuit independently invented by the inventor of the present application as one of the circuits that reasonably meet the requirement for increasing the gate voltage more quickly in view of the characteristics of such IGBTs.

[0075] Figure 2 The structure of FIG. 1 is substantially the same as that of FIG. 1 , but is different in that a startup P-channel MOSFET 30 is newly added and an ON signal is applied to the startup P-channel MOSFET 30 (hereinafter referred to as Q22). Q22 corresponds to a preferred example of a startup P-channel MOSFET in the technical solution. The source terminal of Q22 is connected to Vdc (positive side voltage terminal 24), and the drain terminal is connected to OUT terminal 25. Resistor 29b is connected between Vdc and the gate terminal, and an ON signal is supplied to the gate terminal.

[0076] The following explains Figure 2 The action of the circuit structure.

[0077] when Figure 2 When the ON signal input terminal 28 shown in FIG. 2 is at a low level (LOW), Q22 switches from the OFF state to the ON state. Then, the voltage of the OUT terminal 25 starts to rise toward Vdc. This period is Figure 3 Area A. Furthermore, in Figure 2 However, the IGBT to be driven is connected to Figure 2The region object A mentioned here means the region A of the IGBT which is the driving object.

[0078] Then, when the voltage of the OUT terminal (gate voltage of the IGBT not shown) reaches the gate threshold voltage of the IGBT to be driven, it enters the region B as described above. The voltage V of the b pin of the charge storage circuit 23 is appropriately set based on the above equations (1) and (2). CH and the threshold voltage V of the switch with voltage detection function DET , so that Q21 of the gate drive circuit turns on at this time.

[0079] The proper setting means that Q21 is set to turn on when the IGBT enters region B. Specifically, the gate voltage of the IGBT to be driven when it enters region B corresponds to VO in equation (1). ON , Vdc is determined by design, and according to formula (2), using coefficient k, V is determined according to Vgson of Q21 CH Therefore, based on these values, we can find V in equation (1): DET . Simply set the voltage values ​​in this calculation.

[0080] In the high-side driver set in this way, when the IGBT to be driven enters region B, Q21 turns on, so that a large current can be supplied to the gate terminal of the IGBT to be driven, and the IGBT to be driven can be driven at high speed. When the charge storage circuit 23 of the high-side driver discharges the stored charge, the ON operation of Q21 cannot be maintained, and Q21 turns off. However, if the discharge time constant of the stored charge is set to the time when the IGBT to be driven passes through region B (see Figure 3 ) time is set to be long, the requirement for turning on the IGBT can be met. Figure 3 ), it is not necessary to supply a large current to the gate terminal of the IGBT to be driven, so it is sufficient for Q22, which is a P-channel MOSFET in region C, to supply current. In other words, the IGBT can be driven sufficiently.

[0081] Like this, according to Figure 2 In the circuit structure shown, an N-channel MOSFET (i.e., Q21) capable of handling large current is used for the current supply in area B, and a P-channel MOSFET (i.e., Q22) whose current value is not as high as that of the N-channel MOSFET but to which the power supply voltage Vdc can be applied using a simple circuit is used in areas A and C, thereby achieving reasonable high-speed switching of the IGBT.

[0082] Furthermore, in Figure 2 The feature common to FIG. 1 that the N-channel MOSFET (Q21) of the main switch can be driven without using a photocoupler or a voltage shift circuit can also be efficiently utilized. The present invention (Principle 2) can provide a gate drive circuit that is suitable for high-speed driving of an IGBT to be driven and has a simple circuit structure and is inexpensive.

[0083] 3. Principle 3

[0084] Prior to this, in Principle 1 ( Figure 1A ) or Principle 2 ( Figure 2 ) mainly describes the circuits that have characteristics in the operation when the IGBT as the driving object is transferred from the OFF operation to the ON operation state. On the other hand, at the timing when the IGBT as the driving object is transferred from the ON operation to the OFF operation, another circuit is usually required to operate and start to extract the charge of the gate circuit of the IGBT. At this time, the OFF operation of the IGBT cannot be hindered.

[0085] This shows that Principle 3 ( Figure 4 ) is a circuit structure with high noise resistance that meets these requirements. Figure 4 The circuit configuration shown is a circuit configuration in which a voltage conversion circuit 31 , a gate charge extraction MOSFET 32 (hereinafter referred to as Q32 ), and a backflow prevention circuit 33 are added to the circuit configuration shown in FIG. 1 .

[0086] The g pin of the voltage conversion circuit 31 is connected to Vdc, the i pin is connected to the OFF signal input terminal 34, and the h pin is connected to the gate terminal of Q32. The source terminal of Q32 is connected to the OFF signal input terminal 34, and the drain terminal is connected to the backflow prevention circuit 33. The h pin is an output terminal of the voltage conversion circuit 31, which is equivalent to a preferred example of the output terminal in the technical solution.

[0087] One end of the backflow prevention circuit 33 is connected to the drain terminal of Q32, and the other end is connected to the f terminal of the switch 22 with a voltage detection function, that is, the gate terminal of Q21. The backflow prevention circuit 33 may be, for example, a series circuit of a diode and a resistor, wherein the cathode side of the diode is connected to the drain terminal of Q32, and the anode side is connected to the f pin of the switch 22 with a voltage detection function.

[0088] In order not to interfere with the OFF operation of the IGBT to be driven, Q21 must be rapidly turned into the OFF operation state. When the IGBT to be driven transfers from the ON operation to the OFF operation state, the collector current of the IGBT rapidly decreases. Therefore, noise caused by the generated magnetic flux or spike noise caused by the wiring inductance of the collector circuit, etc. is generated in the system. There are cases where these noises overlap with the control circuit or the drive circuit and cause malfunction of the circuit components. Therefore, for the circuit structure used to transfer Q21 from the ON operation to the OFF operation state, it is particularly required to prevent malfunction caused by noise and to have a high tolerance to noise.

[0089] Figure 4 A circuit structure with a high noise tolerance when turning off the main switch, i.e., the N-channel MOSFET 21 (Q21), of the gate drive circuit is shown. The circuit structure shown here is characterized in that the OFF signal input terminal 34 is connected to the source terminal of the gate charge extraction MOSFET 32 (Q32). That is, a structure with the feature that the OFF signal input terminal 34 is connected to the source terminal instead of the gate terminal of Q32 is adopted. The voltage conversion circuit 31 has a voltage conversion function of dividing the voltage between the g pin and the i pin and / or converting the voltage by processing such as subtracting a certain value, etc. That is, the voltage conversion circuit converts the voltage between the g pin and the i pin using a specified structure and outputs the converted voltage between the h pin and the i pin. Among them, the output voltage is a positive voltage. That is, the h pin is a preferred example of the output terminal in the technical solution.

[0090] In the example described later, regarding the voltage conversion function, the process of subtracting a certain voltage is taken as an example for explanation. However, voltage division (resistive voltage division) can also be performed using a resistor, etc. If described by an equation, for example, it is as follows.

[0091] It can also be expressed as follows:

[0092] h pin - i pin voltage = g pin - i pin voltage - certain voltage

[0093] h pin - i pin voltage = (g pin - i pin voltage) × t. Here, the proportionality constant t can be a number in the range of 0 < t ≤ 1. In addition, the processing of both the above can also be applied. That is, voltage division can be performed after subtracting a certain value. In addition, a certain value can be subtracted after voltage division.

[0094] When the voltage of the OFF signal input terminal 34 is near Vdc, the voltage between the g pin and the i pin is substantially 0 V, so the voltage between the h pin and the i pin is also substantially 0 V, and Q32 is in OFF operation. When the voltage of the OFF signal input terminal 34 changes from Vdc to a decreasing direction, a voltage (potential difference) is generated between the g pin and the i pin, and a voltage converted from the voltage is generated between the h pin and the i pin.

[0095] When the voltage of the OFF signal input terminal 34 further decreases, the voltage (difference) between the g pin and the i pin further increases. Along with this, the voltage between the h pin and the i pin also increases, and when it exceeds the gate threshold voltage of Q32, Q32 turns on. When Q32 turns on, the gate charge of Q21 is discharged to the potential of the OFF signal input terminal 34 via the backflow prevention circuit 33. As a result, the gate potential of Q21 becomes a voltage value higher than the potential of the OFF signal input terminal 34 by the voltage drop caused by the backflow prevention circuit 33.

[0096] If the gate potential of Q21 is set lower than the gate threshold voltage (Vgson) of Q21, Q21 turns OFF. As a result of this operation, the bootstrap circuit does not hinder the OFF operation of the IGBT (IGBT connected to the OUT terminal 25 as a driven object) not shown in the figure.

[0097] By turning off Q21, the OFF operation of the IGBT to be driven is not hindered. However, in order to maintain this state, the OFF operation of Q21 must be maintained even when the OUT terminal 25 is at a low voltage. Therefore, when the low voltage of the OUT terminal 25 is set to VO low , the voltage drop of the backflow prevention circuit 22 is set to V dr When the input voltage V INlow The following formula (4) must be satisfied. In addition, for V that satisfies formula (4) INlow For example, according to the necessity of turning on Q32, when the gate threshold voltage of Q32 is set to VgsonQ32 and the conversion equation of the voltage conversion circuit 31 is expressed by equation (3), equation (5) must also be satisfied. Furthermore, the input voltage of the OFF signal input terminal 34 itself is expressed as V IN In addition, Vm represents a certain voltage used for conversion in the voltage conversion circuit 31. In addition, when the gate threshold voltage of Q21 is represented by Vgson, it is the same as the principle 1.

[0098] Therefore, when the following four conditions are assumed, equations (4) and (5) that satisfy the conditions become Figure 4 The high-side driver shown here does not hinder the OFF operation of the IGBT to be driven.

[0099] (Item 1.) Denote the gate threshold voltage of Q32 as VgsonQ32.

[0100] (Item 2.) When the voltage between the h pin and the i pin is set to V hi When , the conversion equation of the voltage conversion circuit 31 is expressed by the following equation (3).

[0101] V hi =Vdc-V IN -Vm (3)

[0102] (Item 3.) Set the voltage drop value of the backflow prevention circuit 33 to V dr .

[0103] (Item 4.) The voltage of OUT terminal 25 when Q21 is in the OFF state is set to VO low Therefore, the above equations (4) and (5) are as follows:

[0104] V INlow <VO low -V dr +Vgson (4)

[0105] V INlow <Vdc-Vm-VgsonQ32 (5).

[0106] Here, the input voltage of the OFF signal input terminal 34 is near Vdc (=15V), Q32 performs OFF action, and Q21 performs ON action. As a result, the output voltage of the OUT terminal 25 is assumed to be in a state near Vdc. Under this premise, there is a command to turn off the IGBT to be driven, and it is considered that the OUT terminal 25 must be below -5V. That is, VO low ≤-5V.

[0107] In order not to interfere with the instruction, if the voltage drop value V dr =2V, Vgson=4V, then according to the above formula (4), V INlow <-3V. Furthermore, when the gate threshold voltage of Q32 is assumed to be VgsonQ32=4V and V INlow =-3V, according to the above formula (5), the constant Vm of the conversion formula of the voltage conversion circuit 31 is obtained to be less than 14V.

[0108] Like this, Figure 4 The high-side driver shown in the figure connects the OFF signal input terminal 34 to the source terminal of the MOSFET 32 (Q32). Therefore, when the OFF signal input terminal 34 is not connected, the voltage of the OFF signal input terminal 34 can be changed from Vdc to V INlow , the state of this circuit will not change to a state that does not hinder the OFF operation of the IGBT that is the drive object.

[0109] That is, in the specific examples of the above-mentioned voltages, if the OFF signal input terminal 34 is not variable from +15V to -3V, the state will not change to a state that does not hinder the OFF operation of the IGBT. This means that Figure 4 The high-side driver of this invention requires a voltage change of 18V to change the state, but when the opposite view is taken, the state is not changed for a voltage change (noise) less than 18V. In other words, it can be said that the noise tolerance is very high.

[0110] Conventionally, in practical circuits, when it is desired to turn off Q21, the input signal is input to the gate terminal of the gate charge extraction MOSFET 32 (Q32), and the source terminal of Q32 is often connected to a fixed potential such as Vee (negative voltage). In such a case, the input signal is initially Vee, and in order to cause a state change (i.e., to turn off Q21), a voltage of about Vee+5V is applied to the gate terminal of Q32 to turn on Q32, thereby turning off Q21.

[0111] However, in such a structure, the voltage between the gate and source of Q32 changes from 0V to 5V, causing Q32 to turn on, and the state of the high-side driver changes. In particular, the input impedance of the gate terminal of the MOSFET is high and noise is easily carried. In this regard, the circuit shown in Principle 3 ( Figure 4 ) can achieve a voltage difference of more than 3 times, and is significantly superior to previous methods in terms of noise resistance characteristics.

[0112] 4. Example of charge storage circuit

[0113] A specific example of the charge storage circuit 23 described above is shown in FIG. Figure 5A , Figure 5B As shown in Figure 1, Figure 2 , Figure 4 As shown in FIG. 1 , the charge storage circuit 23 has a pin a, a pin b, and a pin c. Figure 5AIn the circuit shown in Example 1, a series circuit of a diode D1 and a capacitor C1 is provided between pin a and pin c, and the connection point of the diode D1 and the capacitor C1 is connected to pin b. With such a circuit structure, when pin a is higher than pin c by the voltage drop of the diode D1, charge is accumulated in the capacitor C1, and as a result, a voltage is generated in the capacitor C1. This voltage appears at pin b (between pin c). As already explained, the voltage appearing at pin b is connected to pin e of the switch 22 with a voltage detection function, and is supplied to the gate terminal of Q21 via the switch 22 with a voltage detection function.

[0114] Depend on Figure 5A The circuit shown in Example 2 is a circuit obtained by connecting a Zener diode D2 and a diode D1 in series with the circuit of Example 1. As a result, the capacitor C1 can be charged (charges can be accumulated) with a voltage lower than the voltage drop of the Zener diode D2.

[0115] Depend on Figure 5A The circuit shown in Example 3 is a circuit obtained by connecting a resistor R1 and a diode D1 in series with the circuit of Example 1. As a result, the charging current can be limited by the value of the resistor R1.

[0116] Depend on Figure 5A The circuit shown in Example 4 is a circuit in which a Zener diode D2 and a resistor R1 are connected in series with the diode D1 in the circuit of Example 1. As a result, the capacitor C1 can be charged (charges can be accumulated) with a voltage lower than the voltage drop of the Zener diode D2, and the charging current can be limited by the value of the resistor R1.

[0117] Depend on Figure 5B The circuit shown in Example 5 is a circuit obtained by connecting a resistor R2 and a capacitor C1 in parallel with the circuit in Example 1. As a result, the charge accumulated in the capacitor C1 can be discharged, and the voltage output to the b pin can be reduced with the passage of time.

[0118] Depend on Figure 5B The circuit shown in Example 6 is a circuit in which a resistor R3 is provided between the connection point between the diode D1 and the capacitor C1 and the b pin in comparison with the circuit in Example 5. As a result, the value of the current discharged from the b pin can be limited by the value of the resistor R3.

[0119] Depend on Figure 5B The circuit shown in Example 7 is a circuit in which a Zener diode D3 is connected between the c pin and the b pin and the resistor R1 is removed from the circuit in Example 6. As a result, the value of the current discharged from the b pin can be limited by the value of the resistor R3, and the voltage output from the b pin can be limited to the voltage drop generated in the Zener diode D3.

[0120] 5. Specific embodiments of the present invention

[0121] exist Fig. 6A , which is an example of a specific embodiment of the present invention, shows a circuit structure of a gate drive circuit. In particular, the range surrounded by the dotted line is the gate drive circuit 40 which is a characteristic circuit in this embodiment. Q21 is a P-channel MOSFET as a main switch. Q44, a diode D4, a resistor R3, and a resistor R5, which are P-channel MOSFETs, constitute a switch 22 with a voltage detection function. Q44 is equivalent to a preferred example of an internal switch in the technical solution.

[0122] The charge storage circuit 23 is composed of a diode D2, a diode D3, and a capacitor C1. The operation of these circuits is as described above. Q22 is a semiconductor switch with a small capacitance, which is equivalent to Figure 2 Q22 in Figure 2 Q22 in the same way. Q32 is equivalent to Figure 4 Q32 in, and Figure 4 Q32 in performs the same action. In addition, Fig. 6A The voltage conversion circuit 31 in the embodiment is composed of a diode D1, a resistor R2, and a resistor R1. Figure 4 The voltage conversion circuit 31 in FIG. 1 operates in the same manner. The backflow prevention circuit 33 is composed of a diode D5 and a resistor R4. Figure 4 The backflow prevention circuit 33 in the circuit operates in the same manner.

[0123] Fig. 6A The high-side driver of the gate drive circuit 40 shown in the figure is composed of a single module, the signal input of this module is IN and inverted IN (in Fig. 6A In the example, the two signals are indicated by a horizontal bar above IN. Inverted IN is the inverted signal of the IN signal (see Fig. 6A ).

[0124] The OUT terminal 25 and the IN terminal 45 swing from approximately Vee to Vdc. In addition, the inversion IN terminal 46 swings from Vdc to a voltage intermediate between Vdc and Vee.

[0125] exist Fig. 6A The circuit outside the gate drive circuit 40 is also shown. The control IC 50 is a device that controls the ON / OFF of the power semiconductor switch. Vdc and Vee are supplied to the control IC 50 as power. The control IC 50 operates using the power supply, generates an IN signal, and supplies it to the IN terminal 45 of the gate drive circuit 40 (see Fig. 6A ). The inverter 51 inverts the IN signal, creates an inverted IN signal, and supplies it to the inverted IN terminal 46 of the gate drive circuit 40 .

[0126] When the potential of the OUT terminal 25 is approximately Vee, the IN terminal 45 is also at the potential of Vee, Q32 turns on and Q21 turns off. This state is a state in which the voltage of the IN terminal 45 satisfies the above-mentioned conditions of equations (4) and (5) and does not hinder the OFF action of the IGBT (not shown) as the driving object. At this time, the capacitor C1 of the charge storage circuit 23 is charged by the current flowing from Vdc to Vee through the diode D3 and the diode D2. The charging voltage V of the capacitor C1 is c1 It is represented by the following formula (6). c1 The constant voltage diode D3 can be used to generate a voltage V zd3 Adjust. The forward voltage drop of diode D2 is set to VF D2 .

[0127] V c1 =Vdc-Vee-V zd3 -VF D2 (6)

[0128] V in the formula (1) has been explained CH With V c1 Equal. Let this equation be (7).

[0129] V c1 =V CH (7)

[0130] The gate voltage V is selected to satisfy the equation (2) in order to apply a gate voltage sufficiently exceeding the gate threshold voltage to Q21. c1 (=V CH ). IN terminal 45 is high (High) (≈Vdc), Q32 turns off, and when the inverted IN terminal 46 becomes low (Low) (≈the middle potential between Vdc and Vee), the P-channel MOSFET Q22, which is a semiconductor switch with a small capacitance, turns on. When Q22 turns on, the voltage of OUT terminal 25 starts to rise. This period is the period during which only the gate voltage of the IGBT rises while the IGBT to be driven is still in the OFF state (please refer to the above Figure 3 As the voltage of the OUT terminal 25 continues to rise, the voltage of the b-pin exceeds Vdc due to the charge accumulated in the charge accumulation circuit 23 and continues to rise. Along with this, the voltage between the e-pin and the d-pin of the switch 22 with a voltage detection function rises.

[0131] When the voltage between the e-pin and the d-pin of the switch 22 with voltage detection function reaches the threshold voltage V DETWhen, that is, when the voltage at the OUT terminal 25 satisfies the equation (1), Q44, which is its own switch, is turned on. As Q44 is turned on, the accumulation voltage V for the charge accumulation circuit 23 is applied between the gate terminal and the source terminal of Q21, which is the main switch N-channel MOSFET. C1 The voltage after multiplying by the constant k causes Q21 to rapidly switch from OFF to ON. When Q21 switches to ON, Q21 controls the large current used to supply the gate current increase accompanying the feedback capacitance of the IGBT (see Figure 3 The charge and discharge time constant of capacitor C1 can provide Figure 3 After the charge of capacitor C1 is discharged and Q21 is turned off, Q22 ensures the gate voltage of the IGBT (refer to Figure 3 area C).

[0132] Next, when the IGBT is in the ON state, when the system receives an instruction to turn the IGBT off, the IN terminal 45 starts to shift to a low level (Low), and the inverted IN terminal 46 shifts to a high level (High). The inverted IN terminal 46 becomes a high level (High), whereby Q22 performs an OFF operation. The gate drive circuit 40 of this embodiment starts to shift Q21 from the ON state to the OFF state in a manner that does not hinder the OFF operation of the IGBT. When the IN terminal 45 drops from Vdc to Vee, a voltage is generated between the g pin and the i pin of the voltage conversion circuit 31. Along with this, the corresponding output voltage is output to the output of the voltage conversion circuit 31, that is, between the h pin and the i pin.

[0133] When the voltage drop of the IN terminal 45 is progressing and the output voltage of the voltage conversion circuit 31 exceeds the gate threshold voltage of Q32, Q32 turns on and extracts the gate charge of the main switch N-channel MOSFET (Q21) through the backflow prevention circuit 33. As a result, the gate potential of Q21 becomes the voltage obtained by adding the voltage drop of the backflow prevention circuit 33 to the potential of the IN terminal 45. Regarding the conversion formula of the voltage conversion circuit 31, if R1>>R2, it is expressed by the following formula (8). In addition, V hi is the output of the voltage conversion circuit 31, that is, the voltage between the h pin and the i pin. In addition, V in equation (3) m Vz is equivalent to the following formula (8): D1 .

[0134] V hi =Vdc-V IN -Vz D1 (8)

[0135] The condition for Q32 to turn on is shown by the formula (5) described above. When the low level (Low) voltage of the OUT terminal 25 when the IGBT turns off is VOlow, the voltage of the IN terminal 45 that maintains the OFF state of Q21 even if the voltage of the OUT terminal 25 decreases is expressed by the above formula (4).

[0136] Fig. 6A Variations of

[0137] Depend on Fig. 6A The specific embodiment shown is a structure in which the terminal c of the charge storage circuit 12 is connected to the OUT terminal 25. Figure 1A (Principle 1) is an example of the circuit structure shown.

[0138] In contrast, we can also use Figure 1B (Variation of Principle 1) Figure 6B The use of Figure 1B The circuit diagram of the specific implementation of the structure. That is, Figure 6B As shown, the terminal c of the charge storage circuit 12 is connected to the IN terminal 45 instead of being connected to the OUT terminal 25 .

[0139] By adopting such a structure, as described in "1.2 Variation of Principle 1", it is not necessary to combine P-channel MOSFET, and a simpler circuit structure can be made. Figure 6B This means that the circuit composed of the resistors R7 and Q22 is not necessarily required.

[0140] 6. Effects and Others

[0141] As described above, according to the high side driver and the gate drive circuit including the high side driver in the present embodiment, the following effects are achieved.

[0142] The voltage generated by the charge storage circuit 23 is supplied to the main switch using the switch 22 with a voltage detection function. Therefore, since the ON operation is performed autonomously by the output voltage, it is not necessary to use a voltage shift circuit or an insulating element, and the circuit structure can be simplified.

[0143] Furthermore, a more rational driving method is adopted in view of the operating characteristics of the power semiconductor switch to be driven, so that a gate driving circuit suitable for high-speed driving of the power semiconductor switch and having a simple circuit structure and low cost can be provided.

[0144] In addition, a circuit can be provided that does not hinder the OFF operation of a power semiconductor switch to be driven when the OFF operation is performed. Furthermore, a circuit having superior noise immunity compared to conventional circuits can be provided.

[0145] In addition, the above-described embodiment is an example of a means for realizing the present invention, and should be appropriately modified or changed according to the structure or various conditions of the device to which the present invention is applied, and the present invention is not limited to the form of this embodiment. For example, in the above-described embodiment, as the driving object, i.e., the power semiconductor switch, the IGBT is mainly described, but it can also be applied to other power semiconductor switches.

[0146] In addition, the structure of the charge storage circuit or the switch circuit with a voltage detection function is an example, and other circuits with the same function may be used. Furthermore, in this embodiment (the present invention), MOSFET is used as a main structural element, but other structures may be used if the same effect is achieved. For example, various semiconductor switches or switches using other materials may be used.

[0147] Description of Reference Numerals

[0148] 1 P-channel MOSFET

[0149] 1a N-channel MOSFET

[0150] 2 IGBT

[0151] 3.3a ​​Gate drive circuit

[0152] 4 Positive voltage terminal

[0153] 5 IN terminal

[0154] 6. 8 GND terminal

[0155] 7 OUT terminal

[0156] 9, 10, 11 Resistors

[0157] 10 Photocoupler

[0158] 12 Diode

[0159] 13. Capacitor

[0160] 21 N-channel MOSFET

[0161] 22 Switch with voltage detection function

[0162] 23 Charge storage circuit

[0163] 24 Positive voltage terminal

[0164] 25 OUT terminal

[0165] 26, 26b Gate drive circuit

[0166] 27 IGBT

[0167] 28 ON signal input terminal

[0168] 29, 29b resistor

[0169] 30 P-channel MOSFET for startup

[0170] 31 Voltage conversion circuit

[0171] 32 MOSFET

[0172] 33 Backflow prevention circuit

[0173] 34 OFF signal input terminal

[0174] 40 Gate drive circuit

[0175] 50 Control IC

[0176] 51 Inverter.

Claims

1. A high-side driver, the high-side driver being a circuit for driving a power semiconductor switch, wherein: The high-side driver has: A main switch N-channel MOSFET, a drain terminal of which is connected to the positive side Vdc of the power supply of the circuit, and a source terminal of which is connected to an OUT terminal, the OUT terminal being a terminal for outputting a signal for driving the power semiconductor switch; a charge accumulation circuit that accumulates charge by injecting current from a positive side Vdc of a power supply of the circuit; The switch with voltage detection function detects the voltage difference between the output terminal of the charge storage circuit and the positive side Vdc of the power supply of the circuit to operate. When the switch with voltage detection function detects that the output terminal voltage of the charge storage circuit is higher than the voltage of the positive side Vdc of the power supply of the circuit by a certain voltage or more, a part or all of the output voltage of the charge storage circuit is applied to the gate terminal of the main switch N-channel MOSFET to turn on the main switch N-channel MOSFET; An OFF signal input terminal for inputting a signal for causing the power semiconductor switch to perform an OFF action; a voltage conversion circuit connected between the positive side Vdc of the power supply of the circuit and the OFF signal input terminal, and performing voltage conversion by dividing the voltage between the positive side Vdc of the power supply of the circuit and the OFF signal input terminal and / or subtracting a certain value; a backflow prevention circuit provided between the gate terminal of the main switch N-channel MOSFET and the gate charge extraction MOSFET, and allowing current to flow only in a direction from the gate terminal of the main switch N-channel MOSFET toward the gate charge extraction MOSFET; and The gate charge extraction MOSFET has a drain terminal connected to the backflow prevention circuit, a source terminal connected to the OFF signal input terminal, and a gate terminal connected to an output terminal for outputting the voltage converted by the voltage conversion circuit. The drain terminal of the gate charge extraction MOSFET is connected to the gate terminal of the main switch N-channel MOSFET via the backflow prevention circuit. A signal for turning off the power semiconductor switch is input to the OFF signal input terminal. When the voltage at the OFF signal input terminal drops from the positive side Vdc of the power supply of the circuit, the output voltage of the output terminal outputting the converted voltage by the voltage conversion circuit rises, the charge extraction MOSFET turns on, and the main switch N-channel MOSFET turns off.

2. The high-side driver according to claim 1, wherein: have: A startup P-channel MOSFET connected in parallel with the main switch N-channel MOSFET, and having a source terminal connected to the positive side Vdc of the power supply and a drain terminal connected to the OUT terminal; as well as The ON signal input terminal inputs a signal for turning on the power semiconductor switch and is connected to the gate terminal of the startup P-channel MOSFET. When a signal for turning on the power semiconductor switch is input to the ON signal input terminal, the startup P-channel MOSFET turns on. The startup P-channel MOSFET turns on, thereby increasing the voltage of the OUT terminal. The switch with voltage detection function detects that the output terminal voltage of the charge storage circuit is higher than the voltage of the positive side Vdc of the power supply of the circuit by a certain voltage or more, and applies part or all of the output voltage of the charge storage circuit to the gate terminal of the main switch N-channel MOSFET, so that the main switch N-channel MOSFET performs an ON action.

3. The high-side driver according to claim 1 or 2, wherein: The switch with voltage detection function has an internal switch, and the internal switch is turned on when the switch with voltage detection function detects that the output terminal voltage of the charge storage circuit is higher than the voltage of the positive side Vdc of the power supply of the circuit by a certain voltage or more, and a part or all of the output voltage of the charge storage circuit is applied to the gate terminal of the main switch N-channel MOSFET.

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