Direct drive circuit for a depletion mode power device

Abstract

The application provides a direct drive circuit of a depletion mode power device, and belongs to the technical field of electronics.The direct drive circuit comprises a depletion mode power device, a gate of which is connected with an output end of a driving circuit; a P-type MOSFET, a source of which is connected with a source of the depletion mode power device; a power supply voltage detection circuit, which is connected with a gate of the P-type MOSFET and a power supply voltage; a first diode, a positive electrode of which is connected between the driving circuit and the gate of the depletion mode power device, and a negative electrode of which is connected with a drain of the P-type MOSFET; a first capacitor, one end of which is connected with a ground end of the driving circuit, and the other end of which is connected with the source of the depletion mode power device; and a first resistor, one end of which is connected between the first capacitor and the source of the depletion mode power device, and the other end of which is connected between the power supply voltage detection circuit and the gate of the P-type MOSFET.The depletion mode power device can be directly driven by the driving circuit, so that the driving speed is improved and the driving loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic technology, in particular to a direct drive circuit of a depletion mode power device. BACKGROUND

[0002] The third generation semiconductor material GaN (gallium nitride) is an outstanding representative of wide band gap semiconductors. The band gap of GaN is 3 times that of Si, and the breakdown field is 10 times that of Si. Therefore, the power device made of gallium nitride has the characteristics of fast switching speed, low on-resistance, small chip area, etc., and is widely used in power adapter, industrial power supply and automotive electronics fields.

[0003] GaN power devices are generally divided into normally on type (depletion mode) and normally off type gallium nitride (enhancement mode). The enhancement mode device has a narrow drive voltage range and generally needs a special drive IC (Integrated Circuit) to drive it, and at the same time, the channel current capacity is weak, so its application is limited. The depletion mode GaN power device has strong current capacity and high reliability, but needs negative voltage to turn off, and generally needs to be cascaded with a low-voltage Si device to form a normally off characteristic, as shown in Figure 1 The cascaded GaN device needs a low-voltage Si MOSFET device and a depletion mode GaN power device to form a normally off characteristic, but the low-voltage Si device has a reverse recovery charge, which will cause switching loss and reduce system efficiency. At the same time, the drive of the cascaded GaN device is not to directly drive the GaN device, but to directly drive the low-voltage Si device, and the junction capacitance of the low-voltage Si device is large, which needs a large drive capacity IC to drive it, and driving the low-voltage Si device also reduces the switching speed of the switching device. That is, the traditional GaN cascaded structure cannot fully exert the advantages of GaN, such as no reverse recovery loss and fast switching speed.

[0004] At the same time, the cascaded GaN device has the problem of mismatching of the output capacitance of the low-voltage Si MOSFET and the depletion mode GaN, which has a risk of failure in high-frequency switching. SUMMARY

[0005] The purpose of the present application is to provide a direct drive circuit of a depletion mode power device, which can directly drive the depletion mode power device, improve the driving speed and reduce the driving loss.

[0006] To achieve the above purpose, the present application provides the following scheme:

[0007] A direct drive circuit of a depletion mode power device, the direct drive circuit of the depletion mode power device comprising:

[0008] a drive circuit, the VCC end being connected with a power supply voltage;

[0009] a depletion mode power device, the gate being connected with the output end of the drive circuit.

[0010] a P-type metal-oxide semiconductor field effect transistor (MOSFET), a source of which is connected to a source of the depletion-mode power device;

[0011] a supply voltage detection circuit, an output of which is connected to a gate of the P-type MOSFET, and an input of which is connected to the supply voltage;

[0012] a first diode, a positive electrode of which is connected between an output of the driving circuit and a gate of the depletion-mode power device, and a negative electrode of which is connected to a drain of the P-type MOSFET;

[0013] a first capacitor, one end of which is connected to a ground of the driving circuit, and the other end of which is connected between a source of the depletion-mode power device and a source of the P-type MOSFET;

[0014] a first resistor, one end of which is connected between the first capacitor and the source of the depletion-mode power device, and the other end of which is connected between the output of the supply voltage detection circuit and the gate of the P-type MOSFET;

[0015] when the supply voltage is greater than a set threshold, the P-type MOSFET is turned on, the source of the depletion-mode power device is the supply voltage, when the driving circuit outputs a high level, the gate of the depletion-mode power device is the high level, the depletion-mode power device is turned on, and when the driving circuit outputs a low level, the gate of the depletion-mode power device is the low level, the depletion-mode power device is turned off.

[0016] Optionally, the depletion-mode power device is a depletion-mode gallium nitride device.

[0017] Optionally, the supply voltage detection circuit comprises a zener diode, a second resistor, a third resistor, and a triode.

[0018] a negative electrode of the zener diode is connected to the supply voltage;

[0019] one end of the second resistor is connected to a positive electrode of the zener diode, and the other end of the second resistor is connected to one end of the third resistor;

[0020] the other end of the third resistor is connected to a supply ground;

[0021] a base of the triode is connected between the second resistor and the third resistor, a collector of the triode is connected to the gate of the P-type MOSFET, and an emitter of the triode is connected to the supply ground.

[0022] Optionally, the direct driving circuit of the depletion-mode power device further comprises:

[0023] A switch tube, one end of which is connected to the power supply voltage and the other end of which is connected between the source of the depletion-mode power device and the source of the P-type MOSFET.

[0024] Optionally, the direct drive circuit of the depletion-mode power device further comprises a current isolation detection circuit and a reverse current detection circuit.

[0025] The input end of the current isolation detection circuit is connected in series with the drain of the P-type MOSFET, the output end of the current isolation detection circuit is connected with the reverse current detection circuit, and the current isolation detection circuit is used to detect the flow direction of the load current and the size of the forward current.

[0026] One end of the reverse current detection circuit is connected with the output end of the current isolation detection circuit, the other end of the reverse current detection circuit is connected with the drive circuit, and the reverse current detection circuit is used to generate an on-off signal when the load current flows from the drain of the P-type MOSFET to the source of the depletion-mode power device, to make the drive circuit output a high level, to make the depletion-mode power device conduct, and to generate a limiting signal when the forward current exceeds a current threshold, to limit the output pulse width of the drive circuit.

[0027] Optionally, the switch tube is a second diode.

[0028] Optionally, the direct drive circuit of the depletion-mode power device further comprises:

[0029] A fourth resistor, one end of which is connected with the enable end of the drive circuit, and the other end of which is connected with the second output end of the power supply circuit detection circuit;

[0030] A second capacitor, one end of which is connected between the fourth resistor and the drive circuit, and the other end of which is connected to the power supply ground;

[0031] A third capacitor, one end of which is connected between the first capacitor and the source of the depletion-mode power device, and the other end of which is connected between the output end of the power supply voltage detection circuit and the gate of the P-type MOSFET;

[0032] When the power supply voltage is greater than a set threshold, the first output end of the power supply circuit detection circuit outputs a low impedance, making the P-type MOSFET conduct, and the second output end of the power supply circuit detection circuit outputs an enable signal, making the output of the drive circuit follow the signal of the input end and amplify;

[0033] When the drive circuit outputs a high level, the depletion-mode power device is turned on, and when the drive circuit outputs a low level, the depletion-mode power device is turned off.

[0034] Optionally, the direct drive circuit of the depletion-mode power device further comprises a current isolation detection circuit and a reverse current detection circuit.

[0035] The input end of the current isolation detection circuit is connected in series with the drain of the P-type MOSFET, and the output end of the current isolation detection circuit is connected with the reverse current detection circuit, and the current isolation detection circuit is used for detecting the flow direction of the load current and the size of the forward current;

[0036] One end of the reverse current detection circuit is connected with the output end of the current isolation detection circuit, and the other end of the reverse current detection circuit is connected with the driving circuit, and the reverse current detection circuit is used for generating an opening signal when the load current flows from the drain of the P-type MOSFET to the source of the depletion-mode power device, so that the driving circuit outputs a high level, so that the depletion-mode power device is turned on, and when the forward current exceeds the current threshold, a limiting signal is generated to limit the output pulse width of the driving circuit.

[0037] Optionally, the depletion-mode power device, the P-type MOSFET, the first diode and the first resistor are integrated.

[0038] Optionally, the driving circuit, the depletion-mode power device, the P-type MOSFET, the power supply voltage detection circuit, the first diode, the first capacitor, the third capacitor, the first resistor, the fourth resistor and the second capacitor are integrated.

[0039] Optionally, the driving circuit, the depletion-mode power device, the P-type MOSFET, the power supply voltage detection circuit, the first diode, the switch tube, the first capacitor, the first resistor, the current isolation detection circuit and the reverse current detection circuit are integrated.

[0040] Optionally, the driving circuit, the depletion-mode power device, the P-type MOSFET, the power supply voltage detection circuit, the first diode, the first capacitor, the second capacitor, the third capacitor, the first resistor, the fourth resistor, the current isolation detection circuit and the reverse current detection circuit are integrated.

[0041] According to the specific embodiments of the present application, the following technical effects are provided: the depletion-mode power device is directly driven by the driving circuit, the depletion-mode power device is directly opened when the driving circuit outputs a high level, the depletion-mode power device is turned off when the driving circuit outputs a low level, which is similar to the general Si MOSFET driving. Since the power device is directly driven, the driving speed is fast, the driving loss is low, and the system switching loss is small. In addition, the P-type MOSFET in the cascade structure is always in a conductive state, so there is no reverse recovery loss. There is also no output capacitor matching problem in the cascade structure. Figure 1 shown. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram illustrating the common cascode connection used in depletion-mode GaN devices to enable high-frequency applications.

[0044] Figure 2 This is a schematic diagram of the first structure of the direct drive circuit for the depletion-type gallium nitride device of the present invention;

[0045] Figure 3 This is a schematic diagram of a second structure of the direct drive circuit for the depletion-type gallium nitride device of the present invention;

[0046] Figure 4 This is a schematic diagram of the third structure of the direct drive circuit for the depletion-type gallium nitride device of the present invention;

[0047] Figure 5 This is a schematic diagram of the fourth structure of the direct drive circuit for the depletion-type gallium nitride device of the present invention;

[0048] Figure 6 This is a schematic diagram of the fifth structure of the direct drive circuit for the depletion-type gallium nitride device of the present invention;

[0049] Figure 7 This is a schematic diagram of packaging a depletion-mode gallium nitride device, a P-type MOSFET, a first diode, and a resistor.

[0050] Figure 8 This is a schematic diagram of a depletion-mode gallium nitride device, a P-type MOSFET, a first diode, a second diode, and a resistor packaged together.

[0051] Figure 9 To be Figure 4 A schematic diagram of the circuit structure being encapsulated;

[0052] Figure 10 To be Figure 5 A schematic diagram of the circuit structure being encapsulated;

[0053] Figure 11 To be Figure 6 A schematic diagram of the circuit structure being encapsulated.

[0054] Symbol explanation:

[0055] Depletion-type power device - S1, P-type MOSFET - S2, First diode - D1, Second diode - D2, First capacitor - C1, Second capacitor - C2, Third capacitor - C3, First resistor - R1, Second resistor - R2, Third resistor - R3, Fourth resistor - R4, Zener diode - Zener, Transistor - S3, Drive circuit - 1, Supply voltage detection circuit - 2, Current isolation detection circuit - 3, Reverse current detection circuit - 4, Depletion-type GaN power device - SS1, Low-voltage Si MOSFET device - SS3. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The purpose of this invention is to provide a direct-drive circuit for depletion-mode power devices. This circuit directly drives the depletion-mode power device via a drive circuit. When the drive circuit outputs a high level, the depletion-mode power device is directly turned on; when the drive circuit outputs a low level, the depletion-mode power device is turned off, similar to a typical Si MOSFET drive. Because it directly drives the power device, the drive speed is fast, the drive loss is low, and the system switching loss is small. Furthermore, the cascaded P-type MOSFETs are always on during operation, therefore there is no reverse recovery loss; that is, the overall reverse recovery charge is zero, and the reverse recovery loss is zero. There is also no issue of output capacitor matching for the depletion-mode power device.

[0058] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] like Figure 2 As shown, the direct drive circuit of the depletion-type power device of the present invention includes: a drive circuit 1, a depletion-type power device S1, a P-type MOSFET S2, a power supply voltage detection circuit 2, a first diode D1, a first capacitor C1, and a first resistor R1. In this embodiment, the depletion-type power device S1 is a depletion-type gallium nitride device. Alternatively, the depletion-type power device S1 can also be a depletion-type SiC device.

[0060] The direct drive circuit of the depletion-type power device also includes a switching transistor. One end of the switching transistor is connected to the supply voltage, and the other end is connected between the source of the depletion-type power device and the source of the P-type MOSFET. In this embodiment, the switching transistor is a second diode D2.

[0061] Specifically, the VCC terminal of the drive circuit 1 is connected with the supply voltage.

[0062] The gate of the depletion-mode power device S1 is connected with the output terminal of the drive circuit 1.

[0063] The source of the P-type MOSFET is connected with the source of the depletion-mode power device S1.

[0064] The first output terminal of the supply voltage detection circuit 2 is connected with the gate of the P-type MOSFET, and the input terminal of the supply voltage detection circuit 2 is connected with the supply voltage.

[0065] The anode of the first diode D1 is connected between the output terminal of the drive circuit 1 and the gate of the depletion-mode power device S1, and the cathode of the first diode D1 is connected with the drain of the P-type MOSFET.

[0066] One end of the first capacitor C1 is connected with the ground terminal of the drive circuit 1, and the other end of the first capacitor C1 is connected between the source of the depletion-mode power device S1 and the source of the P-type MOSFET.

[0067] One end of the first resistor R1 is connected between the first capacitor C1 and the source of the depletion-mode power device S1, and the other end of the first resistor R1 is connected between the output terminal of the supply voltage detection circuit 2 and the gate of the P-type MOSFET.

[0068] The depletion-mode power device S1 needs negative voltage to turn off. The P-type MOSFET needs negative voltage to turn on (threshold voltage is negative) and positive voltage to turn off.

[0069] When there is no supply voltage VCC, the output of the detection circuit is high impedance, and the voltage across the first resistor R1 is 0, that is, the gate-source voltage of the P-type MOSFET S2 is 0, so the P-type MOSFET is in the off state. At the same time, due to the action of the first diode D1, the depletion-mode power device S1 and the P-type MOSFET S2 are equivalent to a cascade structure, and the Drain and Source are in the off state.

[0070] Similarly, when the supply voltage of the drive circuit 1 starts to build up, and the supply voltage VCC is less than the set threshold value before, the output of the detection circuit is high impedance, and the voltage across the first resistor R1 is 0, that is, the gate-source voltage of the P-type MOSFET S2 is 0, so the P-type MOSFET S2 is in the off state, and the Drain and Source are in the off state.

[0071] When the supply voltage is greater than a set threshold, the output impedance is low impedance or 0 impedance, the P-type MOSFET is turned on, the source of the depletion-mode power device S1 is the supply voltage, when the driving circuit 1 outputs high level, the gate of the depletion-mode power device S1 is high level, the depletion-mode power device S1 is turned on, when the driving circuit 1 outputs low level, the gate of the depletion-mode power device S1 is low level, the depletion-mode power device S1 is turned off.

[0072] Further, as shown in the figure, the supply voltage detection circuit comprises a Zener diode, a second resistor R2, a third resistor R3 and a transistor S3. Figure 3

[0073] The negative electrode of the Zener diode is connected with the supply voltage.

[0074] One end of the second resistor R2 is connected with the positive electrode of the Zener diode, and the other end of the second resistor R2 is connected with one end of the third resistor R3.

[0075] The other end of the third resistor R3 is grounded.

[0076] The base of the transistor S3 is connected between the second resistor R2 and the third resistor R3. The collector of the transistor S3 is connected with the gate of the P-type MOSFET. The emitter of the transistor S3 is grounded.

[0077] In addition, the supply voltage detection circuit can be represented by various circuits. A capacitor can also be connected in parallel between the two ends of the first resistor R1 to suppress high-frequency interference. The supply voltage detection circuit can also be integrated with the driving circuit into an IC.

[0078] Specifically, when the supply voltage VCC rises to be greater than a set threshold, the transistor S3 is turned on, and the point F is pulled to a low potential. At this time, the gate-source voltage of the P-type MOSFET S2 is negative, and the P-type MOSFET S2 is turned on. At this time, the turn-on and turn-off of the depletion-mode power device S1 is determined by the output OUT of the driving circuit.

[0079] Since the supply voltage VCC is directly connected with the source of the depletion-mode power device S1 through the second diode D2, the source of the depletion-mode power device S1 is at the VCC level. When the driving circuit 1 outputs high level, the gate of the depletion-mode power device S1 is at the high level VCC, so the gate-source voltage difference of the depletion-mode power device S1 is 0V, and the depletion-mode power device S1 is turned on. When the output of the driving circuit 1 is low level 0, the gate of the depletion-mode power device S1 is at the low level 0V, and the gate-source voltage difference of the depletion-mode power device S1 is -VCC (-VCC < Vth), so the depletion-mode power device S1 is turned off. ​

[0080] Therefore, the drive circuit can directly drive the depletion-mode power device. That is to say, when VCC is established, the drive circuit directly drives the depletion-mode power device. When the drive circuit output is 0 level, the depletion-mode power device is turned off. When the drive circuit output is high level, the depletion-mode power device is turned on.

[0081] like Figure 4 As shown, the direct drive circuit of the depletion-type power device also includes a fourth resistor R4. One end of the fourth resistor is connected to the enable terminal of the drive circuit, and the other end is connected to the second output terminal of the power supply circuit detection circuit.

[0082] When the power supply voltage is greater than the set threshold, the first output terminal of the power supply circuit detection circuit 2 outputs a low impedance to turn on the P-type MOSFET, and the second output terminal of the power supply circuit detection circuit 2 outputs an enable signal to make the output of the drive circuit 1 follow the signal of the input terminal IN.

[0083] When the drive circuit 1 outputs a high level, the depletion-type power device S1 is turned on; when the drive circuit 1 outputs a low level, the depletion-type power device S1 is turned off.

[0084] The direct drive circuit of the depletion-type power device also includes a second capacitor C2. One end of the second capacitor C2 is connected between the fourth resistor R4 and the drive circuit, and the other end is connected to the ground of the power supply VCC.

[0085] The direct drive circuit of the depletion-type power device also includes a third capacitor C3. One end of the third capacitor C3 is connected between the first capacitor C1 and the source of the depletion-type power device S1, and the other end of the third capacitor C3 is connected between the output terminal of the power supply voltage detection circuit 2 and the gate of the P-type MOSFET.

[0086] When the supply voltage VCC is lower than the set threshold, the first output terminal OUT1 pin of the supply voltage detection circuit 2 outputs a high impedance, the voltage across the first resistor R1 is 0, the P-type MOSFET S2 is turned off, and at the same time, the second output terminal OUT2 outputs an enable signal to the enable terminal EN of the drive circuit 1, making the output of the drive circuit 1 low level, and the depletion-type power device S1 is in the off state.

[0087] When the supply voltage VCC of the driving circuit 1 is greater than the set threshold value, the VCC detection circuit outputs a low impedance at the OUT1 pin, the voltage across the first resistor R1 is positive, and the gate-source voltage of the P-type MOSFET is negative, so that the P-type MOSFET is turned on, the second output terminal OUT2 of the supply circuit detection circuit 2 outputs an enable signal, and the signal output by the first output terminal OUT of the driving circuit 1 follows the signal of the input terminal IN. That is, if the driving circuit 1 outputs a high level VCC, the gate-source voltage of the depletion-mode power device S1 is 0V, and the depletion-mode power device is turned on; if the driving circuit 1 outputs a low level 0, the gate-source voltage of the depletion-mode power device S1 is -VCC (-VCC < Vth), and the depletion-mode power device S1 is turned off.

[0088] Therefore, when the supply voltage VCC is greater than the set threshold value, the driving circuit 1 directly drives the depletion-mode power device, the driving circuit 1 outputs a 0 level to turn off the depletion-mode power device S1, and the driving circuit 1 outputs a high level to turn on the depletion-mode power device S1.

[0089] Since when the depletion-mode power device is in an off state and the load current flows from the Source to the Drain in a reverse direction, due to the characteristics of the depletion-mode power device itself, the reverse conduction voltage drop in the off state is relatively large, and the reverse conduction voltage drop of the P-type MOSFET is also about 0.7V due to the existence of the body diode, so the total reverse conduction voltage drop is very high, resulting in a large loss. Therefore, in order to reduce the reverse conduction voltage drop, as shown in Figure 5 and Figure 6 The direct driving circuit of the depletion-mode power device further includes a current isolation detection circuit 3 and a reverse current detection circuit 4.

[0090] Specifically, the input terminal of the current isolation detection circuit 3 is connected in series with the drain of the P-type MOSFET, the output terminal of the current isolation detection circuit 3 is connected with the reverse current detection circuit 4, and the current isolation detection circuit 3 is used to detect the flow direction of the load current and the size of the forward current.

[0091] One end of the reverse current detection circuit 4 is connected with the current isolation detection circuit 3, and the output terminal of the reverse current detection circuit 4 is connected with the driving circuit 1. The reverse current detection circuit 4 is used to generate an on signal when the load current flows from the drain of the P-type MOSFET to the source of the depletion-mode power device S1, so that the driving circuit 1 outputs a high level to turn on the depletion-mode power device S1, and generate a limiting signal when the forward current exceeds a current threshold value to limit the output pulse width of the driving circuit 1.

[0092] In the embodiment, the load current flows from the drain of the P-type MOSFET to the source of the depletion-mode power device, i.e. the load current flows from Source to Drain, and the reverse current detection circuit 3 sends an opening signal to the driving circuit 1 to open the depletion-mode power device S1, thereby realizing a low reverse on-voltage drop.

[0093] The application can keep the depletion-mode power device in a normally closed state, and can directly drive the depletion-mode power device, directly open the depletion-mode power device when the driving circuit outputs a high level, and turn off the depletion-mode power device when the driving circuit outputs a low level, which is similar to the general Si MOSFET driving. Since the depletion-mode power device is directly driven, the driving speed is fast, the driving loss is low, and the system switching loss is small. The cascaded P-type MOSFET is in a normally on state during operation, and therefore no reverse recovery loss occurs, i.e. the overall reverse recovery charge is 0, and the reverse recovery loss is 0.

[0094] Meanwhile, the low-voltage P-type MOSFET of the application is in a normally on state during operation, and therefore there is no Figure 1 capacitance mismatching problem of the depletion-mode GaN device and the low-voltage Silicon device as shown in the prior art.

[0095] The application also provides a plurality of corresponding sealing schemes:

[0096] As shown in Figure 7 , the depletion-mode GaN device S1, the P-type MOSFET S2, the first diode D1 and a resistor R are sealed together to form a new power IC.

[0097] As shown in Figure 8 , the depletion-mode GaN device S1, the P-type MOSFET S2, the first diode D1, the second diode D2 and a resistor R are sealed together to form a new power IC.

[0098] As shown in Figure 9 , the circuit structure of Figure 4 is sealed together to form a new power IC, which has only 5 pin feet, i.e. a PWM signal foot, a VCC power supply foot, a VCC ground signal foot, a Drain foot and a Source foot.

[0099] As shown in Figure 10 , the circuit structure of Figure 5 is sealed together to solve the problem of excessive reverse on-voltage drop, thereby forming a new power IC, which has only 5 pin feet, i.e. a PWM signal foot, a VCC power supply foot, a VCC ground signal foot, a Drain foot and a Source foot.

[0100] As shown in Figure 11 , the circuit structure of Figure 6The circuit structure of the reverse conducting FET is encapsulated together to solve the problem of excessive reverse conducting voltage drop, thereby forming a new power IC with only five pin feet: a PWM signal foot, a VCC power supply foot, a VCC ground signal foot, a drain foot and a source foot.

[0101] The principles and implementation manners of the present application are described herein by using specific examples, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application. In conclusion, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A direct drive circuit for a depletion mode power device, comprising: The direct drive circuit of the depletion mode power device comprises: a driving circuit, a VCC terminal of which is connected with a power supply voltage; a depletion mode power device, a gate of which is connected with an output terminal of the driving circuit; a P-type MOSFET, a source of which is connected with a source of the depletion mode power device; a power supply voltage detection circuit, a first output terminal of which is connected with a gate of the P-type MOSFET, and an input terminal of which is connected with the power supply voltage; a first diode, a positive electrode of which is connected between an output terminal of the driving circuit and a gate of the depletion mode power device, and a negative electrode of which is connected with a drain of the P-type MOSFET; a first capacitor, one end of which is connected with a ground terminal of the driving circuit, and the other end of which is connected between a source of the depletion mode power device and a source of the P-type MOSFET; a first resistor, one end of which is connected between the first capacitor and the source of the depletion mode power device, and the other end of which is connected between an output terminal of the power supply voltage detection circuit and the gate of the P-type MOSFET; a switch tube, one end of which is connected with the power supply voltage, and the other end of which is connected between the source of the depletion mode power device and the source of the P-type MOSFET; when the power supply voltage is greater than a set threshold value, the P-type MOSFET is turned on, the source of the depletion mode power device is the power supply voltage, when the driving circuit outputs a high level, the gate of the depletion mode power device is a high level, the depletion mode power device is turned on, when the driving circuit outputs a low level, the gate of the depletion mode power device is a low level, and the depletion mode power device is turned off.

2. The direct drive circuit for a depletion mode power device of claim 1, wherein, The power supply voltage detection circuit comprises: a voltage stabilizing diode, a second resistor, a third resistor and a triode; a negative electrode of the voltage stabilizing diode is connected with the power supply voltage; one end of the second resistor is connected with a positive electrode of the voltage stabilizing diode, and the other end of the second resistor is connected with one end of the third resistor; the other end of the third resistor is connected with a power supply ground; a base of the triode is connected between the second resistor and the third resistor; a collector of the triode is connected with the gate of the P-type MOSFET; and an emitter of the triode is connected with the power supply ground.

3. The direct drive circuit for a depletion mode power device of claim 1, wherein, The direct drive circuit of the depletion mode power device further comprises: a current isolation detection circuit and a reverse current detection circuit; an input terminal of the current isolation detection circuit is connected in series with a drain of the P-type MOSFET, an output terminal of the current isolation detection circuit is connected with the reverse current detection circuit, and the current isolation detection circuit is used for detecting a flow direction of a load current and a size of a forward current; one end of the reverse current detection circuit is connected with the output terminal of the current isolation detection circuit, the other end of the reverse current detection circuit is connected with the driving circuit, and the reverse current detection circuit is used for generating an opening signal when the load current flows from the drain of the P-type MOSFET to the source of the depletion mode power device, so as to make the driving circuit output a high level, make the depletion mode power device be turned on, and generate a limiting signal when the forward current exceeds a current threshold value, so as to limit a pulse width of an output of the driving circuit.

4. The direct drive circuit for a depletion mode power device of claim 1, wherein, The direct drive circuit of the depletion mode power device further comprises: A fourth resistor, one end of which is connected to the enable terminal of the driving circuit, and the other end of which is connected to the second output terminal of the power supply circuit detection circuit; A second capacitor, one end of which is connected between the fourth resistor and the driving circuit, and the other end of which is connected to the power supply ground; A third capacitor, one end of which is connected between the first capacitor and the source of the depletion-mode power device, and the other end of which is connected between the output terminal of the power supply voltage detection circuit and the gate of the P-type MOSFET; When the power supply voltage is greater than a set threshold, the first output terminal of the power supply circuit detection circuit outputs a low impedance, the P-type MOSFET is turned on, and the second output terminal of the power supply circuit detection circuit outputs an enable signal, so that the output of the driving circuit follows the signal of the input terminal and is amplified; When the driving circuit outputs a high level, the depletion-mode power device is turned on, and when the driving circuit outputs a low level, the depletion-mode power device is turned off.

5. The direct drive circuit for a depletion mode power device of claim 4, wherein, The direct driving circuit of the depletion-mode power device further comprises a current isolation detection circuit and a reverse current detection circuit; The input terminal of the current isolation detection circuit is connected in series with the drain of the P-type MOSFET, the output terminal of the current isolation detection circuit is connected with the reverse current detection circuit, and the current isolation detection circuit is used to detect the flow direction of the load current and the size of the forward current; One end of the reverse current detection circuit is connected with the output terminal of the current isolation detection circuit, the other end of the reverse current detection circuit is connected with the driving circuit, and the reverse current detection circuit is used to generate an on signal when the load current flows from the drain of the P-type MOSFET to the source of the depletion-mode power device, so that the driving circuit outputs a high level, the depletion-mode power device is turned on, and a limiting signal is generated when the forward current exceeds a current threshold, so as to limit the output pulse width of the driving circuit.

6. The direct drive circuit for a depletion mode power device of claim 1, wherein, The depletion-mode power device, the P-type MOSFET, the first diode and the first resistor are integrated.

7. The direct drive circuit for a depletion mode power device of claim 4, wherein, The driving circuit, the depletion-mode power device, the P-type MOSFET, the power supply voltage detection circuit, the first diode, the first capacitor, the first resistor, the fourth resistor, the second capacitor and the third capacitor are integrated.

8. The direct drive circuit for a depletion mode power device of claim 3, wherein, The driving circuit, the depletion-mode power device, the P-type MOSFET, the power supply voltage detection circuit, the first diode, the switch tube, the first capacitor, the first resistor, the current isolation detection circuit and the reverse current detection circuit are integrated.

9. The direct drive circuit for a depletion mode power device of claim 5, wherein, The driving circuit, the depletion-mode power device, the P-type MOSFET, the power supply voltage detection circuit, the first diode, the first capacitor, the second capacitor, the third capacitor, the first resistor, the fourth resistor, the current isolation detection circuit and the reverse current detection circuit are integrated.

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