GaN switch driving circuit and switching power supply circuit

Abstract

The application provides a D-type gallium nitride switch driving circuit and a switching power supply circuit, wherein the drain of the D-type gallium nitride switch is connected to a first voltage, the source of the D-type gallium nitride switch is respectively connected to the first end of a switching module and the first end of a first capacitor, and the gate of the D-type gallium nitride switch is connected to the first end of a first control module; the second end of the first control module is connected to the second end of the first capacitor; a second control module is connected to the control end of the switching module; and the second end of the first capacitor and the third end of the switching module are grounded. In this way, the second control module outputs a control signal to control the conduction and turn-off of the switching module, thereby controlling the conduction and turn-off of the D-type gallium nitride switch; meanwhile, the first control module is used to independently adjust the turn-on speed of the D-type gallium nitride switch, and a lower turn-on speed can reduce the voltage stress of the subsequent circuit and improve the EMI characteristics.

Description

Technical Field

[0001] This invention relates to the field of power supplies, and in particular to a D-type gallium nitride switch driver circuit and a switching power supply circuit. Background Technology

[0002] In recent years, gallium nitride (GaN) switches have been widely used in the field of switching power supply topologies, especially in high-power power supplies and AC / DC switching power supplies.

[0003] Commonly used switching power supply topologies include Buck circuits, Boost circuits, Buck-Boost circuits, forward circuits, flyback circuits, half-bridge power circuits, etc., which are widely used in devices and systems that require voltage transformation.

[0004] In existing switching power supply topologies, the primary gallium nitride (GaN) power transistors typically use E-type GaN switches. While their drive circuits are mature and their switching speed is adjustable, they are more suitable for soft-switching conditions at high frequencies. When topology or control strategies limit the implementation to hard switching, D-type GaN switches offer advantages in terms of conduction losses. However, D-type GaN switches are normally open devices, requiring a normally closed switch in series. Controlling the on / off state of the normally closed switch controls the switching of the D-type GaN switch. Furthermore, the rapid and difficult-to-control turn-on speed of D-type GaN switches can lead to excessive voltage stress on subsequent circuits. In this case, the switching speed of the D-type GaN switch can be adjusted by changing the switching speed of the normally closed switch or by adjusting the capacitance between the gate and source of the D-type GaN switch. However, this approach has limited impact on the turn-on speed but significantly affects the turn-off speed, thus significantly impacting efficiency.

[0005] Therefore, how to control the turn-on speed of the D-type gallium nitride switch without affecting its turn-off speed, so as to reduce the voltage stress of subsequent circuits and improve EMI characteristics, has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] This invention provides a D-type gallium nitride switch driver circuit and a switching power supply circuit to solve the technical problem of controlling the turn-on speed of the D-type gallium nitride switch without affecting its turn-off speed, thereby reducing voltage stress on subsequent circuits and improving EMI characteristics.

[0007] According to a first aspect of the present invention, a D-type gallium nitride switch driving circuit is provided, comprising: a D-type gallium nitride switch, a first control module, a second control module, a first capacitor, and a switch module; wherein:

[0008] The drain of the D-type gallium nitride switch is connected to a first voltage. The source of the D-type gallium nitride switch is coupled to the first terminal of the switch module and the first terminal of the first capacitor, respectively. Its gate is coupled to the first terminal of the first control module. The second terminal of the first control module is coupled to the second terminal of the first capacitor. The second control module is coupled to the control terminal of the switch module. The second terminal of the first capacitor and the third terminal of the switch module are grounded.

[0009] The second control module is used to output control signals to control the switching module to turn on and off, thereby controlling the D-type gallium nitride switch to turn on and off.

[0010] The first control module is used to adjust the turn-on speed of the D-type gallium nitride switch.

[0011] Optionally, the first control module is also used to adjust the turn-off speed of the D-type gallium nitride switch.

[0012] Optionally, the first control module includes an on-speed control module and an off-speed control module connected in parallel, wherein:

[0013] The turn-on speed control module is used to adjust the turn-on speed of the D-type gallium nitride switch;

[0014] The turn-off speed control module is used to adjust the turn-off speed of the D-type gallium nitride switch.

[0015] Optionally, the turn-on speed control module includes a first resistor; wherein:

[0016] The gate of the D-type gallium nitride switch is coupled to the first end of the first resistor, and the second end of the first resistor is also coupled to the second end of the first capacitor;

[0017] The first resistor is used to adjust the turn-on speed of the D-type gallium nitride switch.

[0018] Optionally, the shutdown speed control module includes a first diode and a second resistor;

[0019] The first end of the second resistor is coupled to the gate of the D-type gallium nitride switch, and its second end is coupled to the anode of the first diode; the cathode of the first diode is coupled to the second end of the first resistor.

[0020] The second resistor is used to adjust the turn-off speed of the D-type gallium nitride switch.

[0021] Optionally, a clamping Zener diode may also be included;

[0022] The anode of the clamping Zener diode is coupled to the first terminal of the first resistor, and the cathode of the clamping Zener diode is coupled to the source of the D-type gallium nitride switch.

[0023] Optionally, the switching module is a first NMOS switch.

[0024] The drain of the first NMOS switch is coupled to the source of the D-type gallium nitride switch, its gate is coupled to the second control module, and its source is grounded.

[0025] Optionally, it also includes a sampling module, which includes a current sensing resistor and a second NMOS switch.

[0026] The first terminal of the second control module is coupled to the gate of the second NMOS switch and the gate of the first NMOS switch, respectively; its second terminal is coupled to the drain of the second NMOS switch; its third terminal is coupled to the first terminal of the current sensing resistor; its fourth terminal is coupled to the drain of the first NMOS switch; and its fifth terminal is grounded. The second terminal of the current sensing resistor and the source of the second NMOS switch are grounded.

[0027] The first terminal of the second control module is used to output the control signal to control the conduction and turn-off of the first NMOS switch and the second NMOS switch. Its second and fourth terminals are used to output the same voltage so that the second NMOS switch and the first NMOS switch form a current mirror. The second control module is also used to mirror the current flowing through the second NMOS switch to the current sensing resistor so that the current flowing through the current sensing resistor is equal to the current flowing through the second NMOS switch.

[0028] Optionally, the width-to-length ratio of the first NMOS switch is greater than that of the second NMOS switch.

[0029] Optionally, the input terminal of the second control module receives an input signal; the second control module outputs a corresponding control signal based on the input signal, wherein:

[0030] If the input signal is high, the control signal is an adapted high-level signal;

[0031] If the input signal is low, the control signal is an adapted low-level signal.

[0032] Optionally, an output capacitor may also be included;

[0033] The first end of the output capacitor is coupled to the sixth end of the second control module, and the second end of the output capacitor is grounded.

[0034] Optionally, it also includes a high-voltage start-up module; the high-voltage start-up module includes a second diode, a constant current source, an LDO module, and an input capacitor;

[0035] The source of the D-type gallium nitride switch is coupled to the anode of the second diode, the cathode of the second diode is coupled to the first terminal of the constant current source, the second terminal of the constant current source is coupled to the first terminal of the LDO module, its third terminal is coupled to the seventh terminal of the second control module, the second terminal of the LDO module is coupled to the eighth terminal of the second control module and the first terminal of the input capacitor, and the second terminal of the input capacitor is grounded; wherein...

[0036] The seventh terminal of the second control module is used to control the constant current source to turn on and off;

[0037] The input capacitor is used to power the second control module.

[0038] According to a second aspect of the present invention, a switching power supply circuit is provided, comprising a D-type gallium nitride switch driving circuit, an RCD snubber circuit, and a primary winding as provided in any of the first aspects of the present invention.

[0039] The first end of the primary winding is coupled to the first end of the RCD absorption circuit, and its second end is coupled to the second end of the RCD absorption circuit and the drain of the D-type gallium nitride switch.

[0040] Optionally, the RCD snubber circuit includes a second capacitor, a third resistor, and a third diode;

[0041] The first end of the primary winding is coupled to the first end of the second capacitor and the first end of the third resistor, respectively. The second end of the second capacitor is coupled to the second end of the third resistor. The second end of the third resistor is coupled to the cathode of the third diode. The anode of the third diode is coupled to the second end of the primary winding.

[0042] Optionally, it also includes a power supply side capacitor; the first end of the primary winding is coupled to the first end of the power supply side capacitor, and the second end of the power supply side capacitor is grounded.

[0043] Optionally, a secondary winding may also be included.

[0044] In the D-type gallium nitride switch driving circuit and switching power supply circuit provided by the present invention, the drain of the D-type gallium nitride switch is connected to a first voltage, its source is coupled to the first terminal of the switching module and the first terminal of the first capacitor, its gate is coupled to the first terminal of the first control module, the second terminal of the first control module is coupled to the second terminal of the first capacitor, the second control module is coupled to the control terminal of the switching module, and the second terminal of the first capacitor and the third terminal of the switching module are grounded. This allows the second control module to output a control signal to control the switching module to turn on and off, thereby controlling the D-type gallium nitride switch to turn off and on without affecting its turn-off speed, ensuring efficiency. At the same time, the first control module adjusts the turn-on speed of the D-type gallium nitride switch to reduce the voltage stress of subsequent circuits and improve EMI characteristics. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0046] Figure 1 This is a schematic diagram of the structure of a D-type gallium nitride switch driving circuit in an embodiment of the present invention. Figure 1 ;

[0047] Figure 2 This is a schematic diagram of the structure of a D-type gallium nitride switch driving circuit in an embodiment of the present invention. Figure 2 ;

[0048] Figure 3 This is a schematic diagram of the structure of a D-type gallium nitride switch driving circuit in one embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of the switching power supply circuit structure in another embodiment of the present invention;

[0050] Figure 5 yes Figure 4 The waveform diagram of the switching power supply circuit shown is shown below.

[0051] Figure 6 This is a schematic diagram of the structure of a switching power supply circuit in the prior art;

[0052] Figure 7 yes Figure 6 The waveform diagram of the switching power supply circuit shown is shown below.

[0053] Explanation of reference numerals in the attached figures:

[0054] 10 - First Control Module;

[0055] 20 - Second control module;

[0056] 101 - Activate the speed control module;

[0057] 102 - Shut down the speed control module;

[0058] Vd - First voltage;

[0059] N-GAN-D type gallium nitride switch;

[0060] Cgs - Second parasitic capacitance;

[0061] Main FET - Switch Module;

[0062] SenseFet - Second NMOS Switch;

[0063] D1 - First diode;

[0064] D2 - Second diode;

[0065] D3 - Third diode;

[0066] D4 is the fourth diode;

[0067] R1 - First resistor;

[0068] R2 - Second resistor;

[0069] R3 - Third resistor;

[0070] C1 - First capacitor;

[0071] C2 - Second capacitor;

[0072] DZ1 - Clamping Zener diode;

[0073] Cvcco - Output capacitor;

[0074] Cvcci - Input capacitor;

[0075] Istart - Constant Current Source. Detailed Implementation

[0076] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0077] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0078] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0079] Given the difficulty in simultaneously ensuring efficiency and controlling the turn-on speed of a D-type gallium nitride (GaN) switch in existing technologies, this invention provides a D-type GaN switch driver circuit and a switching power supply circuit. The D-type GaN switch has its drain connected to a first voltage, its source coupled to a first terminal of a switching module and a first terminal of a first capacitor, its gate coupled to a first terminal of a first control module, a second terminal of the first control module coupled to a second terminal of the first capacitor, and a second control module coupled to the control terminal of the switching module. The second terminal of the first capacitor and the third terminal of the switching module are grounded. This allows the second control module to output a control signal to control the switching module's on / off state, thereby controlling the D-type GaN switch's on / off state. Simultaneously, the first control module independently adjusts the turn-on speed of the D-type GaN switch. A lower turn-on speed reduces voltage stress on subsequent circuits and improves EMI characteristics.

[0080] Please refer to Figure 1 This invention provides a D-type gallium nitride switch driving circuit, comprising: a D-type gallium nitride switch D-GAN, a first control module 10, a second control module 20, a first capacitor C1, and a switch module SW; wherein:

[0081] The drain of the D-type gallium nitride switch D-GAN is connected to a first voltage Vd. The source of the D-type gallium nitride switch D-GAN is coupled to the first terminal of the switch module SW and the first terminal of the first capacitor C1, respectively. Its gate is coupled to the first terminal of the first control module 10. The second terminal of the first control module 10 is coupled to the second terminal of the first capacitor C1. The second control module 20 is coupled to the control terminal of the switch module SW. The second terminal of the first capacitor C1 and the third terminal of the switch module SW are grounded.

[0082] The second control module 20 is used to output control signals to control the on and off states of the switch module SW, thereby controlling the on and off states of the D-type gallium nitride switch D-GAN. This is because the D-type gallium nitride switch D-GAN is a normally-on device, but in actual power supply applications, terminal devices typically require the device to be in a normally-off mode. This ensures that the device remains off even if the switch control fails, thus guaranteeing system safety. Figure 1 As shown in the circuit structure, when the gate voltage of the D-type gallium nitride switch D-GAN is 0 and the gate-source voltage is less than its pinch-off threshold, it operates in the forward blocking mode. When the switch module SW is turned on, the gate-source voltage of the D-type gallium nitride switch D-GAN is zero, and a 2DEG channel already exists between its drain and source. The D-type gallium nitride switch D-GAN will then be turned on. Therefore, controlling the on / off state of the switch module SW can control the on / off state of the D-type gallium nitride switch D-GAN.

[0083] The first control module 10 is used to adjust the turn-on speed of the D-type gallium nitride switch D-GAN. If the turn-on speed of the D-type gallium nitride switch D-GAN is too fast, the current flowing through the switch module SW will overshoot in a very short time, which can easily damage the switch module SW and also lead to excessive EMI or even destructive oscillations. This invention, through the first control module 10, can adjust the turn-on speed of the D-type gallium nitride switch D-GAN, thereby effectively protecting the switch module SW and solving the EMI problem.

[0084] Wherein, there is a first parasitic capacitance Cds between the drain and source of the D-type gallium nitride switch D-GAN. The first capacitor C1 is used to form a voltage divider with the first parasitic capacitance Cds (not shown in the figure) to reduce the voltage at the first terminal of the switching module SW when the D-type gallium nitride switch D-GAN is turned off.

[0085] As a preferred embodiment, please refer to Figure 1 The D-type gallium nitride switch D-GAN driving circuit also includes a clamping Zener diode DZ1;

[0086] The anode of the clamping Zener diode DZ1 is coupled to the first terminal of the first resistor, and the cathode of the clamping Zener diode DZ1 is coupled to the source of the D-type gallium nitride switch D-GAN.

[0087] For gallium nitride power transistors, a faster turn-off speed can improve circuit efficiency. In one embodiment, to balance EMI characteristics and circuit efficiency, the first control module 10 is also used to adjust the turn-off speed of the D-type gallium nitride switch (D-GAN). Please refer to [reference needed]. Figure 2 The first control module 10 includes an on-speed control module 101 and an off-speed control module 102 connected in parallel, wherein:

[0088] The turn-on speed control module 101 is used to adjust the turn-on speed of the D-type gallium nitride switch D-GAN;

[0089] The turn-off speed control module 102 is used to adjust the turn-off speed of the D-type gallium nitride switch D-GAN.

[0090] In one example, such as Figure 2 As shown, the turn-on speed control module 101 includes a first resistor R1; wherein:

[0091] The gate of the D-type gallium nitride switch D-GAN is coupled to the first end of the first resistor R1, and the second end of the first resistor R1 is also coupled to the second end of the first capacitor C1.

[0092] The first resistor R1 is used to adjust the turn-on speed of the D-type gallium nitride switch D-GAN. Specifically, please refer to... Figure 2 Because a second parasitic capacitance Cgs exists between the gate and source of the D-type gallium nitride switch D-GAN, the voltage on the second parasitic capacitance Cgs (i.e., the gate-source voltage Vgs of the D-type gallium nitride switch D-GAN) discharges through the first control module 10. Figure 2 In the example shown, the second parasitic capacitance Cgs and the first resistor R1 form the discharge circuit when the D-type gallium nitride switch D-GAN is turned on. Increasing the resistance value of the first resistor R1 can reduce the turn-on speed of the D-type gallium nitride switch D-GAN. A lower turn-on speed can reduce the voltage stress of subsequent circuits, improve EMI, and enhance system reliability.

[0093] In this case, as an example, please refer to Figure 2 The shutdown speed control module 102 includes a first diode D1 and a second resistor R2;

[0094] The first end of the second resistor R2 is coupled to the gate of the D-type gallium nitride switch D-GAN, and its second end is coupled to the anode of the first diode D1; the cathode of the first diode D1 is coupled to the second end of the first resistor R1.

[0095] The second resistor R2 is used to adjust the turn-off speed of the D-type gallium nitride switch D-GAN. Specifically, when the switch module SW is turned off, the source voltage of the D-type gallium nitride switch D-GAN begins to rise, and the voltage on the second parasitic capacitor Cgs begins to charge through the first control module 10. When the gate-source voltage of the D-type gallium nitride switch D-GAN falls below the pinch-off voltage threshold, the D-type gallium nitride switch D-GAN begins to turn off. Figure 2 In the example shown, the second parasitic capacitance Cgs, the second resistor R2, and the first diode D1 constitute the charging circuit during turn-off. Reducing the resistance value of the second resistor R2 can accelerate the turn-off speed of the D-type gallium nitride switch D-GAN and improve system efficiency. The resistance value of the second resistor R2 is much smaller than the resistance value of R1.

[0096] In a preferred embodiment, the resistance of the second resistor R2 is set to 0, so that the D-type gallium nitride switch D-GAN turns off at the fastest speed.

[0097] As an example, the switching module SW can be a MOS switch, and the second control module 20 is connected to the gate of the MOS transistor and sends a control signal to control the switching on and off of the MOS transistor. Of course, the present invention is not limited thereto, and in other examples, the switching module SW can also be a transistor or other normally closed switching device.

[0098] In one implementation method, please refer to Figure 3 The switching module SW is the first NMOS switching transistor Main Fette;

[0099] The drain of the first NMOS switch Main Fet is coupled to the source of the D-type gallium nitride switch D-GAN, its gate is coupled to the second control module 20, and its source is grounded.

[0100] To sample the current flowing through the D-type gallium nitride switch D-GAN, in one embodiment, please refer to... Figure 3 The D-type gallium nitride switch D-GAN driving circuit also includes a sampling module 30, which includes a current sensing resistor Rsense and a second NMOS switch SenseFet.

[0101] The first terminal of the second control module 20 is coupled to the gate of the second NMOS switch SenseFet and the gate of the first NMOS switch MainFet, respectively; its second terminal is coupled to the drain of the second NMOS switch SenseFet; its third terminal is coupled to the first terminal of the current sensing resistor Rsense; its fourth terminal is coupled to the drain of the first NMOS switch MainFet; and its fifth terminal is grounded. The second terminal of the current sensing resistor Rsense and the source of the second NMOS switch SenseFet are grounded.

[0102] The first terminal of the second control module 20 is used to output the control signal to control the conduction and turn-off of the first NMOS switch Main Fet and the second NMOS switch Sense Fet. Its second and fourth terminals are used to output the same voltage so that the second NMOS switch Sense Fet and the first NMOS switch Main Fet form a current mirror. The second control module 20 is also used to mirror the current flowing through the second NMOS switch Sense Fet to the current sensing resistor Rsense, so that the current flowing through the current sensing resistor Rsense is equal to the current flowing through the second NMOS switch Sense Fet.

[0103] In a preferred embodiment, the width-to-length ratio of the first NMOS switch Main Fet is greater than that of the second NMOS switch Sense Fet.

[0104] Since the current flowing through the first NMOS switch Main Fet is almost equal to the current flowing through the D-type gallium nitride switch D-GAN, the current flowing through the D-type gallium nitride switch D-GAN can be obtained by sampling the current of the first NMOS switch Main Fet. Since the Vgs and Vds voltages of the first NMOS switch MainFet are equal to those of the second NMOS switch SenseFet, the Ids current ratio of the first NMOS switch MainFet and the second NMOS switch SenseFet will be directly proportional to their width-to-length ratio. Therefore, by sampling the current flowing through the second NMOS switch SenseFet, the current flowing through the first NMOS switch MainFet can be determined, thus obtaining the current of the D-type gallium nitride switch D-GAN. Furthermore, since the second control module 20 mirrors the current flowing through the second NMOS switch SenseFet to the current sensing resistor Rsense, the current flowing through the current sensing resistor Rsense is equal to the current flowing through the second NMOS switch SenseFet. And since the resistance value of the current sensing resistor Rsense is known after the circuit design is fixed, measuring the voltage across the current sensing resistor Rsense will yield the current flowing through the second NMOS switch SenseFet, and thus the current of the first NMOS switch MainFet.

[0105] Given the current I1 flowing through the first NMOS switch Main Fet, the current I2 flowing through the second NMOS switch Sense Fet, the resistance value of the current sensing resistor Rsense, and the voltage Vcs across the current sensing resistor Rsense, have the following relationship:

[0106] Vcs=I2·Rsense=K·I1·Rsense

[0107] Wherein, K is the width-to-length ratio of the second NMOS switch Sense Fet to the first NMOS switch Main Fet. Typically, K is a fraction of a few thousandths, thus the loss on the current sensing resistor Rsense is low.

[0108] In a further preferred embodiment, the first NMOS switch MainFet and the second NMOS switch SenseFet are integrated on the same substrate, and the MOS switches are manufactured using the same process. In this case, to facilitate measurement of the voltage across the current sensing resistor Rsense, the current sensing resistor Rsense is an off-chip resistor.

[0109] In a preferred embodiment, the second control module 20 performs corresponding signal level processing based on external signals, so that the level of the control signal output by the second control module 20 is adapted to the level that subsequent circuits can receive. Please refer to [reference needed]. Figure 3 The second control module 20 receives an input signal PWM at its input terminal; the second control module 20 outputs a corresponding control signal based on the input signal PWM, wherein:

[0110] If the input signal PWM is high, the control signal is an adapted high-level signal;

[0111] If the input signal PWM is low, the control signal is an adapted low-level signal.

[0112] In this case, in one embodiment, the D-type gallium nitride switch D-GAN drive circuit further includes an output capacitor Cvcco;

[0113] The first terminal of the output capacitor Cvcco is coupled to the sixth terminal of the second control module 20, and the second terminal of the output capacitor Cvcco is grounded.

[0114] In a preferred embodiment, the D-type gallium nitride switch D-GAN driving circuit further includes a high-voltage startup module; the high-voltage startup module includes a second diode D2, a constant current source Istart, an LDO module, and an input capacitor Cvcci;

[0115] The source of the D-type gallium nitride switch D-GAN is coupled to the anode of the second diode D2, the cathode of the second diode D2 is coupled to the first terminal of the constant current source Istart, the second terminal of the constant current source Istart is coupled to the first terminal of the LDO module, its third terminal is coupled to the seventh terminal of the second control module 20, the second terminal of the LDO module is coupled to the eighth terminal of the second control module 20 and the first terminal of the input capacitor Cvcci, and the second terminal of the input capacitor Cvcci is grounded; wherein...

[0116] The seventh terminal of the second control module 20 is used to control the opening and closing of the constant current source Istart;

[0117] The input capacitor Cvcci is used to supply power to the second control module 20.

[0118] When the circuit starts up, the first NMOS switch MainFet is off, the gate voltage of the D-type gallium nitride switch D-GAN is zero, and the source voltage of the D-type gallium nitride switch D-GAN gradually increases. When the Vgs voltage of the D-type gallium nitride switch D-GAN reaches its pinch-off voltage Vth, the D-type gallium nitride switch D-GAN turns off. At this time, the gate voltage of the D-type gallium nitride switch D-GAN is 0, and its source voltage is Vth. At this time, the constant current source Istart draws power from the source of D-GAN and charges the input capacitor Cvcci through the LDO module. When the voltage of the input capacitor Cvcci is the start-up voltage of the second control module 20, the second control module 20 enters the working state and outputs a corresponding shutdown control signal to shut down the constant current source Istart, completing the self-powered start-up. The voltage on the input capacitor Cvcci can also be used as a voltage source for other peripheral circuits.

[0119] In addition, this invention also provides a switching power supply circuit, please refer to... Figure 4 This includes the aforementioned D-type gallium nitride switch drive circuit, RCD absorption circuit 40, and primary winding Np;

[0120] The first end of the primary winding Np is coupled to the first end of the RCD absorption circuit 40, and its second end is coupled to the second end of the RCD absorption circuit 40 and the drain of the D-type gallium nitride switch D-GAN.

[0121] For one example, please refer to Figure 4 The RCD absorption circuit 40 includes a second capacitor C2, a third resistor R3, and a third diode D3;

[0122] The first end of the primary winding Np is coupled to the first end of the second capacitor C2 and the first end of the third resistor R3, respectively. The second end of the second capacitor C2 is coupled to the second end of the third resistor R3. The second end of the third resistor R3 is coupled to the cathode of the third diode D3. The anode of the third diode D3 is coupled to the second end of the primary winding Np.

[0123] As one implementation method, please refer to Figure 4 The switching power supply circuit also includes a secondary winding Ns.

[0124] As a preferred embodiment, please refer to Figure 4 The switching power supply circuit further includes a power supply side capacitor Cin; the first end of the primary winding Np is coupled to the first end of the power supply side capacitor Cin, and the second end of the power supply side capacitor Cin is grounded.

[0125] Please refer to Figure 4 The secondary winding Ns of the switching power supply circuit also includes, for example, a rectifier diode D4, a third capacitor C3, and a fourth resistor R4.

[0126] The circuit configurations of the primary winding Np side and the secondary winding Ns side are the same as those of existing conventional circuits, and will not be described in detail here.

[0127] Now combined Figure 5 as well as Figure 7 The waveform diagrams shown compare the performance of the D-type gallium nitride switch driver circuit of the present invention and the existing D-type gallium nitride switch driver circuit in a switching power supply circuit. Figure 5 The waveform diagram shown is Figure 4 The working effect of the switching power supply circuit. Figure 7 The waveform diagram shown is Figure 6 The working effect of the existing D-type gallium nitride switch driver circuit in the switching power supply circuit is described in detail below:

[0128] PWM can be understood as the control signal output by the second control module 20;

[0129] Vd-gan can be understood as the drain voltage of the D-type gallium nitride switch D-GAN;

[0130] Vd-mos can be understood as the drain voltage of the first NMOS switch, Main Fet.

[0131] Ids can be understood as the current flowing through the first NMOS switch, Main Fet.

[0132] Vcs can be understood as the voltage at the first terminal of the current sensing resistor Rsense;

[0133] Vd2 can be understood as the voltage of the rectifier diode D4 on the Ns side of the secondary winding;

[0134] The current flowing through the first NMOS switch Main Fet has a similar waveform to the voltage at the first terminal of the current sensing resistor Rsense. Figure 5 as well as Figure 7 The same waveform is used to illustrate this.

[0135] Please refer to Figure 6 Existing D-type gallium nitride (GaN) switch driver circuits can adjust the switching speed of the GaN switch by adjusting the resistance value of resistor Rg and / or the capacitance value of capacitor C1 connected between the gate and source of the D-type GaN switch. However, this approach has a limited impact on the turn-on speed of the D-type GaN switch, but a significant impact on its turn-off speed, thus greatly affecting efficiency. Please refer to [reference needed]. Figure 7 The drain voltage waveform of the first NMOS switch Main Fet, the current waveform flowing through the first NMOS switch Main Fet, the voltage waveform of the current sensing resistor Rsense, and the voltage waveform of the rectifier diode D4 on the Ns side of the secondary winding are shown. At the moment the D-type gallium nitride switch D-GAN is turned on, its drain voltage and the drain voltage of the first NMOS switch Main Fet decrease, but the current stress on the first NMOS switch Main Fet, the voltage stress on the current sensing resistor Rsense, and the voltage stress on the rectifier diode D4 on the Ns side of the secondary winding are high. A high voltage spike can also be detected on the rectifier diode D4 on the Ns side of the secondary winding. Its voltage stress is high, and the overshoot of current and voltage will cause EMI to exceed the standard, affecting the safety and reliability of the system.

[0136] In the D-type gallium nitride switch driving circuit provided by this invention, the first resistor R1 can reduce the turn-on speed of the D-type gallium nitride switch D-GAN without affecting its turn-off speed, thus ensuring efficiency. Please refer to... Figure 5 The drain voltage waveform of the first NMOS switch Main Fet, the current waveform flowing through the first NMOS switch Main Fet, the voltage waveform of the current sensing resistor Rsense, and the voltage waveform of the rectifier diode D4 on the Ns side of the secondary winding are shown in the figure. At the moment the D-type gallium nitride switch D-GAN is turned on, the drain voltage of the first NMOS switch Main Fet and the drain voltage of the first NMOS switch Main Fet decrease. The current stress on the first NMOS switch Main Fet, the voltage stress on the current sensing resistor Rsense, and the voltage stress on the rectifier diode D4 on the Ns side of the secondary winding are all lower. A lower voltage spike can be detected in the rectifier diode D4 on the Ns side of the secondary winding. The lower voltage stress effectively prevents current and voltage overshoot, improves EMI characteristics, and enhances the safety and reliability of the system.

[0137] In summary, the D-type gallium nitride switch driving circuit and switching power supply circuit provided by the present invention are configured such that the drain of the D-type gallium nitride switch is connected to a first voltage, its source is coupled to the first terminal of the switching module and the first terminal of the first capacitor, its gate is coupled to the first terminal of the first control module, the second terminal of the first control module is coupled to the second terminal of the first capacitor, the second control module is coupled to the control terminal of the switching module, and the second terminal of the first capacitor and the third terminal of the switching module are grounded. This allows the second control module to output a control signal to control the switching module to turn on and off, thereby controlling the D-type gallium nitride switch to turn on and off. At the same time, the first control module can independently adjust the turn-on speed of the D-type gallium nitride switch. A lower turn-on speed can reduce the voltage stress on subsequent circuits and improve EMI characteristics.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A D-type gallium nitride switch driving circuit, characterized in that, include: The system comprises a D-type gallium nitride switch, a first control module, a second control module, a first capacitor, a sampling module, and a switching module; wherein: The drain of the D-type gallium nitride switch is connected to a first voltage. The source of the D-type gallium nitride switch is coupled to the first terminal of the switch module and the first terminal of the first capacitor, respectively. Its gate is coupled to the first terminal of the first control module. The second terminal of the first control module is coupled to the second terminal of the first capacitor. The second control module is coupled to the control terminal of the switch module. The second terminal of the first capacitor and the third terminal of the switch module are grounded. The second control module is used to output control signals to control the switching module to turn on and off, thereby controlling the D-type gallium nitride switch to turn on and off. The first control module is used to adjust the turn-on speed of the D-type gallium nitride switch; The switching module is a first NMOS switch, the drain of the first NMOS switch is coupled to the source of the D-type gallium nitride switch, its gate is coupled to the second control module, and its source is grounded. The sampling module includes a current sensing resistor and a second NMOS switch. The first terminal of the second control module is coupled to the gate of the second NMOS switch and the gate of the first NMOS switch, respectively. Its second terminal is coupled to the drain of the second NMOS switch. Its third terminal is coupled to the first terminal of the current sensing resistor. Its fourth terminal is coupled to the drain of the first NMOS switch. Its fifth terminal is grounded. The second terminal of the current sensing resistor and the source of the second NMOS switch are grounded.

2. The D-type gallium nitride switch driving circuit according to claim 1, characterized in that, The first control module is also used to adjust the turn-off speed of the D-type gallium nitride switch.

3. The D-type gallium nitride switch driving circuit according to claim 2, characterized in that, The first control module includes an on-speed control module and an off-speed control module connected in parallel, wherein: The turn-on speed control module is used to adjust the turn-on speed of the D-type gallium nitride switch; The turn-off speed control module is used to adjust the turn-off speed of the D-type gallium nitride switch.

4. The D-type gallium nitride switch driving circuit according to claim 3, characterized in that, The activation speed control module includes a first resistor; wherein: The gate of the D-type gallium nitride switch is coupled to the first end of the first resistor, and the second end of the first resistor is also coupled to the second end of the first capacitor; The first resistor is used to adjust the turn-on speed of the D-type gallium nitride switch.

5. The D-type gallium nitride switch driving circuit according to claim 4, characterized in that, The shutdown speed control module includes a first diode and a second resistor; The first end of the second resistor is coupled to the gate of the D-type gallium nitride switch, and its second end is coupled to the anode of the first diode; the cathode of the first diode is coupled to the second end of the first resistor. The second resistor is used to adjust the turn-off speed of the D-type gallium nitride switch.

6. The D-type gallium nitride switch driving circuit according to claim 4, characterized in that, It also includes clamping Zener diodes; The anode of the clamping Zener diode is coupled to the first terminal of the first resistor, and the cathode of the clamping Zener diode is coupled to the source of the D-type gallium nitride switch.

7. The D-type gallium nitride switch driving circuit according to claim 1, characterized in that, The first terminal of the second control module is used to output the control signal to control the conduction and turn-off of the first NMOS switch and the second NMOS switch. Its second and fourth terminals are used to output the same voltage so that the second NMOS switch and the first NMOS switch form a current mirror. The second control module is also used to mirror the current flowing through the second NMOS switch to the current sensing resistor so that the current flowing through the current sensing resistor is equal to the current flowing through the second NMOS switch.

8. The D-type gallium nitride switch driving circuit according to claim 7, characterized in that, The width-to-length ratio of the first NMOS switch is greater than that of the second NMOS switch.

9. The D-type gallium nitride switch driving circuit according to claim 7, characterized in that, The second control module receives input signals at its input terminal; the second control module outputs corresponding control signals based on the input signals, wherein: If the input signal is high, the control signal is an adapted high-level signal; If the input signal is low, the control signal is an adapted low-level signal.

10. The D-type gallium nitride switch driving circuit according to claim 7, characterized in that, It also includes the output capacitor; The first end of the output capacitor is coupled to the sixth end of the second control module, and the second end of the output capacitor is grounded.

11. The D-type gallium nitride switch driving circuit according to claim 7, characterized in that, It also includes a high-voltage start-up module; the high-voltage start-up module includes a second diode, a constant current source, an LDO module, and an input capacitor; The source of the D-type gallium nitride switch is coupled to the anode of the second diode, the cathode of the second diode is coupled to the first terminal of the constant current source, the second terminal of the constant current source is coupled to the first terminal of the LDO module, its third terminal is coupled to the seventh terminal of the second control module, the second terminal of the LDO module is coupled to the eighth terminal of the second control module and the first terminal of the input capacitor, and the second terminal of the input capacitor is grounded; wherein... The seventh terminal of the second control module is used to control the constant current source to turn on and off; The input capacitor is used to power the second control module.

12. A switching power supply circuit, characterized in that, Includes the D-type gallium nitride switch drive circuit, RCD snubber circuit, and primary winding as described in any one of claims 1 to 11; The first end of the primary winding is coupled to the first end of the RCD absorption circuit, and its second end is coupled to the second end of the RCD absorption circuit and the drain of the D-type gallium nitride switch.

13. The switching power supply circuit according to claim 12, characterized in that, The RCD absorption circuit includes a second capacitor, a third resistor, and a third diode; The first end of the primary winding is coupled to the first end of the second capacitor and the first end of the third resistor, respectively. The second end of the second capacitor is coupled to the second end of the third resistor. The second end of the third resistor is coupled to the cathode of the third diode. The anode of the third diode is coupled to the second end of the primary winding.

14. The switching power supply circuit according to claim 12, characterized in that, It also includes a power supply side capacitor; the first end of the primary winding is coupled to the first end of the power supply side capacitor, and the second end of the power supply side capacitor is grounded.

15. The switching power supply circuit according to claim 12, characterized in that, It also includes the secondary winding.

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