A driving circuit and an electrical apparatus

Abstract

The embodiment of the application discloses a driving circuit and electrical equipment, and relates to the technical field of electronic circuits. The driving circuit comprises a depletion-mode gallium nitride switch with a parasitic capacitor, the drain electrode of the depletion-mode gallium nitride switch is connected to a main circuit, the source electrode of the depletion-mode gallium nitride switch is connected to a main switch module, the first driving signal and the second driving signal are responded to be cut off or turned on, when turned on, the source electrode voltage is pulled to the ground end, the gate electrode is biased to a second voltage equal to the absolute value of the first voltage, the switch driving module is connected to the gate electrode of the depletion-mode gallium nitride switch, the first driving signal is responded to be cut off, and the source electrode voltage is lifted to the first voltage; the second driving signal is responded to charge the parasitic capacitor in sections, when charging in sections, the first rate is used first, the preset time length is switched to the second rate which is faster, the voltage difference between the two ends of the parasitic capacitor is greater than the on-voltage drop of the depletion-mode gallium nitride switch, and the depletion-mode gallium nitride switch is triggered to be turned on. The application can effectively shorten the time of the depletion-mode gallium nitride switch being turned on, so that the switching efficiency of the circuit is significantly improved.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, specifically to a drive circuit and electrical equipment. Background Technology

[0002] Gallium nitride (GaN)-based switches offer significant advantages over silicon-based switches, including faster switching speeds (nanosecond-level), lower on-resistance, higher power density, and smaller reverse recovery charge. They can meet the needs of high-efficiency, miniaturized power supply systems and are gradually being applied on a large scale in scenarios such as fast charging, industrial power supplies, and on-board chargers.

[0003] GaN switches are classified into two types: depletion-mode and enhancement-mode. Among them, depletion-mode GaN switches naturally form a two-dimensional electron gas (2DEG) at the AlGaN / GaN interface, and are in the conducting state even without gate voltage. They have lower on-resistance, higher current density, and stronger high-voltage stability. Under hard-switching conditions, the dynamic on-resistance degradation is less than that of enhancement-mode GaN, making them the preferred devices for high-voltage, high-efficiency power conversion.

[0004] The natural operating state of a depletion-mode GaN switch is the on state. It requires the gate-source voltage to be below the negative turn-off threshold voltage to be fully turned off. Current technology typically uses a scheme where the source is grounded while a negative voltage is applied to the gate to control the turn-off of the depletion-mode GaN switch. This scheme requires an independent negative voltage power supply, resulting in complex circuitry and high cost. Furthermore, when a depletion-mode GaN switch switches from the off state to the on state, the gate-source voltage needs to be increased from a negative voltage to near 0V. Current solutions generally use a method of first removing the negative voltage and then returning it to zero. Specifically, a resistor is connected in parallel between the gate and source of the depletion-mode GaN switch, allowing the charge stored at the gate to be directly discharged to the source through this resistor. The gate potential naturally returns to 0V, thus turning on the depletion-mode GaN switch. However, the return-to-zero speed of this scheme is limited by the resistor, slowing down the turn-on speed of the depletion-mode GaN switch.

[0005] In summary, the existing solutions have obvious drawbacks: using a negative voltage power supply to turn off the depletion-type GaN switch carries the risk of abnormal conduction and circuit burnout due to negative voltage power failure; in addition, the negative voltage power supply requires a matching DC-DC converter or an isolation transformer with multiple windings, resulting in complex circuitry and high costs; moreover, the method of using resistance to conduction will slow down the conduction speed of the depletion-type GaN switch. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of this application provide a driving circuit and electrical device that improve upon the complex circuitry, low safety, and slow conduction speed of related technologies.

[0007] In a first aspect, embodiments of this application provide a driving circuit, comprising: a depletion-mode gallium nitride (GaN) switch with parasitic capacitance; a main circuit electrically connected to the drain of the GaN switch; a main switch module electrically connected to the source of the GaN switch, configured to enter a cutoff state in response to a first driving signal, or to enter a conduction state in response to a second driving signal to pull the source voltage of the GaN switch down to ground, such that the gate voltage of the GaN switch is biased to a second voltage, the absolute value of the second voltage being equal to the first voltage; and a switch driving module electrically connected to the gate of the GaN switch, configured to respond to... In response to the first drive signal, the depletion-mode gallium nitride (GNU) switch is controlled to enter the off state, so that the source voltage of the GNU switch is raised to the first voltage when the main switch module is off. Alternatively, in response to the second drive signal, the parasitic capacitance of the GNU switch is charged at a first charging rate. After a preset time, the parasitic capacitance of the GNU switch is charged at a second charging rate. When the voltage difference across the parasitic capacitance is greater than the on-state voltage drop of the GNU switch, the GNU switch is triggered to enter the on state. The second charging rate is greater than the first charging rate.

[0008] Optionally, the switch driving module includes: a first switching current source electrically connected to the gate of the depletion-mode gallium nitride switch, configured to enter a cutoff state in response to a first driving signal, or to enter a saturated constant current operating region in response to a second driving signal, and output a first driving current to charge the parasitic capacitance of the depletion-mode gallium nitride switch; a second switching current source electrically connected to the gate of the depletion-mode gallium nitride switch, configured to enter a cutoff state after a delay in response to the first driving signal, or to enter a saturated constant current operating region after a delay in response to the second driving signal, and output a second driving current to charge the parasitic capacitance of the depletion-mode gallium nitride switch; wherein, the preset duration is the delay duration corresponding to the second switching current source; the first charging rate corresponds to the rate at which the first driving current charges the parasitic capacitance of the depletion-mode gallium nitride switch; the second charging rate corresponds to the sum of the rates at which the first driving current and the second driving current charge the parasitic capacitance of the depletion-mode gallium nitride switch.

[0009] Optionally, the first switch current source includes: a first control unit electrically connected to the first switch, configured to cause the first switch to enter a cutoff state in response to a first drive signal, or to cause the first switch to enter a saturated constant current operating region in response to a second drive signal; a first switch electrically connected to the gate of the depletion-mode gallium nitride switch, configured to provide a first drive current to the gate of the depletion-mode gallium nitride switch when entering the saturated constant current operating region; and a first protection unit electrically connected to the first switch, configured to provide overvoltage protection and / or overcurrent protection to the first switch.

[0010] Optionally, the first control unit includes a first PMOS transistor and a first resistor; the first switch includes a first NMOS transistor; the first protection unit includes a first diode and a second resistor; the source of the first PMOS transistor is connected to the main circuit, the drain of the first PMOS transistor is connected to the first terminal of the first resistor and the gate of the first NMOS transistor, and the gate of the first PMOS transistor receives a first driving signal and a second driving signal; the second terminal of the first resistor is connected to the gate of the depletion-type gallium nitride switch, the drain of the first NMOS transistor is grounded, and the source of the first NMOS transistor is connected to the gate of the depletion-type gallium nitride switch through the second resistor; the anode of the first diode is connected to the gate of the first NMOS transistor, and the cathode of the first diode is connected to the gate of the depletion-type gallium nitride switch.

[0011] Optionally, the second switching current source includes: a delay unit electrically connected to the second control unit, configured to delay the transmission of a first drive signal and a second drive signal to the second control unit; a second control unit electrically connected to the second switch, configured to, in response to the first drive signal transmitted by the delay unit, cause the second switch to enter a cutoff state, or, in response to the second drive signal transmitted by the delay unit, cause the second switch to enter a saturated constant current operating region; a second switch electrically connected to the gate of the depletion-type gallium nitride switch, configured to, when entering the saturated constant current operating region, provide a second drive current to the gate of the depletion-type gallium nitride switch; and a second protection unit electrically connected to the second switch, configured to provide overvoltage protection and / or overcurrent protection to the second switch.

[0012] Optionally, the second control unit includes a second PMOS transistor and a third resistor; the second switch includes a second NMOS transistor; the second protection unit includes a second diode; the source of the second PMOS transistor is connected to the main circuit, the drain of the second PMOS transistor is connected to the first terminal of the third resistor and the gate of the second NMOS transistor, and the gate of the second PMOS transistor receives the first drive signal and the second drive signal sent by the delay unit; the second terminal of the third resistor is connected to the gate of the depletion-type gallium nitride switch, the drain of the second NMOS transistor is grounded, and the source of the second NMOS transistor is connected to the gate of the depletion-type gallium nitride switch; the anode of the second diode is connected to the gate of the second NMOS transistor, and the cathode of the second diode is connected to the gate of the depletion-type gallium nitride switch.

[0013] Optionally, the switch driving module further includes: One current adjustment unit. The current adjustment unit is a positive integer; any current adjustment unit, electrically connected to the gate of the depletion-type gallium nitride switch, is configured to enter the cutoff state in response to the first current adjustment signal and the first drive signal, enter the cutoff state in response to the second current adjustment signal, or enter the saturated constant current operating region in response to the first current adjustment signal and the second drive signal, and output a third drive current to charge the parasitic capacitance of the depletion-type gallium nitride switch; the first current adjustment signal and the second current adjustment signal of each current adjustment unit are set independently.

[0014] Optionally, the current trimming unit includes: a signal integration subunit electrically connected to the control subunit, configured to send a first drive signal to the control subunit upon receiving a first current trimming signal and a first drive signal, send a first drive signal to the control subunit upon receiving a second current trimming signal, and send a second drive signal to the control subunit upon receiving the first current trimming signal and the second drive signal; a control subunit electrically connected to a third switch, configured to cause the third switch to enter a cutoff state in response to the first drive signal sent by the signal integration subunit, or to cause the third switch to enter a saturated constant current operating region in response to the second drive signal sent by the signal integration subunit; a third switch electrically connected to the gate of the depletion-type gallium nitride switch, configured to provide a third drive current to the gate of the depletion-type gallium nitride switch when entering the saturated constant current operating region; and a protection subunit electrically connected to the third switch, configured to provide overvoltage protection and / or overcurrent protection to the third switch.

[0015] Optionally, the signal integration subunit includes an AND gate; the control subunit includes a third PMOS transistor and a fourth resistor; the third switch includes a third NMOS transistor; the protection subunit includes a third diode and a fifth resistor; the source of the third PMOS transistor is connected to the main circuit, the drain of the third PMOS transistor is connected to the first terminal of the fourth resistor and the gate of the third NMOS transistor, the gate of the third PMOS transistor is connected to the output terminal of the AND gate, the first input terminal of the AND gate receives a first driving signal and a second driving signal, and the second input terminal receives a first current adjustment signal and a second current adjustment signal; the second terminal of the fourth resistor is connected to the gate of the depletion-mode gallium nitride switch, the drain of the third NMOS transistor is grounded, and the source of the third NMOS transistor is connected to the gate of the depletion-mode gallium nitride switch through the fifth resistor; the anode of the third diode is connected to the gate of the third NMOS transistor, and the cathode of the third diode is connected to the gate of the depletion-mode gallium nitride switch.

[0016] Optionally, the driving circuit further includes: a fourth switch, or a fourth diode and a sixth resistor; the fourth switch is connected to the gate and ground of the depletion-type gallium nitride switch respectively, and is configured to enter the on state in response to the first driving signal, or to enter the off state in response to the second driving signal; the fourth diode has its anode grounded and its cathode connected to the gate of the depletion-type gallium nitride switch; the sixth resistor is connected in parallel with the fourth diode.

[0017] In a second aspect, embodiments of this application provide an electrical device, including: a drive circuit as described above, and a controller, which are electrically connected to the main switch module and the switch drive module of the drive circuit, respectively.

[0018] The beneficial effects of the driving circuit provided in this application embodiment are as follows: This application embodiment controls the on / off state of the entire circuit by setting a main switch module, ensuring that the circuit will not conduct abnormally and improving the safety of the circuit; at the same time, the switch driving module is used to turn off the depletion-mode gallium nitride switch when the entire circuit needs to be turned off. Because the switch driving module is connected in series with the depletion-mode gallium nitride switch, in a series circuit, the smaller the capacitor, the higher the voltage it receives. Moreover, the parasitic capacitance of the depletion-mode gallium nitride switch is small. Therefore, when it is turned off, the depletion-mode gallium nitride switch bears most of the voltage from the main circuit, ensuring that the main switch module will not be damaged due to excessive voltage applied by the main circuit when it is turned off; when the entire circuit needs to be turned on, the switch driving module first charges the parasitic capacitance of the depletion-mode gallium nitride switch at a first charging speed. After a preset time, it then charges the parasitic capacitance of the depletion-mode gallium nitride switch at a faster second charging rate, shortening the time required for the depletion-mode gallium nitride switch to turn on, thereby significantly improving the switching efficiency of the circuit. The circuit is simple and has a low cost. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 A schematic diagram of a driving circuit structure provided in an embodiment of this application; Figure 2 A schematic diagram of a switch driving module provided in another embodiment of this application; Figure 3 A schematic diagram of the structure of a first switching current source provided in another embodiment of this application; Figure 4 A schematic diagram of the structure of a second switching current source provided in another embodiment of this application; Figure 5 A schematic diagram of the structure of a current adjustment unit provided in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of an electrical device provided in yet another embodiment of this application; Figure 7 This is a schematic diagram of the application of a driving circuit provided in another embodiment of this application. Detailed Implementation

[0021] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "electrically connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "inner," "outer," "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. Furthermore, technical features involved in the different embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0023] Depletion-mode gallium nitride (GaN) switches are naturally turned on and require the gate-source voltage to fall below a negative voltage threshold to turn off. Existing technologies commonly use a source-grounded, gate-switched turn-off method, which requires an independent negative voltage power supply, resulting in complex circuitry and high costs. Existing solutions require returning the gate-source negative voltage to zero when switching from off to on, achieved by discharging gate charge through a parallel resistor between the gate and source. The speed of this zero-return method is limited by the resistor, thus slowing down the turn-on rate of the depletion-mode GaN switch.

[0024] In other words, the existing driving scheme has two major drawbacks: First, negative voltage power supply is prone to abnormal conduction of devices and burnout of circuits due to power failure, and negative voltage power supply requires a DC-DC or multi-winding isolation transformer, which is complex in structure and expensive; Second, the resistor discharge to zero method will reduce the conduction speed of depletion-type gallium nitride switches.

[0025] Therefore, this application provides a driving circuit, please refer to the embodiments thereof. Figure 1 The driving circuit 100 includes: a depletion-type gallium nitride switch 200, configured with parasitic capacitance; The main circuit 300 is electrically connected to the drain of the depletion-type gallium nitride switch 200; As an example, the main circuit 300 may be a flyback switching power supply circuit, a forward switching power supply circuit, a half-bridge DC-DC converter circuit, a full-bridge inverter circuit, etc.

[0026] The main switch module 400 is electrically connected to the source of the depletion-type gallium nitride switch 200 and is configured to enter a cutoff state in response to a first drive signal, or to enter a conduction state in response to a second drive signal to pull the source voltage of the depletion-type gallium nitride switch 200 down to ground GND, so that the gate voltage of the depletion-type gallium nitride switch 200 is biased to a second voltage, the absolute value of which is equal to the first voltage. As an example, the main switch module 400 may be composed of MOSFETs, IGBTs, transistors, analog switches, and / or optocouplers; the first drive signal and the second drive signal may originate from PWM signals, analog levels, the output of logic gate circuits, clock oscillation signals, the output of MCUs, and / or the output of controllers, etc. For example, the first drive signal corresponds to the low level state of the PWM signal, the second drive signal corresponds to the high level state of the logic gate circuit output, or the analog level directly applies the turn-on voltage or turn-off voltage to the switch. Other cases will not be elaborated further. A switch driving module 500, electrically connected to the gate (GATE) of the depletion-mode gallium nitride (GN) switch 200, is configured to, in response to the first driving signal, control the GN switch 200 to enter a cutoff state, such that the source voltage of the GN switch 200 is raised to the first voltage when the main switch module 400 is cut off; or, in response to the second driving signal, charge the parasitic capacitance of the GN switch 200 at a first charging rate, and after a preset time, continue charging the parasitic capacitance of the GN switch 200 at a second charging rate, such that when the voltage difference across the parasitic capacitance is greater than the on-state voltage drop of the GN switch 200, the GN switch 200 is triggered to enter a conduction state, wherein the second charging rate is greater than the first charging rate.

[0027] As an example, the default state of the drive circuit 100 can be set to a state where the main switch module 400 is off and the depletion-type gallium nitride switch 200 is off, and the gate potential in the default state is... The voltage can be adjusted according to actual needs. For ease of explanation, let's assume the gate potential is in the default state. The gate-source voltage is 0V. Understandable Within the turn-off voltage range of the depletion-mode gallium nitride switch 200, and The value is related to the voltage applied by the main circuit 300 to the depletion-type gallium nitride switch 200 under default conditions. For ease of explanation, let's assume... If the voltage is -15V, then under the default state, the source potential is... It is 15V; As an example, the parasitic capacitance is the parasitic capacitance between the gate and source of the depletion-mode gallium nitride switch 200. Subsequently, in order to turn on the drive circuit 100, the main switch module 400 is turned on through the second drive signal, which pulls the source voltage of the depletion-mode gallium nitride switch 200 down to ground. Assuming the ground potential is 0V, the source potential... The voltage jumps from 15V to 0V due to the parasitic capacitance in the depletion-mode gallium nitride switch 200. The charge on a capacitor cannot change instantaneously, and the charge on a capacitor equals the capacitance plus the parasitic capacitance. Voltage at both ends The capacitance of a capacitor cannot change abruptly due to the product of absolute values, therefore the voltage... There was no jump, that is The value is still equal to ,again ,but ,Right now The voltage becomes -15V the instant the main switch module 400 is turned on; that is, under the above assumptions, the second voltage is -15V. Simultaneously, in response to the second drive signal, the switch drive module 500, through the gate, sets the parasitic capacitance according to the first charging rate or the second charging rate. Charging occurs, meaning the gate is charged. When the voltage is charged from -15V to a value greater than the turn-off voltage of the depletion-mode gallium nitride switch 200, the depletion-mode gallium nitride switch 200 begins to conduct. In order to reduce the conduction loss of the depletion-mode gallium nitride switch 200, the time node for charging at the second charging rate can be determined by designing the preset duration. As an example, the order of the charging rates and the charging rate switching nodes can be designed according to the specific circuit conditions in the implementation. In addition, fast charging can be performed first and then slow charging can be performed, or the same charging rate can be used throughout the entire process.

[0028] In one possible implementation, please refer to Figure 2 The switch driving module 500 includes: The first switching current source 510 is electrically connected to the gate of the depletion-type gallium nitride switch and is configured to enter the cut-off state in response to the first driving signal, or to enter the saturated constant current operating region in response to the second driving signal, and output the first driving current to charge the parasitic capacitance of the depletion-type gallium nitride switch 200. The second switching current source 520 is electrically connected to the gate of the depletion-type gallium nitride switch and is configured to delay response to the first drive signal to enter the off state, or delay response to the second drive signal to enter the saturated constant current operating region and output the second drive current to charge the parasitic capacitance of the depletion-type gallium nitride switch 200. The preset duration is the delay duration corresponding to the second switching current source 520; The first charging rate corresponds to the rate at which the first driving current charges the parasitic capacitance of the depletion-type gallium nitride switch. The second charging rate corresponds to the sum of the charging rates of the parasitic capacitance of the depletion-type gallium nitride switch, where the first driving current and the second driving current are used.

[0029] As an example, the first switch current source 510 and the second switch current source 520 use switches as current sources. By taking advantage of the fact that the switches output constant current when they enter the saturated constant current operating region, the stability of the first drive current and the second drive current is ensured, and they are not affected by the load and / or voltage fluctuations of the drive circuit 100. This can effectively protect the depletion-mode gallium nitride switch 200, suppress gate oscillation, and reduce electromagnetic interference (EMI) and losses of the depletion-mode gallium nitride switch 200.

[0030] In one possible implementation, please refer to Figure 3 The first switching current source 510 includes: The first control unit is electrically connected to the first switch and is configured to, in response to the first drive signal, cause the first switch to enter the off state, or, in response to the second drive signal, cause the first switch 512 to enter the saturated constant current operating region. The first switch, electrically connected to the gate GATE of the depletion-type gallium nitride switch 200, is configured to provide a first drive current to the gate GATE of the depletion-type gallium nitride switch 200 when entering the saturated constant current operating region. The first protection unit, electrically connected to the first switch, is configured to provide overvoltage protection and / or overcurrent protection for the first switch.

[0031] In one possible implementation, the first control unit includes: a first PMOS transistor S1 and a first resistor R1; The first switch includes: a first NMOS transistor M1; The first protection unit includes: a first diode DZ1 and a second resistor R2; The source of the first PMOS transistor S1 is connected to the main circuit 300, and the drain of the first PMOS transistor S1 is connected to the first terminal of the first resistor R1 and the gate of the first NMOS transistor M1, respectively. The gate of the first PMOS transistor S1 receives the first driving signal and the second driving signal. The second end of the first resistor R1 is connected to the gate GATE of the depletion-type gallium nitride switch 200, the drain of the first NMOS transistor M1 is grounded, and the source of the first NMOS transistor M1 is connected to the gate GATE of the depletion-type gallium nitride switch 200 through the second resistor R2. The anode of the first diode DZ1 is connected to the gate of the first NMOS transistor M1, and the cathode of the first diode DZ1 is connected to the gate GATE of the depletion-type gallium nitride switch 200.

[0032] It is understandable that, since the internal current of the main circuit 300 is small, it is impossible to use the internal current to drive the depletion-type gallium nitride switch 200. In this embodiment, the source of the first PMOS transistor S1 is connected to the main circuit 300, and the internal current I1 of the main circuit 300 is used as the current source to start the first drive current. Then, the depletion-type gallium nitride switch 200 is driven by the first drive current. There is no need to introduce an additional current source, which can reduce power consumption, simplify the circuit, and reduce costs.

[0033] As an example, the first PMOS transistor S1 enters the cutoff state in response to the first drive signal and enters the conduction state in response to the second drive signal. When the first PMOS transistor S1 is in the conduction state, the voltage across the first resistor R1 is used to provide a voltage drop that turns on the first NMOS transistor M1, and the second resistor is used to limit the magnitude of the first drive current output by the first NMOS transistor M1 to the safe operating range of the first NMOS transistor M1.

[0034] As an example, the ISO (isolation) and SUB (substrate) of the first NMOS transistor M1 are grounded, and the first drive current and ISO bias current output do not need to be provided by the chip, which can reduce power consumption.

[0035] It is understood that the first diode DZ1 can be other components with overvoltage protection or voltage regulation function. For example, the first diode DZ1 is a Zener diode, used to limit the voltage across the first resistor R1 to near the Zener voltage.

[0036] In one possible implementation, please refer to Figure 4 The second switching current source 520 includes: The delay unit Delay is electrically connected to the second control unit and is configured to delay the transmission of the first drive signal and the second drive signal to the second control unit. The second control unit, electrically connected to the second switch, is configured to cause the second switch to enter the off state in response to a first drive signal sent by the delay unit Delay, or to cause the second switch to enter the saturated constant current operating region in response to a second drive signal sent by the delay unit Delay. The second switch, electrically connected to the gate GATE of the depletion-type gallium nitride switch 200, is configured to provide drive current to the gate GATE of the depletion-type gallium nitride switch 200 when entering the saturated constant current operating region. The second protection unit, electrically connected to the second switch, is configured to provide overvoltage protection and / or overcurrent protection for the second switch.

[0037] In one possible implementation, the second control unit includes: a second PMOS transistor S2 and a third resistor R3; The second switch includes: a second NMOS transistor M2; The second protection unit includes: a second diode DZ2; The source of the second PMOS transistor S2 is connected to the main circuit 300, and the drain of the second PMOS transistor S2 is connected to the first end of the third resistor R3 and the gate of the second NMOS transistor M2, respectively. The gate of the second PMOS transistor S2 receives the first drive signal and the second drive signal sent by the delay unit Delay. The second terminal of the third resistor R3 is connected to the gate GATE of the depletion-type gallium nitride switch 200, the drain of the second NMOS transistor M2 is grounded, and the source of the second NMOS transistor M2 is connected to the gate GATE of the depletion-type gallium nitride switch 200. The anode of the second diode DZ2 is connected to the gate of the second NMOS transistor M2, and the cathode of the second diode DZ2 is connected to the gate of the depletion-type gallium nitride switch 200.

[0038] For ease of explanation, let's assume that during the gate charging process, Finally, it is charged to 0V (which allows the gate to be connected to ground via the switch driver module 500, thus...) The final potential is limited to near 0V. When the switch driver module 500 responds to the first drive signal and enters the cutoff state, the source of the depletion-mode gallium nitride switch 200 is floating, and the source potential is... The instantaneous potential is related to the voltage applied by the main circuit 300 to the depletion-type gallium nitride switch 200, assuming The instantaneous potential is 15V, that is, in this state, The voltage jumps from 0V to 15V. Under the aforementioned assumptions, the first voltage is 15V; Similarly to the previous analysis, due to Unable to jump, The voltage jumps from 0V to 15V. Because the drain of the depletion-mode gallium nitride switch 200 is always connected to the main circuit 300, the drain potential remains unchanged, and the gate-drain voltage... The absolute value decreases, parasitic capacitance The amount of charge decreases, i.e., the parasitic capacitance decreases. Rapid discharge; Furthermore, when the main switch module 400 is turned off, the second PMOS transistor remains on for a preset time due to the delayed response of the second control unit to the first drive signal. Since the source of the second NMOS transistor is connected to the gate of the depletion-mode gallium nitride switch 200, the source potential of the second NMOS transistor... The drain of the second NMOS transistor is grounded, that is, the drain of the second NMOS transistor... , Current flows from the source to the drain of the second NMOS transistor, i.e., the parasitic capacitance. The gate of the depletion-mode gallium nitride switch 200 discharges rapidly to ground through the source-to-drain path of the second NMOS transistor, eliminating the need for an additional bleed path. After the gate discharges... When the potential is near 0V, the gate-drain voltage of the second NMOS transistor turns it on, and the second NMOS transistor outputs a second drive current to charge the gate in advance, effectively shortening the charging time required after the subsequent main switch module 400 is turned on.

[0039] Understandably, the current I2 provided by the main circuit 300 flows into the source of the second PMOS transistor S2.

[0040] In one possible implementation, the switch driving module further includes: One current adjustment unit. It is a positive integer; Any current adjustment unit, electrically connected to the gate GATE of the depletion-type gallium nitride switch 200, is configured to enter the cutoff state in response to the first current adjustment signal and the first drive signal, enter the cutoff state in response to the second current adjustment signal, or enter the saturated constant current operating region in response to the first current adjustment signal and the second drive signal, and output a third drive current to charge the parasitic capacitance of the depletion-type gallium nitride switch 200. The first current adjustment signal and the second current adjustment signal of each current adjustment unit are set independently.

[0041] Understandably, since different depletion-mode gallium nitride switches 200 require different drive currents, the drive requirements of different depletion-mode gallium nitride switches 200 can be met by setting multiple current adjustment units and selecting the number of current adjustment units to be connected according to the required drive current.

[0042] In one possible implementation, please refer to Figure 5 , Figure 5 This illustrates a scenario where the drive circuit 100 has one current adjustment unit, which includes: The signal integration subunit, electrically connected to the control subunit, is configured to send a first drive signal to the control subunit when receiving a first current adjustment signal and a first drive signal, send a first drive signal to the control subunit when receiving a second current adjustment signal, and send a second drive signal to the control subunit when receiving both the first current adjustment signal and the second drive signal. The control subunit, electrically connected to the third switch, is configured to, in response to a first drive signal sent by the signal integration subunit, cause the third switch to enter the off state, or, in response to a second drive signal sent by the signal integration subunit, cause the third switch to enter the saturated constant current operating region. The third switch, electrically connected to the gate GATE of the depletion-type gallium nitride switch 200, is configured to provide drive current to the gate GATE of the depletion-type gallium nitride switch 200 when entering the saturated constant current operating region. The protection subunit, electrically connected to the third switch, is configured to provide overvoltage protection and / or overcurrent protection for the third switch.

[0043] As an example, the first current adjustment signal and the second current adjustment signal can be derived from the Trim signal. For example, the first drive signal can be sent when the Trim signal is set to a low level, and the first drive signal can be sent when the first drive signal is received when the Trim signal is high, and the second drive signal can be sent when the second drive signal is received. It is understood that the control logic corresponding to the high and low levels of the Trim signal can be interchanged, and the control logic should not be a limitation of this application.

[0044] In one possible implementation, the signal integration subunit includes: an AND gate ND2; The control subunit includes: a third PMOS transistor S3 and a fourth resistor R4; The third switch includes: a third NMOS transistor M3; The protection subunit includes: a third diode DZ3 and a fifth resistor R5; The source of the third PMOS transistor S3 is connected to the main circuit. The drain of the third PMOS transistor S3 is connected to the first terminal of the fourth resistor R4 and the gate of the third NMOS transistor M3. The gate of the third PMOS transistor S3 is connected to the output terminal of the AND gate ND2. The first input terminal of the AND gate ND2 receives the first driving signal and the second driving signal, and the second input terminal receives the first current adjustment signal and the second current adjustment signal. The second end of the fourth resistor R4 is connected to the gate GATE of the depletion-type gallium nitride switch 200, the drain of the third NMOS transistor M3 is grounded, and the source of the third NMOS transistor M3 is connected to the gate GATE of the depletion-type gallium nitride switch 200 through the fifth resistor R5. The anode of the third diode DZ3 is connected to the gate of the third NMOS transistor M3, and the cathode of the third diode DZ3 is connected to the gate GATE of the depletion-type gallium nitride switch 200.

[0045] In one possible implementation, the drive circuit 100 further includes: a fourth switch, or a fourth diode and a sixth resistor; The fourth switch, connected to the gate and ground of the depletion-mode gallium nitride switch respectively, is configured to enter the on state in response to the first drive signal, or to enter the off state in response to the second drive signal; The fourth diode has its anode grounded and its cathode connected to the gate of a depletion-mode gallium nitride switch. The sixth resistor is connected in parallel with the fourth diode.

[0046] As an example, both the fourth switch and the fourth diode are used to discharge the gate current of the depletion-type gallium nitride switch 200 to ground when the main switch module 400 switches from on to off; the sixth resistor is used to limit the discharge current to prevent the fourth diode from burning out due to overcurrent.

[0047] As another aspect of this application, this application provides an electrical device. Please refer to... Figure 6 Electrical equipment 600 includes: The drive circuit 100 as described in the above embodiments; The controller 610 is electrically connected to the main switch module 400 and the switch drive module 500 of the drive circuit 100, respectively. According to control commands, the controller 610 sends enable signals, such as a first drive signal and a second drive signal, to the main switch module 400 and the switch drive module 500, causing them to enter the working state. The drive circuit 100 is used to control the on and off states of the main switch module 400 and the switch drive module 500 using the controller 610, thereby controlling the on and off states of the depletion-mode gallium nitride switch 200.

[0048] In one possible implementation, please refer to Figure 7 , Figure 7 The main circuit 300 is shown as the drive circuit 100 of a flyback switching power supply circuit; As the cost and size of electronic products continue to decrease, traditional flyback adapters can use either high-voltage enhancement-mode gallium nitride (GaN) or depletion-mode gallium nitride (DMN) power transistors. The advantages of using DMN power transistors are: 1. No high-voltage startup current source or startup resistor is needed; 2. DMN is often cheaper; 3. The DMN driver circuit can be powered by ground, eliminating the need for a high-current 6.5V drive power supply in the chip design, and it consumes less power compared to enhancement-mode devices. Therefore, designing an integrable on-chip DMN driver is a challenge. This application proposes an on-chip design concept for a driver circuit 100, applicable to any system driving DMN devices.

[0049] Figure 7The solution for the low-side application of the depletion-type gallium nitride switch 200 is shown. The solution for the high-side application is similar. The drain of the depletion-type gallium nitride switch 200 is changed to be connected to the positive terminal of the power supply, and the main switch module 400 is changed to be grounded through a transformer.

[0050] As an example, the main switch module 400 can be a medium-voltage PMOS transistor.

[0051] for Figure 7 Here's a brief overview of its working principle: VIN is the high-voltage input power supply after bridge rectification. After power-on, the source of the depletion-mode gallium nitride (GaN) diode automatically rises to the pinch-off point, typically 10V~20V. At this time, the main switch module 400 is in the off state. After the IC power supply is established, the PWM signal continuously switches the power transistors to convert the high voltage into the secondary winding output voltage. Figure 7 The central control loop and other components have been omitted.

[0052] like Figure 7 As shown, if a depletion-mode gallium nitride (GaN) switch 200 is used, the flyback system can achieve the previously mentioned benefits: 1. No high-voltage startup current source or startup resistor is required; 2. Depletion-mode GaN is cheaper; 3. Depletion-mode GaN drive does not require a chip-based drive power supply. If an integrated polysilicon resistor is used to drive the depletion-mode GaN, or the gate is directly grounded and the source is connected to the intermediate voltage PMOS of the lower transistor, the intermediate voltage PMOS turns on, and the GaN device conducts, allowing the transformer to store energy. However, this method makes the GaN turn-on speed insufficient to meet the requirements of various GaN parameters, and also fails to meet the system's EMC (electromagnetic compatibility) and EMI (electromagnetic interference) test requirements. Therefore, this application proposes using a switch driver module 500 to drive the GaN gate. The current source providing the drive current can be adjusted or multi-stage driven to meet the different drive current requirements of different depletion-mode GaNs, ensuring that the drain descent speed always meets the requirements. The diode in the switch driver module 500 clamps the highest voltage of the gate to a diode voltage drop, allowing the GaN to turn off quickly.

[0053] Because the gate of gallium nitride is pulled negative to near the pinch-off voltage (usually -10V to -20V) when the lower transistor is turned on, ordinary current sources cannot be used for this. Figure 7 The image shows a method using BCD (Bipolar-CMOS-DMOS) technology. Complementary metal-oxide-semiconductor The specific implementation of this double-diffused metal-oxide-semiconductor (DMOS) process utilizes NMOS (compared to PMOS) to minimize chip area. Within the safe operating region of the NMOS, it can achieve a fully on state, maximizing current output with minimal area. M1, M2, and M3 in this application are the current sources driving the gate (more current source combinations can be achieved by increasing the number of current adjustment modules) and switches. The drain and ISO of the NMOS are connected to GND, eliminating the need for chip-based current output and saving power. R2 and R5 are used to set the current source size to ensure the safe operating region of the NMOS. Current sources I1, I2, and I3 generate voltage drops across R1, R4, and R3 after passing through switches S1, S2, and S3, activating the driving current sources M1, M2, and M3. I1, I2, and I3 only require a maximum 5V voltage drop across R1, R4, and R3, requiring a relatively small current that can be provided by the internal power supply VDR. Switches S1, S2, and S3 can be implemented using medium-voltage PMOS, and switching control can be easily achieved through internal power supply logic. DZ1, DZ2, and DZ3 are Zener diodes used to protect the gate-source voltages of M1, M2, and M3.

[0054] Switch S1 can be directly controlled by a PWM signal. When PWM is high, the medium-voltage PMOS transistor turns on, and S1 closes simultaneously. The gate-source voltage of the depletion-mode GaN switch 200 is charged by current source M1, turning it on. The GATE voltage is charged from -10V to -20V to near GND at the instant the lower transistor turns on. Different GaN transistors require different current sources for driving. This can be achieved by adding a Trim signal to control any combination of current sources to turn on or off, such as... Figure 5 S2 is controlled by both Trim and PWM. If Trim is high, the switch and PWM signal are synchronized, and M1 and M2 work together to meet the drive requirements of larger currents. If Trim is low, the current source M2 remains off. In the later stages of gallium nitride turn-on, the gate needs to be charged to near GND more quickly to achieve a uniform drain rate.

[0055] Switch S3 is controlled by a logic level derived from a PWM signal with an appropriate delay. Thus, M3 acts as a switch, short-circuiting the gate and ground of the gallium nitride (GaN). Therefore, during the initial startup phase, the GaN is charged by the current source M1. After a delay, the M3 switch is added to quickly pull the gate to GND, making the gallium nitride (GaN) turn-on faster and achieving the optimal overall turn-on rate. Similarly, the turn-on speed can be optimized by adjusting the delay value through logic tuning. When off, the PWM signal is low, the main switch module 400 (lower transistor) is off, the current sources M1 and M2 are off, and the M3 switch is on because the PWM delay signal has not yet toggled. Therefore, the signal is off. Discharge provides a low-resistance path to GND, causing the source of the depletion-mode gallium nitride switch 200 to rapidly rise to the pinch-off voltage, turning off the gallium nitride device. Switches S1 and S2 can also be turned off after the gallium nitride is turned on, further reducing losses. All driving devices in the switch drive module 500 are implemented using NMOS, eliminating the need for a fourth diode for turn-off, significantly reducing chip area. The two-stage drive approach ensures the entire switching process meets performance requirements and EMI / EMC requirements.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some 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 this application.

Claims

1. A driving circuit, characterized in that, include: A depletion-mode gallium nitride switch with parasitic capacitance; The main circuit is electrically connected to the drain of the depletion-type gallium nitride switch; The main switch module, electrically connected to the source of the depletion-type gallium nitride switch, is configured to enter a cutoff state in response to a first drive signal, or to enter a conduction state in response to a second drive signal to pull the source voltage of the depletion-type gallium nitride switch down to ground, such that the gate voltage of the depletion-type gallium nitride switch is biased to a second voltage, the absolute value of which is equal to the first voltage. A switch driving module, electrically connected to the gate of the depletion-mode gallium nitride (GNU) switch, is configured to, in response to the first driving signal, control the GNU switch to enter a cutoff state, such that the source voltage of the GNU switch is raised to the first voltage when the main switch module is cut off; or, in response to the second driving signal, charge the parasitic capacitance of the GNU switch at a first charging rate, and after a preset time, continue charging the parasitic capacitance of the GNU switch at a second charging rate, such that when the voltage difference across the parasitic capacitance is greater than the on-state voltage drop of the GNU switch, triggering the GNU switch to enter a conduction state, wherein the second charging rate is greater than the first charging rate.

2. The driving circuit according to claim 1, characterized in that, The switch driving module includes: The first switching current source is electrically connected to the gate of the depletion-type gallium nitride switch and is configured to enter the cutoff state in response to the first driving signal, or to enter the saturated constant current operating region in response to the second driving signal, and output the first driving current to charge the parasitic capacitance of the depletion-type gallium nitride switch. The second switching current source is electrically connected to the gate of the depletion-type gallium nitride switch and is configured to delay response to the first drive signal to enter the off state, or delay response to the second drive signal to enter the saturated constant current operating region and output the second drive current to charge the parasitic capacitance of the depletion-type gallium nitride switch. Wherein, the preset duration is the delay duration corresponding to the second switching current source; The first charging rate corresponds to the rate at which the first driving current charges the parasitic capacitance of the depletion-type gallium nitride switch. The second charging rate corresponds to the sum of the charging rates of the parasitic capacitance of the depletion-type gallium nitride switch, where the first driving current and the second driving current are used.

3. The driving circuit according to claim 2, characterized in that, The first switching current source includes: A first control unit, electrically connected to a first switch, is configured to, in response to a first drive signal, cause the first switch to enter a cut-off state, or, in response to a second drive signal, cause the first switch to enter a saturated constant current operating region. A first switch, electrically connected to the gate of the depletion-mode gallium nitride switch, is configured to provide a first drive current to the gate of the depletion-mode gallium nitride switch when entering the saturated constant current operating region. The first protection unit, electrically connected to the first switch, is configured to provide overvoltage protection and / or overcurrent protection for the first switch.

4. The driving circuit according to claim 3, characterized in that, The first control unit includes: a first PMOS transistor and a first resistor; The first switch includes: a first NMOS transistor; The first protection unit includes: a first diode and a second resistor; The source of the first PMOS transistor is connected to the main circuit, the drain of the first PMOS transistor is connected to the first terminal of the first resistor and the gate of the first NMOS transistor, and the gate of the first PMOS transistor receives the first driving signal and the second driving signal. The second end of the first resistor is connected to the gate of the depletion-type gallium nitride switch, the drain of the first NMOS transistor is grounded, and the source of the first NMOS transistor is connected to the gate of the depletion-type gallium nitride switch through the second resistor. The anode of the first diode is connected to the gate of the first NMOS transistor, and the cathode of the first diode is connected to the gate of the depletion-mode gallium nitride switch.

5. The driving circuit according to claim 2, characterized in that, The second switching current source includes: The delay unit, electrically connected to the second control unit, is configured to delay the transmission of the first drive signal and the second drive signal to the second control unit. The second control unit, electrically connected to the second switch, is configured to, in response to a first drive signal sent by the delay unit, cause the second switch to enter the off state, or, in response to a second drive signal sent by the delay unit, cause the second switch to enter the saturated constant current operating region. The second switch, electrically connected to the gate of the depletion-mode gallium nitride switch, is configured to provide a second drive current to the gate of the depletion-mode gallium nitride switch when entering the saturated constant current operating region. The second protection unit, electrically connected to the second switch, is configured to provide overvoltage protection and / or overcurrent protection for the second switch.

6. The driving circuit according to claim 5, characterized in that, The second control unit includes: a second PMOS transistor and a third resistor; The second switch includes: a second NMOS transistor; The second protection unit includes: a second diode; The source of the second PMOS transistor is connected to the main circuit, and the drain of the second PMOS transistor is connected to the first terminal of the third resistor and the gate of the second NMOS transistor respectively. The gate of the second PMOS transistor receives the first drive signal and the second drive signal sent by the delay unit. The second terminal of the third resistor is connected to the gate of the depletion-type gallium nitride switch, the drain of the second NMOS transistor is grounded, and the source of the second NMOS transistor is connected to the gate of the depletion-type gallium nitride switch. The anode of the second diode is connected to the gate of the second NMOS transistor, and the cathode of the second diode is connected to the gate of the depletion-mode gallium nitride switch.

7. The driving circuit according to any one of claims 1 to 6, characterized in that, The switch drive module further includes: One current adjustment unit. It is a positive integer; Any current trimming unit, electrically connected to the gate of the depletion-type gallium nitride switch, is configured to enter the cutoff state in response to the first current trimming signal and the first drive signal, enter the cutoff state in response to the second current trimming signal, or enter the saturated constant current operating region in response to the first current trimming signal and the second drive signal, and output a third drive current to charge the parasitic capacitance of the depletion-type gallium nitride switch. The first current adjustment signal and the second current adjustment signal of each current adjustment unit are set independently.

8. The driving circuit according to claim 7, characterized in that, The current adjustment unit includes: The signal integration subunit, electrically connected to the control subunit, is configured to send a first drive signal to the control subunit when receiving a first current adjustment signal and a first drive signal, send a first drive signal to the control subunit when receiving a second current adjustment signal, and send a second drive signal to the control subunit when receiving both the first current adjustment signal and the second drive signal. The control subunit, electrically connected to the third switch, is configured to, in response to a first drive signal sent by the signal integration subunit, cause the third switch to enter the off state, or, in response to a second drive signal sent by the signal integration subunit, cause the third switch to enter the saturated constant current operating region. The third switch, electrically connected to the gate of the depletion-mode gallium nitride switch, is configured to provide a third drive current to the gate of the depletion-mode gallium nitride switch when entering the saturated constant current operating region. The protection subunit, electrically connected to the third switch, is configured to provide overvoltage protection and / or overcurrent protection for the third switch.

9. The driving circuit according to claim 8, characterized in that, The signal integration subunit includes: a logic AND gate; The control subunit includes: a third PMOS transistor and a fourth resistor; The third switch includes: a third NMOS transistor; The protection subunit includes: a third diode and a fifth resistor; The source of the third PMOS transistor is connected to the main circuit. The drain of the third PMOS transistor is connected to the first terminal of the fourth resistor and the gate of the third NMOS transistor. The gate of the third PMOS transistor is connected to the output terminal of the AND gate. The first input terminal of the AND gate receives the first driving signal and the second driving signal, and the second input terminal receives the first current adjustment signal and the second current adjustment signal. The second terminal of the fourth resistor is connected to the gate of the depletion-type gallium nitride switch, the drain of the third NMOS transistor is grounded, and the source of the third NMOS transistor is connected to the gate of the depletion-type gallium nitride switch through the fifth resistor. The anode of the third diode is connected to the gate of the third NMOS transistor, and the cathode of the third diode is connected to the gate of the depletion-mode gallium nitride switch.

10. The driving circuit according to claims 1 to 6, 8 or 9, characterized in that, The driving circuit further includes: a fourth switch, or a fourth diode and a sixth resistor; The fourth switch, connected to the gate and ground of the depletion-mode gallium nitride switch respectively, is configured to enter the on state in response to the first drive signal, or to enter the off state in response to the second drive signal; The fourth diode has its anode grounded and its cathode connected to the gate of a depletion-mode gallium nitride switch. The sixth resistor is connected in parallel with the fourth diode.

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