GaN driving power switch power supply system and control circuit thereof

Abstract

The invention provides a control circuit used in a GaN driving power switch power supply system, which is configured to control a first power supply path control switch to be in a turn-off state when the GaN driving power switch power supply system is in a light load mode, and generating a second path switch control signal for controlling on and off of a second power supply path control switch and a second power switch control signal for controlling on and off of a power drive switch based on a supply voltage on a supply capacitor and a first power switch control signal for controlling on and off of a GaN power switch performing numbering; or under the condition that the GaN driving power switch power supply system is in a non-light load mode, the second power supply path control switch is controlled to be in a turn-off state; and a first path switch control signal and a second power switch control signal which are used for controlling on and off of the first power supply path control switch are generated based on the power supply voltage on the power supply capacitor and the first power switch control signal.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to a GaN driven power switch power supply system and a control circuit thereof. Background Art

[0002] As power devices based on silicon materials have gradually approached their theoretical limits, power devices based on wide bandgap semiconductor materials (e.g., gallium nitride (GaN)) can significantly improve the operating frequency and efficiency of switching power supply systems due to the absence of body diode effects and lower on-resistance and parasitic capacitance, and help reduce the size and weight of chargers. At present, the application demand for GaN power tubes in the charger market is gradually increasing. Summary of the invention

[0003] According to an embodiment of the present invention, a control circuit for use in a GaN-driven power switch power supply system includes a GaN power switch and a power supply capacitor. The control circuit includes a power drive switch connected between the GaN power switch and a circuit reference ground and a first power supply path control switch and a second power supply path control switch connected in parallel between the GaN power switch and the power supply capacitor. The control circuit is configured to: when the GaN-driven power switch power supply system is in a light load mode, control the first power supply path control switch to be in an off state, and generate a second path switch control signal for controlling the on and off of the second power supply path control switch and a second power switch control signal for controlling the on and off of the power drive switch based on a power supply voltage on the power supply capacitor and a first power switch control signal for controlling the on and off of the GaN power switch; or when the GaN-driven power switch power supply system is in a non-light load mode, control the second power supply path control switch to be in an off state, and generate a first path switch control signal and a second power switch control signal for controlling the on and off of the first power supply path control switch based on the power supply voltage on the power supply capacitor and the first power switch control signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0005] Figure 1 This is a schematic diagram of the circuit principle of a traditional GaN-driven power switch power supply system.

[0006] Figure 2 Schematic diagram of the circuit principle of a GaN driven power switch power supply system according to an embodiment of the present invention.

[0007] Figure 3 yes Figure 2 The logical structure diagram of the switching power supply control unit is shown.

[0008] Figure 4A yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it works normally in non-light load mode is shown.

[0009] Figure 4B yes Figure 3 The power supply voltage detection submodule and the drive control module shown are used to implement Figure 4A An example implementation of a portion of the circuitry of the control mechanism shown.

[0010] Figure 4C yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it works normally in non-light load mode is shown.

[0011] Figure 5A yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it works normally in non-light load mode is shown.

[0012] Figure 5B yes Figure 3 The power supply voltage detection submodule and the drive control module shown are used to implement Figure 5A An example implementation of a portion of the circuitry of the control mechanism shown.

[0013] Figure 5C yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it works normally in non-light load mode is shown.

[0014] Figure 6 yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it is working normally in light load mode is shown.

[0015] Figure 7 yes Figure 2 A schematic diagram of a variation of the GaN driven power switch power supply system is shown.

[0016] Figure 8 yes Figure 7 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it works normally in non-light load mode is shown.

[0017] Figures 9 to 12 Various modifications of the GaN driven power switch power supply system according to the embodiment of the present invention are shown. DETAILED DESCRIPTION

[0018] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, parts and algorithms without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention. In addition, it should be noted that the term "A is connected to B" used here can mean "A is directly connected to B" and can also mean "A is indirectly connected to B via one or more other elements".

[0019] Figure 1 This is a schematic diagram of the circuit principle of the traditional GaN-driven power switch power supply system. Figure 1As shown, the GaN driven power switch power supply system 100 includes a full-wave rectifier BD1, a switch power supply control unit U1, a high-voltage startup unit U2, a GaN power switch M1, a transformer T1, diodes D1 and D2, an input capacitor C1, an output capacitor C2, a power supply capacitor C3, and a current detection resistor R2, wherein: the switch power supply control unit U1 includes a pulse width modulation (PWM) control module U11, a drive module U12, and a power drive switch M2, which are used to control the on and off of the GaN power switch M1; the high-voltage startup unit U2 includes a high-voltage resistor or a junction field effect transistor (JFET) and other high-voltage components (not shown in the figure), which are used to charge the power supply capacitor C3 when the system is powered on so that the switch power supply control unit U1 can be normally turned on; after the system is powered on, the full-wave rectifier BD1 charges the AC input voltage VAC Rectification is performed and a voltage VIN is generated on the input capacitor C1. The voltage VIN charges the power supply capacitor C3 via the high-voltage startup unit U2 and the high-voltage power supply pin (i.e., HV pin) and the chip power supply pin (i.e., VDD pin) of the switching power supply control unit U1. The power supply voltage VDD on the power supply capacitor C3 (i.e., the power supply voltage VDD of the switching power supply control unit U1) gradually increases. When the power supply voltage VDD on the power supply capacitor C3 is higher than the undervoltage protection voltage threshold preset inside the switching power supply control unit U1, the switching power supply control unit U1 starts to control the conduction and shutdown of the GaN power switch M1 through the drain of the power drive switch M2 (i.e., the switch control pin (i.e., SW pin) of the switching power supply control unit U1); when the system is working normally, the power supply voltage VDD of the switching power supply control unit U1 is mainly provided by the auxiliary winding L2 of the transformer T1. Here, since the power generation method of supplying power to the switching power supply control unit U1 through the auxiliary winding L2 of the transformer T1 requires additional startup and power supply components, there are disadvantages such as high system cost and low power supply efficiency.

[0020] In view of the above situation, a GaN-driven power switch power supply system and a control circuit thereof according to an embodiment of the present invention are proposed, wherein, compared with the traditional GaN-driven power switch power supply system 100, the high-voltage startup unit U2 and the auxiliary winding L2 of the transformer T1 can be omitted, thereby saving system costs, and through internal optimization control, the power supply loss of the switching power supply control unit can be reduced and stable power supply can be achieved.

[0021] Figure 2 Schematic diagram of the circuit principle of the GaN driven power switch power supply system according to an embodiment of the present invention. Figure 1 and Figure 2As shown, the GaN driven power switch power supply system 200 is different from 100 in that the high voltage startup unit U2 and the auxiliary winding L2 of the transformer T1 are omitted, and the switch power supply control unit U200 includes a PWM control module U201, a power supply module U202, a drive control module U203, a drive module U204, and a power drive switch M2, wherein: the PWM control module U201 is configured to generate a power switch control signal PWM for controlling the on and off of the GaN power switch M1, and to generate a power switch control signal PWM for indicating whether the GaN driven power switch power supply system 200 is in a light load mode or a non-light load mode The power supply module U202 is configured to control the charging of the power supply capacitor C3 by the voltage VIN on the input capacitor C1 via the GaN power switch M1 based on the load mode sensing signal Load_sen; the drive control module U203 is configured to generate a power switch control signal PWM_2 for controlling the on and off of the power drive switch M2 based on the power switch control signal PWM; the drive module U204 is configured to generate a power switch drive signal GATE for driving the on and off of the power drive switch M2 based on the power switch control signal PWM_2. It should be understood that the PWM control module U201 can generate the power switch control signal PWM through various existing control mechanisms, and can generate the load mode sensing signal Load_sen based on the primary current sensing signal representing the primary inductor current ILp of the transformer T1 (for example, the current sensing voltage CS generated by the primary inductor current ILp on the current detection resistor R2) through various existing judgment mechanisms. It should be noted that the power supply capacitor C3 is charged only when the power supply voltage VDD on the power supply capacitor C3 is lower than the preset power supply voltage threshold.

[0022] Figure 3 yes Figure 2 Schematic diagram of the logic structure of the switching power supply control unit shown in FIG. Figure 3As shown, the power supply module U202 includes power supply path control switches K102 and K103 connected in parallel between the GaN power switch M1 and the power supply capacitor C3, a diode D101, a current setting submodule U2021, and a power supply voltage detection submodule U2022, wherein: the switch K102 is used to control the connection between the SW pin and the VDD pin of the switch power control unit U200, which is a path with a relatively large power supply current for the power supply path; the switch K103 is used to control the connection between the SW pin of the switch power control unit U200 and the VDD pin of the switch power control unit U200 via the current setting submodule U301, which is a path with a relatively large power supply current for the power supply path; In terms of the electrical path, this is a path with a relatively small supply current; the diode D101 is located on the power supply path between the SW pin and the VDD pin of the switching power control unit U200, and is used to prevent current backflow when the voltage at the SW pin of the switching power control unit U200 is lower than the voltage at the VDD pin; the current setting submodule U2021 is configured to set the size of the charging current of the power supply capacitor C3; the power supply voltage detection submodule U2022 is configured to detect the power supply voltage VCC on the power supply capacitor C3 and optionally generate a power supply voltage indication signal 106 indicating the size comparison relationship between the power supply voltage VCC on the power supply capacitor C3 and the corresponding voltage threshold. It should be understood that the current setting submodule U2021 and the power supply voltage detection submodule U2022 can adopt various existing implementation methods, so their detailed description is omitted.

[0023] like Figure 3 As shown, in some embodiments, the power supply module U202 also includes a power supply path control switch K104 connected in parallel with the switches K102 and K103 between the GaN power switch and the power supply capacitor C3, and the power supply voltage detection submodule U2022 is also configured to generate a power supply path shutdown signal 104 for controlling the switch K104 to change from an on state to an off state when the power supply voltage VDD on the power supply capacitor C3 is higher than an internally preset undervoltage protection voltage threshold.

[0024] like Figure 3As shown, in some embodiments, the drive control module U203 is also configured to control the switch K102 to be in the off state (for example, based on the load mode detection signal Load_sen, a path switch control signal 102 is generated to control the switch K102 to be in the off state), and to generate the path switch control signal 103 and the power switch control signal 101 (i.e., the power switch control signal PWM_2) based on the power supply voltage VDD on the power supply capacitor C3 and the power switch control signal PWM when the GaN driven power switch power supply system 200 is in the light load mode; or to control the switch K103 to be in the off state (for example, based on the load mode detection signal Load_sen, a path switch control signal 103 is generated to control the switch K103 to be in the off state), and to generate the path switch control signal 102 and the power switch control signal 101 based on the power supply voltage VDD on the power supply capacitor C3 and the power switch control signal PWM when the GaN driven power switch power supply system 200 is in the non-light load mode.

[0025] like Figure 2 and Figure 3 As shown, in some embodiments, the working process of the GaN driven power switch power supply system 200 is as follows: after the system is powered on, the switch K104 is in the on state, the switches K102 and K103 are in the off state, the full-wave rectifier BD1 rectifies the AC input voltage VAC and generates a voltage VIN on the input capacitor C1, the voltage VIN charges the power supply capacitor C3 through the GaN power switch M1, the switch K104, and the current setting submodule U2021, the power supply voltage VDD on the power supply capacitor C3 gradually increases, and the power supply voltage detection unit U2022 detects the power supply voltage VD When D (i.e., the power supply voltage of the switching power supply control unit U200) is higher than the internally preset undervoltage protection voltage threshold, the control switch K104 changes from the on state to the off state; when the system is working normally, the power supply voltage detection submodule U2022 provides the power supply voltage indication signal 106 to the drive control module U203, and the PWM control module U201 provides the power switch control signal PWM to the drive control module U203. The drive control module U203 generates power supply path control signals 102 and 103 based on the power supply voltage indication signal 106 and the power switch control signal PWM to realize power supply control under different loads.

[0026] Figure 4A yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it is working normally in non-light load mode is shown. Figure 4A As shown, in the non-light load mode, the power supply path control signal 103 is at a logic low level (ie, the switch K103 is in the off state). Figure 3The switching power supply control unit U200 shown can implement the following control mechanism:

[0027] ●At time t1, the power switch control signal PWM changes from a logic low level to a logic high level (i.e., the GaN power switch M1 changes from an off state to an on state), the power switch control signal 101 is at a logic low level (i.e., the power drive switch M2 is in an off state), the power supply path control signal 102 changes from a logic low level to a logic high level (i.e., the switch K102 changes from an off state to an on state), and the voltage VIN on the input capacitor C1 begins to supply power to the power supply capacitor C3 via the GaN power switch M1 and the switch K102.

[0028] ● During the period from t1 to t2, the primary inductor current ILp of the transformer T1 gradually increases, and the supply voltage VDD on the power supply capacitor C3 gradually increases. When the charging time Tcharge of the power supply capacitor C3 ends (i.e., at time t2), the power switch control signal 101 changes from a logic low level to a logic high level (i.e., the power drive switch M2 changes from an off state to an on state), and the power supply path control signal 102 changes from a logic high level to a logic low level (i.e., the switch K102 changes from an on state to an off state), and the voltage VIN on the input capacitor C1 stops supplying power to the power supply capacitor C3 via the GaN power switch M1 and the switch K102. Here, the charging time Tcharge of the power supply capacitor C3 (i.e., the duration of the switch K102 being in the on state) is negatively correlated with the supply voltage VDD on the power supply capacitor C3, i.e., the higher the supply voltage VDD on the power supply capacitor C3, the shorter the charging time Tcharge of the power supply capacitor C3.

[0029] During the period t2 to t3, the primary inductor current ILp of the transformer T1 flows into the ground (GND) through the GaN power switch M1, the power drive switch M2, and the current detection resistor R2 and continues to increase until the power switch control signal PWM changes from a logic high level to a logic low level (i.e., at time t3).

[0030] ● During the period t3 to t4, the power switch control signal PWM is at a logic low level, the power switch control signal 101 is at a logic low level (i.e., the power drive switch M2 is in the off state), the charging path control signals 102 and 103 are both at a logic low level (i.e., the switches K102 and K103 are both in the off state), and the primary inductor current ILp of the transformer T1 is 0.

[0031] That is to say, Figure 4AAs shown, when the GaN-driven power switch power supply system 200 is in a non-light load mode, the switch power supply control unit U200 implements the following control mechanism while controlling the switch K103 to be in the off state: when the power switch control signal PWM changes from a logic low level to a logic high level, the switch K102 is controlled to change from the off state to the on state and the power drive switch M2 is controlled to continue to be in the off state; when the power switch control signal PWM is at a logic high level and the switch K102 changes from the on state to the off state, the power drive switch M2 is controlled to change from the off state to the on state; and when the power switch control signal PWM changes from a logic high level to a logic low level, the power drive switch M2 is controlled to change from the on state to the off state and the switch K102 is controlled to continue to be in the off state.

[0032] Figure 4B yes Figure 3 The power supply voltage detection submodule and the drive control module shown are used to implement Figure 4A An example implementation of a portion of the circuitry of the control mechanism shown is shown. Figure 4B As shown, in some embodiments, when the GaN driven power switch power supply system 200 is in a non-light load mode, the following can be implemented Figure 4B The control logic shown is as follows: the power supply voltage detection submodule U2022 generates a power supply voltage divider by dividing the power supply voltage VDD on the power supply capacitor C3, and generates a power supply voltage indication signal 106 based on the power supply voltage divider and the preset voltage threshold Vth1 using a transconductance amplifier; accordingly, the drive control module U203 generates a path switch control signal 102 by comparing the power supply voltage indication signal 106 with the preset voltage threshold Vth2 using a comparator when the power switch control signal PWM is at a logic high level, and generates a path switch control signal 102 by comparing the ground line voltage with the power supply voltage threshold Vth2 using a comparator when the power switch control signal PWM is at a logic low level. In this case, the power supply time Tcharge of the power supply capacitor C3 can be calculated as follows:

[0033] Tcharge = (C11*Vth2) / (gm*((VDD*R12 / (R11+R12)-Vth2)) Equation 1

[0034] Wherein, C11 represents the capacitance value of the capacitor C11 connected between the output terminal of the transconductance amplifier and the ground, gm represents the transconductance of the transconductance amplifier, and R11 and R12 represent the resistance values ​​of the resistors R11 and R12 constituting the voltage divider network for dividing the power supply voltage VDD on the power supply capacitor C3.

[0035] Figure 4C yes Figure 2The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it is working normally in non-light load mode is shown. Figure 4C As shown, in the non-light load mode, the power supply path control signal 103 is at a logic low level (ie, the switch K103 is in the off state). Figure 3 The switching power supply control unit U200 shown can implement the following control mechanism:

[0036] When the power switch control signal PWM changes from a logic low level to a logic high level, if the supply voltage VDD on the supply capacitor C3 is less than the minimum supply voltage threshold VDD_low, the control path switch control signal K102 changes from a logic low level to a logic high level and controls the power switch control signal 101 to continue to be at a logic low level, so that the voltage VIN on the input capacitor C1 charges the supply capacitor C3 (see Figure 4C Otherwise, the power switch control signal 101 is controlled to change from a logic low level to a logic high level and the path switch control signal 102 is controlled to continue to be at a logic low level (see Figure 4C At the moments t4 and t6 in the figure), the voltage VIN on the input capacitor C1 does not charge the power supply capacitor C3;

[0037] ● When the path switch control signal 102 is at a logic high level for a predetermined time (see Figure 4C During the period t1 to t2 in the figure, the path switch control signal 102 is controlled to change from a logic high level to a logic low level and the power switch control signal 101 is controlled to change from a logic low level to a logic high level, so that the voltage VIN on the input capacitor C1 stops charging the power supply capacitor C3.

[0038] In some embodiments, when the GaN-driven power switch power supply system 200 is in a non-light load mode, the following can be implemented: Figure 4C The control logic shown: the power supply voltage detection submodule U2022 generates a power supply voltage indication signal 106 by comparing the power supply voltage VDD on the power supply capacitor C3 with the minimum power supply voltage threshold VDD_low; accordingly, when the power switch control signal PWM changes from a logic low level to a logic high level, if the power supply voltage VDD on the power supply capacitor C3 is lower than the minimum power supply voltage threshold VDD_low, the drive control module U203 controls the switch K102 to change from an off state to an on state and controls the power drive switch M2 to continue to be in an off state, otherwise, the switch K102 continues to be in an off state and controls the power drive switch M2 to change from an off state to an on state, and controls the switch K2 to change from an on state to an off state when the duration of the switch K1 being in the on state reaches a preset time.

[0039] Figure 5A yes Figure 2The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it is working normally in non-light load mode is shown. Figure 5A As shown, in the non-light load mode, the power supply path control signal 103 is at a logic low level (ie, the switch K103 is in the off state). Figure 3 The switching power supply control unit U200 shown can implement the following control mechanism:

[0040] At time t1, the power switch control signal PWM changes from a logic low level to a logic high level (i.e., the GaN power switch M1 changes from an off state to an on state), the power switch control signal 101 changes from a logic low level to a logic high level (i.e., the power drive switch M2 changes from an off state to an on state), the power supply path control signal 102 is a logic low level (i.e., the switch K102 is in an off state), and the primary inductor current ILp of the transformer T1 begins to increase.

[0041] ●During the period from t1 to t2, the primary inductor current ILp of the transformer T1 gradually increases until the power switch control signal PWM changes from a logic high level to a logic low level, the power switch control signal 101 changes from a logic high level to a logic low level (i.e., the power drive switch M2 changes from an on state to an off state), and the power supply path control signal 102 changes from a low level to a high level (i.e., the switch K102 changes from an off state to an on state) (i.e., time t2).

[0042] ● During the period from t2 to t3, the power switch control signal PWM is at a logic low level, the power switch control signal 101 is at a logic low level (i.e., the power drive switch M2 is in the off state), the power supply path control signal 102 is at a logic high level (i.e., the switch K102 is in the on state), the voltage VIN on the input capacitor C1 charges the power supply capacitor C3, and the primary inductor current ILp of the transformer T1 continues to increase until the power supply path control signal 102 changes from a logic high level to a logic low level (i.e., the switch K102 changes from the on state to the off state) (i.e., time t3). Here, the charging time Tcharge of the power supply capacitor C3 is

[0043] (ie, the duration that the switch K102 is in the on state) is negatively correlated with the supply voltage VDD on the supply capacitor C3, that is, the higher the supply voltage VDD on the supply capacitor C3, the shorter the charging time Tcharge of the supply capacitor C3.

[0044] ● During the period t3-t4, the power switch control signal PWM is at a logic low level, the power switch control signal 101 is at a logic low level (ie, the power drive switch M2 is in the off state), the switches K102 and K103 are also in the off state, and the primary inductor current ILp of the transformer T1 is 0.

[0045] That is to say, Figure 5A As shown, when the GaN-driven power switch power supply system 200 is in non-light load mode, the switching power supply control unit U200 implements the following control mechanism while controlling the switch K103 to be in the off state: when the power switch control signal PWM changes from a logic low level to a logic high level, the power drive switch M2 is controlled to change from the off state to the on state and the switch K102 is controlled to continue to be in the off state; and when the power switch control signal PWM changes from a logic high level to a logic low level, the power drive switch M2 is controlled to change from the on state to the off state and the switch K102 is controlled to change from the off state to the on state.

[0046] Figure 5B yes Figure 3 The power supply voltage detection submodule and the drive control module shown are used to implement Figure 5A An example implementation of a portion of the circuitry of the control mechanism shown is shown. Figure 5B Similarly, in some embodiments, when the GaN-driven power switch power supply system 200 is in a non-light load mode, the following can be implemented: Figure 5A The control logic shown is as follows: the power supply voltage detection module U2022 generates a power supply voltage divider by dividing the power supply voltage VDD on the power supply capacitor C3, and generates a power supply voltage indication signal 106 based on the power supply voltage divider and the preset voltage threshold Vth1 using a transconductance amplifier; accordingly, the drive control module U203 generates a path switch control signal 102 by comparing the power supply voltage indication signal 106 with the preset voltage threshold Vth2 using a comparator when the power switch control signal PWM is at a logic low level, and generates a path switch control signal 102 by comparing the ground line voltage with the preset voltage threshold Vth2 using a comparator when the power switch control signal PWM is at a logic high level. In this case, the power supply time Tcharge of the power supply capacitor C3 can be calculated as follows:

[0047] Tcharge = (C11*Vth2) / (gm*((VDD*R12 / (R11+R12)-Vth2)) Equation 2

[0048] Wherein, C11 represents the capacitance value of the capacitor C11 connected between the output terminal of the transconductance amplifier and the ground, gm represents the transconductance of the transconductance amplifier, and R11 and R12 represent the resistance values ​​of the resistors R11 and R12 constituting the voltage divider network for dividing the power supply voltage VDD on the power supply capacitor C3.

[0049] Figure 5C yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it is working normally in non-light load mode is shown. Figure 5C As shown, in the non-light load mode, the power supply path control signal 103 is at a logic low level (ie, the switch K103 is in the off state). Figure 3 The switching power supply control unit U200 shown can implement the following control mechanism:

[0050] ●When the power switch control signal PWM changes from a logic high level to a logic low level, if the supply voltage VDD on the supply capacitor C3 is lower than the minimum supply voltage threshold VDD_low, the control path switch control signal 102 changes from a logic low level to a logic high level and controls the power switch control signal 101 from a logic high level to a logic low level, so that the voltage VIN on the input capacitor C1 charges the supply capacitor C3 (see Figure 5C Otherwise, the control path switch control signal 102 continues to be at a logic low level and controls the power switch control signal 101 to change from a logic high level to a logic low level (see Figure 5C t4 and t6 in the figure).

[0051] When the path switch control signal 102 is at a logic high level for a predetermined time (see Figure 5C During the period t1 to t2 in the figure, the path switch control signal 102 is controlled to change from a logic high level to a logic low level and the power switch control signal 101 is controlled to change from a logic low level to a logic high level, so that the voltage VIN on the input capacitor C1 stops charging the power supply capacitor C3.

[0052] Similarly, in some embodiments, when the GaN-driven power switch power supply system 200 is in a non-light load mode, the following can be implemented: Figure 5C The control logic shown: the power supply voltage detection submodule U2022 generates a power supply voltage indication signal 106 by comparing the power supply voltage VDD on the power supply capacitor C3 with the minimum power supply voltage threshold VDD_low; accordingly, when the power switch control signal PWM changes from a logic high level to a logic low level, if the power supply voltage VDD on the power supply capacitor C3 is lower than the minimum power supply voltage threshold VDD_low, the drive control module U203 controls the switch K102 to change from an off state to an on state and controls the power drive switch M2 to change from an on state to an off state, otherwise, the control switch K102 continues to be in an off state and controls the power drive switch M2 to change from an on state to an off state, and controls the switch K102 to change from an on state to an off state when the duration of the switch K102 being in the on state reaches a preset time.

[0053] Figure 6 yes Figure 2 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it works normally in light load mode is shown. Figure 6As shown, in the non-light load mode, the power supply path control signal 102 is a logic low level (i.e., the switch K102 is in the off state), when the power switch control signal PWM is a logic low level (i.e., the GaN power switch M1 is in the off state), the power switch control signal 101 is a logic low level (i.e., the power drive switch M2 is in the off state), and the power supply path control signal 103 is a logic high level (i.e., the switch K103 is in the on state), which can achieve efficient charging of the power supply capacitor C3.

[0054] Figure 7 yes Figure 2 Variation of the GaN driven power switch power supply system shown. Figure 8 yes Figure 7 The working waveform diagram of the main control signals of the GaN driven power switch power supply system when it is working normally in non-light load mode is shown. It should be noted that although Figure 2 The GaN-driven power switch power supply system shown in the figure adopts a flyback architecture, but combined with Figure 2 The GaN driven power switch power supply system described in the switching power supply control unit U200 can also be applied to Figures 9 to 12 The GaN driven power switch power supply system shown in FIG. That is, the switch power supply control unit U200 can also be applied to a boost (BOOST) architecture (see Fig. 9 and Fig.10 ), Buck architecture (see Fig.11 and Fig.12 ), or buck-boost (BUCK-BOOST) GaN-driven power switch power supply system. Figures 9 to 12 In the GaN driven switching power switch power supply system shown, the inductor current IL1 flowing through the inductor L1 is related to the system load of the GaN driven power switch power supply system. At this time, the switching power supply control unit U200 can generate a load mode sensing signal Load_sen indicating whether the GaN driven power switch power supply system is in light load mode or non-light load mode based on the current sensing signal representing the inductor current IL1 (the current sensing voltage CS generated by the inductor current IL1 on the current detection resistor R2) through various existing judgment mechanisms.

[0055] The present invention can be implemented in other specific forms without departing from its spirit and essential features. For example, the algorithms described in the specific embodiments can be modified, and the system architecture does not depart from the basic spirit of the present invention. Therefore, the current embodiments are regarded as exemplary and non-restrictive in all aspects, and the scope of the present invention is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalent scope of the claims are thus included in the scope of the present invention.

Claims

1. A control circuit for use in a GaN-driven power switch power supply system, the GaN-driven power switch power supply system comprising a GaN power switch and a power supply capacitor, the control circuit comprising a power drive switch connected between the GaN power switch and a circuit reference ground, and a first power supply path control switch and a second power supply path control switch connected in parallel between the GaN power switch and the power supply capacitor, and the control circuit is configured as follows: When the GaN driving power switch power supply system is in a light load mode, the first power supply path control switch is controlled to be in an off state, and a second path switch control signal for controlling the on and off of the second power supply path control switch and a second power switch control signal for controlling the on and off of the power driving switch are generated based on the power supply voltage on the power supply capacitor and the first power switch control signal for controlling the on and off of the GaN power switch; or When the GaN driven power switch power supply system is in a non-light load mode, the second power supply path control switch is controlled to be in an off state, and a first path switch control signal and a second power switch control signal for controlling the on and off of the first power supply path control switch are generated based on the power supply voltage on the power supply capacitor and the first power switch control signal.

2. The control circuit according to claim 1, wherein: The GaN driven power switch power supply system further includes a transformer, and the control circuit is further configured as follows: Based on a primary current sensing signal representing a primary inductor current of the transformer, a load mode sensing signal is generated to indicate whether the GaN driven power switch power supply system is in a light load mode or a non-light load mode.

3. The control circuit according to claim 1, wherein: The GaN-driven power switch power supply system further includes an inductor, and an inductor current flowing through the inductor is related to a system load of the GaN-driven power switch power supply system. The control circuit is further configured as follows: Based on the current sensing signal representing the inductor current, a load mode sensing signal is generated to indicate whether the GaN driven power switch power supply system is in a light load mode or a non-light load mode.

4. The control circuit according to claim 1, wherein: The control circuit further includes a third power supply path control switch connected in parallel with the first power supply path control switch and the second power supply path control switch between the GaN power switch and the power supply capacitor, and the control circuit is further configured as follows: When the system is powered on, the third power supply path control switch is controlled to be in an on state, and when it is detected that the power supply voltage on the power supply capacitor is higher than the undervoltage protection voltage threshold preset in the control circuit, the third power supply path control switch is controlled to change from an on state to an off state.

5. The control circuit according to claim 1, wherein: When the GaN driven power switch power supply system is in a non-light load mode, the duration during which the first power supply path control switch is in the on state is negatively correlated with the power supply voltage on the power supply capacitor.

6. The control circuit according to claim 1, further configured to: when the GaN driven power switch power supply system is in a non-light load mode: When the first power switch control signal changes from a logic low level to a logic high level, the first power supply path control switch is controlled to change from an off state to an on state and the power drive switch is controlled to continue to be in an off state; When the first power switch control signal is at a logic high level and the first power supply path control switch changes from an on state to an off state, controlling the power drive switch to change from an off state to an on state; and When the first power switch control signal changes from a logic high level to a logic low level, the first charging path control switch is controlled to continue to be in an off state and the power driving switch is controlled to change from an on state to an off state.

7. The control circuit according to claim 1, further configured to: when the GaN driven power switch power supply system is in a non-light load mode: When the first power switch control signal changes from a logic low level to a logic high level, if the supply voltage on the supply capacitor is lower than a minimum supply voltage threshold, the first charging path control switch is controlled to change from an off state to an on state and the power drive switch is controlled to remain in an off state; otherwise, the first charging path control switch is controlled to remain in an off state and the power drive switch is controlled to change from an off state to an on state; and When the first charging path control switch is in the on state for a duration of a preset time, the first charging path control switch is controlled to change from the on state to the off state.

8. The control circuit according to claim 1, further configured to: when the GaN driven power switch power supply system is in a non-light load mode: When the first power switch control signal changes from a logic low level to a logic high level, controlling the first charging path control switch to remain in an off state and controlling the power drive switch to change from an off state to an on state; and When the first power switch control signal changes from a logic high level to a logic low level, the first charging path control switch is controlled to change from an off state to an on state and the power drive switch is controlled to change from an on state to an off state.

9. The control circuit according to claim 1, further configured to: when the GaN driven power switch power supply system is in a non-light load mode: When the first power switch control signal changes from a logic high level to a logic low level, if the supply voltage on the supply capacitor is lower than a minimum supply voltage threshold, the first charging path control switch is controlled to change from an off state to an on state and the power drive switch is controlled to change from an on state to an off state; otherwise, the first charging path control switch is controlled to continue to be in an off state and the power drive switch is controlled to change from an on state to an off state; and When the first charging path control switch is in the on state for a duration of a preset time, the first charging path control switch is controlled to change from the on state to the off state.

10. A GaN driven power switch power supply system, comprising the control circuit according to any one of claims 1 to 9.

Images