Switching power supply and control chip thereof
By using a system-level switch of depletion GaN switch tube and low-voltage switch tube in the switching power supply, combined with the current limiting resistor and charging control circuit, the charging process of the power supply capacitor is optimized, and the problems of long start-up time and high standby power consumption are solved, and the effects of fast start-up and low power consumption are achieved, and the system efficiency is improved.
Patent Information
- Application Number
- CN202421488262.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-26
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2034-06-26
AI Technical Summary
The control chip of existing GaN switching power supplies has a long start-up time and high standby power consumption, which affects system efficiency.
The system-level switch of the depletion GaN switch tube and the low-voltage switch tube connected in series, combined with the current limiting resistor and the charging control circuit, optimizes the charging process of the power supply capacitor. The gate of the depletion GaN switch tube is connected to the circuit reference ground, and the gate of the low-voltage switch tube serves as the input control end to receive the pulse width modulation signal, achieving rapid start-up and low power consumption.
It realizes fast start-up of the control chip and low standby power consumption, improving the system efficiency of the switching power supply.
Smart Images
Figure CN223093647U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of circuits, and more particularly to a switching power supply and its control chip. Background Art
[0002] Compared with traditional semiconductor switching tubes, gallium nitride (GaN) switching tubes have a higher switching frequency and a lower on-resistance, so they can reduce switching losses and significantly improve the system efficiency of switching power supplies. In recent years, GaN switching tubes have been increasingly used in switching power supplies. Among them, the driving of enhancement-mode GaN switching tubes is relatively simple and more suitable for applications in the medium and low power segments. The driving of depletion-mode GaN switching tubes requires a low-voltage switching tube, but it has higher reliability and is more suitable for applications in the medium and high power segments. Summary of the Utility Model
[0003] A control chip used in a switching power supply according to an embodiment of the utility model, the switching power supply includes a transformer and a power supply capacitor, and the control chip includes a system-level switch and a charging control circuit, wherein: the system-level switch is connected between the primary winding of the transformer and the circuit reference ground via the system switch drain pin and the current sensing pin of the control chip, and includes a depletion-mode GaN switching tube and a low-voltage switching tube connected in series, wherein the gate of the depletion-mode GaN switching tube is connected to the circuit reference ground, and the gate of the low-voltage switching tube is used as the input control end of the system-level switch to receive a pulse width modulation control signal for controlling the on and off of the system-level switch; and the charging control circuit is connected between the primary winding of the transformer and the power supply capacitor via the system switch drain pin and the chip power pin of the control chip, and includes a depletion-mode GaN switching tube, a charging control switch, and a current limiting resistor connected in series with each other.
[0004] A switching power supply according to an embodiment of the utility model includes the above control chip. Description of the Drawings
[0005] The utility model can be better understood from the following description of the specific embodiments in conjunction with the drawings, wherein:
[0006] Figure 1 Shows a schematic structural diagram of a traditional flyback switching power supply using a GaN switching tube.
[0007] Figure 2 Shows a schematic structural diagram of another traditional flyback switching power supply using a GaN switching tube.
[0008] Figure 3 Shows a schematic example structure diagram of a control chip used in a switching power supply according to an embodiment of the utility model.
[0009] Figure 4 ShowsFigure 3 Schematic diagram of an exemplary implementation circuit of the charging control switch S1 shown Detailed implementation mode
[0010] The features and exemplary embodiments of various aspects of the present utility model will be described in detail below. In the following detailed description, many specific details are presented in order to provide a comprehensive understanding of the present utility model. However, it is obvious to those skilled in the art that the present utility model can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present utility model by showing examples of the present utility model. The present utility model is in no way limited to any specific configuration proposed below, but covers any modification, replacement, and improvement of elements, components, and algorithms without departing from the spirit of the present utility model. Well-known structures and technologies are not shown in the drawings and the following description in order to avoid unnecessary obscurity to the present utility model. In addition, it should be noted that the term "A is connected to B" used here can mean "A is directly connected to B" or "A is indirectly connected to B via one or more other elements".
[0011] Figure 1 Schematic diagram of the structure of a traditional flyback switching power supply using a GaN switching tube is shown. In Figure 1 In the flyback switching power supply 100 shown, the AC input voltage Vin is rectified and then charges the power supply capacitor C1 via the starting resistor R0. When the voltage on the power supply input pin VCC of the control chip 102 (i.e., the voltage on the power supply capacitor C1) reaches the starting voltage UVLO_OFF of the control chip 102, the control chip 102 starts. Here, due to the relatively large resistance value of the starting resistor R0, the starting time of the control chip 102 is relatively long (about 1 to 2 seconds), and at the same time, the loss on the starting resistor R0 is relatively large, which will increase the standby power consumption of the flyback switching power supply 100.
[0012] Figure 2 Schematic diagram of the structure of another traditional flyback switching power supply using a GaN switching tube is shown. In Figure 2In the flyback switching power supply 200 shown, the AC input voltage Vin is rectified and then supplies power to the power supply capacitor C1 via the high-voltage supply pin HV of the control chip 202, the high-voltage switching transistor M3 (e.g., high-voltage junction field effect transistor (JFET) or high-voltage metal oxide field effect transistor (MOSFET)) located inside the control chip 202, the charging control switch S1, the current-limiting resistor R3, and the reverse isolation diode D2, as well as the power input pin VCC of the control chip 202. When the voltage on the power input pin VCC of the control chip 202 (i.e., the voltage on the power supply capacitor C1) reaches the startup voltage UVLO_OFF of the control chip 202, the control chip 202 starts. Here, the current-limiting resistor R3 is used to control the amplitude of the charging current for the power supply capacitor C1. The charging control switch S1 is in the on state during the startup process of the control chip 202 and changes from the on state to the off state at the end of the startup process of the control chip 202. The reverse isolation diode D2 is used to prevent the voltage on the power supply capacitor C1 from discharging reversely to the high-voltage supply pin HV of the control chip 202 after the startup process of the control chip 202. Here, since the resistance value of the current-limiting resistor R3 is much smaller than that of the startup resistor R0, the charging current for the power supply capacitor C1 can be set relatively large, so the control chip 202 can start quickly.
[0013] As Figure 1 and Figure 2 shown, in the flyback switching power supplies 100 and 200, a system-level switch formed by the series connection of the depletion-mode GaN switching transistor M1 and the low-voltage switching transistor M2 is located inside the control chips 102 and 202 and is connected between the primary winding Lp of the transformer T1 and the circuit reference ground, and is used to control the system output voltage and / or system output current of the flyback switching power supplies 100 and 200. Considering that the current / voltage (I / V) curve characteristics of the depletion-mode GaN switching transistor are similar to the I / V curve characteristics of the high-voltage JFET and the high-voltage MOSFET, in the flyback switching power supplies 100 and 200, the depletion-mode GaN switching transistor M1 can be reused to charge the power supply capacitor C1 during the system startup or normal operation process (i.e., the startup or normal operation process of the control chips 102 and 202) (i.e., charge the power supply capacitor C1 when the low-voltage switching transistor M2 is in the off state).
[0014] Figure 3 shows a schematic structural diagram of an example of a control chip used in a switching power supply according to an embodiment of the present invention. As Figure 3As shown, the control chip 300 used in a switching power supply (e.g., a switching power supply adopting various architectures such as flyback architecture, boost architecture, or buck architecture) includes a system-level switch 302 and a charging control circuit 304, where: The system-level switch 302 is connected between the primary winding Lp of the transformer in the switching power supply and the circuit reference ground via the system switch drain pin DRAIN and the current sensing pin CS of the control chip 300, and is used to control the system output voltage and / or system output current of the switching power supply; The system-level switch 302 includes a depletion-mode GaN switch tube M1 and a low-voltage switch tube M2 connected in series. The gate of the depletion-mode GaN switch tube M1 is connected to the circuit reference ground, and the gate of the low-voltage switch tube M2 serves as the input control terminal of the system-level switch 302 for receiving a pulse width modulation (PWM) control signal for controlling the conduction and turn-off of the system-level switch 302; The charging control circuit 302 is connected between the primary winding Lp of the transformer in the switching power supply and the power supply capacitor C1 via the system switch drain pin DRAIN and the chip power supply pin VCC of the control chip 300, and includes a depletion-mode GaN switch tube M1, a charging control switch S1, and a current limiting resistor R1 connected in series with each other.
[0015] As Figure 3 shown, in some embodiments, during the startup process of the control chip 300, the charging control switch S1 is in the on state under the control of the switch control signal SW from the under-voltage lockout and low-dropout linear regulator module. The AC input voltage Vin (not shown in the figure) is rectified and then charges the power supply capacitor C1 via the system switch drain pin DRAIN, the depletion-mode GaN switch tube M1, the charging control switch S1, the current limiting resistor R1, and the chip power supply pin VCC of the control chip 300. When the voltage on the power input pin VCC of the control chip 300 (i.e., the voltage on the power supply capacitor C1) reaches the startup voltage UVLO_OFF of the control chip 300, the control chip 300 starts up.
[0016] As Figure 3 shown, in some embodiments, the charging control circuit 302 further includes a reverse isolation diode D1. Among them, the reverse isolation diode D1 is connected in series with the depletion-mode GaN switch tube M1, the charging control switch S1, and the current limiting resistor R1, and is used to prevent the voltage on the power supply capacitor C1 from discharging reversely to the system switch drain pin DRAIN of the control chip 300 after the startup process of the control chip 300 ends.
[0017] Figure 4 shows Figure 3 the schematic diagram of an example implementation circuit of the charging control switch S1 shown. As Figure 4As shown, in some embodiments, the charging control switch S1 includes switching transistors M3, M4, and M5, where: during the startup process of the control chip 300 (i.e., before the voltage on the chip power supply pin VCC of the control chip 300 reaches the startup voltage UVLO_OFF), the Power Good (PG) signal is at a low level and is provided as the switch control signal SW for controlling the conduction and cutoff of the charging control switch S1 to the gate of the switching transistor M4. The switching transistor M4 is in the cutoff state, and the switching transistors M3 and M5 are in the conduction state. The AC input voltage Vin is rectified and then charges the power supply capacitor C1 via the system switch drain pin DRAIN of the control chip 300, the depletion-mode GaN switching transistor M1, the switching transistor M3, the current-limiting resistor R1, and the chip power supply pin VCC of the control chip 300. Additionally, when the startup process of the control chip 300 ends, the PG signal changes from a low level to a high level, the switching transistor M4 changes from the cutoff state to the conduction state, and the switching transistors M3 and M5 change from the conduction state to the cutoff state, and the power supply capacitor C1 starts to discharge.
[0018] As Figure 4 shown, in some embodiments, during the normal operation process of the control chip 300, the PWM control signal for controlling the conduction and cutoff of the system-level switch 302 is provided as the switch control signal SW for controlling the conduction and cutoff of the charging control switch S1 to the gate of the switching transistor M4, and the charging control switch S1 conducts and cuts off synchronously with the system-level switch 302. When the system-level switch 302 is in the cutoff state (i.e., the low-voltage switching transistor M2 is in the cutoff state), the switching transistor M4 is in the cutoff state, and the switching transistors M3 and M5 are in the conduction state. The AC input voltage Vin is rectified and then charges the power supply capacitor C1 via the system switch drain pin DRAIN of the control chip 300, the depletion-mode GaN switching transistor M1, the switching transistor M3, the current-limiting resistor R1, and the chip power supply pin VCC of the control chip 300. When the system-level switch 302 is in the conduction state (i.e., the low-voltage switching transistor M2 is in the conduction state), the switching transistor M4 is in the conduction state, and the switching transistors M3 and M5 are in the cutoff state, and the power supply capacitor C1 discharges.
[0019] As Figure 4 shown, in some embodiments, the charging control switch S1 includes a first switching transistor M3, a second switching transistor M4, and a third switching transistor M5, and the switch control signal for controlling the conduction and cutoff of the charging control switch S1 is provided to the gate of the second switching transistor M4. When the second switching transistor M4 is in the cutoff state, the first switching transistor M3 and the third switching transistor M5 are in the conduction state; when the second switching transistor M4 is in the conduction state, the first switching transistor M3 and the third switching transistor M5 are in the cutoff state.
[0020] The present utility model may be embodied in other specific forms without departing from its spirit and essential characteristics. For example, the structures described in specific embodiments may be modified without departing from the basic spirit of the present utility model in terms of the system architecture. Therefore, the current embodiments are regarded as exemplary in all aspects rather than restrictive, the scope of the present utility model is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalents of the claims are thus included in the scope of the present utility model.
Claims
1. A control chip used in a switching power supply, the switching power supply including a transformer and a power supply capacitor, the control chip including a system-level switch and a charging control circuit, wherein: The system-level switch is connected between the primary winding of the transformer and the circuit reference ground via the system switch drain pin and the current sensing pin of the control chip, and includes a depletion-mode GaN switch tube and a low-voltage switch tube connected in series. Among them, the gate of the depletion-mode GaN switch tube is connected to the circuit reference ground, and the gate of the low-voltage switch tube serves as the input control terminal of the system-level switch for receiving a pulse width modulation control signal for controlling the conduction and turn-off of the system-level switch; and The charging control circuit is connected between the primary winding of the transformer and the power supply capacitor via the system switch drain pin and the chip power supply pin of the control chip, and includes the depletion-mode GaN switch tube, a charging control switch, and a current limiting resistor connected in series with each other.
2. The control chip according to claim 1, wherein During the startup process of the control chip, the charging control switch is in the on state.
3. The control chip according to claim 1, wherein, During the normal operation process of the control chip, the charging control switch conducts and turns off synchronously with the system-level switch.
4. The control chip according to claim 1, wherein, During the startup process of the control chip, the power ready signal is used as a switch control signal for controlling the conduction and turn-off of the charging control switch.
5. The control chip according to claim 1, wherein, During the normal operation process of the control chip, the pulse width modulation control signal is used as a switch control signal for controlling the conduction and turn-off of the charging control switch.
6. The control chip according to claim 1, wherein The charging control switch includes a first switch tube, a second switch tube, and a third switch tube, and the switch control signal for controlling the conduction and turn-off of the charging control switch is provided to the gate of the second switch tube, and wherein: When the second switch tube is in the off state, the first switch tube and the third switch tube are in the on state; When the second switch tube is in the on state, the first switch tube and the third switch tube are in the off state.
7. The control chip according to claim 1, wherein, The charging control circuit further includes a reverse isolation diode, and the reverse isolation diode is connected in series with the depletion-mode GaN switch tube, the charging control switch, and the current limiting resistor.
8. A switching power supply, including the control chip according to any one of claims 1 to 6.