Self-powered circuit, chip and power supply system for primary side circuit in switching power supply

Abstract

This invention provides a self-powered circuit for the primary side circuit of a switching power supply. The self-powered circuit includes a controller, an excitation current supply circuit, and an energy storage unit connected to the power supply terminal of the controller. One end of the excitation current supply circuit is coupled to the switching node between the upper and lower switching transistors of the primary side circuit, and the other end is coupled to the connection node between the power supply terminal and the energy storage unit. When the primary side circuit is in the excitation period, the controller detects whether the voltage at the power supply terminal is lower than a first voltage threshold. When the voltage at the power supply terminal is lower than the first voltage threshold, the controller's first control terminal controls the excitation current supply circuit to conduct, and the excitation current charges the energy storage unit to ensure that the voltage at the power supply terminal maintains the normal operation of the controller. This invention eliminates the need for auxiliary windings and external voltage regulator circuits, enabling a more stable power supply to the controller and ensuring stable and reliable system operation; it also significantly reduces costs while significantly improving efficiency.

Description

Technical Field

[0001] This invention relates to the field of circuit design technology, and in particular to a self-powered circuit, a self-powered chip, and a switching power supply system for the primary side circuit of a switching power supply. Background Technology

[0002] With the development of power supply technology, the requirements for the output voltage range of power supply equipment are becoming increasingly stringent. For example, the PD3.2 protocol requires an output voltage range of 5V to 48V. This wide output voltage range poses significant challenges to the efficiency and stable power supply of power supply equipment. Currently, isolated power supply equipment generally uses an auxiliary winding power supply method. For an example, please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a schematic diagram of the power supply circuit structure of a flyback power controller commonly used in existing technology. For example... Figure 1 As shown, in this circuit structure, the primary winding Np and the secondary winding Ns have opposite polarities, and the auxiliary winding Naux has opposite polarities to the secondary winding Ns. After the primary switching transistor Q0 is turned off, the secondary winding begins to demagnetize, supplying power to the output, and simultaneously supplying power to the first controller 1 through the auxiliary winding Naux. However, research has revealed that due to the leakage inductance of the transformer, the voltage variation range at the power supply terminal of the first controller 1 is also large in applications with a wide output voltage range. Therefore, a high-voltage withstand process or the addition of a voltage regulator circuit is required, which not only increases the system cost but also reduces the system efficiency.

[0003] Therefore, improving power system efficiency and reducing system costs have become urgent technical problems that need to be solved.

[0004] It should be noted that the information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a self-powered circuit, a self-powered chip, and a switching power supply system for the primary side circuit of a switching power supply. This invention eliminates the need for auxiliary windings and external voltage regulator circuits, enabling more stable power supply to the controller and ensuring stable and reliable system operation. It not only significantly reduces costs but also significantly improves efficiency, and has good applicability.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a self-powered circuit for the primary side circuit in a switching power supply, wherein the primary side circuit includes a primary side winding, an upper switching transistor and a lower switching transistor, one end of the primary side winding receives the input voltage and the other end is connected to the upper switching transistor, the upper switching transistor and the lower switching transistor are connected through a switching node, and the lower switching transistor is coupled to a reference ground;

[0007] The self-powered circuit includes a controller and an excitation current power supply circuit, as well as an energy storage unit connected to the power supply terminal of the controller. One end of the energy storage unit is grounded, one end of the excitation current power supply circuit is coupled to the switching node, and the other end is coupled to the connection node between the power supply terminal and the energy storage unit.

[0008] When the primary side circuit is in the excitation period, the controller detects whether the voltage at the power supply terminal is lower than the first voltage threshold. When the voltage at the power supply terminal is lower than the first voltage threshold, the first control terminal of the controller controls the excitation current power supply circuit to be turned on, and the excitation current charges the energy storage unit to ensure that the voltage at the power supply terminal maintains the normal operation of the controller.

[0009] Optionally, after the primary-side circuit excitation begins in each switching cycle and a first preset time elapses, the controller then detects whether the voltage at the power supply terminal is lower than the first voltage threshold.

[0010] Optionally, when the voltage at the power supply terminal reaches a second voltage threshold, the controller controls the excitation current to stop charging the energy storage unit, wherein the second voltage threshold is greater than the first voltage threshold.

[0011] Optionally, the on-resistance of the lower switching transistor is less than the on-resistance of the excitation current power supply circuit. After the excitation current power supply circuit is turned on by the first control terminal of the controller, the lower switching transistor is turned off by the second control terminal of the controller.

[0012] Optionally, after the excitation current power supply circuit is turned on by the first control terminal of the controller, a second preset time is elapsed, and then the lower switching transistor is turned off by the second control terminal of the controller.

[0013] Optionally, the controller controlling the excitation current to stop charging the energy storage unit includes: the second control terminal controlling the lower switch to turn on.

[0014] Optionally, the first control terminal controls the excitation current power supply circuit to turn off after the lower switch is turned on and before the excitation ends.

[0015] Optionally, if the voltage at the power supply terminal is not charged to the second voltage threshold and the turn-off time of the lower switch during excitation reaches the preset turn-off time, the second control terminal of the controller controls the lower switch to turn on.

[0016] Optionally, the excitation current power supply circuit includes a first controllable switch and a first diode. The control terminal of the first controllable switch is coupled to the first control terminal of the controller, the first terminal of the first controllable switch is coupled to the switching node, the anode of the first diode is connected to the second terminal of the first controllable switch, and the cathode of the first diode is coupled to the power supply terminal of the controller.

[0017] Optionally, the on-resistance of the lower switch is less than the on-resistance of the first controllable switch.

[0018] Optionally, the self-powered circuit further includes a high-voltage power supply circuit. The input terminal of the high-voltage power supply circuit receives an input voltage, and the output terminal is coupled to the connection node between the power supply terminal and the energy storage unit. During the startup phase of the controller, the third control terminal of the controller controls the current generated by the high-voltage power supply circuit to charge the energy storage unit until the voltage of the power supply terminal reaches the startup threshold voltage. Then, the third control terminal controls the high-voltage power supply circuit to turn off, wherein the startup threshold voltage is greater than the first voltage threshold.

[0019] Optionally, during the normal operation phase of the controller, when the voltage at the power supply terminal is less than the lower limit threshold of the power supply voltage, the third control terminal of the controller controls the high-voltage power supply circuit to conduct and generate the current to charge the energy storage unit until the voltage at the power supply terminal is charged to the second voltage threshold. Then, the third control terminal controls the high-voltage power supply circuit to turn off, wherein the first voltage threshold is greater than the lower limit threshold of the power supply voltage.

[0020] Optionally, the self-powered circuit further includes a second diode and a third diode, wherein the anode of the second diode and the anode of the third diode are respectively coupled to the live wire and the neutral wire of the AC power supply, and the cathode of the second diode and the cathode of the third diode are coupled to the input terminal of the high-voltage power supply circuit.

[0021] Optionally, the high-voltage power supply circuit includes a first resistor, a high-voltage switching transistor, and a second controllable switch connected in series. One end of the first resistor is connected to the input voltage, and the other end is connected to the drain of the high-voltage switching transistor. The source of the high-voltage switching transistor is connected to one end of the second controllable switch. The other end of the second controllable switch is coupled to the connection node between the power supply terminal and the energy storage unit. The control terminal of the second controllable switch is coupled to the third control terminal of the controller.

[0022] Optionally, the high-voltage switch is a normally open switch, and the gate of the high-voltage switch is coupled to a reference ground.

[0023] Optionally, the upper switch is a normally open switch, and the gate of the upper switch is coupled to a reference ground.

[0024] Optionally, the upper switching transistor is a D-type gallium nitride switching transistor.

[0025] Optionally, the primary-side circuit further includes a driving circuit, which includes a second resistor and a fourth diode. The first end of the second resistor and the cathode of the fourth diode are coupled to a reference ground, and the second end of the second resistor and the anode of the fourth diode are coupled to the gate of the upper switching transistor.

[0026] To achieve the above objectives, the present invention also provides a self-powered chip, wherein the self-powered chip integrates the self-powered circuit described in any of the above claims.

[0027] To achieve the above objectives, the present invention also provides a switching power supply system, the switching power supply system comprising an AC power supply, a rectifier circuit, a filter capacitor, a primary-side circuit, and a self-powered circuit or a self-powered chip as described above, wherein the input terminal of the rectifier circuit is coupled to the AC power supply, the filter capacitor is connected in parallel with the rectifier circuit, and the output terminal of the rectifier circuit is coupled to the primary winding of the primary-side circuit.

[0028] Compared with the prior art, the self-powered circuit, self-powered chip and switching power supply system for the primary side circuit of the switching power supply provided by the present invention have the following beneficial effects: The present invention can make the power supply of the controller more stable without the need for auxiliary windings and external voltage regulator circuits, thereby ensuring the stable and reliable operation of the system. It can not only significantly reduce costs, but also significantly improve efficiency, and has good applicability.

[0029] Since the self-powered chip and switching power supply system provided by this invention belong to the same inventive concept as the self-powered circuit for the primary side circuit of the switching power supply provided by this invention, the self-powered chip and switching power supply system provided by this invention have at least all the above-mentioned advantages of the self-powered circuit for the primary side circuit of the switching power supply provided by this invention. To avoid redundancy, they will not be described in detail here. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the power supply circuit structure of a flyback power controller in a specific example of the prior art.

[0031] Figure 2 The diagram shows the structure of a self-powered circuit for the primary side circuit of a switching power supply system, as provided in the first embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the circuit topology of a self-powered circuit for the primary side circuit of a switching power supply, provided in one embodiment of the first embodiment of the present invention.

[0033] Figure 4 The diagram below shows the structure of a self-powered circuit for the primary side circuit of a switching power supply system, as provided in the second embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the circuit topology of a self-powered circuit for the primary side circuit of a switching power supply, provided in one embodiment of the second embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram of the circuit topology of a self-powered circuit for the primary side circuit of a switching power supply, provided as another embodiment of the second embodiment of the present invention.

[0036] Figure 7 for Figure 5 The diagram shown is a timing logic diagram of a self-powered circuit used in the primary side circuit of a switching power supply.

[0037] Figure 8 This is a structural block diagram of a switching power supply system provided in another embodiment of the present invention.

[0038] The reference numerals in the attached figures are explained as follows:

[0039] Primary winding - Np, secondary winding - Ns, auxiliary winding - Naux, first controller - 1, primary switching transistor - Q0;

[0040] Primary side circuit -100, primary side winding -Lp, secondary side winding -Ls, upper switch -Q1, switch -Q2, drive circuit -110, second resistor -R2, third resistor -R3, fourth diode -D4; self-powered circuit -200, controller -210, power supply terminal -VCC, first control terminal -G1, second control terminal -G2, third control terminal -G3; excitation current power supply circuit -220, first controllable switch -S1, first diode -D1; energy storage unit -2 30, First capacitor - C1; High voltage power supply circuit - 240, Second diode - D2, Third diode - D3, First resistor - R1, High voltage switching transistor - Q3, Second controllable switch - S2; Switching node - SW, Connection node - N1; Input voltage - Vin, First voltage threshold - V1, Second voltage threshold - V2, Start-up threshold voltage - VCC_ON, Lower limit of power supply voltage - VCC_HOLD; AC power supply - 300, Rectifier circuit - BD, Filter capacitor - C2. Detailed Implementation

[0041] To make the objectives, advantages, and features of the present invention clearer, the self-powered circuit, self-powered chip, and switching power supply system for the primary side circuit of a switching power supply proposed in this invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to facilitate and clarify the illustration of the embodiments of the present invention. It should be understood that the accompanying drawings do not necessarily show the specific structure of the invention to scale, and the illustrative features used to illustrate certain principles of the invention in the accompanying drawings are also drawn in a slightly simplified manner. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and environment in which they are used. Furthermore, in the embodiments described below, the same reference numerals are sometimes used in different drawings to denote the same parts or parts having the same function, and their repeated descriptions are omitted. In this specification, similar reference numerals and letters are used to denote similar items; therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. Where appropriate, these terms used thus can be replaced.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] It should be understood that when a component is referred to as "connected," "connected to," or "coupled to" other components, it may be directly connected to other components, or there may be intermediary components. Conversely, when a component is referred to as "directly connected" or "directly connected to" other components, there are no intermediary components.

[0044] The core idea of ​​this invention is to provide a self-powered circuit, a self-powered chip, and a switching power supply system for the primary side circuit of a switching power supply. This invention eliminates the need for auxiliary windings and external voltage regulator circuits, enabling more stable power supply to the controller and ensuring stable and reliable system operation. It not only significantly reduces costs but also significantly improves efficiency, and has good applicability.

[0045] It should be noted that the self-powered circuit and self-powered chip for the primary side circuit of a switching power supply provided by the present invention can be applied to the switching power supply system provided by the present invention. The switching power supply system provided by the present invention can be applied to scenarios including but not limited to small household appliance power supplies and household appliance auxiliary power supplies.

[0046] To achieve the above-mentioned idea, a first embodiment of the present invention provides a self-powered circuit for the primary side circuit of a switching power supply. For example, please refer to... Figure 2 , Figure 2 This is a block diagram of a self-powered circuit for the primary side circuit of a switching power supply provided in this embodiment. Figure 2 As shown, the primary-side circuit 100 includes a primary-side winding Lp, an upper switch Q1, and a lower switch Q2. One end of the primary-side winding Lp receives the input voltage Vin, and the other end is connected to the upper switch Q1. The upper switch Q1 and the lower switch Q2 are connected through a switching node SW, and the lower switch Q2 is coupled to reference ground. Exemplarily, the self-powered circuit 200 includes a controller 210, an excitation current supply circuit 220, and an energy storage unit 230 connected to the power supply terminal VCC of the controller 210. One end of the energy storage unit 230 is grounded, and one end of the excitation current supply circuit 220 is coupled to the switching node SW, while the other end is coupled to the connection node N1 between the power supply terminal VCC and the energy storage unit 230. When the primary-side circuit 100 is in the excitation period, the controller 210 detects whether the voltage of the power supply terminal VCC is lower than a first voltage threshold V1 (see Appendix). Figure 7 When the voltage at the power supply terminal VCC is lower than the first voltage threshold V1, the first control terminal G1 of the controller 210 controls the excitation current power supply circuit 220 to be turned on, and the excitation current ICC charges the energy storage unit 230 to ensure that the voltage at the power supply terminal VCC maintains the normal operation of the controller 210.

[0047] Therefore, the self-powered circuit 200 provided by the present invention, by adopting a design in which one end of the excitation current power supply circuit 220 is connected to the switching node SW of the upper switch Q1 and the lower switch Q2 of the primary side circuit 100, and the other end is connected to the connection node N1 of the power supply terminal VCC of the controller 210 and the energy storage unit 230, lays a good foundation for powering the energy storage unit 230 through the excitation current ICC during the excitation of the primary side circuit 100, thereby providing an important guarantee for maintaining the normal operating voltage of the power supply terminal VCC; furthermore, in the primary side circuit 100, the self-powered circuit 200 provides ... during the excitation of the primary side circuit 100, the self-powered circuit 200 provides a good foundation for powering the energy storage unit 230 When the stage-side circuit 100 is in the excitation period and the voltage of the power supply terminal VCC is lower than the first voltage threshold V1, the controller 210 can control the excitation current power supply circuit 220 to conduct through its first control terminal G1, thereby enabling the excitation current ICC to power the energy storage unit 230. Through the coordinated operation of the excitation current power supply circuit 220 and the energy storage unit 230, the voltage of the power supply terminal VCC of the controller 210 can be prevented from being too low, ensuring that the voltage of the power supply terminal VCC maintains the normal operation of the controller 210 and effectively improving the system efficiency. Therefore, this invention can make the power supply of the controller 210 more stable without the need for auxiliary windings and external voltage regulator circuits, thus ensuring stable and reliable system operation. It not only significantly reduces costs but also significantly improves efficiency, demonstrating good applicability.

[0048] For example, please see Figure 3 , Figure 3 This is a schematic diagram of the circuit topology of a self-powered circuit for the primary side circuit of a switching power supply, provided in one embodiment of the first embodiment of the present invention. Figure 3 As shown, in some exemplary embodiments, the energy storage unit 230 can be a first capacitor C1. Therefore, using a first capacitor C1 to implement the energy storage unit 230 fully utilizes the advantages of capacitors—high-frequency charging and discharging and fast response—thereby further improving the efficiency and stability of the invention. It is understood that... Figure 3 The use of a first capacitor C1 to implement the energy storage unit 230 is merely an illustrative example of a preferred embodiment and not a limitation of the present invention. The present invention does not impose too many limitations on the specific implementation of the energy storage unit 230. When implementing the present invention, an energy storage device with fast response and high-frequency charging and discharging can be preferred according to actual needs.

[0049] For example, in some exemplary embodiments, the upper switch Q1 is a normally open switch, and the gate of the upper switch Q1 is coupled to a reference ground. Therefore, by using a normally open switch Q1 and coupling the gate of the upper switch Q1 to a reference ground, the design has the advantages of simple circuit structure, ease of implementation, and high reliability.

[0050] Exemplary examples show that, in some of the exemplary embodiments, the upper switch Q1 is a D-type gallium nitride (D-GaN) switch. By employing D-GaN to implement the upper switch Q1, the advantages of lower and more stable voltage at the D-GaN switch junction can be fully utilized, thereby further reducing costs and improving system efficiency through the use of low-voltage processes. Furthermore, the lower switch Q2 can be a Si-MOSFET device, thus forming a Cascode structure with the upper switch, offering advantages such as high voltage withstand and reduced conduction losses.

[0051] It should be understood that using a D-type gallium nitride switch to implement the upper switch Q1 and a Si-MOSFET device to implement the lower switch Q2 is merely an illustrative example of a preferred embodiment and not a limitation of the present invention. The present invention does not limit the specific implementation of the upper switch Q1 and the lower switch Q2. When implementing the present invention, the appropriate implementation should be selected according to actual needs.

[0052] Furthermore, in an exemplary embodiment, after the primary-side circuit 100 starts energizing in each switching cycle (i.e., after the lower switch Q2 is turned on), after a first preset time, the controller 210 detects whether the voltage of the power supply terminal VCC is lower than the first voltage threshold V1. Therefore, by detecting whether the voltage of the power supply terminal VCC is lower than the first voltage threshold V1 after the primary-side circuit 100 starts energizing in each switching cycle, voltage misjudgment caused by noise (turn-on spike) generated at the moment of power device turn-on can be effectively avoided, further improving the stability and reliability of the present invention.

[0053] It should be noted that those skilled in the art should understand that the present invention does not impose too many limitations on the specific value of the first preset duration. When implementing the present invention, it can be reasonably set according to the specific parameters of each device in the primary side circuit 100 through calibration, model calculation and / or the experience of engineers. Preferably, the first preset duration is preferably set according to the leading edge blanking (LEB) duration after the lower switch Q2 is turned on.

[0054] Furthermore, in one exemplary embodiment, the voltage at the power supply terminal VCC is charged to a second voltage threshold V2 (see Appendix). Figure 7When the voltage at the power supply terminal VCC reaches the second voltage threshold V1, the controller 210 controls the excitation current to stop charging the energy storage unit 230, wherein the second voltage threshold V2 is greater than the first voltage threshold V1. Therefore, by controlling the excitation current to stop charging the energy storage unit 230 when the voltage at the power supply terminal VCC reaches the second voltage threshold V2, excessive voltage at the power supply terminal VCC can be effectively avoided, thereby further ensuring the stability and reliability of the system.

[0055] Furthermore, in one exemplary embodiment, the on-resistance of the lower switch Q2 is less than the on-resistance of the excitation current supply circuit 220. After the excitation current supply circuit 220 is turned on by the first control terminal G1 of the controller 210, the lower switch Q2 is turned off by the second control terminal G2 of the controller 210. Therefore, by turning off the lower switch Q2 after the excitation current supply circuit 220 is turned on, it is effectively ensured that the excitation current effectively charges the energy storage unit 230, thereby improving system efficiency.

[0056] Furthermore, in an exemplary embodiment, after the excitation current power supply circuit 220 is turned on by the first control terminal G1 of the controller 210, a second preset time is elapsed, and then the lower switch Q2 is turned off by the second control terminal G2 of the controller 210. Thus, by turning off the lower switch Q2 after the excitation current power supply circuit 220 is turned on and after a second preset time, the excitation current can flow entirely through the lower switch Q2 until the voltage at the power supply terminal VCC of the controller 210 (i.e., connection node N1) continues to drop below the voltage at the switching node SW. This ensures that the excitation current power supply circuit 220 is fully turned on, allowing the excitation current to fully charge the energy storage unit 230 through the excitation current power supply circuit 220. This avoids the situation where the lower switch Q2 is turned off prematurely before the excitation current power supply circuit 220 is fully turned on, causing an interruption in excitation, thereby further improving the stability and reliability of the present invention.

[0057] It should be noted that those skilled in the art should understand that the present invention does not impose excessive limitations on the specific value of the second preset duration. In implementing the present invention, the value can be reasonably set based on the specific parameters of each device in the primary side circuit 100 through calibration, model calculation, and / or the experience of engineers. Preferably, the second preset duration is the time from when the excitation current power supply circuit 220 is turned on until the voltage at the power supply terminal VCC of the controller 210 drops to less than the voltage at the switching node SW, and is preferably set to be greater than this duration.

[0058] Furthermore, in an exemplary embodiment, the controller 210 controlling the excitation current to stop charging the energy storage unit 230 includes: the second control terminal G2 controlling the lower switch Q2 to turn on.

[0059] Furthermore, in one exemplary embodiment, the first control terminal G1 controls the excitation current supply circuit 220 to be turned off after the lower switch Q2 is turned on and before the excitation ends. Therefore, by turning off the excitation current supply circuit 220 after the lower switch Q2 is turned on and before the excitation ends, premature demagnetization can be prevented, thereby further improving the reliability and stability of the system.

[0060] Furthermore, in one exemplary embodiment, when the voltage at the power supply terminal VCC has not reached the second voltage threshold V2 and the off-time of the lower switch Q2 during excitation reaches a preset off-time, the second control terminal G2 of the controller 210 controls the lower switch Q2 to turn on. Thus, by timely controlling the turn-on of the lower switch Q2, premature demagnetization can be effectively avoided, thereby further improving the reliability and stability of the system.

[0061] For example, please continue to see Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the excitation current supply circuit 220 includes a first controllable switch S1 and a first diode D1. The control terminal of the first controllable switch S1 is coupled to the first control terminal G1 of the controller 210, the first terminal of the first controllable switch S1 is coupled to the switching node SW, the anode of the first diode D1 is connected to the second terminal of the first controllable switch S1, and the cathode of the first diode D1 is coupled to the power supply terminal VCC of the controller 210. Thus, the first controllable switch S1 enables reliable control of the on and off states of the excitation current supply circuit 220, thereby laying a good foundation for maintaining good stability of the voltage at the power supply terminal VCC during the excitation period of the primary side circuit 100. The first diode D1 ensures that the excitation current flows from the switching node SW to the energy storage unit 230 during the conduction period of the excitation current supply circuit 220, preventing current backflow, and thus enabling the voltage at the power supply terminal VCC to maintain good stability.

[0062] Furthermore, in one exemplary embodiment, the on-resistance of the lower switch Q2 is less than the on-resistance of the first controllable switch S1. This ensures that during excitation, when both the lower switch Q2 and the first controllable switch S1 are on, the excitation current can first flow entirely through the lower switch Q2, thereby guaranteeing the full conduction of the first controllable switch S1, preventing premature demagnetization, and further improving the safety and reliability of the invention.

[0063] For example, please see Figure 4 and Figure 5 ,in, Figure 4 This is a structural block diagram of a self-powered circuit for the primary side circuit of a switching power supply provided in a second embodiment of the present invention, used in a switching power supply system. Figure 5 This is a schematic diagram of the circuit topology of a self-powered circuit for the primary side circuit of a switching power supply, provided in one embodiment of the second embodiment of the present invention. (Comparison) Figure 2 and Figure 4 ,as well as Figure 3 and Figure 5 It can be seen that the difference between the first embodiment and the second embodiment of the present invention is that the self-powered circuit 200 provided in the second embodiment further includes a high-voltage power supply circuit 240. To avoid redundancy, the following only describes the differences from the first embodiment. For parts not mentioned in this embodiment, please refer to the relevant description in Embodiment 1 for an adaptive understanding. Exemplarily, the input terminal of the high-voltage power supply circuit 240 receives an input voltage Vin, and its output terminal is coupled to the connection node N1 between the power supply terminal VCC and the energy storage unit 230. During the startup phase of the controller 210, the third control terminal G3 of the controller 210 controls the path current IHV generated by the high-voltage power supply circuit 240 to charge the energy storage unit 230 until the voltage of the power supply terminal VCC reaches the startup threshold voltage VCC_ON (see Appendix). Figure 7 When the third control terminal G3 controls the high-voltage power supply circuit 240 to shut down, the start-up threshold voltage VCC_ON is greater than the first voltage threshold V1.

[0064] Therefore, the self-powered circuit 200 provided by the present invention, through the high-voltage power supply circuit 240, can control the path current IHV generated by the high-voltage power supply circuit 240 to charge the energy storage unit 230 during the start-up phase of the controller 210, thereby enabling the voltage of the power supply terminal VCC to be charged to the start-up threshold voltage VCC_ON. This realizes the combination of high-voltage power supply during the start-up phase of the power supply terminal VCC and excitation current power supply circuit 220 during normal operation phase through excitation current power supply. Thus, stable power supply can be achieved without auxiliary windings, which can effectively reduce system cost and improve system efficiency.

[0065] Furthermore, in an exemplary embodiment, during the normal operation phase of the controller 210, the voltage at the power supply terminal VCC is less than the lower limit threshold VCC_HOLD of the power supply voltage (see Appendix). Figure 7 When the voltage at the power supply terminal VCC is less than the power supply voltage threshold V1, the third control terminal G3 of the controller 210 controls the high-voltage power supply circuit 240 to conduct, generating a current IHV to charge the energy storage unit 230 until the voltage at the power supply terminal VCC reaches the second voltage threshold V2. Then, the third control terminal G3 controls the high-voltage power supply circuit 240 to turn off. The first voltage threshold V1 is greater than the lower power supply voltage threshold VCC_HOLD. Therefore, charging the energy storage unit 230 through the high-voltage power supply circuit 240 when the voltage at the power supply terminal VCC is less than the lower power supply voltage threshold VCC_HOLD prevents the system from malfunctioning due to excessively low power supply voltage at lower switching frequencies. By using high-voltage power supply when the power supply voltage is low, the system ensures good stability of the voltage at the power supply terminal VCC of the controller 210, while also further improving the reliability and efficiency of the system.

[0066] In other embodiments, the controller 210 can be powered in other ways during the startup phase, such as by connecting an external constant current source to the power supply terminal VCC. However, using high-voltage power supply will not cause false triggering of the transformer excitation during the startup phase, resulting in more stable performance.

[0067] It should be noted that the present invention does not limit the manner in which the high-voltage power supply circuit 240 receives the input voltage Vin. For example, in some exemplary embodiments, such as Figure 4 and Figure 5 As shown, the input terminal of the high-voltage power supply circuit 240 can be coupled between the rectifier circuit BD of the switching power supply and the primary-side circuit 100 to receive DC power. In other embodiments, for example, please refer to... Figure 6 , Figure 6 This is a schematic diagram of the circuit topology of a self-powered circuit for the primary side circuit of a switching power supply, provided as another embodiment of the first embodiment of the present invention. Figure 6 As shown, the self-powered circuit 200 further includes a second diode D2 and a third diode D3. The anodes of the second diode D2 and the third diode D3 are respectively coupled to the live wire and neutral wire of the AC power supply 300, and the cathodes of the second diode D2 and the third diode D3 are coupled to the input terminal of the high-voltage power supply circuit 240. Therefore, through the second diode D2 and the third diode D3, the self-powered circuit 200 can receive AC power, thereby further improving the applicability of the present invention.

[0068] It should be noted that, apart from the different input voltage Vin received at the input terminal of the high-voltage power supply circuit 240, Figure 5 and Figure 6 The working principle of the self-powered circuit 200 shown is basically the same. To avoid redundancy, this article will only use... Figure 5 The self-powered circuit 200 for the primary side circuit 100 in a switching power supply provided by the present invention will be described using an example. Figure 6 Please refer to the working principle of the self-powered circuit 200 shown. Figure 5 The relevant explanations should be understood adaptively.

[0069] For example, please continue to see Figure 5 ,like Figure 5 As shown, in some exemplary embodiments, the high-voltage power supply circuit 240 includes a first resistor R1, a high-voltage switching transistor Q3, and a second controllable switch S2 connected in series. One end of the first resistor R1 is connected to the input voltage Vin, and the other end is connected to the drain of the high-voltage switching transistor Q3. The source of the high-voltage switching transistor Q3 is connected to one end of the second controllable switch S2. The other end of the second controllable switch S2 is coupled to the connection node N1 between the power supply terminal VCC and the energy storage unit 230. The control terminal of the second controllable switch S2 is coupled to the third control terminal G3 of the controller 210.

[0070] Therefore, the surge current can be effectively limited during the switching between the on and off states of the first controllable switch S1 (i.e., the switching between the current IHV generated by the high-voltage power supply circuit 240 charging the energy storage unit 230 when it is on and when it is off and no longer charging the energy storage unit 230), thereby further improving the stability and reliability of the present invention. The number of first resistors R1 can be one or more. At the same time, the implementation of the high-voltage power supply circuit 240 using the first resistor R1, the high-voltage switch Q3, and the second controllable switch S2 also has the advantages of low cost, simple structure, and ease of implementation.

[0071] Furthermore, in one exemplary embodiment, the high-voltage switch Q3 is a normally open switch, and the gate of the high-voltage switch Q3 is coupled to a reference ground. Therefore, by using a normally open switch for the high-voltage switch Q3 and coupling its gate to a reference ground, the circuit structure is not only simple and easy to implement, but also highly reliable.

[0072] For example, please continue to see Figure 5 ,like Figure 5As shown, in some exemplary embodiments, the primary-side circuit 100 further includes a drive circuit 110, which includes a second resistor R2 and a fourth diode D4. The first end of the second resistor R2 and the cathode of the fourth diode D4 are coupled to a reference ground, and the second end of the second resistor R2 and the anode of the fourth diode D4 are coupled to the gate of the upper switching transistor Q1.

[0073] Furthermore, the driving circuit 110 also includes a third resistor R3 coupled between the second end of the second resistor R2 and the common junction of the anode of the fourth diode D4 and the gate of the upper switching transistor Q1.

[0074] Therefore, the driving circuit 110 adopts the design of the second resistor R2, the fourth diode D4 and the third resistor R3, which is not only simple in logic and easy to implement, but also enables stable and reliable driving of the upper switch Q1, thereby further improving the stability and reliability of the present invention.

[0075] It should be noted that the present invention does not limit the specific values ​​of the first voltage threshold V1 and the second voltage threshold V2. When implementing the present invention, they should be reasonably set according to actual needs. In addition, by way of example, the controller 210 can detect the voltage of its power supply terminal VCC in real time through a built-in comparator or sampling circuit, and control the output level of the first control terminal G1, the second control terminal G2 and the third control terminal G3 when the voltage of the power supply terminal VCC and the corresponding relationship of the first voltage threshold V1, the second voltage threshold V2, the start threshold voltage VCC_ON and the lower limit threshold VCC_HOLD satisfy a preset relationship, and / or the conduction / turn-off of the first controllable switch S1, the second controllable switch S2 and the lower switch Q2 satisfy a preset duration, thereby realizing the control of the conduction and turn-off states of the first controllable switch S1, the second controllable switch S2 and the lower switch Q2. For details, please refer to the relevant technical adaptations known to those skilled in the art. Due to space limitations, this article will not elaborate further.

[0076] For example, please see Figure 7 , Figure 7 for Figure 5 The timing logic diagram shown is for the self-powered circuit 200 used in the primary-side circuit 100 of the switching power supply. Specifically, Figure 7The meanings of the relevant symbols in the diagram are as follows: The waveforms corresponding to G1, G2, and G3 can be understood as the levels corresponding to the first control terminal G1, the second control terminal G2, and the third control terminal G3, respectively; the waveform corresponding to VCC can be understood as the voltage corresponding to the power supply terminal VCC of the controller 210; the waveform corresponding to IHV can be understood as the current generated when the high-voltage power supply circuit 240 is turned on; the waveform corresponding to IL can be understood as the excitation current; the waveform corresponding to ICC can be understood as the excitation current flowing to the energy storage unit 230 when the excitation current power supply circuit 220 is turned on; the waveform corresponding to ICS can be understood as the current flowing through the lower switching transistor Q2; and the waveform corresponding to VSW can be understood as the voltage of the switching node SW. Next, the following will combine... Figure 5 and Figure 7 The working principle and related timing of the self-powered power supply circuit provided by this invention are explained below:

[0077] At time t0: The switching power supply system is in the startup phase. The third control terminal G3 of the controller 210 outputs a high level, causing the second controllable switch S2 to conduct. Since the high-voltage switching transistor Q3 is normally on, the high-voltage input voltage Vin, through the path current IHV, is supplied to the energy storage unit 230 at the power supply terminal VCC. Figure 5 As the first capacitor C1 is charged, the voltage at the power supply terminal VCC begins to rise.

[0078] At time t1: the voltage at the power supply terminal VCC rises to the turn-on threshold voltage, the third control terminal G3 outputs a low level, causing the second controllable switch S2 to turn off the high-voltage power supply, and the system enters normal operation mode. The second control terminal G2 outputs a high level, causing the lower switch Q2 to conduct, and the entire excitation current IL flows through the lower switch Q2 (at this time, the waveform of IL is synchronized with that of ICS). Due to the system's power consumption, the voltage at the power supply terminal VCC of the controller 210 gradually decreases.

[0079] At time t2 (a certain switching cycle): the level of the second control terminal G2 is high, causing the lower switch Q2 to conduct. After the first preset time (leading edge blanking, LEB), at time t3, the controller 210 determines that the voltage of the power supply terminal VCC has fallen below the first voltage threshold V1, and the first control terminal G1 outputs a high level, causing the first controllable switch S1 to conduct. At this time, the lower switch Q2 is still in the conducting state, but because the conduction impedance of the lower switch Q2 is much smaller than the conduction impedance of the first controllable switch S1, the voltage VSW of the switching node SW is less than the voltage of the power supply terminal VCC, and the first diode D1 has unidirectional conductivity, so the magnetizing current IL flows entirely through the lower switch Q2. The magnetizing current IL is equal to the current ICS flowing through the lower switch Q2, and the voltage of the power supply terminal VCC continues to decrease. After a second preset time delay following the conduction of the first controllable switch S1, at time t4, the second control terminal G2 outputs a low level, causing the lower switch Q2 to turn off. The excitation current ICC flows through the excitation current power supply circuit 220 to the power supply terminal VCC, starting to charge the first capacitor C1 and causing the voltage of the power supply terminal VCC to rise.

[0080] At time t5: the voltage of the power supply terminal VCC of controller 210 is greater than the second voltage threshold V2. The second control terminal G2 of controller 210 outputs a high level, causing the lower switch Q2 to turn on. The entire excitation current IL flows through the lower switch Q2, and the charging of the first capacitor C1 of the excitation current ICC ends. After a delay, at time t6, the first control terminal G1 of controller 210 outputs a low level again, causing the first controllable switch S1 to turn off. This ensures that the first controllable switch S1 is turned off after the lower switch Q2 turns on and before it turns off, preventing premature demagnetization.

[0081] Furthermore, during normal operation, if the power supply to the power supply terminal VCC is insufficient due to a decrease in switching frequency or other factors, such as at time t7, when the voltage of the power supply terminal VCC drops below the lower limit threshold VCC_HOLD, the third control terminal G3 of the controller 210 outputs a high level, causing the second controllable switch S2 to conduct. The current IHV generated by the conduction of the high-voltage power supply circuit 240 supplies high-voltage power to the power supply terminal VCC. After the second controllable switch S2 is turned on, the voltage of the power supply terminal VCC rises. At time t8, the voltage of the power supply terminal VCC is greater than the second voltage threshold V2, and the third control terminal G3 of the controller 210 outputs a low level, causing the second controllable switch S2 to turn off and stop the high-voltage power supply.

[0082] In summary, during the startup phase of the switching power supply system, the second controllable switch S2 is turned on, and high-voltage power is supplied to the power supply terminal VCC of the controller 210 through the high-voltage power supply circuit 240. When the voltage of the power supply terminal VCC reaches the startup threshold voltage VCC_ON, the second controllable switch S2 is turned off, and the power supply terminal VCC is powered by the excitation current ICC. Furthermore, during normal operation, after the lower switch Q2 is turned on for a first preset time (leading edge blanking, LEB), the controller 210 detects the voltage of the power supply terminal VCC: if the voltage of the power supply terminal VCC is greater than the first voltage threshold V1, the first controllable switch S1 is not turned on; if the voltage of the power supply terminal VCC is less than the first voltage threshold V1, the first controllable switch S1 is turned on, and after a second preset time delay to ensure that the first controllable switch S1 is fully turned on, the lower switch Q2 is turned off. The excitation current ICC supplies power to the power supply terminal VCC through the excitation current power supply circuit 220. When the voltage of the power supply terminal VCC is greater than the second voltage threshold V2, the lower switch Q2 is turned on again and delayed for a period of time to ensure that the lower switch Q2 is fully turned on before the first controllable switch S1 is turned off, and the power supply to the power supply terminal VCC is stopped. Furthermore, during normal operation, if the voltage of the power supply terminal VCC is less than the lower limit threshold VCC_HOLD, the second controllable switch S2 is turned on, and high voltage power is supplied to the power supply terminal VCC of the controller 210 through the high voltage power supply circuit 240. When the voltage of the power supply terminal VCC is greater than the second voltage threshold V2, the second controllable switch S2 is turned off to restore the excitation power supply.

[0083] Based on the same inventive concept, the present invention also provides a self-powered chip, wherein the self-powered chip integrates a self-powered circuit 200 for the primary side circuit of a switching power supply as described in any of the above embodiments.

[0084] For example, in some exemplary embodiments, the self-powered chip may also integrate, but is not limited to, the upper switch Q1, the lower switch Q2, and the drive circuit 110 of the primary side circuit 100, thereby further improving the integration and applicability of the present invention.

[0085] It is understood that the present invention does not limit the manufacturing process of the chip. For example, the chip may be, but is not limited to, a 180nm chip, a 130nm chip, and a 90nm chip.

[0086] Another embodiment of the present invention provides a switching power supply system, for example, please refer to [link to relevant documentation]. Figure 8 , Figure 8 This is a structural block diagram of the switching power supply system provided in this embodiment. Figure 8As shown, the switching power supply system provided by this invention includes an AC power supply 300, a rectifier circuit BD, a filter capacitor C2, a primary-side circuit 100, and a self-powered circuit 200 as described in any embodiment herein. The input terminal of the rectifier circuit BD is coupled to the AC power supply 300, the filter capacitor C2 is connected in parallel with the rectifier circuit BD, and the output terminal of the rectifier circuit BD is coupled to the primary winding of the primary-side circuit 100. In some other embodiments, the self-powered circuit 200 in the switching power supply system provided by this invention can also be replaced by the self-powered chip provided by this invention, thereby further improving the integration of the switching power supply system provided by this invention and further improving its applicability.

[0087] Since the self-powered chip and switching power supply system provided by this invention belong to the same inventive concept as the self-powered circuit for the primary side circuit of the switching power supply provided by this invention, the self-powered chip and switching power supply system provided by this invention have at least all the above-mentioned advantages of the self-powered circuit for the primary side circuit of the switching power supply provided by this invention. To avoid redundancy, they will not be described in detail here.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0089] Therefore, compared with the prior art, the self-powered circuit, self-powered chip and switching power supply system for the primary side circuit of the switching power supply provided by the present invention have the following beneficial effects: The present invention can make the power supply of the controller more stable without the need for auxiliary windings and external voltage regulator circuits, thereby ensuring the stable and reliable operation of the system. It can not only significantly reduce costs, but also significantly improve efficiency, and has good applicability.

[0090] In summary, the above embodiments have provided detailed descriptions of different configurations of the self-powered circuit, self-powered chip, and switching power supply system for the primary side circuit of a switching power supply provided by the present invention. Of course, the above descriptions are only descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention in any way. The present invention includes, but is not limited to, the configurations listed in the above embodiments. Those skilled in the art can draw inferences from the above embodiments. Any changes or modifications made by those skilled in the art based on the above disclosure are within the protection scope of the claims.

Claims

1. A self-powered circuit for the primary side circuit of a switching power supply, characterized in that, The primary side circuit includes a primary side winding, an upper switch transistor, and a lower switch transistor. One end of the primary side winding receives the input voltage, and the other end is connected to the upper switch transistor. The upper switch transistor and the lower switch transistor are connected through a switching node, and the lower switch transistor is coupled to a reference ground. The self-powered circuit includes a controller and an excitation current power supply circuit, as well as an energy storage unit connected to the power supply terminal of the controller. One end of the energy storage unit is grounded, one end of the excitation current power supply circuit is coupled to the switching node, and the other end is coupled to the connection node between the power supply terminal and the energy storage unit. When the primary side circuit is in the excitation period, the controller detects whether the voltage at the power supply terminal is lower than the first voltage threshold. When the voltage at the power supply terminal is lower than the first voltage threshold, the first control terminal of the controller controls the excitation current power supply circuit to be turned on, and the excitation current charges the energy storage unit to ensure that the voltage at the power supply terminal maintains the normal operation of the controller.

2. The self-powered circuit according to claim 1, characterized in that, After the primary side circuit excitation begins in each switching cycle, and after a first preset time, the controller then detects whether the voltage at the power supply terminal is lower than the first voltage threshold.

3. The self-powered circuit according to claim 1, characterized in that, When the voltage at the power supply terminal reaches the second voltage threshold, the controller controls the excitation current to stop charging the energy storage unit, wherein the second voltage threshold is greater than the first voltage threshold.

4. The self-powered circuit according to claim 3, characterized in that, The on-resistance of the lower switching transistor is less than the on-resistance of the excitation current power supply circuit. After the excitation current power supply circuit is turned on by the first control terminal of the controller, the lower switching transistor is turned off by the second control terminal of the controller.

5. The self-powered circuit according to claim 4, characterized in that, After the excitation current power supply circuit is turned on by the first control terminal of the controller, a second preset time period is elapsed, and then the lower switch transistor is turned off by the second control terminal of the controller.

6. The self-powered circuit according to claim 4, characterized in that, The controller controls the excitation current to stop charging the energy storage unit, including: the second control terminal controls the lower switch to turn on.

7. The self-powered circuit according to claim 6, characterized in that, The first control terminal controls the excitation current power supply circuit to be turned off after the lower switch is turned on and before the excitation ends.

8. The self-powered circuit according to claim 4, characterized in that, When the voltage at the power supply terminal is not charged to the second voltage threshold and the turn-off time of the lower switch during the excitation period reaches the preset turn-off time, the second control terminal of the controller controls the lower switch to turn on.

9. The self-powered circuit according to claim 1, characterized in that, The excitation current power supply circuit includes a first controllable switch and a first diode. The control terminal of the first controllable switch is coupled to the first control terminal of the controller, the first terminal of the first controllable switch is coupled to the switch node, the anode of the first diode is connected to the second terminal of the first controllable switch, and the cathode of the first diode is coupled to the power supply terminal of the controller.

10. The self-powered circuit according to claim 9, characterized in that, The on-resistance of the lower switch is less than the on-resistance of the first controllable switch.

11. The self-powered circuit according to claim 3, characterized in that, The self-powered circuit also includes a high-voltage power supply circuit. The input terminal of the high-voltage power supply circuit receives an input voltage, and the output terminal is coupled to the connection node between the power supply terminal and the energy storage unit. During the startup phase of the controller, the third control terminal of the controller controls the current generated by the high-voltage power supply circuit to charge the energy storage unit until the voltage of the power supply terminal reaches the startup threshold voltage. Then, the third control terminal controls the high-voltage power supply circuit to turn off, wherein the startup threshold voltage is greater than the first voltage threshold.

12. The self-powered circuit according to claim 11, characterized in that, During the normal operation phase of the controller, when the voltage at the power supply terminal is less than the lower limit threshold of the power supply voltage, the third control terminal of the controller controls the high-voltage power supply circuit to conduct and generate the current to charge the energy storage unit until the voltage at the power supply terminal is charged to the second voltage threshold. Then, the third control terminal controls the high-voltage power supply circuit to turn off, wherein the first voltage threshold is greater than the lower limit threshold of the power supply voltage.

13. The self-powered circuit according to claim 11, characterized in that, The self-powered circuit also includes a second diode and a third diode. The anode of the second diode and the anode of the third diode are respectively coupled to the live wire and the neutral wire of the AC power supply, and the cathode of the second diode and the cathode of the third diode are coupled to the input terminal of the high-voltage power supply circuit.

14. The self-powered circuit according to claim 11, characterized in that, The high-voltage power supply circuit includes a first resistor, a high-voltage switching transistor, and a second controllable switch connected in series. One end of the first resistor is connected to the input voltage, and the other end is connected to the drain of the high-voltage switching transistor. The source of the high-voltage switching transistor is connected to one end of the second controllable switch. The other end of the second controllable switch is coupled to the connection node between the power supply terminal and the energy storage unit. The control terminal of the second controllable switch is coupled to the third control terminal of the controller.

15. The self-powered circuit according to claim 14, characterized in that, The high-voltage switch is a normally open switch, and the gate of the high-voltage switch is coupled to a reference ground.

16. The self-powered circuit according to claim 1, characterized in that, The upper switch is a normally open switch, and the gate of the upper switch is coupled to reference ground.

17. The self-powered circuit according to claim 16, characterized in that, The upper switch is a D-type gallium nitride switch.

18. The self-powered circuit according to claim 16, characterized in that, The primary-side circuit further includes a driving circuit, which includes a second resistor and a fourth diode. The first end of the second resistor and the cathode of the fourth diode are coupled to a reference ground, and the second end of the second resistor and the anode of the fourth diode are coupled to the gate of the upper switching transistor.

19. A self-powered chip, characterized in that, It integrates a self-powered circuit as described in any one of claims 1 to 18.

20. A switching power supply system, characterized in that, The switching power supply system includes an AC power supply, a rectifier circuit, a filter capacitor, a primary-side circuit, and a self-powered circuit as described in any one of claims 1 to 18 or a self-powered chip as described in claim 19. The input terminal of the rectifier circuit is coupled to the AC power supply, the filter capacitor is connected in parallel with the rectifier circuit, and the output terminal of the rectifier circuit is coupled to the primary winding of the primary-side circuit.

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