Power supply circuit of power supply control chip and switching power supply

Abstract

The utility model discloses a power supply circuit of a power supply control chip and a switching power supply, and relates to the technical field of electronic circuits. The power supply circuit of the power supply control chip comprises an activation branch, a first switch branch, a controller and a second switch branch. The activation branch starts to store electric energy based on the voltage of the input power supply when the switching element is closed, outputs a first level and a feedback signal, and stops outputting the first level when the stored electric energy is greater than a preset electric energy threshold. The first switching branch is turned on in response to a first level. The controller outputs a control signal based on the feedback signal. The second switch branch is turned on based on the control signal to output a first level. Through the mode, the risk that the power supply control chip is damaged can be reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of electronic circuits, and in particular to a power supply circuit and a switching power supply of a power control chip. Background Art

[0002] A power control chip controls the on / off switching of the switch connected to the primary side of a transformer in a single-ended converter circuit (for example, a flyback converter) to achieve voltage conversion. Currently, powering the power control chip involves first dividing the input power voltage through resistors. The chip then receives power and controls the switching of the switch, which is then powered by the voltage output from the secondary side of the transformer.

[0003] However, for the above power supply method, when the voltage of the input power source fluctuates, the power control chip may be damaged due to excessively high input voltage. Utility Model Content

[0004] The embodiments of the present application provide a power supply circuit and a switching power supply of a power control chip, which can reduce the risk of damage to the power control chip.

[0005] In a first aspect, an embodiment of the present application provides a power supply circuit of a power control chip, wherein the power control chip is used to control a first switching tube connected to the primary side of a transformer in a single-ended conversion circuit, and the power supply circuit includes:

[0006] an activation branch, connected to the input power supply through the switch element, configured to start storing electric energy based on the voltage of the input power supply when the switch element is closed, and simultaneously output a first electrical level and a feedback signal, and configured to stop outputting the first electrical level when the stored electric energy is greater than a preset electric energy threshold;

[0007] a first switch branch, connected between the input power supply and the power control chip and connected to the activation branch, and configured to be turned on in response to the first electrical level to establish a connection between the input power supply and the power control chip, wherein when the input power supply is connected to the power control chip, the power control chip controls the first switch to be alternately turned on and off so that the single-ended conversion circuit outputs a first voltage;

[0008] a controller, connected to the activation branch and the single-ended conversion circuit, respectively, and configured to output a control signal based on the feedback signal when the first voltage is input;

[0009] The second switch branch is connected to the controller and the first switch branch respectively, and is configured to be turned on based on the control signal to output the first electrical level to the first switch branch.

[0010] In one or more embodiments, the power supply circuit further includes a switching element;

[0011] The activated branch includes:

[0012] an energy storage element connected to the switching element and configured to start storing electrical energy based on the voltage of the input power source when the switching element is closed;

[0013] a first switch module, connected to the energy storage element, configured to be turned on when the electric energy stored in the energy storage element is less than or equal to the preset electric energy threshold, so as to output the first electrical level to the first switch branch, and configured to be turned off when the electric energy stored in the energy storage element is greater than the preset electric energy threshold, so as to stop outputting the first electrical level;

[0014] The second switch module is connected to the switch element and the controller, and is configured to be turned on when the switch element is closed to output the feedback signal to the controller, and is configured to be turned off when the switch element is opened to stop outputting the feedback signal.

[0015] In one or more embodiments, the power supply circuit further includes:

[0016] A voltage configuration branch is respectively connected to the input power supply, the first switch branch and the single-ended conversion circuit, and is configured to power the power control chip based on the second voltage when a second voltage is received, and is also configured to stabilize the voltage of the input power supply to a third voltage, and power the power control chip based on the third voltage when the second voltage is not received, wherein the single-ended conversion circuit also outputs the second voltage when the input power supply is connected to the power control chip.

[0017] In one or more embodiments, the first switch branch includes a first resistor and a second switch tube;

[0018] The first end of the first resistor is connected to the activation branch and the second switch branch respectively, the second end of the first resistor is connected to the first end of the second switch tube, the second end of the second switch tube is connected to the input power supply, and the third end of the second switch tube is connected to the power control chip.

[0019] In one or more embodiments, the second switch branch includes a second resistor, a third resistor, a fourth resistor, a first capacitor, a third switch tube and a first optocoupler;

[0020] The first end of the second resistor is connected to the controller, the second end of the second resistor is respectively connected to the first end of the first capacitor, the first end of the third resistor and the first end of the third switching tube, the second end of the first capacitor, the second end of the third resistor and the second end of the third switching tube are all connected to the second ground, the third end of the third switching tube is connected to the cathode of the light emitting device of the first optocoupler, the anode of the light emitting device of the first optocoupler is connected to the first voltage through the fourth resistor, the first end of the light receiver of the first optocoupler is connected to the first switch branch, and the second end of the light receiver of the first optocoupler is connected to the first ground.

[0021] In one or more embodiments, the power supply circuit further includes: a voltage sampling branch, connected to the input power supply and the controller, respectively, and configured to output a sampled voltage to the controller based on the voltage of the input power supply, so that the controller stops outputting the control signal when the sampled voltage is greater than a preset voltage threshold;

[0022] The voltage sampling branch includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, an operational amplifier, a first diode, and a second diode;

[0023] The sixth resistor and the fifth resistor are connected in series between a first voltage and a first ground. The connection point between the fifth and sixth resistors is connected to the first end of the second capacitor and the first end of the seventh resistor, respectively. The second end of the seventh resistor is connected to the inverting input terminal of the operational amplifier, the first end of the fourth capacitor, and the first end of the eighth resistor, respectively. The tenth and ninth resistors are connected in series between the first voltage and the input power supply. The connection point between the ninth and tenth resistors is connected to the second end of the second capacitor and the first end of the eleventh resistor, respectively. The second end of the eleventh resistor is connected to the first end of the third capacitor, the first end of the twelfth resistor, and the non-inverting input terminal of the operational amplifier, respectively. The second end of the third capacitor and the second end of the twelfth resistor are both connected to the second ground. The output terminal of the operational amplifier is connected to the second end of the fourth capacitor, the second end of the eighth resistor, and the first end of the thirteenth resistor, respectively. The second end of the thirteenth resistor is connected to the first end of the fifth capacitor, the cathode of the first diode, the anode of the second diode, and the controller, respectively. The second end of the fifth capacitor and the anode of the first diode are both connected to the second ground, and the cathode of the second diode is connected to the fourth voltage.

[0024] In one or more embodiments, the first switch module includes a fourteenth resistor, a fifteenth resistor and a fourth switch tube;

[0025] The first end of the fourteenth resistor is connected to the energy storage element, the second end of the fourteenth resistor is respectively connected to the first end of the fifteenth resistor and the first end of the fourth switch tube, the second end of the fifteenth resistor and the second end of the fourth switch tube are both connected to the second ground, and the third end of the fourth switch tube is connected to the first switch branch.

[0026] In one or more embodiments, the second switch module includes a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor and a second optocoupler;

[0027] The sixteenth resistor and the seventeenth resistor are connected in series between the switching element and the first ground, the connection point between the sixteenth resistor and the seventeenth resistor is connected to the anode of the light emitting device of the second optocoupler, the cathode of the light emitting device of the second optocoupler is connected to the first ground, the first end of the light receiver of the second optocoupler is connected to the first voltage through the eighteenth resistor, the second end of the second optocoupler is connected to the second ground through the nineteenth resistor, and the second end of the second optocoupler is connected to the controller.

[0028] In one or more embodiments, the voltage configuration branch includes a 20th resistor, a 21st resistor, a fifth switch tube, a voltage stabilizing diode, and a third diode;

[0029] The twentieth resistor is connected between the input power supply and the third end of the fifth switching tube, the twenty-first resistor is connected between the input power supply and the first end of the fifth switching tube, the cathode of the voltage regulator diode is connected to the first end of the fifth switching tube, the cathode of the voltage regulator diode is connected to the first ground, the second end of the fifth switching tube is respectively connected to the cathode of the third diode and the first switching branch, and the anode of the third diode is connected to the single-ended conversion circuit.

[0030] In a second aspect, an embodiment of the present application provides a switching power supply, including a single-ended conversion circuit, a power control chip, and a power supply circuit of the power control chip as described above;

[0031] The power control chip is connected to the power supply circuit and the single-ended conversion circuit respectively, wherein the single-ended conversion circuit is a forward conversion circuit or a flyback conversion circuit.

[0032] The present application has the beneficial effect of providing a power supply circuit for a power control chip according to an embodiment of the present application, including an activation branch, a first switch branch, a controller, and a second switch branch. This reduces the risk of damage to the power control chip. The activation branch stores electrical energy based on the voltage of the input power supply and simultaneously outputs a first electrical level and a feedback signal. The first electrical level is input to the first switch branch, turning the first switch branch on. The connection between the input power supply and the power control chip energizes the power control chip and enables it to operate. The power control chip controls the first switch transistor to alternately turn on and off, causing the single-ended converter circuit to output a first voltage. The first voltage is input to the controller, which, upon receiving the feedback signal, outputs a control signal to the second switch branch, turning the second switch branch on and outputting the first electrical level to the first switch branch to maintain the first switch branch on. In this case, even if the activation branch stops outputting the first electrical level due to stored electrical energy exceeding a preset energy threshold, the first electrical level output by the second switch branch can still maintain the first switch branch on. Consequently, the power control chip remains energized, causing the single-ended converter circuit to maintain outputting the first voltage. Since the activation branch stops outputting the first level when the stored electrical energy is greater than the preset electrical energy threshold, the first switch branch is disconnected and the connection between the input power supply and the power control chip is disconnected, which helps to reduce the risk of damage to the power control chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] One or more embodiments are exemplarily described by the figures in the accompanying drawings, which are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0034] Figure 1 This is a schematic diagram of the composition block diagram of the power supply circuit of the power control chip provided in the embodiment of the present application Figure 1 ;

[0035] Figure 2 This is a schematic diagram of the composition block diagram of the power supply circuit of the power control chip provided in the embodiment of the present application Figure 2 ;

[0036] Figure 3 This is a schematic diagram of the composition block diagram of the power supply circuit of the power control chip provided in the embodiment of the present application Figure 3 ;

[0037] Figure 4 It is a schematic diagram of the circuit structure of the power supply circuit of the power control chip provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0039] It should be noted that, when an element is referred to as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may exist therebetween.

[0040] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0041] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a block diagram of the power supply circuit of a power control chip provided in an embodiment of the present application. The power control chip 200 is used to control the first switch Q1 connected to the primary side L1 of the transformer T1 in the single-ended conversion circuit 300. In some embodiments, the power control chip 200 outputs a pulse-width modulation signal to control the alternating on and off of the first switch Q1. In some embodiments, the power control chip 200 can utilize a device such as UC2845, UC3845, or TL494 that can control the switching frequency of the first switch Q1 through pulse-width modulation (PWM) technology.

[0042] The single-ended conversion circuit 300 includes a forward conversion circuit and a flyback conversion circuit. Both the forward conversion circuit and the flyback conversion circuit are DC-to-DC (DC / DC) power converters, primarily used to convert a DC voltage into a different DC voltage. The forward conversion circuit operates as follows: When the first switch Q1 is turned on, the input current flows through the energy storage inductor connected between the input power source and the primary L1 in the forward conversion circuit. The energy storage inductor begins to store energy, and the input current flows through the primary L1, generating an induced voltage on the secondary side of the transformer T1. When the first switch Q1 is turned off, the current in the energy storage inductor continues to flow, generating a reverse voltage on the primary L1. This reverse voltage, combined with the voltage of the input power source, acts on the primary L1, resulting in a higher voltage on the secondary side of the transformer T1. The flyback converter circuit operates as follows: When the first switch Q1 is turned on, the input power voltage is applied to the primary side L1, causing current to build in the coil and energy to be stored in the transformer's magnetic field. When the first switch Q1 is turned off, the current in the primary side L1 abruptly stops, causing the magnetic field to collapse and generating a reverse voltage. This reverse voltage, combined with the input power voltage, acts on the primary side L1, causing a voltage to appear on the secondary side. The specific implementation of the forward and flyback converter circuits is well known in the art and will not be elaborated on here.

[0043] like Figure 1 As shown, the power supply circuit 100 includes a switch element 10 , an activation branch 20 , a first switch branch 30 , a controller 40 , a second switch branch 50 and a voltage sampling branch 60 .

[0044] Among them, the activation branch 20 is connected to the input power supply V1 N through the switching element 10; the first switch branch 30 is connected between the input power supply V1 N and the power control chip 200, and is connected to the activation branch 20; the controller 40 is respectively connected to the activation branch 20 and the single-ended conversion circuit 300; the second switch branch 50 is respectively connected to the controller 40 and the first switch branch 30; and the voltage sampling branch 60 is respectively connected to the input power supply V1 N and the controller 40.

[0045] Specifically, the switching element 10 is configured to open or close. The activation branch 20 is configured to begin storing electrical energy based on the voltage of the input power supply V1 N when the switching element 10 is closed, while simultaneously outputting a first electrical level and a feedback signal. The activation branch 20 is configured to stop outputting the first electrical level when the stored electrical energy exceeds a preset electrical energy threshold. The first switching branch 30 is configured to conduct in response to the first electrical level to establish a connection between the input power supply V1 N and the power control chip 200. When the input power supply V1 N is connected to the power control chip 200, the power control chip 200 controls the first switching transistor to alternately conduct and shut down, causing the single-ended converter circuit 300 to output a first voltage V1. The controller 40 is configured to output a control signal based on the feedback signal when the first voltage V1 is input. The second switching branch 50 is configured to conduct based on the control signal to output the first electrical level to the first switching branch 30. The voltage sampling branch 60 is configured to output a sampled voltage to the controller 40 based on the voltage of the input power supply V1 N, causing the controller 40 to stop outputting the control signal when the sampled voltage exceeds a preset voltage threshold. When the sampled voltage is less than or equal to the preset voltage threshold, the corresponding voltage input to the power control chip 200 will not cause damage to the chip. Conversely, when the sampled voltage is greater than the preset voltage threshold, the corresponding voltage input to the power control chip 200 may cause damage to the chip. In this embodiment, the first level is a high level or a low level.

[0046] The preset power threshold is a preset power threshold, which can be set based on actual application scenarios and is not specifically limited in the embodiments of the present application. The preset voltage threshold is a preset voltage threshold, which can be set based on actual application scenarios and is not specifically limited in the embodiments of the present application.

[0047] When the single-ended conversion circuit 300 needs to be activated to output a voltage, the switch element 10 is first closed. The input power source VIN is connected to the activation branch 20 via the switch element 10. The activation branch 20 begins storing energy based on the voltage of the input power source VIN (and the amount of energy stored in the activation branch 20 continues to increase), while simultaneously outputting a first electrical level and a feedback signal. The first electrical level is input to the first switch branch 30, turning it on. The connection between the input power source VIN and the power control chip 200 energizes the power control chip 200 and enables operation. The power control chip 200 then controls the first switch Q1 to alternately turn on and off, causing the single-ended conversion circuit 300 to output the first voltage V1. In this embodiment, the user can control the power control chip 200 to activate the single-ended conversion circuit 300 based on their needs. For example, they can only activate the power control chip 200 when the voltage of the input power source VIN is determined to be relatively stable. This also helps reduce the risk of damage to the power control chip 200.

[0048] After the first voltage V1 is input to the controller 40, the controller 40 is powered. Furthermore, due to the feedback signal from the activation branch 20, the controller 40 outputs a control signal to the second switch branch 50, turning on the second switch branch 50 and outputting the first electrical level to the first switch branch 30 to maintain the first switch branch 30 on. At this point, even if the activation branch 20 stops outputting the first electrical level due to stored electrical energy exceeding a preset electrical energy threshold, the first electrical level output by the second switch branch 50 can still maintain the first switch branch 30 on. Consequently, the power supply control chip 200 remains powered, allowing the single-ended converter circuit 300 to maintain outputting the first voltage V1.

[0049] When the input power VIN fluctuates, causing the sampled voltage output by the voltage sampling branch 60 to exceed a preset voltage threshold, the controller 40, regardless of whether it receives a feedback signal, stops outputting control signals to the second switch branch 50, thereby disconnecting the second switch branch 50 and causing the second switch branch 50 to cease outputting the first voltage level. Furthermore, because the activation branch 20 has already stopped outputting the first voltage level due to the stored energy exceeding the preset energy threshold, the first switch branch 30 is disconnected, disconnecting the input power VIN and the power control chip 200, thereby reducing the risk of damage to the power control chip 200.

[0050] In one embodiment, if Figure 2 As shown, the activation branch 20 includes a first switch module 21, a second switch module 22 and an energy storage element 23. The energy storage element 23 is connected to the switch element 10, the first switch module 21 and the second switch module 22 respectively, and the second switch module 22 is also connected to the controller 40.

[0051] Specifically, the energy storage element 23 is configured to begin storing electrical energy based on the voltage of the input power supply V1 N when the switch element 10 is closed, and the stored electrical energy continues to increase. The first switch module 21 is configured to turn on when the electrical energy stored in the energy storage element 23 is less than or equal to a preset electrical energy threshold, so as to output a first electrical level to the first switch branch 21, and is configured to turn off when the electrical energy stored in the energy storage element 23 is greater than the preset electrical energy threshold, so as to stop outputting the first electrical level. The second switch module 22 is configured to turn on when the switch element 10 is closed, so as to output a feedback signal to the controller 40, and is configured to turn off when the switch element 10 is open, so as to stop outputting the feedback signal.

[0052] When the switch element 10 is closed, the input power supply V1 N is connected to the energy storage element 23 and the second switch module 22 respectively through the switch element 10. On the one hand, the energy storage element 23 starts to store electrical energy based on the voltage of the input power supply V1 N, and the electrical energy stored in the energy storage element 23 gradually increases. Before the electrical energy stored in the energy storage element 23 increases to be greater than the preset electrical energy threshold (that is, the electrical energy stored in the energy storage element 23 is less than or equal to the preset electrical energy threshold), the first switch module 21 remains on and outputs the first electrical level to the first switch branch 21. Until the electrical energy stored in the energy storage element 23 increases to be greater than the preset electrical energy threshold, the first switch module 21 is turned off and stops outputting the first electrical level. On the other hand, the second switch module 22 is turned on in response to being connected to the input power supply V1 N and outputs a feedback signal to the controller 40.

[0053] When the switch element 10 is turned off, the connection between the input power source V1 N and the energy storage element 23 and the second switch module 22 is disconnected. On the one hand, the electric energy stored in the energy storage element 23 stops increasing. On the other hand, the second switch module 22 is turned off and stops outputting the feedback signal.

[0054] In one embodiment, if Figure 3 As shown, the power supply circuit 100 further includes a voltage configuration branch 70. The voltage configuration branch 70 is connected to the input power source V1 N, the first switch branch 30, and the single-ended conversion circuit 300 respectively.

[0055] Specifically, the voltage configuration branch 70 is configured to power the power control chip 200 based on the second voltage V2 when the second voltage is received, and is also configured to stabilize the voltage of the input power supply V1 N to a third voltage, and power the power control chip 200 based on the third voltage when the second voltage V2 is not received, wherein the single-ended conversion circuit 300 also outputs the second voltage when the input power supply V1 N is connected to the power control chip 200.

[0056] When the power control chip 200 is not powered, the first switch branch 30 is turned on by closing the switch element 10. The voltage of the input power source V1 N is then regulated to a third voltage to supply power to the power control chip 200. This powers the power control chip 200 and causes the single-ended converter circuit 300 to output the first voltage V1 and the second voltage V2. The second voltage V2 then powers the power control chip 200 through the voltage configuration branch 70 and the first switch branch 30, maintaining stable operation of the power control chip 200.

[0057] Please refer to Figure 4 , Figure 4 The following is an example of a circuit structure of a power supply circuit of a power control chip. Figure 4As shown, the switch element 10 includes a button K1. When the button K1 is pressed, the corresponding switch element 10 is closed and remains closed; when the button K1 is released (including both the case where the button K1 is not pressed and the case where the pressed button K1 is released), the corresponding switch element 10 is opened.

[0058] In this embodiment, the first switch branch 30 includes a first resistor R1 and a second switch Q2 .

[0059] The first end of the first resistor R1 is connected to the first switch module 21 and the second switch branch 50 in the activation branch 20, respectively. The second end of the first resistor R1 is connected to the first end of the second switch tube Q2. The second end of the second switch tube Q2 is connected to the input power supply V1 N. The third end of the second switch tube Q2 is connected to the power control chip 200. The first resistor R1 is a current-limiting resistor.

[0060] In this embodiment, the second switch tube Q2 is a PNP transistor. The base of the PNP transistor is the first terminal of the second switch tube Q2, the emitter of the PNP transistor is the second terminal of the second switch tube Q2, and the collector of the PNP transistor is the third terminal of the second switch tube Q2.

[0061] In addition, the second switch tube Q2 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate-commutated thyristor (IGCT) device, a gate-turn-off thyristor (GTO) device, a silicon-controlled rectifier (SCR) device, a junction-gate field-effect transistor (JFET) device, a MOS-controlled thyristor (MCT) device, etc.

[0062] In this embodiment, the second switch branch 50 includes a second resistor R2 , a third resistor R3 , a fourth resistor R4 , a first capacitor C1 , a third switch Q3 , and a first optocoupler UA1 .

[0063] Among them, the first end of the second resistor R2 is connected to the controller 40, the second end of the second resistor R2 is respectively connected to the first end of the first capacitor C1, the first end of the third resistor R3 and the first end of the third switch tube Q3, the second end of the first capacitor C1, the second end of the third resistor R3 and the second end of the third switch tube Q3 are all connected to the second ground GND2, the third end of the third switch tube Q3 is connected to the cathode of the light emitting device of the first optocoupler UA1, the anode of the light emitting device of the first optocoupler UA1 is connected to the first voltage V1 through the fourth resistor R4, the first end of the light receiver of the first optocoupler UA1 is connected to the first switch branch 30, and the second end of the light receiver of the first optocoupler UA1 is connected to the first ground GND1.

[0064] Specifically, the second resistor R2 and the third resistor R3 are used for voltage division, the first capacitor C1 is used for filtering, and the fourth resistor R4 is a current limiting resistor.

[0065] In this embodiment, the third switch tube Q3 is an NPN transistor. The base of the NPN transistor is the first terminal of the third switch tube Q3, the emitter of the NPN transistor is the second terminal of the third switch tube Q3, and the collector of the NPN transistor is the third terminal of the third switch tube Q3.

[0066] In addition, the third switch tube Q3 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate-commutated thyristor (IGCT) device, a gate-turn-off thyristor (GTO) device, a silicon-controlled rectifier (SCR) device, a junction-gate field-effect transistor (JFET) device, a MOS-controlled thyristor (MCT) device, etc.

[0067] In this embodiment, the voltage sampling branch 60 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, an operational amplifier UB1, a first diode D1, and a second diode D2.

[0068] The sixth resistor R6 and the fifth resistor R5 are connected in series between the first voltage V1 and the first ground GND1. The connection point between the fifth resistor R5 and the sixth resistor R6 (the first node N1) is connected to the first end of the second capacitor C2 and the first end of the seventh resistor R7, respectively. The second end of the seventh resistor R7 is connected to the inverting input terminal of the operational amplifier UB1, the first end of the fourth capacitor C4, and the first end of the eighth resistor R8, respectively. The tenth resistor R10 and the ninth resistor R9 are connected in series between the first voltage V1 and the input power supply VI. N, a connection point between the ninth resistor R9 and the tenth resistor R10 (which is a second node N2) is respectively connected to the second end of the second capacitor C2 and the first end of the eleventh resistor R11. The second end of the eleventh resistor R11 is respectively connected to the first end of the third capacitor C3, the first end of the twelfth resistor R12, and the non-inverting input terminal of the operational amplifier UB1. The second end of the third capacitor C3 and the second end of the twelfth resistor R12 are both connected to the second ground GND2. The output terminal of the operational amplifier UB1 is respectively connected to the second end of the fourth capacitor C4, the second end of the eighth resistor R8, and the first end of the thirteenth resistor R13. The second end of the thirteenth resistor R13 is respectively connected to the first end of the fifth capacitor C5, the cathode of the first diode D1, the anode of the second diode D2, and the controller 40. The second end of the fifth capacitor C5 and the anode of the first diode D1 are both connected to the second ground GND2, and the cathode of the second diode D2 is connected to the fourth voltage V4.

[0069] Specifically, the voltage sampling branch 60 is a differential operational amplifier branch. It divides the voltage of the input power supply V1N to obtain the voltage at the first node N1 (denoted as VN1) and the voltage at the second node N2 (denoted as VN2). The sampled voltage Vsam is then: Vsam = r8 / r7*(VN2-VN1).

[0070] In this embodiment, the first switch module 21 includes a fourteenth resistor R14 , a fifteenth resistor R15 , and a fourth switch tube Q4 .

[0071] Among them, a first end of the fourteenth resistor R14 is connected to the energy storage element 23, a second end of the fourteenth resistor R14 is respectively connected to the first end of the fifteenth resistor R15 and the first end of the fourth switch tube Q4, a second end of the fifteenth resistor R15 and the second end of the fourth switch tube Q4 are both connected to the second ground GND2, and a third end of the fourth switch tube Q4 is connected to the first switch branch 20.

[0072] Specifically, the fourteenth resistor R14 and the fifteenth resistor R15 are used for voltage division.

[0073] In this embodiment, the fourth switch tube Q4 is an NPN transistor. The base of the NPN transistor is the first terminal of the fourth switch tube Q4, the emitter of the NPN transistor is the second terminal of the fourth switch tube Q4, and the collector of the NPN transistor is the third terminal of the fourth switch tube Q4.

[0074] In addition, the fourth switch tube Q4 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate-commutated thyristor (IGCT) device, a gate-turn-off thyristor (GTO) device, a silicon-controlled rectifier (SCR) device, a junction-gate field-effect transistor (JFET) device, a MOS-controlled thyristor (MCT) device, etc.

[0075] In this embodiment, the second switch module 22 includes a sixteenth resistor R16 , a seventeenth resistor R17 , an eighteenth resistor R18 , a nineteenth resistor R19 and a second optical coupler UA2 .

[0076] Among them, the sixteenth resistor R16 and the seventeenth resistor R17 are connected in series between the switching element 10 and the first ground GND1, the connection point between the sixteenth resistor R16 and the seventeenth resistor R17 is connected to the anode of the light emitting device of the second optocoupler UA2, the cathode of the light emitting device of the second optocoupler UA2 is connected to the first ground GND1, the first end of the light receiver of the second optocoupler UA2 is connected to the first voltage V1 through the eighteenth resistor R18, the second end of the second optocoupler UA2 is connected to the second ground GND2 through the nineteenth resistor R19, and the second end of the second optocoupler UA2 is connected to the controller 40.

[0077] In this embodiment, the energy storage element 23 includes a sixth capacitor C6 , wherein a first end of the sixth capacitor C6 is connected to the button K1 and the sixteenth resistor R16 , respectively, and a second end of the sixth capacitor C6 is connected to a first end of the fourth switch Q4 .

[0078] In this embodiment, the voltage configuration branch 70 includes a twentieth resistor R20 , a twenty-first resistor R21 , a fifth switch Q5 , a Zener diode DW1 , and a third diode D3 .

[0079] The twentieth resistor R20 is connected between the input power source V1 N and the third terminal of the fifth switch Q5. The twenty-first resistor R21 is connected between the input power source V1 N and the first terminal of the fifth switch Q5. The cathode of the Zener diode DW1 is connected to the first terminal of the fifth switch Q5. The cathode of the Zener diode DW1 is connected to the first ground GND1. The second terminal of the fifth switch Q5 is respectively connected to the cathode of the third diode D3 and the first switch branch 20. The anode of the third diode D3 is connected to the single-ended conversion circuit 300.

[0080] In this embodiment, the fifth switch Q5 is an NPN transistor. The base of the NPN transistor is the first terminal of the fifth switch Q5, the emitter of the NPN transistor is the second terminal of the fifth switch Q5, and the collector of the NPN transistor is the third terminal of the fifth switch Q5.

[0081] In addition, the fifth switch tube Q5 can be any controllable switch, such as an insulated gate bipolar transistor (IGBT) device, an integrated gate-commutated thyristor (IGCT) device, a gate-turn-off thyristor (GTO) device, a silicon-controlled rectifier (SCR) device, a junction-gate field-effect transistor (JFET) device, a MOS-controlled thyristor (MCT) device, etc.

[0082] In this embodiment, the power supply circuit 100 further includes a fourth diode D4 and a seventh capacitor C7. The anode of the fourth diode D4 is connected to the second end of the second switch Q2 and the first end of the seventh capacitor C7, respectively. The cathode of the fourth diode D4 is connected to the key K1. The second end of the seventh capacitor C7 is connected to the first ground GND1.

[0083] The following Figure 4 The principle of the circuit structure shown is explained.

[0084] When button K1 is closed, the voltage of the input power supply VIN begins charging the sixth capacitor C6 through the 20th resistor R20, the fifth switch Q5, the fourth diode D4, and the button K1, storing electrical energy in the sixth capacitor C6. Simultaneously, because the voltage difference across the sixth capacitor C6 cannot change suddenly, the left side of the sixth capacitor C6 is instantly pulled high, and the right side of the sixth capacitor C6 is correspondingly pulled high. Therefore, the first end of the fourth switch Q4 is instantly pulled high, turning on the fourth switch Q4. The first end of the second switch Q2 is connected to the second ground GND2 via the first resistor R1 and the fourth switch Q4, corresponding to the first switch module 21 outputting the first voltage level (low in this embodiment) to the first switch branch 30. Subsequently, the voltage of the fifth switch Q5 (the third voltage) is input to the power control chip 200 through the second switch Q2. The power control chip 200 controls the first switch Q1 to alternately turn on and off, causing the single-ended conversion circuit 300 to output the first voltage V1 and the second voltage V2.

[0085] On the other hand, when the button K1 is closed, the voltage of the input power supply VI N passes through the twentieth resistor R20, the fifth switch tube Q5, the fourth diode D4, the button K1, the sixteenth resistor R16 and the light-emitting device of the second optocoupler UA2, so that the light-emitting device of the second optocoupler UA2 is turned on, and the light-receiver of the second optocoupler UA2 is also turned on. The first voltage V1 is input to the controller 40 through the eighteenth resistor R18 and the light-receiver of the second optocoupler UA2, corresponding to the output feedback signal (high level in this embodiment) to the controller 40.

[0086] On the other hand, during the charging process of the sixth capacitor C6, as the charging time increases, the electric energy stored in the sixth capacitor C6 gradually increases, and the voltage difference across the sixth capacitor C6 gradually increases, that is, the voltage on the left side of the sixth capacitor C6 remains unchanged and the voltage on the right side of the sixth capacitor C6 gradually decreases. Before the electric energy stored in the sixth capacitor C6 increases to greater than the preset electric energy threshold, the voltage on the right side of the sixth capacitor C6 can still maintain the fourth switch tube Q4 on. Until the electric energy stored in the sixth capacitor C6 increases to greater than the preset electric energy threshold, the voltage on the right side of the sixth capacitor C6 has decreased to the point where it can no longer maintain the fourth switch tube Q4 on. The fourth switch tube Q4 is then turned off, corresponding to the first switch module 21 ceasing to output the first electrical level to the first switch branch 30.

[0087] It can be understood that in this embodiment, the fifth switch tube Q5 remains turned on to clamp the voltage of the emitter of the second switch tube Q2 based on the reverse breakdown voltage of the Zener diode DW1 and the base-emitter voltage of the fifth switch tube Q5 (that is, the voltage Vbe between the base and the emitter, which is typically 0.6V or 0.7V). That is, the voltage of the emitter of the second switch tube Q2 is the sum of the reverse breakdown voltage of the Zener diode DW1 and the base-emitter voltage of the fifth switch tube Q5, that is, the third voltage.

[0088] After the single-ended conversion circuit 300 outputs the first voltage V1, the first voltage V1 is input to the controller 40, powering the controller 40. Furthermore, due to receiving the feedback signal, the controller 40 can now output a control signal (high in this embodiment). The control signal is input to the base of the third switch Q3 via the second resistor R2, turning on the third switch Q3. The first voltage V1, the fourth resistor R4, the first optocoupler UA1, and the third switch Q3 form a loop, turning on the light emitter of the first optocoupler UA1 and the light receiver of the first optocoupler UA1. The base of the second switch Q2 is connected to the first ground GND1 via the first resistor R1 and the light receiver of the first optocoupler UA1, corresponding to the second switch branch 50 outputting the first electrical level to the first switch branch 30. At this point, even if the fourth switch Q4 is turned off and stops outputting the first electrical level, the first electrical level output by the second switch branch 50 can still maintain the second switch Q2 on. Therefore, the power control chip 200 remains powered, so that the single-ended conversion circuit 300 keeps outputting the first voltage V1.

[0089] After the single-ended converter circuit 300 outputs the second voltage V2, the second voltage V2 acts on the third diode D3 to forward conduct the third diode D3. The second voltage V2 powers the power control chip 200 through the third diode D3 and the second switch Q2.

[0090] In the embodiment of the present application, the first ground GND is a ground connected to the primary side L1 , and the second ground GND2 is a ground connected to the secondary side L2 .

[0091] When the sampled voltage output by the voltage sampling branch 60 exceeds the preset voltage threshold, the controller 40 stops outputting the control signal to the base of the third switch Q3. If the first switch module 21 also stops outputting the first voltage level at this point, the second switch Q2 turns off. This disconnects the power control chip 200 from the input power source V1N, reducing the risk of damage to the power control chip 200.

[0092] Furthermore, when key K1 is released, the connection between the second optocoupler UA2 and the input power supply VIN is disconnected, the light emitter and light receiver of the second optocoupler UA2 are both disconnected, and the second switch module 22 stops outputting the feedback signal. Subsequently, the controller 40, having not received the feedback signal, stops outputting the control signal. The third switch Q3 turns off, the light emitter and light receiver of the first optocoupler UA1 are both disconnected, and the second switch branch 50 stops outputting the first voltage level. If the first switch module 21 has also stopped outputting the first voltage level at this point, the second switch Q2 turns off. This disconnects the power control chip 200 from the input power supply VIN.

[0093] An embodiment of the present application further provides a switching power supply, which includes a single-ended conversion circuit 300, a power control chip 200, and a power supply circuit 100 of the power control chip in any embodiment of the present application.

[0094] The power control chip 200 is connected to the power supply circuit 100 and the single-ended conversion circuit 300 respectively, wherein the single-ended conversion circuit 300 is a forward conversion circuit or a flyback conversion circuit.

[0095] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0096] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Based on the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, and the steps may be implemented in any order. A person skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some of the technical features may be replaced by equivalents. However, such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power supply circuit for a power control chip, characterized in that: The power control chip is used to control the first switch connected to the primary side of the transformer in the single-ended conversion circuit. The power supply circuit includes: an activation branch connected to an input power source, configured to store electric energy based on the voltage of the input power source, output a first electrical level and a feedback signal simultaneously, and configured to stop outputting the first electrical level when the stored electric energy is greater than a preset electric energy threshold; a first switch branch, connected between the input power supply and the power control chip and connected to the activation branch, and configured to be turned on in response to the first electrical level to establish a connection between the input power supply and the power control chip, wherein when the input power supply is connected to the power control chip, the power control chip controls the first switch to be alternately turned on and off so that the single-ended conversion circuit outputs a first voltage; a controller, connected to the activation branch and the single-ended conversion circuit, respectively, and configured to output a control signal based on the feedback signal when the first voltage is input; The second switch branch is connected to the controller and the first switch branch respectively, and is configured to be turned on based on the control signal to output the first electrical level to the first switch branch.

2. The power supply circuit according to claim 1, wherein: The power supply circuit further includes a switching element; The activated branch includes: an energy storage element connected to the switching element and configured to start storing electrical energy based on the voltage of the input power source when the switching element is closed; a first switch module, connected to the energy storage element, configured to be turned on when the electric energy stored in the energy storage element is less than or equal to the preset electric energy threshold, so as to output the first electrical level to the first switch branch, and configured to be turned off when the electric energy stored in the energy storage element is greater than the preset electric energy threshold, so as to stop outputting the first electrical level; The second switch module is connected to the switch element and the controller, and is configured to be turned on when the switch element is closed to output the feedback signal to the controller, and is configured to be turned off when the switch element is opened to stop outputting the feedback signal.

3. The power supply circuit according to claim 1 or 2, characterized in that: The power supply circuit further includes: A voltage configuration branch is respectively connected to the input power supply, the first switch branch and the single-ended conversion circuit, and is configured to power the power control chip based on the second voltage when a second voltage is received, and is also configured to stabilize the voltage of the input power supply to a third voltage, and power the power control chip based on the third voltage when the second voltage is not received, wherein the single-ended conversion circuit also outputs the second voltage when the input power supply is connected to the power control chip.

4. The power supply circuit according to claim 1, wherein: The first switch branch includes a first resistor and a second switch tube; The first end of the first resistor is connected to the activation branch and the second switch branch respectively, the second end of the first resistor is connected to the first end of the second switch tube, the second end of the second switch tube is connected to the input power supply, and the third end of the second switch tube is connected to the power control chip.

5. The power supply circuit according to claim 1, wherein: The second switch branch includes a second resistor, a third resistor, a fourth resistor, a first capacitor, a third switch tube and a first optical coupler; The first end of the second resistor is connected to the controller, the second end of the second resistor is respectively connected to the first end of the first capacitor, the first end of the third resistor and the first end of the third switching tube, the second end of the first capacitor, the second end of the third resistor and the second end of the third switching tube are all connected to the second ground, the third end of the third switching tube is connected to the cathode of the light emitting device of the first optocoupler, the anode of the light emitting device of the first optocoupler is connected to the first voltage through the fourth resistor, the first end of the light receiver of the first optocoupler is connected to the first switch branch, and the second end of the light receiver of the first optocoupler is connected to the first ground.

6. The power supply circuit according to claim 1, wherein: The power supply circuit further includes: a voltage sampling branch, connected to the input power supply and the controller respectively, and configured to output a sampling voltage to the controller based on the voltage of the input power supply, so that the controller stops outputting the control signal when the sampling voltage is greater than a preset voltage threshold; The voltage sampling branch includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, an operational amplifier, a first diode, and a second diode; The sixth resistor and the fifth resistor are connected in series between a first voltage and a first ground. The connection point between the fifth and sixth resistors is connected to the first end of the second capacitor and the first end of the seventh resistor, respectively. The second end of the seventh resistor is connected to the inverting input terminal of the operational amplifier, the first end of the fourth capacitor, and the first end of the eighth resistor, respectively. The tenth and ninth resistors are connected in series between the first voltage and the input power supply. The connection point between the ninth and tenth resistors is connected to the second end of the second capacitor and the first end of the eleventh resistor, respectively. The second end of the eleventh resistor is connected to the first end of the third capacitor, the first end of the twelfth resistor, and the non-inverting input terminal of the operational amplifier, respectively. The second end of the third capacitor and the second end of the twelfth resistor are both connected to the second ground. The output terminal of the operational amplifier is connected to the second end of the fourth capacitor, the second end of the eighth resistor, and the first end of the thirteenth resistor, respectively. The second end of the thirteenth resistor is connected to the first end of the fifth capacitor, the cathode of the first diode, the anode of the second diode, and the controller, respectively. The second end of the fifth capacitor and the anode of the first diode are both connected to the second ground, and the cathode of the second diode is connected to the fourth voltage.

7. The power supply circuit according to claim 2, wherein: The first switch module includes a fourteenth resistor, a fifteenth resistor and a fourth switch tube; The first end of the fourteenth resistor is connected to the energy storage element, the second end of the fourteenth resistor is respectively connected to the first end of the fifteenth resistor and the first end of the fourth switch tube, the second end of the fifteenth resistor and the second end of the fourth switch tube are both connected to the second ground, and the third end of the fourth switch tube is connected to the first switch branch.

8. The power supply circuit according to claim 2, wherein: The second switch module includes a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor and a second optical coupler; The sixteenth resistor and the seventeenth resistor are connected in series between the switching element and the first ground, the connection point between the sixteenth resistor and the seventeenth resistor is connected to the anode of the light emitting device of the second optocoupler, the cathode of the light emitting device of the second optocoupler is connected to the first ground, the first end of the light receiver of the second optocoupler is connected to the first voltage through the eighteenth resistor, the second end of the second optocoupler is connected to the second ground through the nineteenth resistor, and the second end of the second optocoupler is connected to the controller.

9. The power supply circuit according to claim 3, characterized in that: The voltage configuration branch includes a 20th resistor, a 21st resistor, a fifth switch tube, a voltage stabilizing diode and a third diode; The twentieth resistor is connected between the input power supply and the third end of the fifth switching tube, the twenty-first resistor is connected between the input power supply and the first end of the fifth switching tube, the cathode of the voltage regulator diode is connected to the first end of the fifth switching tube, the cathode of the voltage regulator diode is connected to the first ground, the second end of the fifth switching tube is respectively connected to the cathode of the third diode and the first switching branch, and the anode of the third diode is connected to the single-ended conversion circuit.

10. A switching power supply, characterized in that: A power supply circuit comprising a single-ended conversion circuit, a power control chip, and the power control chip according to any one of claims 1 to 9; The power control chip is connected to the power supply circuit and the single-ended conversion circuit respectively, wherein the single-ended conversion circuit is a forward conversion circuit or a flyback conversion circuit.

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