Power supply circuit

Abstract

The embodiment of the utility model discloses a power supply circuit. The power supply circuit comprises a power supply input end; the filter circuit is electrically connected with the power supply input end to form a first connection point; the detection circuit comprises a first end and a second end, and the first end is electrically connected with the power supply input end; the switching circuit comprises a third end, a fourth end and a fifth end, the third end is electrically connected with the first connection point, the fourth end is connected to a load, and the fifth end is electrically connected with the second end; when the detection circuit detects that the voltage at the power supply input end is smaller than the preset voltage, the detection circuit controls the third end and the fourth end of the switching circuit to be connected, so that the filter circuit supplies power to the load, and therefore, a large capacitor does not need to be additionally arranged in a power supply product to prolong the power supply to the load. The material cost is reduced, the internal space of a power supply product is reduced, and the size of the power supply product is reduced.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a power supply circuit. Background Art

[0002] With the continuous development of science and technology, the functions of power products are becoming more and more intelligent, which enables the application of black box testing technology in power products. During the black box testing of power products, the MCU chip in the power product needs to record the operation information and fault information of the power product in an abnormal state. If the MCU chip cannot supply power for a long time, it cannot record the complete data of the power product in an abnormal state.

[0003] At present, the power supply duration of the MCU chip in the power supply product is only a few milliseconds to more than ten milliseconds after power failure, which makes it impossible to meet the requirements of black box testing. Therefore, the traditional improvement method is to add a large energy storage capacitor to the power supply end of the MCU chip to ensure that the MCU can be powered for a long time. However, the above method not only increases the material cost, but also increases the internal space of the power supply product, which leads to a larger size of the power supply product. Utility Model Content

[0004] In view of the deficiencies in the prior art, the present application provides a power supply circuit, aiming to solve the technical problems of large size and high cost of power supply products in the prior art.

[0005] In order to solve the above problems, the present application provides a power supply circuit, which includes:

[0006] Power input terminal;

[0007] A filter circuit electrically connected to the power input terminal to form a first connection point;

[0008] A detection circuit, comprising a first end and a second end, wherein the first end is electrically connected to the power input end;

[0009] A switch circuit, comprising a third terminal, a fourth terminal and a fifth terminal, wherein the third terminal is electrically connected to the first connection point, the fourth terminal is connected to a load, and the fifth terminal is electrically connected to the second terminal;

[0010] When the detection circuit detects that the voltage at the power input terminal is less than a preset voltage, the detection circuit controls the third terminal and the fourth terminal of the switch circuit to be turned on, so that the filter circuit supplies power to the load.

[0011] Further, in the power supply circuit, the power supply circuit further includes an auxiliary transformer;

[0012] Among them, the auxiliary transformer includes a primary winding and an auxiliary winding, the primary winding is electrically connected to the first connection point, the auxiliary winding is connected to the load, and the auxiliary winding and the primary winding are on the same side of the transformer; when the voltage at the power input end is not less than a preset voltage, the voltage generated by the auxiliary winding supplies power to the load.

[0013] Further, in the power supply circuit, the power supply circuit also includes a conversion circuit;

[0014] Wherein, the conversion circuit is arranged between the load and the fourth end, and is electrically connected to the load and the fourth end respectively.

[0015] Furthermore, in the power supply circuit, the conversion circuit includes a buck converter, a first diode, a first inductor and a first capacitor;

[0016] The buck converter is electrically connected to the fourth end, the cathode of the first diode and one end of the first inductor respectively; the other end of the first inductor is electrically connected to one end of the first capacitor and connected to the load; the anode of the first diode and the other end of the first capacitor are grounded.

[0017] Furthermore, in the power supply circuit, the conversion circuit further includes a second capacitor;

[0018] One end of the second capacitor is electrically connected to the fourth end, and the other end of the second capacitor is grounded; the second capacitor is used for filtering the voltage input from the conversion circuit, and / or for supplying power to the load.

[0019] Further, in the power supply circuit, the filter circuit includes a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor;

[0020] Among them, the third capacitor, the fourth capacitor, the fifth capacitor, the sixth capacitor, the seventh capacitor, and the eighth capacitor are connected in parallel to form the first connection point and the second connection point; the first connection point is electrically connected to the power input end and the third end respectively, and the second connection point is grounded.

[0021] Further, in the power supply circuit, the detection circuit includes a comparator;

[0022] The positive input terminal of the comparator is electrically connected to the fourth terminal, the negative input terminal of the comparator is electrically connected to the power input terminal, and the output terminal of the comparator is electrically connected to the fifth terminal.

[0023] Further, in the power supply circuit, the switch circuit includes a first transistor and a second transistor;

[0024] Among them, the base of the first transistor is electrically connected to the second end, the collector of the first transistor is electrically connected to the base of the second transistor, the emitter of the first transistor is grounded, the emitter of the second transistor is electrically connected to the first connection point, and the collector of the second transistor is connected to the load.

[0025] Further, in the power supply circuit, the power supply circuit also includes a surge protection circuit and an EMI suppression circuit;

[0026] Among them, one end of the EMI suppression circuit is electrically connected to the power input end, the other end of the EMI suppression circuit is electrically connected to one end of the surge protection circuit, and the other end of the surge protection circuit is electrically connected to the second connection point.

[0027] Furthermore, in the power supply circuit, the load includes an MCU chip.

[0028] The power supply circuit provided in the present application includes a power input terminal, a filter circuit, a detection circuit and a switch circuit. The filter circuit is electrically connected to the power input terminal to form a first connection point. The first end and the second end of the detection circuit are electrically connected to the power input terminal and the fifth end of the switch circuit respectively. The third end and the fourth end of the switch circuit are electrically connected to the first connection and the load respectively. When the detection circuit detects that the voltage at the power input terminal is less than a preset voltage, the third end and the fourth end of the switch circuit can be controlled to be conductive, so that the filter circuit supplies power to the load, thereby eliminating the need to add additional large capacitors to the power supply product to extend the power supply to the load, thereby achieving full and more reasonable use of internal existing resources to solve technical problems existing in the power supply product, not only reducing material costs, but also reducing the internal space of the power supply product and reducing the volume of the power supply product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A schematic block diagram of a power supply circuit provided in an embodiment of the present application;

[0031] Figure 2 A circuit diagram of the primary side of the auxiliary transformer provided in an embodiment of the present application;

[0032] Figure 3A circuit diagram of a conversion circuit provided in an embodiment of the present application;

[0033] Figure 4 A circuit diagram of a detection circuit provided in an embodiment of the present application;

[0034] Figure 5 A circuit diagram of a switch circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0038] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0039] See also Figure 1 , Figure 1 This is a schematic block diagram of a power supply circuit provided in an embodiment of the present application. Figure 1 As shown, a power supply circuit comprises:

[0040] A power input terminal 110;

[0041] A filter circuit 140, electrically connected to the power input terminal 110 to form a first connection point;

[0042] The detection circuit 180 comprises a first terminal and a second terminal, wherein the first terminal is electrically connected to the power input terminal 110;

[0043] The switch circuit 190 comprises a third terminal, a fourth terminal and a fifth terminal, wherein the third terminal is electrically connected to the first connection point, the fourth terminal is connected to a load, and the fifth terminal is electrically connected to the second terminal;

[0044] When the detection circuit 180 detects that the voltage at the power input terminal 110 is less than a preset voltage, the detection circuit 180 controls the third terminal and the fourth terminal of the switch circuit 190 to be turned on, so that the filter circuit 140 supplies power to the load.

[0045] Specifically, the power input terminal 110 is the power input terminal 110 of the power supply product where the power supply circuit is located, and the filter circuit 140 is the filter circuit 140 that already exists in the power supply product, which includes a large filter capacitor. The filter circuit 140 is not only used to filter the input power supply in this application, but also can be used to continuously supply power to the load when the power supply product has a power supply abnormality. Among them, the load mentioned in this application refers to the internal chip of the power supply product, such as an IC control chip, an MCU (Microcontroller Unit, micro control unit) chip, etc. Preferably, the load can be an MCU chip, and its model can be STM32G474CBT6.

[0046] The detection circuit 180 can be an additional circuit added to the power supply product, or it can be implemented by modifying the circuit that already exists in the power supply product. In order to reduce material costs, the present application prefers to improve the circuit that already exists in the power supply product to obtain the detection circuit 180 of the present application. For example, the detection module that controls the on and off of the relay in the power supply product can be improved to obtain the detection circuit 180 of the present application.

[0047] The switch circuit 190 is in an off state when the power supply product operates normally, and is in an on state when the power supply product operates abnormally. At this time, the filter circuit 140 can continuously power the MCU in the power supply product through the switch circuit 190 to ensure that the MCU can fully record the operation information and fault information of the power supply product. Among them, when the power supply product operates abnormally, the power input terminal 110 is in a power-off state, that is, the preset voltage mentioned in this application can be zero.

[0048] The power supply circuit provided in the present application includes a power input terminal 110, a filter circuit 140, a detection circuit 180 and a switch circuit 190. The filter circuit 140 is electrically connected to the power input terminal 110 to form a first connection point. The first end and the second end of the detection circuit 180 are electrically connected to the power input terminal 110 and the fifth end of the switch circuit 190 respectively. The third end and the fourth end of the switch circuit 190 are electrically connected to the first connection and the load respectively. When the detection circuit 180 detects that the voltage at the power input terminal 110 is less than a preset voltage, the third end and the fourth end of the switch circuit 190 can be controlled to be conductive, so that the filter circuit 140 supplies power to the load, thereby eliminating the need to add additional large capacitors to the power supply product to extend the power supply to the load, thereby achieving full and more reasonable use of internal existing resources to solve technical problems existing in the power supply product, not only reducing material costs, but also reducing the internal space of the power supply product and reducing the volume of the power supply product.

[0049] In some embodiments, Figure 1 and Figure 2 As shown, the power supply circuit also includes an auxiliary transformer 150; wherein, the auxiliary transformer 150 includes a primary winding Wp and an auxiliary winding Wa, the primary winding Wp is electrically connected to the first connection point, the auxiliary winding Wa is connected to the load, and the auxiliary winding Wa and the primary winding Wp are on the same side of the transformer; when the voltage at the power input terminal 110 is not less than a preset voltage, the voltage generated by the auxiliary winding Wa supplies power to the load.

[0050] Specifically, when the power supply product where the power supply circuit is located is in a normal operating state, that is, when the voltage at the power input terminal 110 is not less than the preset voltage, the switch circuit 190 is in an off state, and at this time, the power supply voltage required by the chip inside the power supply product can be obtained after being processed by the auxiliary transformer 150. Among them, the voltage generated by the auxiliary winding Wa in the auxiliary transformer 150 can be used to power the MCU chip inside the power supply product.

[0051] In this embodiment, the auxiliary transformer 150 is used to perform step-up and step-down conversion on the input power supply to generate a corresponding voltage, thereby supplying power to the chip inside the power supply product and the external load. The auxiliary transformer 150 includes a primary winding Wp, a secondary winding (not shown in the figure), an auxiliary winding Wa and a magnetic core T1.

[0052] Among them, one end 1 of the primary winding Wp is electrically connected to the first connection point, that is, this end is electrically connected to the filter circuit 140, and the other end 2 of the primary winding Wp is grounded; the voltage generated by one end 3 of the auxiliary winding Wa is used to power the MCU chip inside the power supply product through diodes D3 and D4, and the other end 4 of the auxiliary winding Wa is grounded. At the same time, a capacitor C13 is connected between the two ends of the auxiliary winding Wa for filtering.

[0053] It can be understood that when the voltage generated on the auxiliary winding Wa is large, the capacitor C13 needs to be a large capacitor. At this time, the capacitor C13 can also be used as a filter circuit 140 in the power supply circuit to continuously power the MCU chip inside the power supply product when the power input terminal 110 is powered off. At this time, the power supply does not require an additional switching circuit 190 to be added to the power supply product, and there is no need to improve the detection circuit 180 in the power supply product.

[0054] At the same time, capacitor C13 can also cooperate with the filter circuit 140 to continuously supply power to the MCU chip inside the power supply product. That is, when the power input terminal 110 is powered off, capacitor C13 first continuously supplies power to the MCU chip. At this time, the detection circuit 180 delays the closing of the switch circuit 190, and when capacitor C13 cannot continuously supply power to the MCU chip, the detection circuit 180 controls the switch circuit 190 to close, and then the filter circuit 140 is used to power the MCU.

[0055] In addition, when the power input terminal 110 is powered off, while using capacitor C13 to continuously power the MCU chip inside the power product, the detection circuit 180 can close the switch circuit 190 without delay, that is, immediately control the conduction between other large energy storage capacitors in the filter circuit 140 and other loads after the switch circuit 190, so that other large energy storage capacitors in the filter circuit 140 can continuously supply power to other loads after the switch circuit 190. When capacitor C13 cannot continuously power the MCU chip and other large energy storage capacitors in the filter circuit 140 cannot continuously power other loads after the switch circuit 190, the detection circuit 180 can control the conduction between other large energy storage capacitors in the filter circuit 140 and the MCU chip, thereby controlling other large energy storage capacitors in the filter circuit 140 to continuously supply power to the MCU chip.

[0056] It should also be noted that the present application can not only use capacitor C13 to power the MCU chip, but also use a large filter capacitor set at the secondary winding to continuously power the MCU chip in the case of power failure. At the same time, a pulse width modulation circuit can be set on one side of the primary winding Wp, and a synchronous rectification circuit can be set on one side of the secondary winding, which can be designed according to actual applications, and this application does not make specific limitations.

[0057] In some embodiments, Figure 1 and Figure 3 As shown, the power supply circuit further includes a conversion circuit 160; wherein the conversion circuit 160 is disposed between the load and the fourth end, and is electrically connected to the load and the fourth end respectively.

[0058] In this embodiment, the load is preferably an MCU chip inside the power supply product. Usually, the power supply voltage required by the MCU chip is 3.3V, and the voltage generated by the auxiliary winding Wa of the auxiliary transformer 150 and the voltage generated by the filter circuit 140 are not necessarily 3.3V. They may be higher than 3.3V or lower than 3.3V. In this case, a conversion circuit 160 needs to be set in the power supply circuit to convert the voltage generated by the auxiliary winding Wa and the voltage generated by the filter circuit 140 to realize power supply for the MCU chip.

[0059] Among them, the conversion circuit 160 can be a circuit that already exists inside the power supply product, or it can be a circuit that is an improvement on the conversion circuit 160 inside the power supply product. That is, the design of the conversion circuit 160 in the power supply circuit mentioned in this application can be selected according to actual applications, and this application does not make any specific limitations.

[0060] Further, in Figure 3 In the specific embodiment shown, the conversion circuit 160 includes a buck converter U1, a first diode D5, a first inductor L1 and a first capacitor C18; wherein the buck converter U1 is electrically connected to the fourth end of the switch circuit 190, the cathode of the first diode D5 and one end of the first inductor L1 respectively; the other end of the first inductor L1 is electrically connected to one end of the first capacitor C18 and connected to the load; the anode of the first diode D5 and the other end of the first capacitor C18 are grounded.

[0061] Specifically, the conversion circuit 160 can be a Buck circuit, and the buck converter U1 includes pins BST, GND, FB, LX, VIN, and EN. A capacitor C14 is provided between pins BST and LX; one end of the first inductor L1 is electrically connected to the cathode of the first diode D5 and is also electrically connected to pin LX; the other end of the first inductor L1 is electrically connected to pin BST through diode D6, and the other end of the first inductor L1 is also electrically connected to the power supply pin P_3.3VCC of the MCU chip through diode D7; pin GND is grounded, and an RC circuit is provided between the power supply pin P_3.3VCC of the MCU chip and pin FB, and the RC circuit includes capacitor C19, resistor R11, and resistor R12, and the power supply pin P_3.3VCC of the MCU chip is connected to the ground. One end of the capacitor C19, the resistor R11 and the resistor R12 connected in parallel is electrically connected to the pin FB, and one end of the capacitor C19, the resistor R11 and the resistor R12 connected in parallel is grounded through the resistor R13 and the resistor R14, and the other end of the capacitor C19, the resistor R11 and the resistor R12 connected in parallel is electrically connected to the power supply pin P_3.3VCC, and the pin FB is grounded through the capacitor C15; the pin VIN is electrically connected to the first connection, the pin EN is electrically connected to the first connection point through the resistor R10, and the pin EN is grounded through an RC circuit, and the RC circuit includes a capacitor C16 and a resistor R9 connected in parallel. In addition, the power supply pin P_3.3VCC of the MCU chip is also grounded through the parallel Zener diode ZD1, the capacitor C20 and the capacitor C21.

[0062] Furthermore, in Figure 3 In the specific embodiment shown, the conversion circuit 160 also includes a second capacitor C17; wherein one end of the second capacitor C17 is electrically connected to the fourth end, and the other end of the second capacitor C17 is grounded; the second capacitor C17 is used to filter the voltage input at the conversion circuit 160, and / or to power the load.

[0063] In this embodiment, the second capacitor C17 can be a large filtering capacitor, which can not only filter the voltage at the pin VIN, but also when the power supply product is operating abnormally, that is, when the power input terminal 110 is powered off, the second capacitor C17 can supply power to the MCU chip through the conversion circuit 160. The second capacitor C17 is similar to the capacitor C13 mentioned in the above embodiment, and it can be set with reference to the capacitor C13, which is not specifically described in this embodiment.

[0064] In some embodiments, Figure 2As shown, the filtering circuit 140 includes a third capacitor C7, a fourth capacitor C8, a fifth capacitor C9, a sixth capacitor C10, a seventh capacitor C11 and an eighth capacitor C12; wherein the third capacitor C7, the fourth capacitor C8, the fifth capacitor C9, the sixth capacitor C10, the seventh capacitor C11 and the eighth capacitor C12 are connected in parallel to form a first connection point and a second connection point; the first connection point is electrically connected to the power input terminal 110 and the third terminal respectively, and the second connection point is grounded.

[0065] In this embodiment, the third capacitor C7, the fourth capacitor C8, the fifth capacitor C9, the sixth capacitor C10, the seventh capacitor C11 and the eighth capacitor C12 are arranged between the primary winding Wp of the auxiliary transformer 150 and the power input terminal 110, and the power input terminal 110 includes a terminal VIN+ and a terminal VIN-. At the same time, the filtering circuit 140 also includes a resistor R7 and a resistor R8, and one end of the resistor R7 and the resistor R8 after being connected in parallel is electrically connected to the terminal VIN-, and the other end of the resistor R7 and the resistor R8 after being connected in parallel is grounded.

[0066] In some embodiments, Figure 4 As shown, the detection circuit 180 includes a comparator U2; wherein the positive input terminal of the comparator U2 is electrically connected to the fourth terminal, the negative input terminal of the comparator U2 is electrically connected to the power input terminal 110, and the output terminal of the comparator U2 is electrically connected to the fifth terminal.

[0067] In this embodiment, the detection circuit 180 is a detection circuit 180 inside the power supply product, which is mainly used to control the on and off of the relay in the surge protection circuit 130 at the power input terminal 110. This application only needs to add an additional switch circuit 190 to the power supply product, and at the same time, the output end of the comparator U2 in the detection circuit 180 is electrically connected to the control end of the switch circuit 190, that is, the fifth end, so that the filter circuit 140 in the power supply product can be used to continuously power the MCU in the case of power failure. Among them, the time for the filter circuit 140 to continuously power the MCU can be determined according to the capacitance in the filter circuit 140, and this application does not make specific restrictions.

[0068] Continue reading Figure 4The comparator U2 also includes a first power supply terminal and a second power supply terminal. The first power supply terminal can be powered from the power supply input terminal 110, specifically, powered from the surge protection circuit 130 through the wiring terminal P_PVCC. At the same time, the first power supply terminal is connected to the analog ground AGND through the capacitor C24, and the second power supply terminal is grounded; the positive input terminal of the comparator U2 is connected to the reference voltage from the power supply pin P_3.3VCC of the MCU chip through the resistor R17, and the positive input terminal is grounded through the resistor R15 and the capacitor C23. In addition, the positive input terminal of the comparator U2 is electrically connected to the output terminal of the comparator U2 through the diode D9 and the resistor R19; the negative input terminal of the comparator U2 is electrically connected to the power supply input terminal 110 through the resistor R16, and the negative input terminal of the comparator U2 is also grounded through the parallel capacitor C22 and the resistor R18. In addition, the negative input terminal of the comparator U2 is connected to the analog ground AGND through the diode D8 and the capacitor C24.

[0069] In some embodiments, Figure 5 As shown, the switching circuit 190 includes a first transistor Q2 and a second transistor Q3; wherein, the base of the first transistor Q2 is electrically connected to the second end, the collector of the first transistor Q2 is electrically connected to the base of the second transistor Q3, the emitter of the first transistor Q2 is grounded, the emitter of the second transistor Q3 is electrically connected to the first connection point, and the collector of the second transistor Q3 is connected to the load.

[0070] Specifically, the first transistor Q2 may be an NPN transistor, the second transistor Q3 may be a PNP transistor, the terminal DC+ may be used as the third end of the switch circuit 190, the terminal DC+ is electrically connected to the emitter of the second transistor Q3 through a diode D10 and a resistor R20, and the terminal DC+ is electrically connected to the base of the second transistor Q3 through a diode D10 and a resistor R21, and the collector of the second transistor Q3 may be used as the fourth end of the switch circuit 190; the terminal UUVP_1 may be As the fifth end of the switch circuit 190, the terminal UUVP_1 can be electrically connected to the terminal VIN+ in the power input terminal 110. The terminal UUVP_1 is electrically connected to the base of the first transistor Q2 through a diode D12 and a resistor R24. The base of the first transistor Q2 is grounded through an RC circuit. The RC circuit includes a capacitor C25 and a resistor R25 connected in parallel. The emitter of the first transistor Q2 is grounded, and the collector of the first transistor Q2 is electrically connected to the base of the second transistor Q3 through a resistor R22. In addition, the base of the first transistor Q2 is also electrically connected to the pin C_PVCC-1 of the MCU chip, and a diode D11 and a resistor R23 are provided between the base of the first transistor Q2 and the pin C_PVCC-1 of the MCU chip.

[0071] In this embodiment, when the detection circuit 180 detects that the power input terminal 110 is powered off, the output terminal of the comparator U2 in the detection circuit 180 outputs a high voltage to the base of the first transistor Q2, and the first transistor Q2 is turned on. At this time, the base of the second transistor Q3 is pulled down to ground, and the second transistor Q3 is turned on. The circuit generated by the filter circuit 140 is input into the conversion circuit 160 through the second transistor Q3, and is stepped down by the conversion circuit 160 to obtain a 3.3V voltage, and continuously powers the MCU chip.

[0072] In some embodiments, Figure 1 and Figure 2 As shown, the power supply circuit also includes an anti-surge circuit 130 and an EMI suppression circuit 120; wherein, one end of the EMI suppression circuit 120 is electrically connected to the power input terminal 110, the other end of the EMI suppression circuit 120 is electrically connected to one end of the anti-surge circuit 130, and the other end of the anti-surge circuit 130 is electrically connected to the second connection point.

[0073] In this embodiment, the EMI suppression circuit 120 includes a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a common-mode inductor LF1, and a common-mode inductor LF2, wherein one end of the capacitor C1 and the capacitor C2 connected in series is electrically connected to the terminal VIN+, and the other end of the capacitor C1 and the capacitor C2 connected in series is electrically connected to the terminal VIN- through a fuse F101, and the capacitor C1 and the capacitor C2 are connected in series to form a connection point, which is connected to the safety ground CHGND; the common-mode inductor LF1 includes a sixth end, a seventh end, an eighth end, and a ninth end, and the common-mode inductor LF2 includes a tenth end. The sixth end is electrically connected to the terminal VIN+, the seventh end is electrically connected to the terminal VIN- through the fuse F101, the eighth end is electrically connected to the tenth end, the ninth end is electrically connected to the eleventh end, and the twelfth end and the thirteenth end are electrically connected to the surge protection circuit 130 respectively; one end of the capacitor C3 and the capacitor C4 connected in series is electrically connected to the eighth end and the tenth end respectively, and the other end of the capacitor C3 and the capacitor C4 connected in series is electrically connected to the ninth end and the eleventh end respectively, and the capacitor C3 and the capacitor C4 are connected in series to form a connection point, which is connected to the safety ground CHGND. In addition, one end of the fuse is electrically connected to the terminal VIN-, and the other end of the fuse is electrically connected to the terminal VIN+ through the thermistor RT1.

[0074] The surge protection circuit 130 includes a relay RLY1, a thermistor THR1 and a transistor Q1. The relay RLY1 includes a pin 1, a pin 2, a pin 3 and a pin 4. The pin 1 is electrically connected to the twelfth terminal. The thermistor THR1 is arranged between the pin 1 and the pin 2. A diode D1 is also arranged between the pin 1 and the thermistor THR1. The pin 3 is electrically connected to the collector of the transistor Q1 through a resistor R1, a resistor R2 and a resistor R3 connected in parallel. At the same time, the pin 3 is electrically connected to the terminal P_PVCC through a diode D2. The pin 4 is grounded through a capacitor C5. At the same time, the pin 4 is also electrically connected to the terminal P_PVCC. The base of the transistor Q1 is electrically connected to the terminal T_DRV through resistors R4 and R5. The emitter of the transistor Q1 is grounded. At the same time, an RC circuit is arranged between the emitter and the base of the transistor Q1. The RC circuit includes a resistor R6 and a capacitor C6 connected in parallel.

[0075] Furthermore, if Figure 4 As shown, the switching circuit 190 also includes a transistor Q4, the output end of the comparator U2 is electrically connected to the base of the transistor Q4 through a resistor R26, the collector of the transistor Q4 is electrically connected to the terminal T_DRV, the collector and emitter of the transistor Q4 are grounded, and an RC circuit is arranged between the emitter and the base of the transistor Q4, and the RC circuit includes a resistor R27 and a capacitor C26 connected in parallel.

[0076] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A power supply circuit, characterized in that: include: Power input terminal; A filter circuit electrically connected to the power input terminal to form a first connection point; A detection circuit, comprising a first end and a second end, wherein the first end is electrically connected to the power input end; A switch circuit, comprising a third terminal, a fourth terminal and a fifth terminal, wherein the third terminal is electrically connected to the first connection point, the fourth terminal is connected to a load, and the fifth terminal is electrically connected to the second terminal; When the detection circuit detects that the voltage at the power input terminal is less than a preset voltage, the detection circuit controls the third terminal and the fourth terminal of the switch circuit to be turned on, so that the filter circuit supplies power to the load.

2. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes an auxiliary transformer; Among them, the auxiliary transformer includes a primary winding and an auxiliary winding, the primary winding is electrically connected to the first connection point, the auxiliary winding is connected to the load, and the auxiliary winding and the primary winding are on the same side of the transformer; when the voltage at the power input end is not less than a preset voltage, the voltage generated by the auxiliary winding supplies power to the load.

3. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes a conversion circuit; Wherein, the conversion circuit is arranged between the load and the fourth end, and is electrically connected to the load and the fourth end respectively.

4. The power supply circuit according to claim 3, characterized in that: The conversion circuit includes a buck converter, a first diode, a first inductor and a first capacitor; The buck converter is electrically connected to the fourth end, the cathode of the first diode and one end of the first inductor respectively; the other end of the first inductor is electrically connected to one end of the first capacitor and connected to the load; the anode of the first diode and the other end of the first capacitor are grounded.

5. The power supply circuit according to claim 3, characterized in that: The conversion circuit also includes a second capacitor; One end of the second capacitor is electrically connected to the fourth end, and the other end of the second capacitor is grounded; the second capacitor is used for filtering the voltage input from the conversion circuit, and / or for supplying power to the load.

6. The power supply circuit according to claim 1, characterized in that: The filtering circuit includes a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor; Among them, the third capacitor, the fourth capacitor, the fifth capacitor, the sixth capacitor, the seventh capacitor, and the eighth capacitor are connected in parallel to form the first connection point and the second connection point; the first connection point is electrically connected to the power input end and the third end respectively, and the second connection point is grounded.

7. The power supply circuit according to claim 1, characterized in that: The detection circuit includes a comparator; The positive input terminal of the comparator is electrically connected to the fourth terminal, the negative input terminal of the comparator is electrically connected to the power input terminal, and the output terminal of the comparator is electrically connected to the fifth terminal.

8. The power supply circuit according to claim 1, characterized in that: The switch circuit comprises a first triode and a second triode; Among them, the base of the first transistor is electrically connected to the second end, the collector of the first transistor is electrically connected to the base of the second transistor, the emitter of the first transistor is grounded, the emitter of the second transistor is electrically connected to the first connection point, and the collector of the second transistor is connected to the load.

9. The power supply circuit according to any one of claims 1 to 8, characterized in that: The power supply circuit also includes a surge protection circuit and an EMI suppression circuit; Among them, one end of the EMI suppression circuit is electrically connected to the power input end, the other end of the EMI suppression circuit is electrically connected to one end of the surge protection circuit, and the other end of the surge protection circuit is electrically connected to the second connection point.

10. The power supply circuit according to any one of claims 1 to 8, characterized in that: The load includes an MCU chip.

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