Switching power supply device

Abstract

The utility model relates to a switching power supply device. The switching power supply device comprises a conversion circuit, wherein the first end of the conversion circuit is connected with the input end of the device; the first end of the control circuit is connected with the second end of the conversion circuit; the first end of the feedback circuit is connected with the third end of the conversion circuit, the second end of the feedback circuit is connected with the second end of the control circuit, and the third end of the feedback circuit is connected with the output end of the device; and when the conversion circuit is in a no-load state, the feedback circuit is switched off in response to a second level signal output by the conversion circuit, so that the control circuit stops running.

Description

Technical Field

[0001] This utility model relates to the technical field of charging power supplies, and more specifically, to a switching power supply device. Background Technology

[0002] With the rapid development of charging power supplies, they can provide relatively stable power to devices or batteries. To charge devices or batteries, existing charging power supplies can be connected to the power grid and can continuously charge them. However, existing charging power supplies experience significant no-load losses under idle conditions. Utility Model Content

[0003] One objective of this invention is to provide a switching power supply device.

[0004] According to one aspect of the present invention, a switching power supply device is provided, the device comprising:

[0005] A conversion circuit, wherein the first terminal of the conversion circuit is connected to the input terminal of the device;

[0006] A control circuit, wherein a first terminal of the control circuit is connected to a second terminal of the conversion circuit;

[0007] A feedback circuit, wherein the first terminal of the feedback circuit is connected to the third terminal of the conversion circuit, the second terminal of the feedback circuit is connected to the second terminal of the control circuit, and the third terminal of the feedback circuit is connected to the output terminal of the device;

[0008] When the conversion circuit is in an unloaded state, the feedback circuit responds to the second level signal output by the conversion circuit and disconnects, causing the control circuit to stop operating.

[0009] Optionally, when the conversion circuit is under load, the feedback circuit responds to the first level signal output by the conversion circuit and is turned on, causing the control circuit to operate.

[0010] Optionally, the conversion circuit includes a primary conversion circuit, a transformer, and a secondary conversion circuit. The first terminal of the primary conversion circuit serves as the first terminal of the conversion circuit, the second terminal of the primary conversion circuit is connected to the first terminal of the first primary winding of the transformer, and the third terminal of the primary conversion circuit serves as the second terminal of the conversion circuit.

[0011] The second end of the first primary winding of the transformer is connected to the third end of the control circuit;

[0012] The secondary winding of the transformer is connected to the first terminal of the secondary conversion circuit, and the second terminal of the secondary conversion circuit serves as the third terminal of the conversion circuit.

[0013] Optionally, the primary conversion circuit includes a rectifier, a first inductor, a first resistor, a first electrolytic capacitor, a second electrolytic capacitor, and a primary-side capacitor;

[0014] Wherein, the first end of the rectifier is connected to the first end of the first inductor, the second end of the first inductor is connected to the first end of the first primary winding of the transformer, the first resistor is connected across the first inductor, the first electrolytic capacitor is connected across the first end of the first inductor and the grounding terminal of the device, the second electrolytic capacitor is connected across the second end of the first inductor and the grounding terminal of the device, and the primary winding capacitor is connected across the first primary winding of the transformer.

[0015] Optionally, the secondary conversion circuit includes a third chip, a ninth capacitor, a twelfth resistor, a fourth electrolytic capacitor, a fourteenth resistor, and a seventh capacitor;

[0016] Specifically, the connection point between the third chip and the first end of the ninth capacitor is connected to the second end of the secondary coil of the transformer; the second end of the ninth capacitor is connected to the first end of the twelfth resistor; the connection point between the second end of the twelfth resistor and the third chip is connected to the ground terminal of the device; the connection point between the first end of the fourth electrolytic capacitor and the first end of the fourteenth resistor is connected to the ground terminal of the device; the connection point between the second end of the fourth electrolytic capacitor and the second end of the fourteenth resistor is connected to the first end of the secondary coil of the transformer; the third chip is also connected to the first end of the seventh capacitor; and the second end of the seventh capacitor is connected to the ground terminal of the device.

[0017] Optionally, the feedback circuit includes a detection circuit and a switching circuit, wherein a first terminal of the detection circuit serves as a first terminal of the feedback circuit, a second terminal of the detection circuit serves as a third terminal of the feedback circuit, the third terminal of the detection circuit is connected to the first terminal of the switching circuit, and the second terminal of the switching circuit serves as a second terminal of the feedback circuit.

[0018] Optionally, the detection circuit includes a fifth chip, a thirteenth resistor, a fifteenth resistor, a thirty-first resistor, a thirty-first capacitor, a first optocoupler, a fifth capacitor, an eleventh resistor, a tenth resistor, and a second diode;

[0019] The fifth chip is connected to the output terminal of the device. The connection point between the fifth chip and the first end of the thirteenth resistor is connected to the second terminal of the detection circuit. The second end of the thirteenth resistor is connected to the first end of the fifteenth resistor. The second end of the fifteenth resistor is connected to the first end of the thirty-first resistor. The second end of the thirty-first resistor is connected to the first end of the thirty-first capacitor. The connection point between the thirty-first capacitor and the fifth chip is connected to the switching circuit. The fifth chip is also connected to the switching circuit. The light-emitting diode of the first optocoupler is connected across the fifteenth resistor. The phototransistor of the first optocoupler is connected across the fifth capacitor. The first terminal of the fifth capacitor is connected to the control circuit. The connection point between the second terminal of the fifth capacitor and the first end of the eleventh resistor is connected to the ground terminal of the device. The connection point between the second terminal of the eleventh resistor and the first end of the tenth resistor is connected to the control circuit. The connection point between the second terminal of the tenth resistor and the anode of the second diode is connected to the first terminal of the second primary winding of the transformer. The second terminal of the second primary winding is connected to the ground terminal of the device. The cathode of the second diode is connected to the control circuit.

[0020] Optionally, the switching circuit includes a sixty-second resistor, a sixty-sixth resistor, a sixty-seventh resistor, a first MOSFET, a second optocoupler, a sixty-third resistor, a thirty-third capacitor, a first Zener diode, a fifth transistor, a thirteenth diode, a sixty-fifth resistor, and a thirtieth capacitor;

[0021] In this circuit, the first terminal of the sixty-second resistor is connected to the fifth chip, the second terminal of the sixty-second resistor is connected to the anode of the light-emitting diode of the second optocoupler, the first terminal of the sixty-sixth resistor is connected to the cathode of the light-emitting diode of the second optocoupler, the connection point of the second terminal of the sixty-sixth resistor and the drain of the first MOS transistor is connected to the ground terminal of the device, the connection point of the first terminal of the sixty-seventh resistor and the gate of the first MOS transistor is connected to the fifth chip, the second terminal of the sixty-seventh resistor is connected to the source of the first MOS transistor, and the connection point of the collector of the phototransistor of the second optocoupler and the collector of the thirteenth diode is connected to the control circuit. The emitter of the phototransistor of the second optocoupler is connected to the first end of the sixty-third resistor. The connection point between the second end of the sixty-third resistor and the first end of the sixty-fifth resistor is connected to the base of the thirteenth diode. The first Zener diode is connected across the sixty-fifth resistor. The second end of the sixty-fifth resistor is connected to the first end of the thirty-third capacitor. The second end of the thirty-third capacitor is connected to the collector of the phototransistor of the second optocoupler. The connection point between the cathode of the thirteenth diode and the first end of the thirtieth capacitor is connected to the control circuit. The connection point between the second end of the thirtieth capacitor and the second end of the sixty-fifth resistor is connected to the ground terminal of the device.

[0022] Optionally, the control circuit includes a first chip, a fourth capacitor, a seventy-first capacitor, a seventy-second capacitor, a second resistor, a third resistor, a seventy-third capacitor, a temperature control switch, a sixth resistor, and a seventh resistor;

[0023] In this configuration, the first chip is connected to the second end of the first primary winding of the transformer; the first end of the third resistor is connected to the first chip and then to the first end of the seventy-third capacitor; the second end of the seventy-third capacitor is connected to the second end of the first primary winding of the transformer; the second end of the third resistor is connected to the ground terminal of the device; the second resistor is connected across the third resistor; the seventy-first and seventy-second capacitors are connected in series; the other end of the seventy-first capacitor is connected to the first chip; the connection point between the other end of the seventy-second capacitor and the ground terminal of the device is connected to the first chip; the fourth capacitor is connected across the seventy-first and seventy-second capacitors; the first end of the sixth resistor is connected to the access terminal of the device; the second end of the sixth resistor is connected to the first end of the seventh resistor; the second end of the seventh resistor is connected to the first end of the temperature control switch; and the second end of the temperature control switch is connected to the first chip.

[0024] Optionally, a fuse is provided between the first terminal of the conversion circuit and the input terminal of the device.

[0025] One technical advantage of this invention is that the switching power supply device provided by this invention can send a second-level signal to the feedback circuit when the switching circuit is not connected to a load device, thereby disconnecting the feedback circuit. Consequently, the feedback circuit will not continue to supply power to the control circuit, thus disconnecting the control circuit. This reduces the no-load loss of the switching power supply device and effectively improves the energy utilization efficiency of the switching power supply device.

[0026] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings, which form part of this specification, illustrate embodiments of the present invention and, together with the specification, serve to explain the principles of the present invention.

[0028] Figure 1 This is a circuit diagram of a switching power supply device according to an embodiment of this application. Detailed Implementation

[0029] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0030] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0031] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0032] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0034] A switching power supply device provided according to an embodiment of this application, such as... Figure 1 As shown, the device includes a conversion circuit, a control circuit, and a feedback circuit.

[0035] The first terminal of the conversion circuit is connected to the input terminal of the device;

[0036] The first terminal of the control circuit is connected to the second terminal of the conversion circuit;

[0037] The first terminal of the feedback circuit is connected to the third terminal of the conversion circuit, the second terminal of the feedback circuit is connected to the second terminal of the control circuit, and the third terminal of the feedback circuit is connected to the output terminal of the device.

[0038] When the conversion circuit is in an unloaded state, the feedback circuit responds to the second level signal output by the conversion circuit and disconnects, causing the control circuit to stop running.

[0039] In this embodiment, when the conversion circuit is not connected to the load device, the conversion circuit feeds back a second level signal to the feedback circuit, causing the feedback circuit to disconnect. Consequently, the feedback circuit stops supplying power to the control circuit, causing the control circuit to disconnect. This allows the conversion circuit to be in an unloaded state, reducing the no-load loss of the switching power supply device and effectively improving the energy utilization efficiency of the switching power supply device.

[0040] In some embodiments, in order to enable the load device to be charged when the feedback circuit is connected to the load device, the feedback circuit is turned on in response to the first level signal output by the conversion circuit when the conversion circuit is under load, so that the control circuit operates.

[0041] In some embodiments, in order to output the required electrical energy to the load device, the conversion circuit includes a primary conversion circuit, a transformer T1 and a secondary conversion circuit. The first terminal of the primary conversion circuit is used as the first terminal of the conversion circuit, the second terminal of the primary conversion circuit is connected to the first terminal of the first primary winding of the transformer T1, and the third terminal of the primary conversion circuit is used as the second terminal of the conversion circuit.

[0042] The second terminal of the first primary winding of transformer T1 is connected to the third terminal of the control circuit;

[0043] The secondary winding of transformer T1 is connected to the first terminal of the secondary conversion circuit, and the second terminal of the secondary conversion circuit serves as the third terminal of the conversion circuit.

[0044] In some embodiments, such as Figure 1 As shown, the primary conversion circuit includes a rectifier BD1, a first inductor L1, a first resistor R1, a first electrolytic capacitor EC1, a second electrolytic capacitor EC2, and a primary-side capacitor CC / NC;

[0045] In this circuit, the first terminal of rectifier BD1 is connected to the first terminal of the first inductor L1, the second terminal of the first inductor L1 is connected to the first terminal of the first primary winding of transformer T1, the first resistor R1 is connected across the first inductor L1, the first electrolytic capacitor EC1 is connected across the first terminal of the first inductor L1 and the ground terminal of the device, the second electrolytic capacitor EC2 is connected across the second terminal of the first inductor L1 and the ground terminal of the device, and the primary capacitor CC / NC is connected across the first primary winding of transformer T1.

[0046] In this embodiment, the rectifier BD1 is a bridge rectifier, which can convert the AC power input from the positive (L) and negative (N) terminals of the device into DC power. After passing through the π-type filter composed of the first electrolytic capacitor EC1, the second electrolytic capacitor EC2 and the first inductor L1, the filtered DC power is output to the first primary coil of the transformer T1.

[0047] In some embodiments, in order to output the required DC power to the feedback circuit to provide power to the load device, the secondary conversion circuit includes a third chip U3, a ninth capacitor C9, a twelfth resistor R12, a fourth electrolytic capacitor EC4, a fourteenth resistor R14, and a seventh capacitor C7.

[0048] Specifically, the connection point between the third chip U3 and the first end of the ninth capacitor C9 is connected to the second end of the secondary coil of the transformer T1; the second end of the ninth capacitor C9 is connected to the first end of the twelfth resistor R12; the connection point between the second end of the twelfth resistor R12 and the third chip U3 is connected to the ground terminal of the device; the connection point between the first end of the fourth electrolytic capacitor EC4 and the first end of the fourteenth resistor R14 is connected to the ground terminal of the device; the connection point between the second end of the fourth electrolytic capacitor EC4 and the second end of the fourteenth resistor R14 is connected to the first end of the secondary coil of the transformer T1; the third chip U3 is also connected to the first end of the seventh capacitor C7; and the second end of the seventh capacitor C7 is connected to the ground terminal of the device.

[0049] By setting the third chip U3, the ninth capacitor C9 and the twelfth resistor R12, secondary rectification can be achieved, and the fourth electrolytic capacitor EC4 is used for filtering, so that the required DC power is output to pin 1 and pin 9 of the fifth chip U5.

[0050] In some embodiments, in order to control the operation of the control circuit, the feedback circuit includes a detection circuit and a switching circuit. The first terminal of the detection circuit serves as the first terminal of the feedback circuit, the second terminal of the detection circuit serves as the third terminal of the feedback circuit, the third terminal of the detection circuit is connected to the first terminal of the switching circuit, and the second terminal of the switching circuit serves as the second terminal of the feedback circuit.

[0051] In some embodiments, in order to power the control circuit, the detection circuit includes a fifth chip U5, a thirteenth resistor R13, a fifteenth resistor R15, a thirty-first resistor R31, a thirty-first capacitor C31, a first optocoupler U2, a fifth capacitor C5, an eleventh resistor R11, a tenth resistor R10, and a second diode D2.

[0052] Among them, the fifth chip U5 is connected to the output terminal of the device; the connection point between the fifth chip U5 and the first end of the thirteenth resistor R13 is connected to the second terminal of the detection circuit; the second end of the thirteenth resistor R13 is connected to the first end of the fifteenth resistor R15; the second end of the fifteenth resistor R15 is connected to the first end of the thirty-first resistor R31; the second end of the thirty-first resistor R31 is connected to the first end of the thirty-first capacitor C31; the connection point between the thirty-first capacitor C31 and the fifth chip U5 is connected to the switching circuit; the fifth chip U5 is also connected to the switching circuit; the light-emitting diode of the first optocoupler U2 is connected across the fifteenth resistor R15; and the photosensitive transistor of the first optocoupler U2... The tube is connected across the fifth capacitor C5. The first end of the fifth capacitor C5 is connected to the first chip U1 (COMP) of the control circuit. The connection point between the second end of the fifth capacitor C5 and the first end of the eleventh resistor R11 is connected to the ground terminal of the device. The connection point between the second end of the eleventh resistor R11 and the first end of the tenth resistor R10 is connected to the first chip U1 (FB) of the control circuit. The connection point between the second end of the tenth resistor R10 and the anode of the second diode D2 is connected to the first end of the second primary winding of the transformer T1. The second end of the second primary winding is connected to the ground terminal of the device. The cathode of the second diode D2 is connected to the first chip U1 (VCC) of the control circuit.

[0053] In this embodiment, the fifth chip U5 is a protocol detection circuit that can detect the output voltage. It can also identify the access signal transmitted by the load device through its CC1 / CC2 / DM / DP pins, thereby transmitting a signal to the first optocoupler U2 via pin 2 of the fifth chip U5 to control the output. Pin 3 of the fifth chip U5 is connected to the thirty-first resistor R31 and the thirty-first capacitor C31 to form an RC filter circuit. By adjusting appropriate parameters, the DC output of this conversion circuit becomes more stable. Pins 4, 5, 6, and 7 of the fifth chip U5 can also identify whether a load device is connected. If a load device is connected, the fifth chip U5 can recognize the load device's access signal, i.e., output a high level through pin 10 of the fifth chip U5.

[0054] In this embodiment, the first optocoupler U2 and the fifth capacitor C5 are connected to the 6th pin of the first chip U1 and are fed back to the first chip U1 via a protocol, thereby controlling the conversion efficiency of the conversion circuit.

[0055] In some embodiments, in order to achieve high-level conduction of the response conversion circuit output, the switching circuit includes a sixty-second resistor R62, a sixty-sixth resistor R66, a sixty-seventh resistor R67, a first MOSFET Q6A, a second optocoupler U6, a sixty-third resistor R63, a thirty-third capacitor C33, a first Zener diode ZD2, a fifth transistor Q5, a thirteenth diode D13, a sixty-fifth resistor R65, and a thirtieth capacitor C30;

[0056] In this circuit, the first terminal of the sixty-second resistor R62 is connected to the fifth chip U5 (VFB), and the second terminal of the sixty-second resistor R62 is connected to the anode of the light-emitting diode of the second optocoupler U6. The first terminal of the sixty-sixth resistor R66 is connected to the cathode of the light-emitting diode of the second optocoupler U6, and the connection point between the second terminal of the sixty-sixth resistor R66 and the drain of the first MOSFET Q6A is connected to the ground terminal of the device. The connection point between the first terminal of the sixty-seventh resistor R67 and the gate of the first MOSFET Q6A is connected to the fifth chip U5 (P), and the second terminal of the sixty-seventh resistor R67 is connected to the source of the first MOSFET Q6A. The connection point between the collector of the phototransistor of the second optocoupler U6 and the collector of the thirteenth diode D13 is connected to the first chip U1 (VCC) of the control circuit. The emitter of the phototransistor in optocoupler U6 is connected to the first end of the sixty-third resistor R63. The connection point between the second end of the sixty-third resistor R63 and the first end of the sixty-fifth resistor R65 is connected to the base of the thirteenth diode D13. The first Zener diode ZD2 is connected across the sixty-fifth resistor R65. The second end of the sixty-fifth resistor R65 is connected to the first end of the thirty-third capacitor C33. The second end of the thirty-third capacitor C33 is connected to the collector of the phototransistor in the second optocoupler U6. The connection point between the cathode of the thirteenth diode D13 and the first end of the thirtieth capacitor C30 is connected to the first chip U1 (VCC-2C) of the control circuit. The connection point between the second end of the thirtieth capacitor C30 and the second end of the sixty-fifth resistor R65 is connected to the ground terminal of the device.

[0057] In this embodiment, when pin 10 of the fifth chip U5 outputs a high-level signal, the first MOSFET Q6A is turned on, and the LED of the second optocoupler U6 forms a loop. Subsequently, the fifth transistor Q5 is turned on, allowing pin 7 of the first chip U1 to receive operating DC power. If the fifth chip U5 does not detect a load device, pin 10 of the fifth chip U5 outputs a low-level signal, the first MOSFET Q6A is turned off, and the fifth transistor Q5 is turned off, causing the conversion circuit to be in an unloaded state and the first chip U1 to stop operating. Here, the low-level signal is the second-level signal, and the high-level signal is the first-level signal.

[0058] In some embodiments, in order to enable the control circuit to start and be controlled by the feedback circuit, the control circuit includes a first chip U1, a fourth capacitor C4, a seventy-first capacitor C71, a seventy-second capacitor C72, a second resistor R2, a third resistor R3, a seventy-third capacitor C73, a temperature control switch K1, a sixth resistor R6, and a seventh resistor R7.

[0059] In this configuration, the first chip U1 is connected to the second end of the first primary winding of transformer T1; the first end of the third resistor R3 is connected to the first chip U1 and then to the first end of the seventy-third capacitor C73; the second end of the seventy-third capacitor C73 is connected to the second end of the first primary winding of transformer T1; the second end of the third resistor R3 is connected to the ground terminal of the device; the second resistor R2 is connected across the third resistor R3; the seventy-first capacitor C71 and the seventy-second capacitor C72 are connected in series; the other end of the seventy-first capacitor C71 is connected to the first chip U1 (VCC); the other end of the seventy-second capacitor C72 and the connection point of the ground terminal of the device are connected to the first chip U1 (GND); the fourth capacitor C4 is connected across the seventy-first capacitor C71 and the seventy-second capacitor C72; the first end of the sixth resistor R6 is connected to the access terminal of the device; the second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7; the second end of the seventh resistor R7 is connected to the first end of the temperature control switch K1; and the second end of the temperature control switch K1 is connected to the first chip U1 (VCC).

[0060] In this embodiment, the sixth resistor R6, the seventh resistor R7, and the temperature control switch K1 form a startup circuit to provide energy for the initial startup of the power supply. Simultaneously, it connects to the second optocoupler U6, the fifth transistor Q5, and the thirteenth diode D13. Energy is stored by the fourth capacitor C4, the thirtieth capacitor C30, the seventy-first capacitor C71, and the seventy-second capacitor C72, and then supplied to pin 7 of the first chip U1 to provide voltage and current to the conversion circuit under load. The temperature control switch K1 disconnects approximately 10 minutes after the conversion circuit has been operating normally, reducing losses caused by the startup circuit after the switching power supply has been operating normally.

[0061] In this embodiment, the first chip U1 has a built-in gallium nitride (GaN) chip, which can simultaneously control the magnitude of the DC current output by the conversion circuit. The tenth resistor R10 and the eleventh resistor R11 are the upper and lower biases of the 5th pin of the first chip U1. The state of the conversion circuit is detected through the second primary coil of the transformer T1, and the conversion frequency of the conversion circuit is adjusted in a timely manner.

[0062] In some embodiments, to enhance the safety of the switching power supply device, such as Figure 1 As shown, a fuse FU1 is provided between the first terminal of the conversion circuit and the input terminal of the device.

[0063] While specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A switching power supply device, characterized by comprising: The device comprises: a conversion circuit, a first end of the conversion circuit being connected with an input end of the device; a control circuit, a first end of the control circuit being connected with a second end of the conversion circuit; a feedback circuit, a first end of the feedback circuit being connected with a third end of the conversion circuit, a second end of the feedback circuit being connected with a second end of the control circuit, and a third end of the feedback circuit being connected with an output end of the device; wherein, when the conversion circuit is in an idle state, the feedback circuit is turned off in response to a second level signal output by the conversion circuit, so that the control circuit stops running.

2. The switching power supply device according to claim 1, characterized by When the conversion circuit is in a loaded state, the feedback circuit is turned on in response to a first level signal output by the conversion circuit, so that the control circuit runs.

3. The switching power supply device according to claim 1, wherein The conversion circuit comprises a primary conversion circuit, a transformer and a secondary conversion circuit, a first end of the primary conversion circuit serving as the first end of the conversion circuit, a second end of the primary conversion circuit being connected with a first end of a first primary winding of the transformer, and a third end of the primary conversion circuit serving as the second end of the conversion circuit; a second end of the first primary winding of the transformer being connected with a third end of the control circuit; a secondary winding of the transformer being connected with a first end of the secondary conversion circuit, and a second end of the secondary conversion circuit serving as the third end of the conversion circuit.

4. The switching power supply device according to claim 3, wherein The primary conversion circuit comprises a rectifier, a first inductor, a first resistor, a first electrolytic capacitor, a second electrolytic capacitor and a primary capacitor; wherein, a first end of the rectifier is connected with a first end of the first inductor, a second end of the first inductor is connected with the first end of the first primary winding of the transformer, the first resistor is connected across the first inductor, the first electrolytic capacitor is connected across the first end of the first inductor and a ground end of the device, the second electrolytic capacitor is connected across the second end of the first inductor and the ground end of the device, and the primary capacitor is connected across the first primary winding of the transformer.

5. The switching power supply device according to claim 3, wherein The secondary conversion circuit comprises a third chip, a ninth capacitor, a twelfth resistor, a fourth electrolytic capacitor, a fourteenth resistor and a seventh capacitor; wherein, a connection point of the third chip and a first end of the ninth capacitor is connected with a second end of the secondary winding of the transformer, a second end of the ninth capacitor is connected with a first end of the twelfth resistor, a connection point of a second end of the twelfth resistor and the third chip is connected with the ground end of the device, a connection point of a first end of the fourth electrolytic capacitor and a first end of the fourteenth resistor is connected with the ground end of the device, a connection point of a second end of the fourth electrolytic capacitor and a second end of the fourteenth resistor is connected with a first end of the secondary winding of the transformer, the third chip is further connected with a first end of the seventh capacitor, and a second end of the seventh capacitor is connected with the ground end of the device.

6. The switching power supply device according to claim 3, wherein The feedback circuit comprises a detection circuit and a switch circuit, a first end of the detection circuit is a first end of the feedback circuit, a second end of the detection circuit is a third end of the feedback circuit, a third end of the detection circuit is connected with a first end of the switch circuit, and a second end of the switch circuit is a second end of the feedback circuit.

7. The switching power supply device according to claim 6, wherein The detection circuit comprises a fifth chip, a thirteenth resistor, a fifteenth resistor, a thirty-first resistor, a thirty-first capacitor, a first optocoupler, a fifth capacitor, an eleventh resistor, a tenth resistor and a second diode. The fifth chip is connected with an output end of the device, a connection point of the fifth chip and a first end of the thirteenth resistor is connected with a second end of the detection circuit, a second end of the thirteenth resistor is connected with a first end of the fifteenth resistor, a second end of the fifteenth resistor is connected with a first end of the thirty-first resistor, a second end of the thirty-first resistor is connected with a first end of the thirty-first capacitor, a connection point of the thirty-first capacitor and the fifth chip is connected with the switch circuit, the fifth chip is also connected with the switch circuit, an LED of the first optocoupler is connected across the fifteenth resistor, a photosensitive triode of the first optocoupler is connected across the fifth capacitor, a first end of the fifth capacitor is connected to the control circuit, a connection point of a second end of the fifth capacitor and a first end of the eleventh resistor is connected with a ground end of the device, a connection point of a second end of the eleventh resistor and a first end of the tenth resistor is connected to the control circuit, a connection point of a second end of the tenth resistor and an anode of the second diode is connected with a first end of a second primary coil of the transformer, a second end of the second primary coil is connected with the ground end of the device, and a cathode of the second diode is connected to the control circuit.

8. The switching power supply device according to claim 7, wherein The switch circuit comprises a sixty-second resistor, a sixty-sixth resistor, a sixty-seventh resistor, a first MOS tube, a second optocoupler, a sixty-third resistor, a thirty-third capacitor, a first voltage stabilizing diode, a fifth triode, a thirteenth diode, a sixty-fifth resistor and a thirtieth capacitor. The first end of the sixty-second resistor is connected to the fifth chip, the second end of the sixty-second resistor is connected to the anode of the light-emitting diode of the second optocoupler, the first end of the sixty-sixth resistor is connected to the cathode of the light-emitting diode of the second optocoupler, the second end of the sixty-sixth resistor is connected to the connection point of the drain of the first MOS tube and the ground terminal of the device, the first end of the sixty-seventh resistor and the connection point of the gate of the first MOS tube are connected to the fifth chip, the second end of the sixty-seventh resistor is connected to the source of the first MOS tube, the connection point of the collector of the phototriode of the second optocoupler and the collector of the thirteenth diode is connected to the control circuit, the first end of the sixty-third resistor is connected to the emitter of the phototriode of the second optocoupler, the connection point of the second end of the sixty-third resistor and the first end of the sixty-fifth resistor is connected to the base of the thirteenth diode, the first stable voltage diode is connected across the sixty-fifth resistor, the second end of the sixty-fifth resistor is connected to the first end of the thirty-third capacitor, the second end of the thirty-third capacitor is connected to the collector of the phototriode of the second optocoupler, the connection point of the first end of the thirtieth capacitor and the cathode of the thirteenth diode is connected to the control circuit, and the connection point of the second end of the thirtieth capacitor and the second end of the sixty-fifth resistor is connected to the ground terminal of the device.

9. The switching power supply device according to claim 5, wherein The control circuit comprises a first chip, a fourth capacitor, a seventy-first capacitor, a seventy-second capacitor, a second resistor, a third resistor, a seventy-third capacitor, a temperature control switch, a sixth resistor, and a seventh resistor. The first chip is connected to the second end of the first primary coil of the transformer, the first end of the third resistor is connected to the first chip and then connected to the first end of the seventy-third capacitor, the second end of the seventy-third capacitor is connected to the second end of the first primary coil of the transformer, the second end of the third resistor is connected to the ground terminal of the device, the second resistor is connected across the third resistor, the series connection of the seventy-first capacitor and the seventy-second capacitor, the other end of the seventy-first capacitor is connected to the first chip, the connection point of the other end of the seventy-second capacitor and the ground terminal of the device is connected to the first chip, the fourth capacitor is connected across the seventy-first capacitor and the seventy-second capacitor, the first end of the sixth resistor is connected to the input terminal of the device, the second end of the sixth resistor is connected to the first end of the seventh resistor, the second end of the seventh resistor is connected to the first end of the temperature control switch, and the second end of the temperature control switch is connected to the first chip.

10. The switching power supply device according to claim 1, wherein A fuse is arranged between the first end of the conversion circuit and the input terminal of the device.

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