Charging circuit for charging equipment

Abstract

The embodiment of the utility model provides a charging circuit for charging equipment, which comprises a transformer T2, a current source detection circuit, a comparison feedback circuit and a control chip U1, a primary coil of the transformer T2 is connected with commercial power, a first secondary coil of the transformer T2 is connected with an output end of the charging circuit, and a second secondary coil of the transformer T2 is connected with an output end of the charging circuit. A second secondary coil of the transformer T2 is connected with the input end of the current source detection circuit 1, the output end of the current source detection circuit 1 is connected with the output end of the charging circuit and the input end of the comparison feedback circuit 2, and the output end of the comparison feedback circuit 2 is connected with a primary coil of the transformer T2 through the control chip U1; only one secondary coil, the current source detection circuit and the comparison feedback circuit need to be additionally arranged on the transformer, the function of no output voltage without load can be achieved, the production cost is low, implementation is convenient, and practicability is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of charging circuits, and specifically relates to a charging circuit for a charging device. Background Art

[0002] With the continuous development of science and technology, PC and mobile devices have become necessities in people's lives. Therefore, various power adapters and chargers are needed to power these devices. In actual use, when the device is fully charged, people are accustomed to only unplugging the charger on the PC and mobile phone, and are basically too lazy to unplug the AC plug plugged into the mains. At this time, the output end of the charger is basically measured, and it basically has voltage output, that is to say, the charger has a certain power loss even if it is not connected to the load; such as computers and mobile phones, except for the Type Cadapter adapter that needs to be connected to the PC and has a PD controller chip to match before there will be output voltage, the rest of the adapters and chargers will still have output voltage after disconnecting the charging device, so there will be too much power loss. Taking the 5 billion terminal devices in the world as an example, before adding this solution, each charger consumes about 0.3W per day on average, then the power consumed by these devices in a year will reach: 5 billion × 0.3 × 24 × 365 / 1000 = 1.314 billion kWh.

[0003] The idea of ​​the existing solution is to implant a microcontroller MCU in the charger, such as Figure 3 As shown, by additionally adding signal 1 and signal 2 to detect whether the portable device needs to be charged, if the device is disconnected or charging is completed, signal 1 and signal 2 are fed back to the MCU, and then the MCU sends a command to the relay to turn off the relay, thereby disconnecting from the main power supply to achieve the purpose of saving power.

[0004] This solution is to add a microcontroller MCU to the charger, a shutdown relay, and two signal lines to detect whether the load is turned off. These are relatively complex and the total cost is relatively high. Imagine that the overall cost of a common charging device like a mobile phone charger is not high. If these modules are added, its cost performance will be greatly reduced. Therefore, it is unlikely that this solution will be introduced in such charging devices. Summary of the invention

[0005] In order to solve one of the above-mentioned technical defects, a charging circuit for a charging device is provided in an embodiment of the present application. When no load is connected, the charging circuit has no voltage output.

[0006] According to a first aspect of an embodiment of the present application, a charging circuit for a charging device is provided, including: a transformer T2, a current source detection circuit, a comparison feedback circuit and a control chip U1, wherein the primary coil of the transformer T2 is connected to the mains, the first secondary coil of the transformer T2 is connected to the output end of the charging circuit, the second secondary coil of the transformer T2 is connected to the input end of the current source detection circuit, the output end of the current source detection circuit is respectively connected to the output end of the charging circuit and the input end of the comparison feedback circuit, and the output end of the comparison feedback circuit is connected to the primary coil of the transformer T2 through the control chip U1.

[0007] Preferably, the current source detection circuit comprises: a transistor Q4, a transistor Q5, a capacitor C9, a resistor R18, a resistor R19 and a resistor R20;

[0008] The emitter of the transistor Q5 is respectively connected to one end of the second secondary coil L7 of the transformer T2, the emitter of the transistor Q4, and one end of the capacitor C9; the collector of the transistor Q5 is connected in series with resistors R19 and R20 in sequence and then grounded; the connection between the resistors R19 and R20 is respectively connected to the output end of the charging circuit and the input end of the comparison feedback circuit; the base of the transistor Q5 is respectively connected to the base of the transistor Q4, the collector of the transistor Q4, and one end of the resistor R18; the other end of the second secondary coil L7 of the transformer T2, the other end of the resistor R18, and the other end of the capacitor C9 are respectively grounded.

[0009] Preferably, the comparison feedback circuit comprises: a comparator P1, a resistor R15, a resistor R16, a resistor R17 and a MOS tube Q1;

[0010] The non-inverting input end of the comparator P1 is connected to the connection line between the resistor R19 and the resistor R20, the reverse input end of the comparator P1 is respectively connected to one end of the resistor R16 and one end of the resistor R17, the other end of the resistor R17 is grounded, the other end of the resistor R16 is respectively connected to the emitter of the transistor Q5, the power supply end of the comparator P1, and one end of the resistor R15, the other end of the resistor R15 is respectively connected to the output end of the comparator P1 and the gate of the MOS tube Q1, the drain of the MOS tube Q1 is connected to the control chip U1, and the source of the MOS tube Q1 is connected to the primary coil of the transformer T2.

[0011] Preferably, the charging circuit for a charging device comprises: a transformer T1 and a rectifier bridge W1;

[0012] The power input end of the rectifier bridge W1 is connected to the mains through the transformer T1, the output positive end of the rectifier bridge W1 is respectively connected to one end of the capacitor C1, one end of the inductor L2, one end of the capacitor C2, one end of the resistor R2, one end of the resistor R4, one end of the capacitor C3, and one end of the first primary coil L4 of the transformer T2, the other end of the capacitor C1 is connected to the output negative end of the rectifier bridge W1 and one end of the inductor L3, the other end of the inductor L3 is connected in series with the other end of the capacitor C2 and then grounded, the other end of the resistor R2 is connected in series with the resistor R3 and the resistor R8 in sequence and then connected to the negative electrode of the Schottky diode D4, the positive electrode of the Schottky diode D4 is connected to one end of the second primary coil L6 of the transformer T2, the other end of the second primary coil L6 is grounded, the connection between the resistor R3 and the resistor R8 is connected to the source of the MOS tube Q1, the connection between the other end of the resistor R4 and the other end of the capacitor C3 is connected in series with the resistor R5 and then connected to the negative electrode of the diode D1, the positive electrode of the diode D1 is respectively connected to the other end of the first primary coil L4 of the transformer T2 , the drain of the MOS tube Q3, the source of the MOS tube Q3 is respectively connected to one end of the resistor R14, one end of the resistor R13, one end of the resistor R11, and one end of the resistor R12, the other end of the resistor R14 and the other end of the resistor R13 are respectively grounded, the other end of the resistor R11 is respectively connected to the gate of the MOS tube Q3, the positive electrode of the Schottky diode D5, and one end of the resistor R10, the other end of the resistor R10 is respectively connected to the negative electrode of the Schottky diode D5 and the GATE end of the control chip U1 , the other end of the resistor R12 is connected to the CS end of the control chip U1, the VDD end of the control chip U1 is respectively connected to the drain of the MOS tube Q1 and one end of the capacitor C8, the other end of the capacitor C8 is grounded, the GND end of the control chip U1 is respectively connected to one end of the resistor R9, the ground end, one end of the capacitor C7, and the emitter of the transistor Q2, the collector of the transistor Q2 is respectively connected to the other end of the capacitor C7 and the FB end of the control chip U1, and the other end of the resistor R9 is connected to the RT end of the control chip U1;

[0013] Preferably, the charging circuit for a charging device comprises: a voltage regulator M1;

[0014] One end of the first secondary coil L5 of the transformer T2 is respectively connected to one end of the capacitor C4 and the positive electrode of the diode D2, the other end of the capacitor C4 is connected in series with the resistor R6 and then respectively connected to the negative electrode of the diode D2, one end of the capacitor C5, one end of the capacitor C6, the negative electrode of the Schottky diode D3, one end of the resistor R7, the positive output end of the charging circuit, one end of the resistor R21, and the negative electrode of the Schottky diode D6, the positive electrode of the Schottky diode D6 is connected to the connection between the resistor R19 and the resistor R20, the other end of the capacitor C5 is connected to the other end of the first secondary coil L5 of the transformer T2, the other end of the capacitor C6, the positive electrode of the Schottky diode D3, the other end of the resistor R7, and the negative output end of the charging circuit and then grounded;

[0015] The other end of the resistor R21 is respectively connected to the positive electrode of the diode D7 and one end of the resistor R22. The other end of the resistor R22 is respectively connected to the negative electrode of the diode D7, one end of the capacitor C10, the cathode of the regulator M1, one end of the capacitor C11, the other end of the capacitor C11, the reference electrode of the regulator M1, and one end of the resistor R23. The other end of the resistor R23 is connected to the anode of the regulator M1 and the other end of the capacitor C10 and then grounded.

[0016] Preferably, the capacitor C9 is a super capacitor, which is used to provide power to the current source detection circuit.

[0017] Preferably, the model of the control chip U1 is SF1530.

[0018] Preferably, the model of the rectifier bridge W1 is ABS10.

[0019] Preferably, the model of the voltage regulator M1 is TL431.

[0020] Preferably, the model of the diode D2 is PS1550L.

[0021] A charging circuit for a charging device provided in an embodiment of the present application includes: a transformer T2, a current source detection circuit, a comparison feedback circuit and a control chip U1. When in use, when the AC plug of the charging device is inserted into the mains, the charging device starts working, and the newly added second secondary coil generates a 5VSB voltage, thereby starting the current source detection circuit to start working to detect whether there is a load connected to the output end of the charging circuit. If there is a load at the output end, the charger enters a normal output working state; if it is detected that there is no load at the output end, that is, through the comparator feedback circuit, the VDD end of the control chip U1 is disconnected, the control chip U1 stops working, and there is no output at the output end of the charging device, thereby achieving the effect of no output voltage of the charger; the present application only needs to add a secondary coil, a current source detection circuit, and a comparison feedback circuit to the transformer to realize the function of no output voltage when there is no load, and the production cost is low, it is easy to implement, and it is practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 A circuit structure diagram of a charging circuit for a charging device provided in an embodiment of the present application;

[0024] Figure 2 A circuit schematic diagram of a charging circuit for a charging device provided in an embodiment of the present application;

[0025] Figure 3 It is a charging circuit schematic diagram of a charging device in the prior art;

[0026] In the figure, 1 is a current source detection circuit, and 2 is a comparison feedback circuit. DETAILED DESCRIPTION

[0027] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0028] In view of the above problems, an embodiment of the present application provides a charging circuit for a charging device, such as Figure 1 As shown, it includes: a transformer T2, a current source detection circuit 1, a comparison feedback circuit 2 and a control chip U1, the primary coil of the transformer T2 is connected to the mains, the first secondary coil of the transformer T2 is connected to the output end of the charging circuit, the second secondary coil of the transformer T2 is connected to the input end of the current source detection circuit 1, the output end of the current source detection circuit 1 is respectively connected to the output end of the charging circuit and the input end of the comparison feedback circuit 2, the output end of the comparison feedback circuit 2 is connected to the primary coil of the transformer T2 through the control chip U1, and the model of the control chip U1 is SF1530.

[0029] During use, after the AC plug of the charging device is plugged into the mains, the charging device starts working, and the newly added second secondary coil generates a 5VSB voltage, thereby starting the current source detection circuit 1 to start working to detect whether there is a load connected to the output end of the charging circuit. If there is a load at the output end, the charger enters a normal output working state; if it is detected that there is no load at the output end, the VDD end of the control chip U1 is disconnected through the comparator feedback circuit 2, the control chip U1 stops working, and there is no output at the output end of the charging device, thereby achieving the effect of no output voltage of the charger.

[0030] In the prior art, a special microcontroller must be used and a relay must be used to disconnect the main power supply. In addition, two detection signal lines are required to detect whether there is a load to realize the function. The present embodiment only needs to add a secondary coil, a current source detection circuit 1, and a comparison feedback circuit 2 to the transformer to realize the function of no output voltage when there is no load. The production cost is low, the implementation is convenient, and the invention is practical.

[0031] like Figure 2 As shown, the current source detection circuit 1 includes: a transistor Q4, a transistor Q5, a capacitor C9, a resistor R18, a resistor R19 and a resistor R20;

[0032] The emitter of the transistor Q5 is respectively connected to one end of the second secondary coil L7 of the transformer T2, the emitter of the transistor Q4, and one end of the capacitor C9; the collector of the transistor Q5 is connected in series with resistors R19 and R20 in sequence and then grounded; the connection between the resistors R19 and R20 is respectively connected to the output end of the charging circuit and the input end of the comparison feedback circuit 2; the base of the transistor Q5 is respectively connected to the base of the transistor Q4, the collector of the transistor Q4, and one end of the resistor R18; the other end of the second secondary coil L7 of the transformer T2, the other end of the resistor R18, and the other end of the capacitor C9 are respectively grounded; the capacitor C9 is a supercapacitor used to provide power to the current source detection circuit; the capacitor C9 is an electrochemical capacitor with high energy density, which is hundreds to thousands of times higher than the capacity of traditional electrolytic capacitors.

[0033] Specifically, when the AC plug of the charging device is plugged into the mains, the charging device starts to work, and the second secondary coil L7 of the transformer T2 provides a low-voltage power supply VCC for the current source detection circuit 1, and charges the supercapacitor C9 at the same time. The current source detection circuit 1 provides a very small current source at the output end of the charging circuit through the Schottky diode D6. When the current source detection circuit 1 is working, the transistor Q5 is turned on, and the voltage division V1 composed of the resistor R19 and the resistor R20 is compared with the voltage division V2 composed of the resistor R16 and the resistor R17. When there is no load connected to the output end, the voltage V1 is higher than the voltage V2. When connected, the divided voltage V1 is slightly greater than V2, the comparator P1 outputs a high level, the MOS tube Q1 is a PMOS tube, so the MOS tube Q1 is cut off, the VDD end of the control chip U1 is disconnected, the control chip U1 stops working, thereby disconnecting the back-end switch circuit, and the output end of the charging device has no output; when a load is connected, the load has impedance in parallel with the resistor R20, the divided voltage V1 is slightly less than the divided voltage V2, the comparator P1 outputs a low level, the MOS tube Q1 is turned on, and the VDD end of the control chip U1 is turned on, so that the output end has an output voltage.

[0034] Since the current source detection circuit 1 has a super capacitor C9 to discharge, and the current of the current source is set to be relatively small, the current source detection circuit 1 can continue to work for several minutes until the capacitor C9 is discharged and the current source detection circuit 1 stops working. Subsequently, the control chip U1 starts working to charge the capacitor C9, the circuit is connected, and the newly added second secondary coil generates a 5VSB voltage. The current source detection circuit 1 starts working again to detect whether there is a load at the output end. If no load is connected, the control chip U1 stops working, and the cycle continues. In this embodiment, transistors Q4 and Q5 form the current source detection circuit 1, which saves cost, and the power consumption of the current source detection circuit 1 is very small, which plays a role in energy saving and environmental protection.

[0035] Furthermore, the comparison feedback circuit 2 includes: a comparator P1, a resistor R15, a resistor R16, a resistor R17 and a MOS tube Q1;

[0036] The non-inverting input end of the comparator P1 is connected to the connection line between the resistor R19 and the resistor R20, the reverse input end of the comparator P1 is respectively connected to one end of the resistor R16 and one end of the resistor R17, the other end of the resistor R17 is grounded, the other end of the resistor R16 is respectively connected to the emitter of the transistor Q5, the power supply end of the comparator P1, and one end of the resistor R15, the other end of the resistor R15 is respectively connected to the output end of the comparator P1 and the gate of the MOS tube Q1, the drain of the MOS tube Q1 is connected to the control chip U1, and the source of the MOS tube Q1 is connected to the primary coil of the transformer T2.

[0037] Furthermore, a charging circuit for a charging device includes: a transformer T1 and a rectifier bridge W1; the model of the rectifier bridge W1 is ABS10; the power input end of the rectifier bridge W1 is connected to the mains through the transformer T1, the output positive end of the rectifier bridge W1 is respectively connected to one end of the capacitor C1, one end of the inductor L2, one end of the capacitor C2, one end of the resistor R2, one end of the resistor R4, one end of the capacitor C3, and one end of the first primary coil L4 of the transformer T2, and the other end of the capacitor C1 is connected to the output negative end of the rectifier bridge W1 and one end of the inductor L3. The other end of the inductor L3 is connected in series with the other end of the capacitor C2 and then grounded. The other end of the resistor R2 is connected in series with the resistor R3 and the resistor R8 in sequence and then connected to the cathode of the Schottky diode D4. The anode of the Schottky diode D4 is connected to one end of the second primary coil L6 of the transformer T2. The other end of the second primary coil L6 is grounded. The connection line between the resistor R3 and the resistor R8 is connected to the source of the MOS tube Q1. The connection line between the other end of the resistor R4 and the other end of the capacitor C3 is connected in series with the resistor R5 and then connected to the cathode of the diode D1. The The positive electrode is respectively connected to the other end of the first primary coil L4 of the transformer T2 and the drain of the MOS tube Q3. The source of the MOS tube Q3 is respectively connected to one end of the resistor R14, one end of the resistor R13, one end of the resistor R11, and one end of the resistor R12. The other end of the resistor R14 and the other end of the resistor R13 are respectively grounded. The other end of the resistor R11 is respectively connected to the gate of the MOS tube Q3, the positive electrode of the Schottky diode D5, and one end of the resistor R10. The other end of the resistor R10 is respectively connected to the negative electrode of the Schottky diode D5, the control core The GATE end of the control chip U1 is connected to the GATE end of the control chip U1, the other end of the resistor R12 is connected to the CS end of the control chip U1, the VDD end of the control chip U1 is respectively connected to the drain of the MOS tube Q1 and one end of the capacitor C8, the other end of the capacitor C8 is grounded, the GND end of the control chip U1 is respectively connected to one end of the resistor R9, the ground end, one end of the capacitor C7, and the emitter of the transistor Q2, the collector of the transistor Q2 is respectively connected to the other end of the capacitor C7 and the FB end of the control chip U1, and the other end of the resistor R9 is connected to the RT end of the control chip U1;

[0038] Further, a charging circuit for a charging device includes: a voltage stabilizer M1, the model of the voltage stabilizer M1 is TL431; one end of the first secondary coil L5 of the transformer T2 is respectively connected to one end of the capacitor C4 and the positive electrode of the diode D2, the other end of the capacitor C4 is connected in series with the resistor R6 and is respectively connected to the negative electrode of the diode D2, one end of the capacitor C5, one end of the capacitor C6, the negative electrode of the Schottky diode D3, one end of the resistor R7, the positive output end of the charging circuit, one end of the resistor R21, and the negative electrode of the Schottky diode D6, the positive electrode of the Schottky diode D6 is connected to the connection between the resistor R19 and the resistor R20, the other end of the capacitor C5 is connected to the other end of the first secondary coil L5 of the transformer T2, the other end of the capacitor C6, the positive electrode of the Schottky diode D3, the other end of the resistor R7, and the negative output end of the charging circuit and then grounded, and the model of the diode D2 is PS1550L;

[0039] The other end of the resistor R21 is respectively connected to the positive electrode of the diode D7 and one end of the resistor R22. The other end of the resistor R22 is respectively connected to the negative electrode of the diode D7, one end of the capacitor C10, the cathode of the regulator M1, one end of the capacitor C11, the other end of the capacitor C11, the reference electrode of the regulator M1, and one end of the resistor R23. The other end of the resistor R23 is connected to the anode of the regulator M1 and the other end of the capacitor C10 and then grounded.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0044] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A charging circuit for a charging device, characterized in that: include: A transformer T2, a current source detection circuit (1), a comparison feedback circuit (2) and a control chip U1, wherein the primary coil of the transformer T2 is connected to the mains, the first secondary coil of the transformer T2 is connected to the output end of the charging circuit, the second secondary coil of the transformer T2 is connected to the input end of the current source detection circuit (1), the output end of the current source detection circuit (1) is respectively connected to the output end of the charging circuit and the input end of the comparison feedback circuit (2), and the output end of the comparison feedback circuit (2) is connected to the primary coil of the transformer T2 through the control chip U1.

2. A charging circuit for a charging device according to claim 1, characterized in that: The current source detection circuit (1) comprises: a transistor Q4, a transistor Q5, a capacitor C9, a resistor R18, a resistor R19 and a resistor R20; The emitter of the transistor Q5 is respectively connected to one end of the second secondary coil L7 of the transformer T2, the emitter of the transistor Q4, and one end of the capacitor C9; the collector of the transistor Q5 is connected in series with a resistor R19 and a resistor R20 in sequence and then grounded; the connection between the resistor R19 and the resistor R20 is respectively connected to the output end of the charging circuit and the input end of the comparison feedback circuit (2); the base of the transistor Q5 is respectively connected to the base of the transistor Q4, the collector of the transistor Q4, and one end of the resistor R18; the other end of the second secondary coil L7 of the transformer T2, the other end of the resistor R18, and the other end of the capacitor C9 are respectively grounded.

3. A charging circuit for a charging device according to claim 2, characterized in that: The comparison feedback circuit (2) comprises: a comparator P1, a resistor R15, a resistor R16, a resistor R17 and a MOS tube Q1; The non-inverting input end of the comparator P1 is connected to the connection line between the resistor R19 and the resistor R20, the reverse input end of the comparator P1 is respectively connected to one end of the resistor R16 and one end of the resistor R17, the other end of the resistor R17 is grounded, the other end of the resistor R16 is respectively connected to the emitter of the transistor Q5, the power supply end of the comparator P1, and one end of the resistor R15, the other end of the resistor R15 is respectively connected to the output end of the comparator P1 and the gate of the MOS tube Q1, the drain of the MOS tube Q1 is connected to the control chip U1, and the source of the MOS tube Q1 is connected to the primary coil of the transformer T2.

4. A charging circuit for a charging device according to claim 3, characterized in that: include: Transformer T1 and rectifier bridge W1; The power input end of the rectifier bridge W1 is connected to the mains through the transformer T1, the output positive end of the rectifier bridge W1 is respectively connected to one end of the capacitor C1, one end of the inductor L2, one end of the capacitor C2, one end of the resistor R2, one end of the resistor R4, one end of the capacitor C3, and one end of the first primary coil L4 of the transformer T2, the other end of the capacitor C1 is connected to the output negative end of the rectifier bridge W1 and one end of the inductor L3, the other end of the inductor L3 is connected in series with the other end of the capacitor C2 and then grounded, the other end of the resistor R2 is connected in series with the resistor R3 and the resistor R8 in sequence and then connected to the negative electrode of the Schottky diode D4, the positive electrode of the Schottky diode D4 is connected to one end of the second primary coil L6 of the transformer T2, the other end of the second primary coil L6 is grounded, the connection between the resistor R3 and the resistor R8 is connected to the source of the MOS tube Q1, the connection between the other end of the resistor R4 and the other end of the capacitor C3 is connected in series with the resistor R5 and then connected to the negative electrode of the diode D1, the positive electrode of the diode D1 is respectively connected to the other end of the first primary coil L4 of the transformer T2 , the drain of the MOS tube Q3, the source of the MOS tube Q3 is respectively connected to one end of the resistor R14, one end of the resistor R13, one end of the resistor R11, and one end of the resistor R12, the other end of the resistor R14 and the other end of the resistor R13 are respectively grounded, the other end of the resistor R11 is respectively connected to the gate of the MOS tube Q3, the positive electrode of the Schottky diode D5, and one end of the resistor R10, the other end of the resistor R10 is respectively connected to the negative electrode of the Schottky diode D5 and the GATE end of the control chip U1 The other end of the resistor R12 is connected to the CS end of the control chip U1, the VDD end of the control chip U1 is respectively connected to the drain of the MOS tube Q1 and one end of the capacitor C8, the other end of the capacitor C8 is grounded, the GND end of the control chip U1 is respectively connected to one end of the resistor R9, the ground end, one end of the capacitor C7, and the emitter of the transistor Q2, the collector of the transistor Q2 is respectively connected to the other end of the capacitor C7 and the FB end of the control chip U1, and the other end of the resistor R9 is connected to the RT end of the control chip U1.

5. A charging circuit for a charging device according to claim 4, characterized in that: include: Voltage regulator M1; One end of the first secondary coil L5 of the transformer T2 is respectively connected to one end of the capacitor C4 and the positive electrode of the diode D2, the other end of the capacitor C4 is connected in series with the resistor R6 and then respectively connected to the negative electrode of the diode D2, one end of the capacitor C5, one end of the capacitor C6, the negative electrode of the Schottky diode D3, one end of the resistor R7, the positive output end of the charging circuit, one end of the resistor R21, and the negative electrode of the Schottky diode D6, the positive electrode of the Schottky diode D6 is connected to the connection between the resistor R19 and the resistor R20, the other end of the capacitor C5 is connected to the other end of the first secondary coil L5 of the transformer T2, the other end of the capacitor C6, the positive electrode of the Schottky diode D3, the other end of the resistor R7, and the negative output end of the charging circuit and then grounded; The other end of the resistor R21 is respectively connected to the positive electrode of the diode D7 and one end of the resistor R22. The other end of the resistor R22 is respectively connected to the negative electrode of the diode D7, one end of the capacitor C10, the cathode of the regulator M1, one end of the capacitor C11, the other end of the capacitor C11, the reference electrode of the regulator M1, and one end of the resistor R23. The other end of the resistor R23 is connected to the anode of the regulator M1 and the other end of the capacitor C10 and then grounded.

6. A charging circuit for a charging device according to claim 2, characterized in that: The capacitor C9 is a supercapacitor, used to provide power to the current source detection circuit (1).

7. A charging circuit for a charging device according to claim 1, characterized in that: The model of the control chip U1 is SF1530.

8. A charging circuit for a charging device according to claim 4, characterized in that: The model of the rectifier bridge W1 is ABS10.

9. A charging circuit for a charging device according to claim 5, characterized in that: The model of the voltage regulator M1 is TL431.

10. A charging circuit for a charging device according to claim 4, characterized in that: The model of the diode D2 is PS1550L.

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