An AC-DC isolated power supply chip, its application circuit and charging circuit

Abstract

The present invention provides an AC-DC isolated power chip, its application circuit and charging circuit, which are used to be connected to a transformer. It includes a chip body, and in the chip body, there are provided: a rectification circuit for accessing high-voltage alternating current and rectifying it into high-voltage direct current; a high-voltage power extraction circuit for converting the high-voltage direct current into low-voltage direct current and generating the internal power supply voltage of the chip; an output driving circuit for driving the transformer to work; a logic processing circuit for outputting a driving control signal to the driving circuit; the rectification circuit is connected to the AC power supply, the transformer and the high-voltage power extraction circuit, the high-voltage power extraction circuit is also connected to the logic processing circuit and the driving circuit, the logic processing circuit is also connected to the driving circuit, and the driving circuit is also connected to the transformer. By integrating the primary-side devices in the same chip and realizing the primary-side power supply and driving of the transformer only through the chip and the transformer, the present invention reduces the primary-side devices of the transformer and simplifies the circuit structure.

Description

Technical Field

[0001] The present invention relates to the field of power chips, and particularly to an AC-DC isolated power chip, its application circuit and charging circuit. Background Art

[0002] In existing isolated switching power chips, generally, high-voltage alternating current is rectified by a diode or a bridge rectifier for half-wave or full-wave rectification, filtered by a high-voltage capacitor, and then input to the chip for power supply through rectification and filtering of the feedback winding of the transformer. Finally, a PWM is generated to control the high-voltage transistor for switching modulation, and the output is adjusted through a feedback resistor and the spike pulse of the high-voltage power transistor is absorbed. However, the above method has many primary-side devices and a complex circuit.

[0003] Therefore, the existing technology still needs to be improved. Summary of the Invention

[0004] In view of the deficiencies of the above-mentioned existing technology, the purpose of the present invention is to provide an AC-DC isolated power chip, its application circuit and charging circuit. By integrating the primary-side devices in the same chip, only the chip and the transformer are used to realize the power supply and drive of the primary side of the transformer, reducing the primary-side devices of the transformer and streamlining the circuit structure.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides an AC-DC isolated power chip for connecting with a transformer, including a chip body, and in the chip body, there are provided:

[0007] A rectification circuit for accessing high-voltage alternating current and rectifying it into high-voltage direct current;

[0008] A high-voltage power extraction circuit for converting the high-voltage direct current into low-voltage direct current and generating the internal power supply voltage of the chip;

[0009] An output driving circuit for driving the transformer to work;

[0010] A logic processing circuit for outputting a driving control signal to the driving circuit;

[0011] The rectification circuit is connected to an AC power supply, a transformer and the high-voltage power extraction circuit. The high-voltage power extraction circuit is also connected to the logic processing circuit and the driving circuit. The logic processing circuit is also connected to the driving circuit. The driving circuit is also connected to the transformer.

[0012] The AC-DC isolated power chip further includes:

[0013] A feedback circuit for sampling signals of the transformer to generate a sampling voltage;

[0014] An error amplification circuit for receiving the sampled voltage for amplification;

[0015] The feedback circuit is connected to the transformer and the error amplification circuit, and the error amplification circuit is also connected to the logic processing circuit.

[0016] The AC-DC isolated power supply chip further includes:

[0017] An overcurrent protection circuit respectively connected to the output driving circuit and the logic processing circuit for overcurrent protection of the chip;

[0018] An over-temperature protection circuit for AC-DC connected to the logic processing circuit for over-temperature protection of the chip.

[0019] The AC-DC isolated power supply chip further includes:

[0020] An oscillation circuit connected to the logic processing circuit for providing a low-frequency oscillation for the logic processing circuit.

[0021] Five or six pins are provided on the chip body, which are respectively: a first pin, a second pin (reserved), a third pin, a fourth pin, a fifth pin and a sixth pin;

[0022] The first pin is connected to the feedback circuit for signal sampling;

[0023] The second pin is a reserved pin;

[0024] The third pin is connected to the output driving circuit for driving external devices;

[0025] The fourth pin is connected to the output end of the rectification circuit for outputting high-voltage direct current;

[0026] The fifth pin is connected to the input end of the rectification circuit for accessing high-voltage alternating current;

[0027] The sixth pin is the chip grounding pin.

[0028] The high-voltage power extraction circuit includes:

[0029] A voltage conversion circuit for converting high-voltage direct current into low-voltage direct current;

[0030] A controllable high-voltage MOS circuit for accessing the low-voltage direct current;

[0031] A voltage sampling circuit for voltage sampling of the low-voltage direct current;

[0032] A voltage regulation circuit for converting the low-voltage direct current into an internal power supply voltage of the chip;

[0033] An operational amplifier for feedback regulation;

[0034] The input end of the voltage conversion circuit is connected to the output end of the rectification circuit, the output end of the voltage conversion circuit is connected to the input end of the controllable high-voltage MOS circuit, the output end of the controllable high-voltage MOS circuit is connected to the voltage sampling circuit and the voltage regulation circuit, the voltage sampling circuit is also connected to the inverting input end of the operational amplifier, the voltage regulation circuit is also connected to the non-inverting input end of the operational amplifier, and the output end of the operational amplifier is connected to the control end of the controllable high-voltage MOS circuit.

[0035] The voltage conversion circuit includes a high-voltage JFET transistor, and the controllable high-voltage MOS circuit includes a first transistor; the high-voltage JFET transistor converts the high-voltage direct current into low-voltage direct current and transmits it to the first transistor, and then the first transistor accesses the low-voltage direct current and provides input protection for the subsequent circuit.

[0036] An application circuit of an AC-DC isolated power supply chip, including a transformer for voltage conversion, an output circuit for rectifying and filtering the output voltage of the transformer, and the AC-DC isolated power supply chip as described above;

[0037] The first end of the primary main winding of the transformer is connected to the fourth pin, the second end of the primary main winding of the transformer is connected to the third pin, the first end of the feedback winding of the transformer is connected to the first pin, the second end of the feedback winding of the transformer is grounded, and the first end and the second end of the secondary winding of the transformer are both connected to the output circuit.

[0038] The output circuit includes a first diode, a first resistor and a first capacitor. The input end of the first diode is connected to the first end of the secondary winding of the transformer. The output end of the first diode is connected to one end of the first capacitor and one end of the first resistor and supplies power to the output end device. The second end of the secondary winding of the transformer is connected to the other end of the first capacitor and the other end of the first resistor and is grounded.

[0039] A charging circuit, comprising:

[0040] A charging chip for charging a battery;

[0041] A first indicator light and a second indicator light for indicating the charging state;

[0042] And the application circuit of the AC-DC isolated power supply chip as described above;

[0043] The power input terminal of the charging chip is connected to the first end of the secondary winding of the transformer and the output circuit. The positive charging terminal of the charging chip is connected to the positive power supply of the battery, and the negative charging terminal of the charging chip is connected to the negative power supply of the battery. The first indication terminal and the second indication terminal of the charging chip are respectively connected to the first indicator light and the second indicator light.

[0044] Compared with the prior art, the AC-DC isolated power supply chip provided by the present invention is used to connect with a transformer and includes a chip body. In the chip body, there are provided: a rectification circuit for accessing high-voltage alternating current and rectifying it into high-voltage direct current; a high-voltage power extraction circuit for converting the high-voltage direct current into low-voltage direct current and generating the internal power supply voltage of the chip; an output drive circuit for driving the transformer to work; a logic processing circuit for outputting a drive control signal to the drive circuit. The rectification circuit is connected to the AC power supply, the transformer, and the high-voltage power extraction circuit. The high-voltage power extraction circuit is also connected to the logic processing circuit and the drive circuit. The logic processing circuit is also connected to the drive circuit, and the drive circuit is also connected to the transformer. By integrating the primary devices in the same chip, the present invention realizes the primary power supply and drive of the transformer only through the chip and the transformer, reducing the primary devices of the transformer and streamlining the circuit structure. Description of the Drawings

[0045] Figure 1 It is a structural block diagram of the AC-DC isolated power supply chip provided by the present invention;

[0046] Figure 2 It is a circuit schematic diagram of the high-voltage power extraction circuit provided by the present invention;

[0047] Figure 3 It is a pin diagram of the AC-DC isolated power supply chip provided by the present invention;

[0048] Figure 4 It is a circuit diagram of the application circuit of the AC-DC isolated power supply chip provided by the present invention;

[0049] Figure 5 It is a circuit diagram of the charging circuit provided by the present invention. Detailed Embodiments

[0050] The present invention provides an AC-DC isolated power supply chip, its application circuit and charging circuit. By integrating the primary devices in the same chip, the present invention realizes the primary power supply and drive of the transformer only through the chip and the transformer, reducing the primary devices of the transformer and streamlining the circuit structure.

[0051] The specific embodiments of the present invention are for the purpose of making a more detailed description of the technical concept, the technical problems to be solved, the technical features constituting the technical solution, and the technical effects brought by the present invention. It should be noted that the explanatory description of these embodiments does not constitute a limitation on the protection scope of the present invention. In addition, the technical features involved in the embodiments described below can be combined with each other as long as they do not conflict with each other.

[0052] To facilitate the understanding of the embodiments of the present application, the relevant elements involved in the embodiments of the present application are introduced here first.

[0053] Please refer to Figure 1 , the present invention provides an AC-DC isolated power supply chip U1, which is used to connect to a transformer T1A, and includes a chip body 10. In the chip body 10, there are provided: a rectification circuit 100 for accessing high-voltage alternating current and rectifying it into high-voltage direct current; a high-voltage power extraction circuit 200 for converting the high-voltage direct current into low-voltage direct current and generating the internal power supply voltage of the chip; an output driving circuit 400 for driving the transformer T1A to work; a logic processing circuit 300 for outputting a driving control signal to the driving circuit; the rectification circuit 100 is connected to an AC power supply, the transformer T1A, and the high-voltage power extraction circuit 200, the high-voltage power extraction circuit 200 is also connected to the logic processing circuit 300 and the driving circuit, the logic processing circuit 300 is also connected to the driving circuit, and the driving circuit is also connected to the transformer T1A.

[0054] In specific implementation, the AC-DC isolated power supply chip U1 in this embodiment can access the commercial power or other high-voltage alternating current. The input end of the rectification circuit 100 is connected to the live wire of the high-voltage AC power supply to access the high-voltage alternating current, and then rectify the high-voltage alternating current into high-voltage direct current and output it to the high-voltage power extraction circuit 200 and the transformer T1A outside the chip. The high-voltage power extraction circuit converts the high-voltage direct current into low-voltage direct current, and then converts the low-voltage alternating current into the internal power supply voltage VDD of the chip to supply power to each device inside the chip; for example, both the output driving circuit 400 and the logic processing circuit 300 need to be powered by the internal power supply voltage of the chip. When the logic circuit is powered on, it outputs a driving control signal to the output driving circuit 400. After receiving the driving control signal, the driving control circuit outputs a driving signal to drive the transformer T1A to work. The transformer T1A converts the high-voltage direct current into the corresponding external power supply voltage to supply power to external devices. In this embodiment, by integrating the primary devices in the same chip, only the chip and the transformer T1A are used to realize the primary power supply of the transformer T1A. While realizing the function of the switching power supply, the primary devices of the transformer T1A are reduced, and the circuit structure is simplified.

[0055] Specifically, please continue to refer to Figure 1 The AC-DC isolated power supply chip U1 further includes: a feedback circuit 500 for performing signal sampling on the transformer T1A to generate a sampling voltage; an error amplification circuit 600 for receiving and amplifying the sampling voltage; the feedback circuit 500 is connected to the transformer T1A and the error amplification circuit 600, and the error amplification circuit 600 is further connected to the logic processing circuit 300.

[0056] In specific implementation, in this embodiment, in the transformer T1A with a feedback winding, the feedback circuit 500 is connected to the feedback winding of the transformer T1A, performs signal sampling on the feedback winding, then outputs the obtained sampling voltage to the error amplifier for amplification to obtain a feedback signal, and finally outputs it to the logic processing circuit 300. The logic processing circuit 300 outputs a corresponding drive control signal according to the feedback signal to control the on / off of the output drive circuit 400, so as to control the working state (on or off) of the transformer T1A and realize the feedback regulation function.

[0057] Specifically, please continue to refer to Figure 1 The AC-DC isolated power supply chip U1 further includes: an overcurrent protection circuit 700 for performing overcurrent protection on the chip; the overcurrent protection circuit 700 is respectively connected to the output drive circuit 400 and the logic processing circuit 300.

[0058] In specific implementation, in this embodiment, the overcurrent protection circuit 700 is connected between the logic processing circuit 300 and the output drive circuit 400 to sample and analyze the current of the output drive circuit 400; when the current of the output drive circuit 400 is greater than the set value, an overcurrent feedback signal is output to the logic processing circuit 300, and the logic processing circuit 300 outputs a drive control signal to turn off the drive switch of the output drive circuit 400, so that the transformer T1A stops working, playing a role in overcurrent protection.

[0059] Specifically, please continue to refer to Figure 1 The AC-DC isolated power supply chip U1 further includes: an overtemperature protection circuit 800 connected to the logic processing circuit 300 for performing overtemperature protection on the chip.

[0060] In specific implementation, in this embodiment, the over-temperature protection circuit 800 detects the chip temperature. A temperature analysis circuit is internally provided. When the temperature inside the AC-DC isolated power supply chip U1 is higher than a preset value, an over-temperature feedback signal is output to the logic processing circuit 300. After receiving the over-temperature feedback signal, the logic processing circuit 300 outputs a drive control signal to turn off the drive switch of the output drive circuit 400, causing the transformer T1A to stop working, thus playing the role of over-temperature protection.

[0061] Specifically, please continue to refer to Figure 1 The AC-DC isolated power supply chip U1 further includes: an oscillation circuit 900 connected to the logic processing circuit 300 for providing a low-frequency oscillation to the logic processing circuit 300. In this embodiment, the oscillation circuit 900 is an RC oscillation circuit 900, which provides a low-frequency oscillation to the logic processing circuit 300 to enable the normal operation of the logic processing circuit 300.

[0062] Specifically, please refer to Figure 2 The high-voltage power extraction circuit 200 includes: a voltage conversion circuit 204 for converting high-voltage direct current into low-voltage direct current; a controllable high-voltage MOS circuit 205 for accessing the low-voltage direct current; a voltage sampling circuit 201 for sampling the voltage of the low-voltage direct current; a voltage regulation circuit 202 for converting the low-voltage direct current into an internal power supply voltage of the chip; an operational amplifier 203 for performing feedback regulation. The input end of the voltage conversion circuit 204 is connected to the output end of the rectification circuit 100. The output end of the voltage conversion circuit 204 is connected to the input end of the controllable high-voltage MOS circuit 205. The output end of the controllable high-voltage MOS circuit 205 is connected to the voltage sampling circuit 201 and the voltage regulation circuit 202. The voltage sampling circuit 201 is further connected to the inverting input end of the operational amplifier 203. The voltage regulation circuit 202 is further connected to the non-inverting input end of the operational amplifier 203. The output end of the operational amplifier 203 is connected to the control end of the controllable high-voltage MOS circuit 205.

[0063] In specific implementation, in this embodiment, the voltage conversion circuit accesses the high-voltage direct current obtained after rectification by the rectification circuit, converts the high-voltage direct current into low-voltage direct current, and then outputs it to the controllable high-voltage MOS circuit. The controllable high-voltage MOS circuit receives the low-voltage direct current and outputs it to the voltage sampling circuit and the voltage regulation circuit. Finally, the voltage regulation circuit obtains the internal power supply voltage (VDD) of the chip to supply power to each circuit inside the chip, and at the same time uses the internal power supply voltage of the chip as the feedback signal of the operational amplifier to achieve feedback regulation.

[0064] Specifically, the voltage conversion circuit includes a high-voltage JFET Q2, and the controllable high-voltage MOS circuit includes a first transistor Q1. The high-voltage JFET Q2 converts the high-voltage direct current into low-voltage direct current and transmits it to the first transistor. Then, the first transistor accesses the low-voltage direct current and provides input protection for the subsequent circuit.

[0065] During specific implementation, in this embodiment, the source of the high-voltage JFET Q2 (high-voltage junction field-effect transistor) accesses the high-voltage direct current. Through the characteristics of the junction field-effect transistor, low-voltage direct current is output from the high-voltage JFET Q2 to the drain of the first transistor Q1. The first transistor Q1 is a depletion-type MOS field-effect transistor. Since the depletion-type MOS transistor is a normally closed device and is in the conducting state when no voltage is applied to the gate, when the high-voltage direct current is accessed from the drain of the first transistor Q1, it can be directly transmitted to the source. After being sampled by the voltage sampling circuit 201 and regulated by the voltage regulation circuit 202, it is respectively output to the operational amplifier 203. A feedback loop is formed between the operational amplifier 203 and the gate of the first transistor Q1 to adjust the source current of the first transistor Q1. After the stable feedback regulation is stable, the required low-voltage direct current is obtained. Then, the internal supply voltage of the chip is obtained through the voltage regulation circuit, and the internal supply voltage of the chip is used as the feedback reference voltage of the operational amplifier 203. According to the feedback loop regulation in this embodiment, even if the voltage accessed by the output of the first transistor Q1 is extremely low, the source still has sufficient power supply capacity. Therefore, the AC-DC isolation power supply chip U1 can work normally from extremely low voltage to high voltage, which enables the cancellation of the high-voltage filter capacitor, simplifies the structure, reduces the cost, and improves the performance at the same time.

[0066] Specifically, please refer to Figure 3 , there are five or six pins provided on the chip body 10. When the number of pins is six, they are: the first pin FB, the second pin NC (spare), the third pin D, the fourth pin DC, the fifth pin AC, and the sixth pin GND. When the number of pins is five, they are the first pin FB, the third pin D, the fourth pin DC, the fifth pin AC, and the sixth pin GND. The first pin FB is connected to the feedback circuit 500 for signal sampling. The second pin NC is a reserved pin. The third pin D is connected to the output drive circuit 400 for driving external devices. The fourth pin DC is connected to the output end of the rectification circuit 100 for outputting high-voltage direct current. The fifth pin AC is connected to the input end of the rectification circuit 100 for accessing high-voltage alternating current. The sixth pin GND is the chip ground pin.

[0067] In specific implementation, in this embodiment, the first pin FB is a feedback pin, the second pin NC is a reserved pin, the third pin D is a drive pin, the fourth pin DC is a DC output pin, the fifth pin AC is an AC access pin, and the sixth pin GND is the chip ground pin. When the chip is in use, high-voltage alternating current is accessed through the fifth pin AC, and after being converted by the internal rectification circuit 100, high-voltage direct current is output from the fourth pin DC; at the same time, the high-voltage power extraction circuit 200 inside the chip also receives and obtains the high-voltage direct current as input, converts the high-voltage direct current into low-voltage direct current, and then generates the internal power supply voltage of the chip to supply power to other circuits inside the chip; after being powered on by the logic processing circuit 300, a drive control signal is output to the output drive circuit 400, so that the drive circuit is turned on to control the operation of the transformer T1A; then the first pin FB is connected to the feedback winding of the transformer T1A to obtain a feedback signal, and the logic processing circuit 300 controls the switching of the output drive circuit 400 according to the feedback signal to achieve the function of a controllable high-voltage MOS circuit.

[0068] Based on the above AC-DC isolated power supply chip U1, please refer to Figure 4 , the present invention also provides an application circuit of the AC-DC isolated power supply chip U1, including a transformer T1A for voltage conversion, an output circuit for rectifying and filtering the output voltage of the transformer T1A, and the AC-DC isolated power supply chip U1 as described above;

[0069] The first end of the primary main winding of the transformer T1A is connected to the fourth pin DC, the second end of the primary main winding of the transformer T1A is connected to the third pin D, the first end of the feedback winding of the transformer T1A is connected to the first pin FB, the second end of the feedback winding of the transformer T1A is grounded, and the first end and the second end of the secondary winding of the transformer T1A are both connected to the output circuit.

[0070] In specific implementation, in this embodiment, only the AC-DC isolated power supply chip U1 is provided on the primary side of the transformer T1A. The primary side of the transformer T1A directly obtains power from the AC-DC isolated power supply chip U1, and the AC-DC isolated power supply chip U1 controls the working state of the transformer T1A, so that it is possible to achieve the corresponding switching power supply function without adding additional devices on the primary side of the transformer T1A, simplifying the circuit structure and reducing the cost. Since the AC-DC isolated power supply chip U1 has been described in detail above, it will not be elaborated here.

[0071] Specifically, the output circuit includes a first diode D1, a first resistor R1, and a first capacitor C1. The input end of the first diode D1 is connected to the first end of the secondary winding of the transformer T1A. The output end of the first diode D1 is connected to one end of the first capacitor C1 and one end of the first resistor R1 and supplies power to the output device. The second end of the secondary winding of the transformer T1A is connected to the other end of the first capacitor C1 and the other end of the first resistor R1 and is grounded. In this embodiment, the first diode D1 is used to prevent the voltage of the subsequent circuit from backflushing, and the first capacitor C1 and the first resistor R1 form a filter circuit to filter the output of the transformer T1A.

[0072] Based on the above application circuit of the AC-DC isolation power supply chip U1, please refer to Figure 5 , the present invention also provides a charging circuit, including: a charging chip U2 for charging the battery; a first indicator light L1 and a second indicator light L2 for indicating the charging state; and the application circuit of the above-mentioned AC-DC isolation power supply chip U1. The power input terminal VCC of the charging chip U2 is connected to the first end of the secondary winding of the transformer T1A and the output circuit. The positive charging terminal BTP of the charging chip U2 is connected to the positive power supply of the battery. The negative charging terminal BTN of the charging chip U2 is connected to the negative power supply of the battery. The first indicator terminal LED1 and the second indicator terminal LED2 of the charging chip U2 are respectively connected to the first indicator light L1 and the second indicator light L2. Specifically, in this embodiment, a second capacitor C2 is further included. The second capacitor C2 is connected to the output ends of the first indicator light and the second indicator light, and the other end of the second capacitor C2 is grounded.

[0073] During specific implementation, in this embodiment, the power input terminal VCC of the charging chip U2 accesses the output voltage of the transformer T1A, and after internal processing by the chip, it is connected to the positive and negative electrodes of the battery to charge the battery. At the same time, the charging state (charging, charging completed, etc.) is indicated by the first indicator light L1 and the second indicator light L2. Specifically, the model of the charging chip U2 is 3582. Since the application circuit of the AC-DC isolation power supply chip U1 has been described in detail above, and the charging method is prior art, it will not be elaborated here.

[0074] In summary, an AC-DC isolated power supply chip provided by the present invention is used to connect to a transformer and includes a chip body. In the chip body, there are provided: a rectification circuit for accessing high-voltage alternating current and rectifying it into high-voltage direct current; a high-voltage power extraction circuit for converting the high-voltage direct current into low-voltage direct current and generating an internal power supply voltage of the chip; an output driving circuit for driving the transformer to work; a logic processing circuit for outputting a driving control signal to the driving circuit. The rectification circuit is connected to an AC power supply, a transformer, and the high-voltage power extraction circuit. The high-voltage power extraction circuit is also connected to the logic processing circuit and the driving circuit. The logic processing circuit is also connected to the driving circuit. The driving circuit is also connected to the transformer. By integrating the primary side devices in the same chip, the present invention realizes the power supply and driving of the primary side of the transformer only through the chip and the transformer, reduces the primary side devices of the transformer, and simplifies the circuit structure.

[0075] It can be understood that for those of ordinary skill in the art, equivalent substitutions or changes can be made according to the technical solutions and inventive concepts of the present invention, and all such changes or substitutions should fall within the protection scope of the claims appended to the present invention.

Claims

1. An AC-DC isolated power supply chip, characterized in that, For connection with a transformer, including a chip body, in which there are provided: A rectification circuit for accessing high-voltage alternating current and rectifying it into high-voltage direct current; A high-voltage power extraction circuit for converting the high-voltage direct current into low-voltage direct current and generating the internal power supply voltage of the chip; An output drive circuit for driving the transformer to work; A logic processing circuit for outputting a drive control signal to the drive circuit; The rectification circuit is connected to an AC power supply, a transformer and the high-voltage power extraction circuit, the high-voltage power extraction circuit is also connected to the logic processing circuit and the drive circuit, the logic processing circuit is also connected to the drive circuit, and the drive circuit is also connected to the transformer; The high-voltage power extraction circuit includes: A voltage conversion circuit for converting high-voltage direct current into low-voltage direct current; A controllable high-voltage MOS circuit for accessing the low-voltage direct current; A voltage sampling circuit for sampling the voltage of the low-voltage direct current; A voltage regulation circuit for converting the low-voltage direct current into the internal power supply voltage of the chip; An operational amplifier for performing feedback regulation; The input end of the voltage conversion circuit is connected to the output end of the rectification circuit, the output end of the voltage conversion circuit is connected to the input end of the controllable high-voltage MOS circuit, the output end of the controllable high-voltage MOS circuit is connected to the voltage sampling circuit and the voltage regulation circuit, the voltage sampling circuit is also connected to the inverting input end of the operational amplifier, the voltage regulation circuit is also connected to the non-inverting input end of the operational amplifier, and the output end of the operational amplifier is connected to the control end of the controllable high-voltage MOS circuit.

2. The AC-DC isolated power supply chip according to claim 1, wherein The AC-DC isolated power supply chip further includes: A feedback circuit for sampling signals of the transformer to generate a sampling voltage; An error amplification circuit for receiving the sampling voltage and amplifying it; The feedback circuit is connected to the transformer and the error amplification circuit, and the error amplification circuit is also connected to the logic processing circuit.

3. The AC-DC isolated power supply chip according to claim 2, wherein, The AC-DC isolated power supply chip further includes: An overcurrent protection circuit connected to the output drive circuit and the logic processing circuit for overcurrent protection of the chip; An overtemperature protection circuit connected to the logic processing circuit for overtemperature protection of the chip.

4. The AC-DC isolated power supply chip according to claim 3, wherein The AC-DC isolated power supply chip further includes: An oscillation circuit connected to the logic processing circuit for providing a low-frequency oscillation for the logic processing circuit.

5. The AC-DC isolated power supply chip according to claim 4, wherein, There are five or six pins provided on the chip body; when the number of pins is six, they are respectively: the first pin, the second pin, the third pin, the fourth pin, the fifth pin and the sixth pin; when the number of pins is five, they are respectively the first pin, the third pin, the fourth pin, the fifth pin and the sixth pin; The first pin is connected to the feedback circuit for signal sampling; The second pin is a reserved pin; The third pin is connected to the output drive circuit for driving external devices; The fourth pin is connected to the output end of the rectification circuit for outputting high-voltage direct current; The fifth pin is connected to the input end of the rectification circuit for accessing high-voltage alternating current; The sixth pin is the chip ground pin.

6. The AC-DC isolated power supply chip according to claim 5, wherein, The voltage conversion circuit includes a high-voltage JFET transistor, and the controllable high-voltage MOS circuit includes a first transistor; the high-voltage JFET transistor converts the high-voltage direct current into low-voltage direct current and transmits it to the first transistor, and then the first transistor accesses the low-voltage direct current and provides input protection for the subsequent circuit.

7. An application circuit of an AC-DC isolated power supply chip, characterized in that, It includes a transformer for voltage conversion, an output circuit for rectifying and filtering the output voltage of the transformer, and the AC-DC isolation power supply chip as claimed in claim 6; The first end of the primary main winding of the transformer is connected to the fourth pin, the second end of the primary main winding of the transformer is connected to the third pin, the first end of the feedback winding of the transformer is connected to the first pin, the second end of the feedback winding of the transformer is grounded, and the first end and the second end of the secondary winding of the transformer are both connected to the output circuit.

8. The application circuit of the AC-DC isolated power chip according to claim 7, wherein The output circuit includes a first diode, a first resistor and a first capacitor. The input end of the first diode is connected to the first end of the secondary winding of the transformer. The output end of the first diode is connected to one end of the first capacitor and one end of the first resistor and supplies power to the output device. The second end of the secondary winding of the transformer is connected to the other end of the first capacitor and the other end of the first resistor and is grounded.

9. A charging circuit, characterized in that, It includes: A charging chip for charging the battery; A first indicator light and a second indicator light for indicating the charging status; And the application circuit of the AC-DC isolation power supply chip as claimed in claim 7; The power input end of the charging chip is connected to the first end of the secondary winding of the transformer and the output circuit. The positive charging end of the charging chip is connected to the positive power supply of the battery. The negative charging end of the charging chip is connected to the negative power supply of the battery. The first indicating end and the second indicating end of the charging chip are respectively connected to the first indicator light and the second indicator light.

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