A BUCK circuit based on uc3843

Abstract

This application relates to the technical field of circuit transformers, and in particular to a BUCK circuit based on the UC3843, comprising: a control module for receiving a transformer signal and generating a switch on / off signal based on the transformer signal; a drive module connected to the control module to receive the switch on / off signal and isolate and transmit the switch on / off signal to generate an isolation on / off signal; and a voltage adjustment module for receiving the isolation on / off signal and adjusting the voltage output according to the isolation on / off signal. This application converts a higher DC input voltage to a lower DC output voltage. The circuit achieves the same function as a transformer through a step-down method, reducing costs and improving space utilization.

Description

Technical Field

[0001] This application relates to the technical field of circuit transformers, and in particular to a BUCK circuit based on uc3843. Background Technology

[0002] Industrial electricity is an important guarantee for enterprise production. For factors such as power transmission, equipment safety, security, and economy, the appropriate voltage level is selected according to the power of the equipment. High-power equipment usually uses high-voltage power supply to reduce losses, while low-power equipment needs to use low-voltage power supply.

[0003] Currently, most industrial electricity uses transformers for voltage conversion, utilizing the principle of electromagnetic induction to transform alternating current from one voltage level to another while maintaining a constant frequency. Its core functions are voltage transformation, current transformation, and impedance matching.

[0004] However, a transformer is a static electrical device with a certain volume. In areas with limited space, installing a transformer for voltage transformation will occupy a certain amount of space, resulting in low space utilization and high cost. Utility Model Content

[0005] To reduce costs and improve space utilization, this application provides a BUCK circuit based on uc3843.

[0006] This application provides a BUCK circuit based on uc3843, which adopts the following technical solution:

[0007] A BUCK circuit based on uc3843 includes:

[0008] A control module is used to receive transformer signals and generate switch on / off signals based on the transformer signals;

[0009] A drive module is signal-connected to the control module to receive the switch on / off signal and isolate and transmit the switch on / off signal to generate an isolated on / off signal;

[0010] A voltage adjustment module is provided, which receives the isolation on / off signal and adjusts the voltage output according to the isolation on / off signal.

[0011] By adopting the above technical solution, the higher DC input voltage is converted into a lower DC output voltage based on the adjustment of the control module, drive module and voltage adjustment module. The circuit achieves the same function as the transformer by stepping down the voltage, reducing costs and improving space utilization.

[0012] Preferably, the control module includes a control unit and a detection unit. The control unit generates a switch on / off signal based on the transformer signal to control the switching transistor of the voltage regulation module to turn on and off.

[0013] The detection unit is used to detect the main circuit current and compare the main circuit current with the level inside the control unit. If the main circuit current is greater than the level inside the control unit, the current output of the main circuit is turned off.

[0014] By adopting the above technical solution, based on the real-time monitoring of the main circuit current by the detection unit, if the main circuit current is greater than the internal level of the control unit, the current output of the main circuit is shut off, thereby achieving overcurrent protection for the main circuit.

[0015] Preferably, the control module further includes a feedback unit, which provides a feedback signal and compares the feedback signal with a voltage reference signal of the control unit to output a stable voltage.

[0016] By adopting the above technical solution, the feedback signal is compared with the voltage reference signal of the control unit based on the feedback unit, and a stable voltage is output, thereby achieving the same function as a transformer, reducing costs and improving space utilization.

[0017] Preferably, the control module further includes a dynamic adjustment unit, which is used to monitor and compare the output signal at the output terminal with the error output in the control unit in order to adjust the duty cycle of the control unit.

[0018] By adopting the above technical solution, the output signal at the monitoring output terminal is compared with the error output in the control unit to adjust the duty cycle of the control unit and realize the voltage regulation of the main circuit.

[0019] Preferably, the drive module includes an isolation unit, a boosting unit, and a protection unit. The isolation unit is used to isolate the switch on / off signals and has generated isolated on / off signals.

[0020] The boosting unit is used to obtain the shutdown speed sent by the voltage adjustment module, and adjust the shutdown speed of the voltage adjustment module based on the shutdown speed.

[0021] The protection unit is used to monitor the output voltage of the voltage adjustment module in real time and generate a limiting voltage based on the output voltage.

[0022] By adopting the above technical solution, based on the isolation unit, the boosting unit and the protection unit, isolated signal transmission and feedback control are realized in the main circuit, the high voltage main circuit and the low voltage control circuit are physically isolated, and common mode noise interference or high voltage surge can be avoided to prevent damage to the chip; voltage spikes are suppressed to protect key components from instantaneous high voltage damage.

[0023] Preferably, the voltage adjustment module includes a voltage control unit and a signal suppression unit. The voltage control unit is used to receive the isolation on / off signal and adjust the voltage output according to the isolation on / off signal. The signal suppression unit is used to periodically monitor the current value of the voltage control unit and perform filtering operation based on the current value.

[0024] By adopting the above technical solution, based on the voltage control unit and the signal suppression unit, the stability and anti-interference capability of the main circuit are improved.

[0025] Preferably, the voltage control unit includes a switch Q1, and the protection unit includes TVS diodes D2 and D3. Port 1 of the switch Q1 is connected to one end of the TVS diodes D2 and D3 connected in series. Port 2 of the switch Q1 is connected to the VDC terminal, and port 3 of the switch Q1 is connected to port 2 of the mutual inductance transformer T1 of the detection unit.

[0026] By employing the above technical solution, when a voltage spike occurs in the circuit, the TVS diode quickly conducts, clamping the voltage within a safe range; TVS diode D2 is used to absorb and clamp voltage spikes, protecting critical components. TVS diode D3 prevents reverse voltage from damaging the optocoupler or UC3843.

[0027] Preferably, the boosting unit includes a resistor R10, a resistor R11, and a diode D1. The resistor R11 and the diode D1 are connected in series, and the series-connected resistor R11 is connected in parallel with the diode D1 and the resistor R10. One end of the parallel connection is connected to the isolation unit, and the other end of the parallel connection is connected to the protection unit.

[0028] By adopting the above technical solution, when the optocoupler secondary is turned on, the main circuit current charges the MOSFET gate of the voltage control unit switch through resistor R10. When the optocoupler secondary is turned off, the MOSFET gate charge is quickly discharged through diode D1, which significantly shortens the turn-off time, reduces the MOSFET turn-off loss, avoids the half-conducting state, and suppresses high-frequency oscillation.

[0029] Preferably, the signal suppression unit includes diode D5, diode D6, inductor L1, inductor L2, diode D7, diode D8, capacitor C7, and capacitor C8. Diode D5 is connected in series with inductor L1, and the series-connected diode D5, inductor L1, and diode D6 are connected in parallel. One end of the parallel connection is connected to one end of capacitor C7, and the other end of capacitor C7 is grounded. Capacitor C8, diode D7, and inductor L2 are connected in series, and the series-connected capacitor C8, diode D7, inductor L2, and diode D6 are connected in parallel.

[0030] By adopting the above technical solution, high-frequency current surges on the input side are suppressed. When switch Q1 is turned off, inductor L2 can slow down the rate of change of freewheeling current through diodes D7 and D8, reducing the impact of current surges on the load. Inductor L1 provides the freewheeling path when switch Q1 is turned off, diode D6 provides the freewheeling path of inductor L2 when switch Q1 is turned on, and capacitors C7 and C8 slow down the rate of change of freewheeling voltage when switch Q1 is turned off.

[0031] Preferably, the voltage control unit further includes resistors R14 and R15, which are voltage equalization resistors.

[0032] In summary, this application includes at least one of the following beneficial technical effects:

[0033] The circuit converts a higher DC input voltage to a lower DC output voltage by adjusting the control module, drive module, and voltage adjustment module. The circuit achieves the same function as a transformer by stepping down the voltage, reducing costs and improving space utilization.

[0034] Based on the real-time monitoring of the main circuit current by the detection unit, if the main circuit current is greater than the internal level of the control unit, the current output of the main circuit is shut off, thereby achieving overcurrent protection for the main circuit.

[0035] When the optocoupler secondary is turned on, the main circuit current charges the MOSFET gate of the voltage control unit's switch through resistor R10. When the optocoupler secondary is turned off, the MOSFET gate charge is quickly discharged through diode D1, significantly shortening the turn-off time, reducing MOSFET turn-off losses, avoiding the half-conducting state, and suppressing high-frequency oscillations. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the voltage input terminal structure of the voltage adjustment module.

[0038] Explanation of reference numerals in the attached drawings: 10, Control module; 11, Control unit; 12, Detection unit; 13, Feedback unit; 14, Dynamic adjustment unit; 20, Drive module; 21, Isolation unit; 22, Boosting unit; 23, Protection unit; 30, Voltage adjustment module; 31, Voltage control unit; 32, Signal suppression unit. Detailed Implementation

[0039] The present application will be further described in detail below with reference to the accompanying drawings.

[0040] This application discloses a BUCK circuit based on uc3843, which is applied in an industrial production system. It is mainly used to adjust the voltage conversion in industrial production. The controller based on uc3843 controls the conduction and disconnection of the BUCK circuit, which can convert a higher DC input voltage into a lower DC output voltage, thereby realizing the step-down operation of the circuit.

[0041] like Figure 1 As shown, the BUCK circuit based on uc3843 includes a control module 10, a drive module 20, and a voltage adjustment module 30. The control module 10 receives a transformer signal and generates a switch on / off signal based on the transformer signal. The drive module 20 is signal-connected to the control module 10 to receive the switch on / off signal and isolates and transmits the switch on / off signal to generate an isolation on / off signal. The voltage adjustment module 30 receives the isolation on / off signal and adjusts the voltage output according to the isolation on / off signal.

[0042] The transformer signal is primarily the signal required for transformer operation using the BUCK circuit based on the uc3843. In this embodiment, the transformer signal is received by default when the control module 10 is powered on, but it is not limited to this. The switch on / off signal represents the PWM wave signal generated by the control module 10, while the isolation on / off signal is generated by isolating the switch on / off signal through the drive module 20. The voltage adjustment module 30 receives the isolation on / off signal and, through its own operating mode, controls the switching transistor to turn on and off to achieve the step-down function.

[0043] The control module 10 includes a control unit 11, a detection unit 12, a feedback unit 13, and a dynamic adjustment unit 14. The control unit 11 generates a switch on / off signal based on the transformer signal to adjust the conduction and shutdown of the voltage adjustment module 30. The detection unit 12 detects the main circuit current and compares it with the internal level of the control unit 11. If the main circuit current is greater than the internal level of the control unit 11, the current output of the main circuit is turned off. When the main circuit current exceeds the internal level of the control unit 11, the control unit 11 immediately turns off the output of the switch on / off signal to prevent damage to the voltage adjustment module 30 or other loads due to overcurrent. The feedback unit 13 provides a feedback signal and compares it with the voltage reference signal of the control unit 11 to output a stable voltage. The dynamic adjustment unit 14 monitors the output signal at the output terminal and compares it with the error output in the control unit to adjust the duty cycle of the control unit 11.

[0044] Specifically, the control unit 11 includes a UC3843 chip. The output terminal OUT of the UC3843 chip is connected to one end of resistor R6, and the other end of resistor R6 is connected to the optocoupler U2 of the drive module 20. The power supply terminal VCC of the UC3843 chip is connected to an external power supply VCC to power on the UC3843 chip. The external power supply VCC is provided with power through VPWM.

[0045] The detection unit 12 includes a resistor R16, a diode D4, a resistor R13, a capacitor C4, and a mutual inductance transformer T1. The fourth port of the mutual inductance transformer T1 is connected to one end of the resistor R16, and the other end of the resistor R16 is grounded. The third port of the mutual inductance transformer T1 is grounded. The anode of the diode D4 is connected to the junction of the fourth port of the mutual inductance transformer T1 and the resistor R16, and the cathode of the diode D4 is connected to the ISENSE pin of the UC3843 chip. The junction between the cathode of the diode D4 and the ISENSE pin of the UC3843 chip is connected to both the resistor R13 and the capacitor C4, with the other end of both resistor R13 and capacitor C4 grounded.

[0046] Specifically, resistor R16 is a 519-ohm resistor, and resistor R13 is a 100-ohm resistor, but this is not a limitation. The mutual inductance transformer T1 detects the current in the main circuit by adjusting the turns ratio of the preceding and following stages. The current signal is converted into a voltage signal through resistor R16, diode D4, resistor R13, and capacitor C4, and finally, overcurrent protection is provided by the ISENSE pin of the UC3843 chip.

[0047] Feedback unit 13 includes resistors R1, R2, R3, R4, and R5, and capacitors C1, C2, and C3. One end of resistor R1 is grounded, and the other end is connected in series with resistors R2, R3, and R4. The connection points between resistors R1 and R2 include a first connection point and a second connection point. The COMP terminal of the UC3843 chip is connected to one end of capacitor C2, and the other end of capacitor C2 is connected to resistor R5. The other end of resistor R5 is connected to the second connection point. The VFB terminal of the UC3843 chip is connected to capacitor C3, and the other end of capacitor C3 is connected to the connection point between the COMP terminal of the UC3843 chip and capacitor C2. The VFB terminal of the UC3843 chip is connected to one end of capacitor C1, and the other end of capacitor C1 is grounded. The first connection point is located at the connection point between capacitor C3 and the VFB terminal of the UC3843 chip.

[0048] Voltage feedback signals are obtained through resistors R1, R2, R3, and R4, and capacitor C1. These signals are compared with the voltage reference signal inside the UC3843 chip to form a closed loop, achieving a stable output voltage. The output voltage value can be adjusted by changing the voltage divider values ​​of resistors R1, R2, R3, and R4. Resistors R1, R2, R3, and R4 can all be of the same type.

[0049] The dynamic adjustment unit 14 includes resistors R7, R8, and R9, capacitors C5 and C6, and a selector Q2. The collector of selector Q2 is connected to the VREF terminal, and the emitter of selector Q2 is connected to one end of resistor R8. The other end of resistor R8 is grounded. Resistor R7 and capacitor C5 are connected in series, with one end connected to the ISENSE pin of the UC3843 chip and the other end connected to the junction between resistor R8 and selector Q2. The base of selector Q2 is connected in series with one end of capacitor C6. The RT / CT pin of the UC3843 chip and capacitor C6 are connected in parallel to the base of selector Q2, and the other end of capacitor C6 is grounded. One end of resistor R9 is connected in parallel with capacitor C6, and the other end of resistor R6 is connected to VREF. Resistor R9 is a timing resistor, and capacitor C6 is a timing capacitor. Resistor R9 and capacitor C6 together determine the oscillator frequency and maximum duty cycle of the UC3843 chip.

[0050] It should be noted that the VREF pin is the 5V reference output of the UC3843. In PWM control chips such as the UC3843, VREF is a key pin used to provide a high-precision and stable reference voltage, usually 5V, to provide a reference voltage for the internal and external circuits of the chip.

[0051] The drive module 20 includes an isolation unit 21, a boosting unit 22, and a protection unit 23. The isolation unit 21 is used to isolate the switch on / off signal and generate an isolated on / off signal. The boosting unit 22 is used to obtain the turn-off speed sent by the voltage adjustment module 30 and adjust the turn-off speed of the voltage adjustment module 30 based on the turn-off speed. The protection unit 23 is used to monitor the output voltage of the voltage adjustment module 30 in real time and generate a limiting voltage based on the output voltage.

[0052] The isolation unit 21 includes an optocoupler U2. The anode of the optocoupler U2 is connected to one end of the resistor R6, the cathode of the optocoupler U2 is grounded, and the optocoupler U2 is powered by a power supply, specifically a 12V power supply.

[0053] The boosting unit 22 includes resistors R10 and R11 and diode D1. The protection unit 23 includes TVS diodes D2 and D3, which are connected in series. Resistor R11 is connected in series with diode D1, and the series-connected resistor R11, diode D1, and resistor R10 are connected in parallel. The parallel connection is connected to the input terminal of the U2B port of optocoupler U2, and the other end of the parallel connection is connected to the series-connected TVS diodes D2 and D3. The other end of the series-connected TVS diodes D2 and D3 is connected to the collector of optocoupler U2.

[0054] The voltage adjustment module 30 includes a voltage control unit 31 and a signal suppression unit 32. The voltage control unit 31 is used to receive the isolation on / off signal and adjust the voltage output according to the isolation on / off signal. The signal suppression unit 32 is used to periodically monitor the current value of the voltage control unit 31 and perform filtering operation based on the current value.

[0055] The voltage control unit 31 includes a switch Q1, a diode D9, an inductor L3, a capacitor C9, and a capacitor C10. Port 1 of switch Q1 is connected to one end of a series-connected TVS diode D2 and TVS diode D3. A resistor R12 is connected in parallel between ports 1 and 3 of switch Q1, with one end of the parallel connection connected to one end of resistor R10, and the other end connected to the output terminal of port U2B of optocoupler U2. Port 2 of switch Q1 is connected to the VDC terminal. Port 2 of mutual inductance transformer T1 is connected at the connection point between port 3 of switch Q1 and the emitter of optocoupler U2.

[0056] Combination Figure 2 The two ports of switch Q1 are connected to the VDC terminal, specifically using... Figure 2 The circuit components rectify the three-phase 380V input to a DC bus VDC of 540V via a rectifier bridge. This VDC input is then fed into a BUCK circuit based on the uc3843 to perform voltage step-down. Resistors R71, R192, R202, and R203, along with capacitors C197 and C198, are used. Resistors R71 and R192 are connected in series, as are R202 and R203. The series resistors R71 and R192 and capacitor C197 are connected in parallel, as are the series resistors R202 and R203 and capacitor C198. One end of the parallel connection is grounded, and the other end is connected to the VDC output. The three-phase rectifier bridge (BD1) rectifies the AC power (R, S, and T phases) into DC power, which is then output through the VDC port.

[0057] It should be noted that the input 3-phase 380V AC power is converted into 540V DC power. The DC voltage after rectification is smoothed by filtering through capacitors C197 and C198. The specific rectification method used is conventional and will not be elaborated upon here.

[0058] The voltage control unit 31 also includes a capacitor C9 and a resistor R14 connected in parallel, and a capacitor C10 and a resistor R15 connected in parallel. The parallel capacitors C9 and R14 and C10 and R15 are connected in series, with one end of the series connection grounded and the other end connected to one end of the series resistor R4. Furthermore, the two ends of the parallel capacitor C9 and resistor R14 are respectively connected to one end of inductor L3 and the output terminal of VDC1. The other end of inductor L3 is connected to the negative terminal of diode D9, and the positive terminal of diode D9 is grounded.

[0059] The signal suppression unit 32 includes diodes D5 and D6, inductors L1 and L2, diodes D7 and D8, capacitors C7 and C8. One end of inductor L1 is connected to the first port of mutual inductance transformer T1, and the other end is connected to the connection point of inductor L3 and diode D9. Diode D5 and capacitor C7 are connected in series, with one end connected to the connection point of inductor L1 and the first port of mutual inductance transformer T1, and the other end grounded. Diodes D8, D7, L2, and D6 are connected in series, with one end connected to the connection point between inductor L1 and inductor L3, and the other end grounded. One end of capacitor C8 is connected to the connection point between inductor L1 and inductor L3, and the other end is connected to the negative terminal of diode D8. The positive terminal of diode D5 is connected to capacitor C7, and the connection point between diode D5 and capacitor C7 is connected to the connection point between diode D6 and inductor L2.

[0060] Inductor L1 is several orders of magnitude smaller than inductor L3. Inductor L1 primarily suppresses high-frequency current changes, while inductor L3 suppresses low-frequency current changes. Their combination effectively extends the frequency range. Inductor L2 slows down the rate of change of freewheeling current through diodes D7 and D8 when switch Q1 is off, reducing the impact of sudden current changes on the load. Diode D5, inductor L2, diodes D7 and D8 form the freewheeling path of inductor L1 when switch Q1 is off, while diode D6 forms the freewheeling path of inductor L2 when switch Q1 is on. Capacitors C7 and C8 slow down the rate of change of freewheeling voltage when switch Q1 is off. Capacitors C9 and C10 are connected in series to improve the capacitor's voltage withstand capability. Resistors R14 and R15 are voltage equalization resistors for the capacitors.

[0061] The implementation principle is as follows:

[0062] The two ports of switch Q1 are connected to the VDC terminal, which receives a three-phase 380V input voltage and rectifies it to a 540V DC bus voltage via a rectifier bridge. A voltage feedback signal is then obtained through resistors R1, R2, R3, and R4, and capacitor C1. This feedback signal is compared with the voltage reference signal inside the UC3843 chip to form a closed loop, achieving a stable output voltage. The output voltage at the VDC1 terminal can be adjusted by changing the voltage divider values ​​of resistors R1, R2, R3, and R4. When switch Q1 is off, the rate of change of freewheeling current through diodes D7 and D8 is reduced, minimizing the impact of sudden current changes on the load. Diodes D5, L2, D7, and D8 form the freewheeling path for inductor L1 when switch Q1 is off, and D6 forms the freewheeling path for inductor L2 when switch Q1 is on. Capacitors C7 and C8 mitigate the rate of change of freewheeling voltage when switch Q1 is off.

[0063] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A BUCK circuit based on uc3843, characterized in that, include: The control module (10) is used to receive the transformer signal and generate a switch on / off signal based on the transformer signal; The drive module (20) is signal-connected to the control module (10) to receive the switch on / off signal and to isolate and transmit the switch on / off signal to generate an isolated on / off signal; Voltage adjustment module (30) is used to receive the isolation on / off signal and adjust the voltage output according to the isolation on / off signal.

2. The BUCK circuit based on uc3843 according to claim 1, characterized in that, The control module (10) includes a control unit (11) and a detection unit (12). The control unit (11) generates a switch on / off signal based on the transformer signal in order to control the switching transistor of the voltage adjustment module (30) to turn on and off. The detection unit (12) is used to detect the main circuit current and compare the main circuit current with the level inside the control unit (11). If the main circuit current is greater than the level inside the control unit (11), the current output of the main circuit is turned off.

3. The BUCK circuit based on uc3843 according to claim 2, characterized in that, The control module (10) further includes a feedback unit (13), which provides a feedback signal and compares the feedback signal with the voltage reference signal of the control unit (11) to output a stable voltage.

4. The BUCK circuit based on uc3843 according to claim 2, characterized in that, The control module (10) further includes a dynamic adjustment unit (14), which is used to monitor the output signal at the output terminal and compare it with the error output in the control unit (11) to adjust the duty cycle of the control unit (11).

5. The BUCK circuit based on uc3843 according to claim 2, characterized in that, The drive module (20) includes an isolation unit (21), a boosting unit (22), and a protection unit (23). The isolation unit (21) is used to isolate the switch on / off signal and has generated an isolated on / off signal. The boosting unit (22) is used to obtain the turn-off speed sent by the voltage adjustment module (30) and adjust the turn-off speed of the voltage adjustment module (30) based on the turn-off speed; The protection unit (23) is used to monitor the output voltage of the voltage adjustment module (30) in real time and generate a limiting voltage based on the output voltage.

6. The BUCK circuit based on uc3843 according to claim 5, characterized in that, The voltage adjustment module (30) includes a voltage control unit (31) and a signal suppression unit (32). The voltage control unit (31) is used to receive the isolation on / off signal and adjust the voltage output according to the isolation on / off signal. The signal suppression unit (32) is used to periodically monitor the current value of the voltage control unit (31) and perform filtering operation based on the current value.

7. The BUCK circuit based on uc3843 according to claim 6, characterized in that, The voltage control unit (31) includes a switch Q1, and the protection unit (23) includes a TVS diode D2 and a TVS diode D3. Port 1 of the switch Q1 is connected to one end of the TVS diodes D2 and D3 connected in series. Port 2 of the switch Q1 is connected to the VDC terminal. Port 3 of the switch Q1 is connected to port 2 of the mutual inductance transformer T1 of the detection unit (12).

8. The BUCK circuit based on uc3843 according to claim 7, characterized in that, The lifting unit (22) includes a resistor R10, a resistor R11 and a diode D1. The resistor R11 and the diode D1 are connected in series. The series resistor R11 is connected in parallel with the diode D1 and the resistor R10. One end of the parallel connection is connected to the isolation unit (21), and the other end of the parallel connection is connected to the protection unit (23).

9. The BUCK circuit based on uc3843 according to claim 6, characterized in that, The signal suppression unit (32) includes diode D5, diode D6, inductor L1, inductor L2, diode D7, diode D8, capacitor C7, and capacitor C8. Diode D5 is connected in series with inductor L1, and the series-connected diode D5, inductor L1, and diode D6 are connected in parallel. One end of the parallel connection is connected to one end of capacitor C7, and the other end of capacitor C7 is grounded. Capacitor C8, diode D7, and inductor L2 are connected in series in sequence, and the series-connected capacitor C8, diode D7, inductor L2, and diode D6 are connected in parallel. The negative end of diode D8 is connected to the connection point of capacitor C8 and diode D7, and the positive end of diode D8 is grounded.

10. The BUCK circuit based on uc3843 according to claim 7, characterized in that, The voltage control unit (31) also includes resistors R14 and R15, which are equalizing resistors.

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