Driving circuit of switching tube

Abstract

The utility model discloses a driving circuit of a switching tube, which comprises a suppression circuit, a first rectifying circuit, an energy storage circuit, a transformer T1, a PWM (Pulse Width Modulation) control circuit, a feedback circuit, a second rectifying circuit, an output energy storage circuit, an output voltage / current control circuit and an EMC (Electro Magnetic Compatibility) control circuit. An L line of the commercial power AC is connected with the fuse F1, and the suppression circuit carries out filtering and surge suppression on the commercial power; the first rectifying circuit converts alternating current into direct current, and the energy storage circuit stores electric energy; the PWM control circuit controls the switching tube to realize energy conversion of the transformer, and the feedback circuit ensures that the output voltage is stable; the second rectification circuit and the output energy storage circuit carry out rectification and energy storage on the secondary output of the transformer; the output voltage / current control circuit accurately adjusts output parameters; and the EMC control circuit enhances the electromagnetic compatibility of the circuit. The driving circuit can provide a stable switching tube driving waveform, and the stability, the reliability and the electromagnetic compatibility of a power supply system are effectively improved.

Description

A driving circuit for a switching transistor Technical Field

[0001] This utility model relates to the field of power supply drive circuit technology, and specifically to a drive circuit for a switching transistor. Background Technology

[0002] With the rapid development of technology, the number of electronic products has exploded, and the electromagnetic interference generated by various electronic devices during operation is also increasing. In power supply systems, the switching transistor, as a core component, plays a decisive role in the performance of the power supply due to the stability of its driving waveform. For some sensitive devices with extremely high requirements for power supply stability, such as precision instruments and medical equipment, distortion of the switching transistor's driving waveform may lead to unstable power output, thereby affecting the normal operation of the entire device and even causing serious malfunctions. Although the distortion of the driving waveform under extreme conditions is a low-probability event, in order to ensure the high quality and reliability of products, it is urgent to develop a switching transistor driving circuit that can provide a stable driving waveform.

[0003] Current switching transistor drive circuits struggle to guarantee the stability of the drive waveform in complex electromagnetic interference environments, and thus cannot effectively meet the operating requirements of sensitive power supplies. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a driving circuit for a switching transistor. By optimizing the circuit structure and functional module design, the problem of unstable driving waveform of the switching transistor in the prior art is solved, ensuring that the switching transistor can obtain a stable driving waveform under various complex electromagnetic interference environments, thereby ensuring the stable operation of the power supply system and related equipment, and improving the quality and reliability of the product.

[0005] To solve the above-mentioned technical problems, this utility model achieves this through the following solution: A driving circuit for a switching transistor according to this utility model includes a suppression circuit connected to AC mains power, a first rectifier circuit connected to the output terminal of the suppression circuit, an energy storage circuit connected to the output terminal of the first rectifier circuit, and a transformer T1 connected to the energy storage circuit. The driving circuit further includes:

[0006] A PWM control circuit for controlling the switching of the switching transistor and enabling the transformer T1 to perform energy conversion, the PWM control circuit being connected to the primary coil of the transformer T1.

[0007] A feedback circuit that controls the output voltage range, the feedback circuit being connected to the PWM control circuit;

[0008] The second rectifier circuit is connected to the secondary coil of the transformer T1;

[0009] The output energy storage circuit is connected to the output terminal of the second rectifier circuit;

[0010] The output voltage / current control circuit is connected to the output terminal of the second rectifier circuit;

[0011] The EMC control circuit is connected to the output terminal of the second rectifier circuit.

[0012] Furthermore, the L line of the AC mains power supply is connected to a fuse F1;

[0013] The suppression circuit includes an inductor LF1, a thermistor NTC1, resistors R31, R32, R33T, R34, and a capacitor CX1. Resistors R31 and R32 are connected in series to form a first series circuit, and resistors R33T and R34 are connected in series to form a second series circuit. The first series circuit, the second series circuit, and the capacitor CX1 are connected in parallel to form a parallel circuit. One end of the parallel circuit is connected to the rear circuit of the fuse F1, and the other end is connected to the neutral (N) line of the AC mains power supply.

[0014] The first end of the first coil of the inductor LF1 is connected to the rear circuit of the fuse F1;

[0015] The neutral (N) line of the AC mains power is connected to the thermistor NTC1, and the other end of the thermistor NTC1 is connected to the first end of the second coil of the inductor LF1.

[0016] Furthermore, the first rectifier circuit includes a first rectifier bridge BD1 and a second rectifier bridge BD2, and the negative output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 are interconnected and grounded to PGND;

[0017] The input terminal of the first rectifier bridge BD1 is connected to the second terminal of the first coil of the inductor LF1;

[0018] The input terminal of the second rectifier bridge BD2 is connected to the second terminal of the second coil of the inductor LF1.

[0019] Furthermore, the energy storage circuit includes polarized capacitors EC1, EC2, EC3, and EC4. The two ends of the parallel connection of polarized capacitors EC1 and EC2 are respectively connected to the positive output terminal and the negative output terminal of the first rectifier bridge BD1. The negative terminals of polarized capacitors EC1, EC2, EC3, and EC4 are grounded to PGND and connected to the negative output terminal of the first rectifier bridge BD1.

[0020] The positive output of the first rectifier bridge BD1 is connected to the first terminal of the inductor L2, and the inductor L2 is connected in parallel with a resistor R28.

[0021] The two ends of the parallel connection of the polarized capacitor EC3 and the polarized capacitor EC4 are respectively connected to the second end of the inductor L2 and the negative output terminal of the first rectifier bridge BD1.

[0022] Furthermore, the primary coil of the transformer T1 is provided with a primary first coil and a primary second coil. The two ends of the primary first coil are connected to a capacitor C12, the fourth pin of which is connected to the second end of the inductor L2, and the fifth pin of which is connected to the positive terminal of the diode D1. The negative terminal of the diode D1 is connected to a resistor R6, and a resistor R5 is connected in parallel with the resistor R6.

[0023] The other end of the resistor R6 is connected to the capacitor C1, and the other end of the capacitor C1 is connected to pin 4 of the primary first coil. The capacitor C1 is connected in parallel with resistors R4 and R3.

[0024] The first coil of the initial line is also connected to a resistor R1 at its 4th pin. The other end of the resistor R1 is connected to a resistor R2, and the other end of the resistor R2 is connected to the VCC circuit.

[0025] Furthermore, the PWM control circuit includes transistor Q1, PWM control chip U1, diode D4, resistor R8, capacitor C2, resistor R7, resistor R9, surface mount ferrite bead L1, resistor R10, Zener diode ZD1, resistor R11, resistor RS1, resistor RS2, resistor RS3 and capacitor C3.

[0026] The drain D of transistor Q1 is connected to pin 5 of the primary first coil. The first terminal of the parallel connection of resistors RS1, RS2, and RS3 is connected to the source S of transistor Q1. The second terminal of the parallel connection of resistors RS1, RS2, and RS3 is grounded to PGND.

[0027] The gate of the transistor Q1 is connected to the first end of the surface mount bead L1, the second end of the surface mount bead L1 is connected to the first end of the capacitor C2, and the capacitor C2 and the resistor R9 are connected in parallel.

[0028] The second end of the surface mount ferrite bead L1 is also connected to the first end of the resistor R10. The resistor R10 is connected in parallel with the Zener diode ZD1. The second end of the resistor R10 is connected to the source S of the transistor Q1, and the positive terminal of the Zener diode ZD1 is connected to the source S of the transistor Q1.

[0029] The first end of the resistor R11 is connected to the source S of the transistor Q1, and its second end is connected to the capacitor C3. The second end of the capacitor C3 is connected to the ground terminal of the resistor RS1.

[0030] Resistor R8 and diode D4 are connected in series and then in parallel with resistor R7. The first end of resistor R7 is connected to the second end of capacitor C2, and the cathode of diode D4 is connected to pin 6 (GATE) of PWM control chip U1.

[0031] The PWM control chip U1's pin 5 (VCC) is connected to the VCC circuit;

[0032] The 4th pin CS of the PWM control chip U1 is connected to the second end of the resistor R11;

[0033] The PWM control chip U1 has pin 1 (GND) grounded to PGND, and pin 2 is the feedback pin, which is connected to capacitor C4. The other end of capacitor C4 is connected to pin 1 (GND) of the PWM control chip U1.

[0034] The feedback pin is also connected to the collector of the light-receiving end U2B of the optocoupler U2, and the emitter of the light-receiving end U2B of the optocoupler U2 is grounded to PGND and connected to the ground terminal of the capacitor C4.

[0035] The PWM control chip U1 has its 4th pin CS connected to the first end of resistor R12. The second end of resistor R12 is connected to the cathode of diode D3. The anode of diode D3 is connected to resistors R15 and R13. The other end of resistor R15 is connected to the anode of diode D2. The other end of resistor R13 is connected to resistor R14. The other end of resistor R14 is grounded PGND. The circuit node between resistors R13 and R14 is connected to the PWM control chip U1's 3rd pin DEM.

[0036] The positive terminal of diode D3 is also connected to an NA circuit, which is connected to the NA pin of the primary second coil, and the other pin of the primary second coil is grounded to PGND.

[0037] The negative terminal of diode D2 is connected to capacitor C5, and capacitor C5 is connected in parallel with a polarized capacitor EC5. The negative terminal of the polarized capacitor EC5 is connected to the ground terminal of resistor R14, and the negative terminal of diode D2 is connected to the VCC circuit.

[0038] Furthermore, the second rectifier circuit includes a rectifier diode U3, a capacitor C6, a resistor R30, a resistor R13, a capacitor C7, and a diode D5. The VCC pin 2 of the rectifier diode U3 is connected to the first terminal of the capacitor C6, and the second terminal of the capacitor C6 is connected to the first terminal of the secondary coil. The GND pin 3 and the GND pin 4 of the rectifier diode U3 are interconnected and connected to the first terminal of the secondary coil.

[0039] The rectifier tube U3 has multiple D-pins, and the multiple D-pins are interconnected;

[0040] The resistor R16 and capacitor C7 are connected in series, and then connected in parallel with the diode D5;

[0041] The positive terminal of diode D5 is connected to the first end of the secondary coil, and its negative terminal is connected to pin D of rectifier U3. A resistor R30 is connected between pin D of rectifier U3 and pin VD of rectifier U3.

[0042] Furthermore, the output energy storage circuit includes a polarized capacitor EC7 and a polarized capacitor EC6, the negative terminals of which are connected to the second end of the secondary coil and grounded to GND.

[0043] The second end of the primary coil is also connected to capacitors CY2 and CY4 respectively. The other end of capacitor CY2 is connected to capacitor CY1. The other end of capacitor CY1 is connected to pin 4 of the primary first coil. The other end of capacitor CY4 is connected to capacitor CY3. The other end of capacitor CY3 is grounded to PGND.

[0044] The second end of the initial coil is also connected to the first end of the resistor RS4.

[0045] Furthermore, the EMC control circuit includes an inductor LF2, a resistor R17, and a capacitor C11. The first end of the first coil of the inductor LF2 is connected to the D pin of the rectifier U3. The second end of the first coil of the inductor LF2 outputs the VO+ circuit, and the second end of the first coil of the inductor LF2 is connected to the first end of the resistor R17.

[0046] The first end of the second coil of the inductor LF2 is connected to the second end of the resistor RS4, the second end of the second coil of the inductor LF2 outputs the VO- circuit, and the second end of the second coil of the inductor LF2 is connected to the second end of the resistor R17;

[0047] The resistor R17 and the capacitor C11 are connected in parallel.

[0048] Furthermore, the output voltage / current control circuit includes the light-emitting terminal U2A of the optocoupler U2, resistors R23, R22, and R21, capacitors C14, C13, and C9, resistors R24, R27, R19, R20, R29, R25, and R26, capacitors C10, R18, and C8;

[0049] The output voltage / current control circuit also includes three operational amplifiers, namely the first operational amplifier, the second operational amplifier, and the third operational amplifier;

[0050] A first resistor is connected between the non-inverting input terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier;

[0051] A second resistor is connected between the non-inverting input terminal of the second operational amplifier and the non-inverting input terminal of the third operational amplifier;

[0052] The non-inverting input terminal of the third operational amplifier is also connected to a third resistor, the second end of which is connected to the first end of resistor R26, and the second end of resistor R26 is grounded to GND.

[0053] The output terminals of the first operational amplifier and the second operational amplifier are connected. The positive power supply terminal of the first operational amplifier is connected to resistor R18 and capacitor C8, respectively. The other end of resistor R18 is connected to VO+, and the other end of capacitor C8 is grounded to GND.

[0054] The negative power supply pin of the second operational amplifier is grounded to GND and connected to the first end of resistor R29. The second end of resistor R29 is connected to the first end of resistor R20. The second end of resistor R20 is connected to the first end of resistor R19. The second end of resistor R19 is connected to the VO+ circuit.

[0055] The third operational amplifier has two negative power supply terminals. One negative power supply terminal is connected to the negative terminal of RED LED1, and the other negative power supply terminal is connected to the negative terminal of GREEN LED2. The positive terminals of RED LED1 and GREEN LED2 are interconnected and connected to the first terminal of resistor R27. The second terminal of resistor R27 is connected to the VO+ circuit.

[0056] The first end of resistor R25 is connected to the second end of resistor RS4. The second end of resistor R25 is connected to the first end of resistor R24, the first end of capacitor C10, and the inverting input of the third operational amplifier. The second end of capacitor C10 is connected to the ground terminal of resistor R26.

[0057] The second end of resistor R24 ​​is connected to the first end of capacitor C9, and the second end of capacitor C9 is connected to resistor R21, resistor R22, capacitor C13, and the output of the first operational amplifier.

[0058] The other end of the resistor R21 is connected to the capacitor C14, and the other end of the capacitor C14 is connected to the first end of the resistor R19.

[0059] The other end of the resistor R22 is connected to the negative terminal of the light-emitting terminal U2A of the optocoupler U2. The light-emitting terminal U2A of the optocoupler U2 is connected in parallel with the resistor R23. The positive terminal of the light-emitting terminal U2A of the optocoupler U2 is connected to the VO+ circuit.

[0060] Compared with the prior art, the beneficial effects of this utility model are:

[0061] High-stability drive waveform: Through the coordinated operation of multiple functional modules such as PWM control circuit, feedback circuit and output voltage / current control circuit, the switching action of the switching transistor can be precisely controlled, effectively preventing the distortion of the drive waveform under extreme conditions, providing a stable drive waveform for the switching transistor, ensuring the stable operation of the power supply system, and greatly improving the reliability of the product in complex electromagnetic environments.

[0062] 1. The driving circuit of the switching transistor in this utility model has excellent EMC performance: The design of the EMC control circuit, combined with the protection of the driving voltage by components such as resistors R7, R9, R10, and Zener diode ZD1, the filtering function of the surface-mount ferrite bead L1 for abnormal signals and interference, and the adjustment function of capacitor C2, resistor R8, and diode D4 for EMC, significantly enhances the electromagnetic compatibility of the circuit, reduces the electromagnetic interference generated by the circuit itself, and improves the circuit's ability to resist external electromagnetic interference, enabling the product to better meet the requirements of electromagnetic compatibility standards.

[0063] 2. The driving circuit of the switching transistor of this utility model can accurately control voltage and current: The output voltage / current control circuit, through the cooperation of multiple operational amplifiers and related resistors and capacitors, can achieve precise control and adjustment of output voltage and current. The output parameters can be flexibly adjusted according to actual application needs to meet the power supply requirements of different loads, further improving the applicability and reliability of the power supply.

[0064] 3. The driving circuit of the switching transistor of this utility model has comprehensive circuit protection functions: the fuse F1 set at the mains power input terminal can quickly cut off the circuit when the circuit is overloaded or short-circuited, protecting the circuit components from damage; the thermistor NTC1 and other components in the suppression circuit can effectively suppress surge current, protect the subsequent circuit to work stably, and enhance the safety and stability of the circuit. Attached Figure Description

[0065] Figures 1 to 6, when connected, form the overall circuit diagram of the driving circuit for the switching transistor of this utility model. Detailed Implementation

[0066] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments, so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present utility model. Obviously, the embodiments described in this utility model are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0067] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0068] Example 1: The specific structure of this utility model is as follows:

[0069] Please refer to Figures 1-6 and connect AA, BB, CC, DD, EE, FF, and GG in Figures 1-6 to form the overall circuit diagram of the drive circuit for the switching transistor of this utility model.

[0070] This utility model discloses a driving circuit for a switching transistor, comprising a suppression circuit connected to AC mains power, a first rectifier circuit connected to the output terminal of the suppression circuit, an energy storage circuit connected to the output terminal of the first rectifier circuit, and a transformer T1 connected to the energy storage circuit. The driving circuit further includes:

[0071] A PWM control circuit for controlling the switching of the switching transistor and enabling the transformer T1 to perform energy conversion, the PWM control circuit being connected to the primary coil of the transformer T1.

[0072] A feedback circuit that controls the output voltage range, the feedback circuit being connected to the PWM control circuit;

[0073] The second rectifier circuit is connected to the secondary coil of the transformer T1;

[0074] The output energy storage circuit is connected to the output terminal of the second rectifier circuit;

[0075] The output voltage / current control circuit is connected to the output terminal of the second rectifier circuit;

[0076] The EMC control circuit is connected to the output terminal of the second rectifier circuit.

[0077] Example 2:

[0078] The AC mains line is connected to a fuse F1. Fuse F1 is used for circuit protection. When a large current passes through fuse F1, fuse F1 will burn out.

[0079] As shown in Figure 1, the suppression circuit includes an inductor LF1, a thermistor NTC1, resistors R31, R32, R33T, R34, and a capacitor CX1. Resistors R31 and R32 are connected in series to form a first series circuit. Resistors R33T and R34 are connected in series to form a second series circuit. The first series circuit, the second series circuit, and the capacitor CX1 are connected in parallel to form a parallel circuit. One end of this parallel circuit is connected to the rear circuit of the fuse F1, and the other end is connected to the neutral (N) line of the AC mains. The first end of the first coil of the inductor LF1 is connected to the rear circuit of the fuse F1. The neutral (N) line of the AC mains is connected to the thermistor NTC1, and the other end of the thermistor NTC1 is connected to the first end of the second coil of the inductor LF1.

[0080] The suppression circuit suppresses inrush current: At the moment of circuit startup, the thermistor NTC1, due to its inherent characteristics, has a relatively high cold-state resistance, effectively limiting the inrush current entering the circuit and preventing excessive current from impacting the components, thus protecting subsequent components from damage by sudden large current surges. As the circuit operates, the temperature of NTC1 rises, and its resistance gradually decreases, reducing its obstruction to the normal operating current and not affecting the normal operation of the circuit.

[0081] The filtering function of the suppression circuit: Capacitor CX1 and inductor LF1 constitute the filter circuit. Capacitor CX1 has the characteristic of "passing AC and blocking DC", which can absorb high-frequency interference signals present in the AC mains power and guide them to the ground wire, making the output current smoother. Inductor LF1, on the other hand, "passes DC and blocks AC", hindering the passage of high-frequency AC signals, further filtering out high-frequency noise in the mains power, reducing the impact of interference on the circuit, and improving the stability and reliability of the circuit operation.

[0082] The suppression circuit utilizes voltage division and sampling: Resistors R31 and R32 are connected in series to form a first series circuit, and resistors R33T and R34 are connected in series to form a second series circuit. These two series circuits function as voltage dividers. By appropriately setting the resistor values, higher mains voltages can be proportionally reduced, providing suitable voltage signals for subsequent circuits. Simultaneously, these resistors can also be used for voltage sampling. By detecting the voltage after voltage division, feedback is sent to the control circuit to monitor and control the overall circuit operation. For example, when mains voltage fluctuates, the control circuit can adjust circuit parameters promptly through resistor voltage division sampling to ensure stable circuit operation. Overvoltage protection and stabilization: When the mains voltage rises abnormally, the parallel circuit composed of resistors and capacitors can dissipate some energy through its own characteristics, suppressing and buffering the excessively high voltage to a certain extent. This prevents the excessively high voltage from directly affecting downstream circuit components, providing overvoltage protection and ensuring the safety of circuit components. Furthermore, this circuit structure can stabilize the voltage in the circuit to a certain extent, reducing the impact of voltage fluctuations on circuit operation.

[0083] Example 3:

[0084] As shown in Figure 2, the function of the first rectifier circuit is to convert AC to DC output. The first rectifier circuit includes a first rectifier bridge BD1 and a second rectifier bridge BD2. The negative output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 are interconnected and grounded to PGND.

[0085] The input terminal of the first rectifier bridge BD1 is connected to the second terminal of the first coil of the inductor LF1.

[0086] The input terminal of the second rectifier bridge BD2 is connected to the second terminal of the second coil of the inductor LF1.

[0087] The function of inductor LF1 is that it is typically a transformer with two coils, and its main function is to transform the input AC voltage. Through electromagnetic induction between the two coils, the input AC voltage is converted into a suitable AC voltage value, which is then sent to the first rectifier bridge BD1 and the second rectifier bridge BD2 respectively.

[0088] The working principle of a rectifier bridge: A rectifier bridge consists of four diodes, and its function is to convert AC voltage into DC voltage. Taking the first rectifier bridge BD1 as an example, when the AC voltage at the second terminal of the first coil of inductor LF1 is in the positive half-cycle, some diodes in the rectifier bridge will conduct, and the current will flow along a specific path, thus generating a positive voltage at the output terminal. During the negative half-cycle of the AC voltage, the other diodes conduct, and the current still flows along a certain path, ultimately resulting in a positive voltage at the output terminal. Similarly, the second rectifier bridge BD2 will perform the same rectification operation on the AC voltage at the second terminal of the second coil of inductor LF1. Since the negative output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 are connected to ground PGND, their rectified DC voltages will be superimposed at the output terminal or distributed according to the specific load conditions, ultimately outputting a stable DC voltage.

[0089] Example 4:

[0090] As shown in Figure 2, the energy storage circuit includes polarized capacitors EC1, EC2, EC3, and EC4. The two ends of the parallel connection of polarized capacitors EC1 and EC2 are connected to the positive and negative output terminals of the first rectifier bridge BD1, respectively. The negative terminals of polarized capacitors EC1, EC2, EC3, and EC4 are grounded to PGND and connected to the negative output terminal of the first rectifier bridge BD1.

[0091] The polarized capacitors EC1, EC2, EC3, and EC4 are used for energy storage after rectification.

[0092] The charging process of the energy storage circuit is as follows: When the first rectifier bridge BD1 is working, it converts alternating current (AC) into direct current (DC). During the positive half-cycle of the DC output, current flows out from the positive terminal of the first rectifier bridge BD1. A portion of this current passes through the parallel branch of polarized capacitors EC1 and EC2, charging the capacitors. Since the voltage across the capacitor cannot change abruptly, the voltage across the capacitor gradually increases as charging progresses, until it approaches the DC voltage output by the rectifier bridge. During this process, electrical energy is stored between the capacitor plates in the form of electric field energy.

[0093] The energy storage circuit maintains voltage stability: after charging is complete, when the load in the circuit needs to consume electrical energy, polarized capacitors EC1 and EC2 release their stored charge to provide current to the load. Due to the energy storage function of the capacitors, even if the DC voltage output by the rectifier bridge fluctuates or the load current changes, the capacitors can maintain the stability of the output voltage to a certain extent, ensuring that the load can work normally.

[0094] The energy storage circuit employs a synergistic energy storage mechanism: although polarized capacitors EC3 and EC4 are described as having their negative terminals grounded and connected to the negative output terminal of the first rectifier bridge BD1, they also participate in the energy storage process. In the entire energy storage circuit, these four capacitors work together. By appropriately selecting parameters such as capacitance and voltage rating, the circuit's requirements for energy storage capacity and voltage stability can be met. For example, when the load experiences a large current demand, all four capacitors can simultaneously release charge, providing sufficient energy to meet the load's instantaneous high-power demand.

[0095] The positive output of the first rectifier bridge BD1 is connected to the first terminal of the inductor L2, and the inductor L2 is connected in parallel with a resistor R28.

[0096] The two ends of the parallel connection of the polarized capacitor EC3 and the polarized capacitor EC4 are respectively connected to the second end of the inductor L2 and the negative output terminal of the first rectifier bridge BD1.

[0097] As shown in Figure 3, the primary coil of the transformer T1 is provided with a primary first coil and a primary second coil. The two ends of the primary first coil are connected to a capacitor C12, the fourth pin of which is connected to the second end of the inductor L2, and the fifth pin of which is connected to the positive terminal of the diode D1. The negative terminal of the diode D1 is connected to a resistor R6, and a resistor R5 is connected in parallel with the resistor R6.

[0098] The other end of the resistor R6 is connected to the capacitor C1, and the other end of the capacitor C1 is connected to pin 4 of the primary first coil. The capacitor C1 is connected in parallel with resistors R4 and R3.

[0099] The first coil of the initial line is also connected to a resistor R1 at its 4th pin. The other end of the resistor R1 is connected to a resistor R2, and the other end of the resistor R2 is connected to the VCC circuit.

[0100] Example 5:

[0101] As shown in Figure 4, the PWM control circuit includes transistor Q1, PWM control chip U1, diode D4, resistor R8, capacitor C2, resistor R7, resistor R9, surface mount ferrite bead L1, resistor R10, Zener diode ZD1, resistor R11, resistor RS1, resistor RS2, resistor RS3 and capacitor C3. Resistor R7 is used to adjust the turn-on speed of PWM control chip U1.

[0102] The drain D of transistor Q1 is connected to pin 5 of the primary first coil. The first terminal of the parallel connection of resistors RS1, RS2, and RS3 is connected to the source S of transistor Q1. The second terminal of the parallel connection of resistors RS1, RS2, and RS3 is grounded to PGND.

[0103] The gate of transistor Q1 is connected to the first terminal of surface-mount ferrite bead L1, and the second terminal of surface-mount ferrite bead L1 is connected to the first terminal of capacitor C2. Capacitor C2 and resistor R9 are connected in parallel. Surface-mount ferrite bead L1 can effectively filter out interference waveforms that drive transistor Q1.

[0104] The second end of the surface-mount ferrite bead L1 is also connected to the first end of resistor R10. Resistor R10 is connected in parallel with Zener diode ZD1. The second end of resistor R10 is connected to the source S of transistor Q1, and the anode of Zener diode ZD1 is connected to the source S of transistor Q1. Resistors R9 and R10 form a voltage divider circuit, with part of the voltage fed into PWM control chip U1 and the other part output. Zener diode ZD1 regulates the driving voltage to prevent abnormal voltage fluctuations.

[0105] The first end of the resistor R11 is connected to the source S of the transistor Q1, and its second end is connected to the capacitor C3. The second end of the capacitor C3 is connected to the ground terminal of the resistor RS1.

[0106] Resistor R8 and diode D4 are connected in series, then in parallel with resistor R7. The first terminal of resistor R7 is connected to the second terminal of capacitor C2, and the cathode of diode D4 is connected to pin 6 (GATE) of the PWM control chip U1. This series circuit of resistor R8 and diode D4 is used to adjust the turn-off speed and waveform of MOSFET Q1, affecting EMC and energy efficiency. Changing the capacitance of capacitor C2 can accelerate the turn-on speed of MOSFET Q1.

[0107] The PWM control chip U1 has its 5-pin VCC pin connected to the VCC circuit.

[0108] The 4th pin CS of the PWM control chip U1 is connected to the second end of the resistor R11.

[0109] The PWM control chip U1 has pin 1 (GND) grounded to PGND, and pin 2 is the feedback pin, which is connected to capacitor C4. The other end of capacitor C4 is connected to pin 1 (GND) of the PWM control chip U1.

[0110] The feedback pin is also connected to the collector of the light-receiving end U2B of the optocoupler U2, and the emitter of the light-receiving end U2B of the optocoupler U2 is grounded to PGND and connected to the ground terminal of the capacitor C4.

[0111] The PWM control chip U1 has its 4th pin CS connected to the first end of resistor R12. The second end of resistor R12 is connected to the cathode of diode D3. The anode of diode D3 is connected to resistors R15 and R13. The other end of resistor R15 is connected to the anode of diode D2. The other end of resistor R13 is connected to resistor R14. The other end of resistor R14 is grounded to PGND. The circuit node between resistors R13 and R14 is connected to the PWM control chip U1's 3rd pin DEM.

[0112] The positive terminal of diode D3 is also connected to an NA circuit, which is connected to the NA pin of the primary second coil. The other pin of the primary second coil is grounded to PGND.

[0113] The negative terminal of diode D2 is connected to capacitor C5, and capacitor C5 is connected in parallel with a polarized capacitor EC5. The negative terminal of the polarized capacitor EC5 is connected to the ground terminal of resistor R14, and the negative terminal of diode D2 is connected to the VCC circuit.

[0114] The PWM control circuit startup phase: The VCC circuit supplies power to pin 5 (VCC) of the PWM control chip U1, enabling the chip to start working. Resistor R7 is used to adjust the turn-on speed of the PWM control chip U1. It is connected in parallel with the series circuit consisting of resistor R8 and diode D4, affecting the chip's operating state during startup. Transistor Q1 driving: The GATE output signal from pin 6 of the PWM control chip U1 drives transistor Q1 through a circuit consisting of a surface-mount bead L1, capacitor C2, resistors R9 and R10, and Zener diode ZD1. The surface-mount bead L1 filters out interference waveforms, ensuring the purity of the drive signal. Resistors R9 and R10 form a voltage divider circuit, sending a portion of the voltage to the PWM control chip U1 and using the other portion as the drive voltage. Zener diode ZD1 regulates the drive voltage to prevent abnormal voltage fluctuations. The capacitance of capacitor C2 affects the turn-on speed of MOSFET Q1; changing its capacitance can accelerate the turn-on of Q1.

[0115] The PWM control circuit uses three resistors, RS1, RS2, and RS3, connected in parallel between the source S of transistor Q1 and ground to detect the source current of Q1. Pin 4 (CS) of the PWM control chip U1 is connected to the second end of resistor R11. This circuit, consisting of resistor R11 and capacitor C3, detects the source current signal, thereby enabling the monitoring and control of the circuit current.

[0116] Feedback control: Pin 2 of the PWM control chip U1 is the feedback pin, connected to capacitor C4 and the collector of the light-receiving terminal U2B of optocoupler U2. Optocoupler U2 adjusts the output of the PWM control chip U1 based on the feedback signal from the secondary circuit, thereby achieving stable control of the output voltage or current.

[0117] The PWM control circuit's turn-off control: The series circuit consisting of resistor R8 and diode D4 is used to adjust the speed and waveform of MOSFET Q1's turn-off, which affects electromagnetic compatibility (EMC) and energy efficiency. When the PWM control chip U1 controls Q1 to turn off, this circuit optimizes the turn-off process.

[0118] Other related circuits of the PWM control circuit: Pin 3 (DEM) of the PWM control chip U1 is connected to relevant nodes through a circuit composed of resistor R12, diode D3, resistor R13, and resistor R14, etc., for detecting and processing specific signals, such as signals related to the primary second coil, to achieve comprehensive control of the entire circuit. A circuit composed of diode D2, capacitor C5, and polarized capacitor EC5 is connected to the VCC circuit to provide stable voltage support for the circuit.

[0119] Example 6:

[0120] As shown in Figure 5, the second rectifier circuit includes a rectifier U3, a capacitor C6, a resistor R30, a resistor R13, a capacitor C7, and a diode D5. The VCC pin 2 of the rectifier U3 is connected to the first end of the capacitor C6, and the second end of the capacitor C6 is connected to the first end of the secondary coil. The GND pin 3 and the GND pin 4 of the rectifier U3 are interconnected and connected to the first end of the secondary coil.

[0121] The rectifier tube U3 has multiple D-pins, which are interconnected.

[0122] The resistor R16 and capacitor C7 are connected in series, and then connected in parallel with the diode D5.

[0123] The positive terminal of diode D5 is connected to the first end of the secondary coil, and its negative terminal is connected to pin D of rectifier U3. A resistor R30 is connected between pin D of rectifier U3 and pin VD of rectifier U3.

[0124] The output energy storage circuit includes a polarized capacitor EC7 and a polarized capacitor EC6. The negative terminals of both the polarized capacitors EC7 and EC6 are connected to the second terminal of the secondary coil and grounded to GND.

[0125] The second end of the primary coil is also connected to capacitors CY2 and CY4 respectively. The other end of capacitor CY2 is connected to capacitor CY1. The other end of capacitor CY1 is connected to pin 4 of the primary first coil. The other end of capacitor CY4 is connected to capacitor CY3. The other end of capacitor CY3 is grounded to PGND.

[0126] The second end of the initial coil is also connected to the first end of the resistor RS4.

[0127] The second rectifier circuit input stage: The AC signal output from the transformer secondary coil is the input to the second rectifier circuit. An AC voltage exists between the first and second terminals of the secondary coil.

[0128] The second rectifier circuit's rectification stage: Rectifier diode U3 is the core rectifier component. Pin 2 (VCC) of rectifier diode U3 is connected to the first terminal of capacitor C6, and the second terminal of capacitor C6 is connected to the first terminal of the secondary coil; pins 3 (GND) and 4 (GND) of rectifier diode U3 are interconnected and connected to the first terminal of the secondary coil. When the secondary coil outputs a positive half-cycle AC signal, the current is rectified through the internal circuitry of rectifier diode U3, converting the AC signal into a DC signal.

[0129] The second rectifier circuit filtering stage: Capacitor C6: After the rectifier diode U3 outputs a DC signal, capacitor C6 starts working. It stores a portion of charge, and when the output voltage fluctuates, capacitor C6 releases or absorbs the charge, thereby smoothing the output voltage and reducing voltage ripple. Resistor R16 and capacitor C7: Resistor R16 and capacitor C7 are connected in series and then in parallel with diode D5. They form an RC filter circuit, further filtering out high-frequency noise and ripple, making the output DC signal more stable.

[0130] The second rectifier circuit protection stage: The positive terminal of diode D5 is connected to the first end of the secondary coil, and the negative terminal is connected to pin D of rectifier U3. When the output voltage of rectifier U3 experiences abnormal fluctuations or reverse voltage, diode D5 can prevent reverse current from flowing into rectifier U3, protecting rectifier U3 from damage.

[0131] The second rectifier circuit output stage: After rectification, filtering and protection, pin 1 VD of rectifier tube U3 outputs a relatively stable DC voltage, which can power the subsequent output energy storage circuit or other loads.

[0132] The second rectifier circuit and the output energy storage circuit are related as follows: The output energy storage circuit includes a polarized capacitor EC7 and a polarized capacitor EC6, both of whose negative terminals are connected to the second terminal of the secondary coil and grounded (GND). The DC voltage output by the second rectifier circuit charges the polarized capacitors EC7 and EC6, allowing them to store energy. When the load requires energy, the polarized capacitors EC7 and EC6 release the stored energy to power the load, ensuring stable operation.

[0133] In summary, the main function of the second rectifier circuit is to convert the AC signal output from the secondary coil of the transformer into a stable DC signal and supply power to the subsequent energy storage circuit or load.

[0134] Example 7:

[0135] As shown in Figure 6, the EMC control circuit includes an inductor LF2, a resistor R17, and a capacitor C11. The first end of the first coil of the inductor LF2 is connected to the D pin of the rectifier U3. The second end of the first coil of the inductor LF2 outputs the VO+ circuit, and the second end of the first coil of the inductor LF2 is connected to the first end of the resistor R17.

[0136] The first end of the second coil of the inductor LF2 is connected to the second end of the resistor RS4, the second end of the second coil of the inductor LF2 outputs the VO- circuit, and the second end of the second coil of the inductor LF2 is connected to the second end of the resistor R17.

[0137] The resistor R17 and the capacitor C11 are connected in parallel.

[0138] The output voltage / current control circuit includes the light-emitting terminal U2A of optocoupler U2, resistors R23, R22, and R21, capacitors C14, C13, and C9, resistors R24, R27, R19, R20, R29, R25, and R26, capacitors C10, R18, and C8.

[0139] The output voltage / current control circuit also includes three operational amplifiers, namely the first operational amplifier, the second operational amplifier, and the third operational amplifier.

[0140] A first resistor is connected between the non-inverting input terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier.

[0141] A second resistor is connected between the non-inverting input of the second operational amplifier and the non-inverting input of the third operational amplifier.

[0142] The non-inverting input of the third operational amplifier is also connected to a third resistor, the second end of which is connected to the first end of resistor R26, and the second end of resistor R26 is grounded to GND.

[0143] The output terminals of the first operational amplifier and the second operational amplifier are connected. The positive power supply terminal of the first operational amplifier is connected to resistor R18 and capacitor C8, respectively. The other end of resistor R18 is connected to VO+, and the other end of capacitor C8 is grounded to GND.

[0144] The negative power supply pin of the second operational amplifier is grounded to GND and connected to the first end of resistor R29. The second end of resistor R29 is connected to the first end of resistor R20. The second end of resistor R20 is connected to the first end of resistor R19. The second end of resistor R19 is connected to the VO+ circuit.

[0145] The third operational amplifier has two negative power supply terminals. One negative power supply terminal is connected to the negative terminal of RED LED1, and the other negative power supply terminal is connected to the negative terminal of GREEN LED2. The positive terminals of RED LED1 and GREEN LED2 are interconnected and connected to the first terminal of resistor R27. The second terminal of resistor R27 is connected to the VO+ circuit.

[0146] The first end of resistor R25 is connected to the second end of resistor RS4. The second end of resistor R25 is connected to the first end of resistor R24, the first end of capacitor C10, and the inverting input of the third operational amplifier. The second end of capacitor C10 is connected to the ground terminal of resistor R26.

[0147] The second end of resistor R24 ​​is connected to the first end of capacitor C9, and the second end of capacitor C9 is connected to resistor R21, resistor R22, capacitor C13, and the output of the first operational amplifier.

[0148] The other end of the resistor R21 is connected to the capacitor C14, and the other end of the capacitor C14 is connected to the first end of the resistor R19.

[0149] The other end of the resistor R22 is connected to the negative terminal of the light-emitting terminal U2A of the optocoupler U2. The light-emitting terminal U2A of the optocoupler U2 is connected in parallel with the resistor R23. The positive terminal of the light-emitting terminal U2A of the optocoupler U2 is connected to the VO+ circuit.

[0150] The function of inductor LF2: Inductor LF2 has two coils and acts as a common-mode inductor. A common-mode inductor effectively suppresses common-mode interference, which refers to interference signals that appear simultaneously on two or more conductors. First coil: The first end is connected to pin D of rectifier U3, and the second end outputs the VO+ circuit. It suppresses common-mode interference in the VO+ circuit, preventing it from being conducted through the power line. Second coil: The first end is connected to the second end of resistor RS4, and the second end outputs the VO- circuit, while also connecting to the second end of resistor R17. It suppresses common-mode interference in the VO- circuit. The function of resistor R17 and capacitor C11: Resistor R17 and capacitor C11 are connected in parallel, forming an RC filter network. Their functions are as follows: Capacitor C11: Presents low impedance to high-frequency interference signals, bypassing them to ground, thereby reducing the impact of high-frequency interference on the output voltage. Resistor R17: Limits the charging and discharging current of capacitor C11, preventing excessive current surges, and also acts as a damper to prevent circuit oscillation.

[0151] Overall operation process:

[0152] 1. Common-mode interference suppression: When common-mode interference signals exist in the circuit, since the two coils of the common-mode inductor LF2 are wound in the same direction, the magnetic field generated by the interference signal in the two coils is in the same direction, and the inductor presents high impedance, thereby suppressing the conduction of common-mode interference signals.

[0153] 2. High-frequency interference filtering: High-frequency interference signals are bypassed to ground through capacitor C11, while resistor R17 limits the charging and discharging current of capacitor C11, ensuring circuit stability. In this way, after processing by the EMC control circuit, the electromagnetic interference in the output VO+ and VO- signals is greatly reduced, meeting electromagnetic compatibility requirements.

[0154] This EMC control circuit uses the common-mode inductor LF2 to suppress common-mode interference and uses an RC filter network to filter high-frequency interference, ultimately achieving effective control of electromagnetic interference.

[0155] In summary, the driving circuit of the switching transistor of this utility model has excellent EMC performance: the design of the EMC control circuit, combined with the protection of the driving voltage by components such as resistors R7, R9, R10, and Zener diode ZD1, the filtering function of the surface-mount ferrite bead L1 for abnormal signals and interference, and the adjustment function of capacitor C2, resistor R8, and diode D4 for EMC, significantly enhances the electromagnetic compatibility of the circuit, reduces the electromagnetic interference generated by the circuit itself, and improves the circuit's ability to resist external electromagnetic interference, enabling the product to better meet the requirements of electromagnetic compatibility standards.

[0156] The driving circuit of the switching transistor in this invention can achieve precise voltage and current control: the output voltage / current control circuit, through the cooperation of multiple operational amplifiers and related resistors and capacitors, can achieve precise control and adjustment of output voltage and current. The output parameters can be flexibly adjusted according to actual application needs to meet the power supply requirements of different loads, further improving the applicability and reliability of the power supply.

[0157] The driving circuit of the switching transistor of this utility model has comprehensive circuit protection functions: the fuse F1 set at the mains input terminal can quickly cut off the circuit when the circuit fails due to overload or short circuit, protecting the circuit components from damage; the thermistor NTC1 and other components in the suppression circuit can effectively suppress surge current, protect the subsequent circuit to work stably, and enhance the safety and stability of the circuit.

[0158] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A driving circuit for a switching transistor, comprising a suppression circuit connected to AC mains power, a first rectifier circuit connected to the output terminal of the suppression circuit, an energy storage circuit connected to the output terminal of the first rectifier circuit, and a transformer T1 connected to the energy storage circuit, characterized in that, The drive circuit further includes: a PWM control circuit for controlling the switching of the switching transistor and enabling the transformer T1 to perform energy conversion, the PWM control circuit being connected to the primary coil of the transformer T1; a feedback circuit for controlling the output voltage range, the feedback circuit being connected to the PWM control circuit; a second rectifier circuit connected to the secondary coil of the transformer T1; an output energy storage circuit connected to the output terminal of the second rectifier circuit; an output voltage / current control circuit connected to the output terminal of the second rectifier circuit; and an EMC control circuit connected to the output terminal of the second rectifier circuit.

2. The driving circuit for a switching transistor according to claim 1, characterized in that, The L line of the AC mains power is connected to a fuse F1; the suppression circuit includes an inductor LF1, a thermistor NTC1, resistors R31, R32, R33T, R34, and a capacitor CX1. Resistors R31 and R32 are connected in series to form a first series circuit, and resistors R33T and R34 are connected in series to form a second series circuit. The first series circuit, the second series circuit, and the capacitor CX1 are connected in parallel to form a parallel circuit. One end of the parallel circuit is connected to the rear circuit of the fuse F1, and the other end is connected to the N line of the AC mains power; the first end of the first coil of the inductor LF1 is connected to the rear circuit of the fuse F1; the N line of the AC mains power is connected to the thermistor NTC1, and the other end of the thermistor NTC1 is connected to the first end of the second coil of the inductor LF1.

3. The driving circuit for a switching transistor according to claim 2, characterized in that, The first rectifier circuit includes a first rectifier bridge BD1 and a second rectifier bridge BD2. The negative output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 are interconnected and grounded to PGND. The input terminal of the first rectifier bridge BD1 is connected to the second terminal of the first coil of the inductor LF1. The input terminal of the second rectifier bridge BD2 is connected to the second terminal of the second coil of the inductor LF1.

4. The driving circuit for a switching transistor according to claim 3, characterized in that, The energy storage circuit includes polarized capacitors EC1, EC2, EC3, and EC4. The two ends of the parallel connection of polarized capacitors EC1 and EC2 are respectively connected to the positive and negative output terminals of the first rectifier bridge BD1. The negative terminals of polarized capacitors EC1, EC2, EC3, and EC4 are grounded to PGND and connected to the negative output terminal of the first rectifier bridge BD1. The positive output terminal of the first rectifier bridge BD1 is connected to the first terminal of inductor L2, and a resistor R28 is connected in parallel with inductor L2. The two ends of the parallel connection of polarized capacitors EC3 and EC4 are respectively connected to the second terminal of inductor L2 and the negative output terminal of the first rectifier bridge BD1.

5. The driving circuit for a switching transistor according to claim 4, characterized in that, The primary coil of the transformer T1 includes a primary first coil and a primary second coil. The two ends of the primary first coil are connected to a capacitor C12. Its fourth pin is connected to the second end of the inductor L2, and its fifth pin is connected to the positive terminal of a diode D1. The negative terminal of the diode D1 is connected to a resistor R6, and a resistor R5 is connected in parallel with the resistor R6. The other end of the resistor R6 is connected to a capacitor C1, and the other end of the capacitor C1 is connected to the fourth pin of the primary first coil. A resistor R4 and a resistor R3 are connected in parallel with the capacitor C1. The fourth pin of the primary first coil is also connected to a resistor R1, and the other end of the resistor R1 is connected to a resistor R2. The other end of the resistor R2 is connected to the VCC circuit.

6. The driving circuit for a switching transistor according to claim 5, characterized in that, The PWM control circuit includes a transistor Q1, a PWM control chip U1, a diode D4, a resistor R8, a capacitor C2, a resistor R7, a resistor R9, a surface-mount bead L1, a resistor R10, a Zener diode ZD1, a resistor R11, a resistor RS1, a resistor RS2, a resistor RS3, and a capacitor C3. The drain D of the transistor Q1 is connected to pin 5 of the primary winding. The first terminal of the parallel connection of resistors RS1, RS2, and RS3 is connected to the source S of the transistor Q1, and the second terminal of the parallel connection of resistors RS1, RS2, and RS3 is grounded to PGND. The gate of the transistor Q1 is connected to the first terminal of the surface-mount bead L1, and the second terminal of the surface-mount bead L1 is connected to the first terminal of the capacitor C2. The capacitor C2 and resistor R9 are connected in parallel; the second end of the surface-mount bead L1 is also connected to the first end of resistor R10, and resistor R10 is connected in parallel with the Zener diode ZD1. The second end of resistor R10 is connected to the source S of transistor Q1, and the anode of Zener diode ZD1 is connected to the source S of transistor Q1. The first end of resistor R11 is connected to the source S of transistor Q1, and its second end is connected to capacitor C3. The second end of capacitor C3 is connected to the ground terminal of resistor RS1. Resistor R8 and diode D4 are connected in series and then in parallel with resistor R7. The first end of resistor R7 is connected to the second end of capacitor C2, and the cathode of diode D4 is connected to pin 6 of the PWM control chip U1. GATE; Pin 5 (VCC) of the PWM control chip U1 is connected to the VCC circuit; Pin 4 (CS) of the PWM control chip U1 is connected to the second end of the resistor R11; Pin 1 (GND) of the PWM control chip U1 is grounded to PGND, and Pin 2 is the feedback pin, which is connected to capacitor C4. The other end of capacitor C4 is connected to Pin 1 (GND) of the PWM control chip U1; The feedback pin is also connected to the collector of the light-receiving end U2B of the optocoupler U2. The emitter of the light-receiving end U2B of the optocoupler U2 is grounded to PGND and connected to the ground terminal of capacitor C4; Pin 4 (CS) of the PWM control chip U1 is connected to the first end of the resistor R12, and the second end of the resistor R12 is connected to the cathode of diode D3. The positive terminal of diode D3 is connected to resistors R15 and R13. The other end of resistor R15 is connected to the positive terminal of diode D2. The other end of resistor R13 is connected to resistor R14. The other end of resistor R14 is grounded at PGND. The circuit node between resistors R13 and R14 is connected to pin 3 (DEM) of the PWM control chip U1. The positive terminal of diode D3 is also connected to the NA circuit, which is connected to the NA pin of the primary second coil. The other pin of the primary second coil is grounded at PGND. The negative terminal of diode D2 is connected to capacitor C5. Capacitor C5 is connected in parallel with a polarized capacitor EC5. The negative terminal of polarized capacitor EC5 is connected to the ground terminal of resistor R14. The negative terminal of diode D2 is connected to the VCC circuit.

7. The driving circuit for a switching transistor according to claim 6, characterized in that, The second rectifier circuit includes a rectifier diode U3, a capacitor C6, a resistor R30, a resistor R13, a capacitor C7, and a diode D5. Pin 2 (VCC) of the rectifier diode U3 is connected to the first terminal of the capacitor C6, and the second terminal of the capacitor C6 is connected to the first terminal of the secondary coil. Pins 3 (GND) and 4 (GND) of the rectifier diode U3 are interconnected and connected to the first terminal of the secondary coil. The rectifier diode U3 has multiple connected terminals (D), which are interconnected. The resistor R16 and capacitor C7 are connected in series and then in parallel with the diode D5. The anode of the diode D5 is connected to the first terminal of the secondary coil, and its cathode is connected to a connected terminal (D) of the rectifier diode U3. A resistor R30 is connected between the connected terminals (D) and pin 1 (VD) of the rectifier diode U3.

8. The driving circuit for a switching transistor according to claim 7, characterized in that, The output energy storage circuit includes polarized capacitors EC7 and EC6. The negative terminals of both polarized capacitors EC7 and EC6 are connected to the second terminal of the secondary coil and grounded to GND. The second terminal of the primary coil is also connected to capacitors CY2 and CY4. The other end of capacitor CY2 is connected to capacitor CY1, and the other end of capacitor CY1 is connected to pin 4 of the primary coil. The other end of capacitor CY4 is connected to capacitor CY3, and the other end of capacitor CY3 is grounded to PGND. The second terminal of the primary coil is also connected to the first terminal of resistor RS4.

9. The driving circuit for a switching transistor according to claim 8, characterized in that, The EMC control circuit includes an inductor LF2, a resistor R17, and a capacitor C11. The first end of the first coil of the inductor LF2 is connected to the D pin of the rectifier U3. The second end of the first coil of the inductor LF2 outputs a VO+ circuit, and the second end of the first coil of the inductor LF2 is connected to the first end of the resistor R17. The first end of the second coil of the inductor LF2 is connected to the second end of the resistor RS4. The second end of the second coil of the inductor LF2 outputs a VO- circuit, and the second end of the second coil of the inductor LF2 is connected to the second end of the resistor R17. The resistor R17 and the capacitor C11 are connected in parallel.

10. The driving circuit for a switching transistor according to claim 9, characterized in that, The output voltage / current control circuit includes the light-emitting terminal U2A of optocoupler U2, resistors R23, R22, and R21, capacitors C14, C13, and C9, resistors R24, R27, R19, R20, R29, R25, and R26, capacitors C10, R18, and C8; the output voltage / current control circuit also includes three operational amplifiers, namely a first operational amplifier, a second operational amplifier, and a third operational amplifier; a first resistor is connected between the non-inverting input terminals of the first and second operational amplifiers; a second resistor is connected between the non-inverting input terminals of the second and third operational amplifiers; the third operational amplifier... The non-inverting input is also connected to a third resistor, the second end of which is connected to the first end of resistor R26, and the second end of resistor R26 is grounded to GND. The outputs of the first operational amplifier and the second operational amplifier are connected. The positive power supply of the first operational amplifier is connected to resistor R18 and capacitor C8, respectively. The other end of resistor R18 is connected to VO+, and the other end of capacitor C8 is grounded to GND. The negative power supply pin of the second operational amplifier is grounded to GND and connected to the first end of resistor R29. The second end of resistor R29 is connected to the first end of resistor R20, the second end of resistor R20 is connected to the first end of resistor R19, and the second end of resistor R19 is connected to the VO+ circuit. The third operational amplifier has two negative power supplies. One negative power supply is connected to the negative terminal of RED LED1, and the other negative power supply is connected to the negative terminal of GREEN LED2. The positive terminals of RED LED1 and GREEN LED2 are connected to each other. The positive terminals of LED2 are interconnected and connected to the first terminal of resistor R27, and the second terminal of resistor R27 is connected to the VO+ circuit. The first terminal of resistor R25 is connected to the second terminal of resistor RS4. The second terminal of resistor R25 is connected to the first terminal of resistor R24, the first terminal of capacitor C10, and the inverting input terminal of the third operational amplifier. The second terminal of capacitor C10 is connected to the ground terminal of resistor R26. The second terminal of resistor R24 ​​is connected to the first terminal of capacitor C9. The second terminal of capacitor C9 is connected to resistor R21, resistor R22, capacitor C13, and the output terminal of the first operational amplifier. The other terminal of resistor R21 is connected to capacitor C14. The other terminal of capacitor C14 is connected to the first terminal of resistor R19. The other terminal of resistor R22 is connected to the negative terminal of the light-emitting terminal U2A of optocoupler U2. The light-emitting terminal U2A of optocoupler U2 is connected in parallel with resistor R23. The positive terminal of the light-emitting terminal U2A of optocoupler U2 is connected to the VO+ circuit.

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