Practical high-power switching regulated power supply circuit schematic diagram

The figure shows the schematic diagram of a practical high-power switching regulated power supply circuit . The mains power is stepped down by power transformer TR1, rectified by diodes VD1~VD4, and filtered by capacitors C1 and C2 to obtain a DC voltage of nearly 40 V. Pins 1 and 2 of the switching regulator integrated circuit IC are DC voltage input terminals, and its maximum input voltage is +40 V. This DC voltage is modulated by the oscillator inside the IC into a high-frequency switching voltage of about ⒛0kHz. The switching frequency of the oscillator is determined by the external oscillation capacitor C4. When the value of C is 3300 pF, the switching frequency of the power supply is about 25kHz; resistor R3 and capacitor C6 form a loop adjustment amplifier frequency compensation network, which is input by pin 7 of the IC. Pin 4 of the IC is the suppression input terminal, and the threshold of the blocking voltage is 0.7 V. The output voltage is fed back to pin 4 through the sampling resistor R2 and then compared with R1. When the threshold voltage is greater than 0.7 V, the output is turned off. Short circuit overcurrent protection. Pin 6 is the output voltage adjustment control terminal. The output voltage is divided by the potentiometer RP and the resistor R4 to obtain the adjusted voltage detection value. Adjusting the potentiometer RP can control the output voltage. Pin 8 is the output terminal. In addition, VT is the current amplifier tube, VD5 is the reverse freewheeling diode, and L is the filter inductor.