Switching voltage regulated power supply circuit diagram based on DN-25

After power on, the oscillator starts to oscillate, and the output VF signal is transformed and shaped by the RS trigger to generate a rectangular pulse excitation voltage that maintains the original frequency, which is then amplified by the Darlington circuit composed of Q1 and Q2 and output from pin ②. The adjustment of the output voltage V0 is achieved by adjusting the voltage of the inverting input terminal of the comparator, pin ⑤. The change of the voltage of pin ⑤ can adjust the excitation pulse width output by the RS trigger, thereby causing the output voltage Vo to change. The voltage regulator VIN=25V, Vo = (1+RP/R)×VREF, the stability is 0.12%; the load adjustment rate is 0.03%; the short-circuit limiting current IOSH=1.1A; the efficiency η=82.50%; the ripple is less than 120mVp-p. If the ripple needs to be further reduced, an LC filter can be added to its output. As shown in the figure, the switch voltage regulator of the DN-25 integrated circuit :