Switching power supply monolithic switching regulator DN-25 configuration

Posted on Mar 28, 2007

As shown in FIG by DN-25 IC switching power supply. DN-25 is a monolithic switching power supply device, suitable for the production of medium output current, wide voltage rang

Switching power supply monolithic switching regulator DN-25 configuration
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e power supply. Its main performance indicators are as follows: Input voltage VIN 3 ~ 40V, output voltage Vo 1.25 ~ 24V (adjustable), the maximum output current IOM 1A, the maximum output power POM 36W, load short-circuit current limit IOSH 1.1A. DN-25 8-pin double-line package (DIP-8), the internal circuit includes: (1) an oscillator (OSC); (2) RS flip-flop; (3) output switch; (4) Voltage reference (VREF 1.25V) and a comparator. DN-25 internal oscillator frequency f foot accessed by the timing capacitor CT decision, f 1/CT.When turned on, the oscillator start-up, the output signal by the RS flip-flop VF converting plastic to produce a frequency to maintain the original, rectangular pulse excitation voltage, after the Darlington circuit and then by Q1, Q2 composed amplified by the output pin. Adjust the output voltage V0 is achieved by adjusting the voltage comparator inverting input pin can be realized. Change pin voltage can be adjusted RS flip-flop output excitation pulse width to cause a change in the output voltage Vo. The power supply VIN 25V, Vo (1 + RP/R) VREF, stability is 0.12%; load regulation of 0.03%; short-circuit current limit IOSH 1.1A; efficiency 82.50%; ripple is less than 120mVp-p. To further reduce the ripple, you can add a section LC filter at its output.

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