Patent ID: 7852642

Claim:
A full digital soft-start circuit, adapted for a power supply system, the full digital soft-start circuit comprising: a ring oscillator, adapted for generating a plurality of clock signals which are different in phase, while equivalent in duty cycle and frequency, according to an enable signal; a pulse generator, coupled to the ring oscillator, adapted for performing a digital logical operation, so as to generate a plurality of pulse signals with different duty cycles; a counter, coupled to the ring oscillator, and adapted for counting according to a corresponding one of the clock signals generated by the ring oscillator and thus generating a multi-bit counting signal, wherein the counter affects a soft-start time of the full digital soft-start circuit; and a multiplexer, coupled to the pulse generator and the counter, wherein the multiplexer determines whether to transmit the pulse signals with different duty cycles generated by the pulse generator, according to the counting signal generated by the counter, so as to generate an output pulse which duty cycle increases as time going on.