A power supply system, for discharging a resume and reset (RSMRST) signal during the RSMRST signal pull down, includes a voltage regulating circuit, a delay circuit, a switch circuit, and a discharge circuit. The voltage regulating circuit receives a first voltage signal and converts the first voltage signal to a second voltage signal. The delay circuit is charged by the second voltage signal and outputs the second voltage signal once fully charged. The switch circuit receives the second voltage signal and then outputs a RSMRST signal. The discharge circuit discharges the delay circuit. The delay circuit is charged during a first state and discharged during a second state.