The purpose of this paper is to present a digital control method which suppresses the delay-time for the switching power supplies. The operation part of power supply has two controllers as the fast PD and the conventional PID, which are processed in parallel. Therefore, the fast PD control can improve the transient response of switching pulses. Obtained simulation results show that the proposed method can improve the transient response compared with the conventional PID control method. It is confirmed that 39% and 28% improvements have been obtained for undershoot and convergence time respectively.