Soft-Start with Hiccup Mode Short-Circuit Protection

Aiming at the voltage overshoot and output short-circuit problems of DC_DC switching power supply, a soft start circuit with hiccup mode short circuit protection is designed. Soft-start eliminates voltage overshoot caused by power-on, while short-circuit hiccup protection makes the system work safely and effectively. The structure proposed in this paper additionally realizes the short-circuit protection with “hiccup mode” in the traditional soft-start circuit, which saves the layout area. In addition, the circuit uses MOS capacitors instead of traditional MIM capacitors to further reduce the soft-start layout area. A DC_DC switching power supply chip is designed using 0.4 um BCD process to verify the proposed soft start circuit. The simulation results show that the power chip successfully realizes the soft start and short circuit protection mechanism. The layout area of the soft start is only 0.122 mm × 0.109 mm, and the power consumption is about 0.00612 mW.