A High Speed On-Chip Soft-Start Technique With High Start-Up Stability for Current-Mode DC-DC Converter

In high efficiency and high-frequency applications, the soft-start methods for DC-DC converter with fast output voltage settling speed have attracted widespread attention. A novel soft-start circuit with controllable start-up time, high start-up speed, high stability, and no off-chip capacitor for a current mode DC-DC is proposed in this paper. The proposed soft-start circuit introduces a current-limiting feedback technique so that the inductor current during soft-start is controllable. The stability of the soft-start technique is verified theoretically in this paper. A Boost converter using this novel soft-start technique is fabricated in 0.35 μm BCD process. The soft-start time of the Boost converter is only 380 μs at the conditions of 45 V output voltage, 20 μF load capacitance, and 500 mA load current.