导通时间渐增的软启动电路

Soft-start circuit with progressive on-time

设计了一种控制开关管导通时间的软启动电路,消除了软启动过程中出现的浪涌电流和过冲电压,同时实现了启动时间的负载自适应,减少了轻载的启动时间.该电路可集成在DC-DC开关电源芯片中,有效地节省了应用电路板空间和元件成本.通过Cadence仿真验证,对于输入电压为3.6 V,输出电压为1.82 V的降压型开关电源,利用该启动电路,在启动过程中电感电流平稳变化,输出电压平滑上升无过冲;50 mA负载时启动时间为53μs,250 mA负载时启动时间为192μs.

A novel soft-start circuit based technology of controlling the switch time was presented to eliminate the surge current and the overshoot of the output voltage.This technology can realize load adapting of soft-start time,so the start-up time at light load is reduced.Because the circuit can be integrated on chip,the board space and component cost were reduced.For output voltage 1.82 V at input voltage 3.6 V,the simulation result by cadence indicates that the output voltage can start up stably in 53 μs under 50 mA load or 192 μs under 250 mA load with the circuit.And the inductor current keeps stable and the output voltage rises smoothly without overshot.