Current limiting in a DC-DC converter

摘要

Current limiting in a DC-DC converter comprises monitoring the inductor L current when the high side supply switch 10 is on against a peak current limit threshold 601. If the inductor current reaches the peak current limit threshold the high side switch is turned off. The inductor current when the low side switch 20 is off is monitored against a valley current threshold 602. As long as the inductor current is above the valley current threshold turn on of the low side switch is inhibited. In this way current limiting is provided and the problems of stair-stepping are avoided. Lossless current sensing may be provided. The invention may be implemented in a start-up mode of operation where the converter is controlled purely by the peak current limit and valley current threshold which are increased over time.