Dimming control for a switching power supply

摘要

A controller for dimming control of a switching power supply includes a phase angle measurement block and a drive logic block. The phase angle measurement block is to be coupled to receive an input sense signal. The phase angle measurement block generates a phase angle signal representative of a phase angle of an input voltage of the power supply in response to the input sense signal. The drive logic block is to be coupled to control switching of a switch included in the power supply. The drive logic block controls the switch in a closed loop dimming control when the phase angle is less than or equal to a phase threshold and in a open loop dimming control when the phase angle is greater than the phase threshold.