Timing based signal valley detection

Abstract

An embodiment of a timing-based signal valley detection technique improves efficiency and reduces electromagnetic emissions due to ringing by controlling the off-time of a power switch in an LED driver or power converter application. The timing-based technique estimates a time of occurrence of a valley in the drain voltage of the power switch. The timing-based technique uses an analog comparator to sense the drain voltage of a power switch. The timing-based technique uses digital circuits to estimate the time of occurrence of the valley in the drain voltage and to adjust the duty cycle (e.g., adjusts the off-time by terminating the off-time) of a gate control signal of the power switch. The technique may use off-chip resistive voltage divider circuits to sense the drain voltage of the power switch and to generate a reference voltage and other circuits are integrated in an integrated circuit device.