Switch controller with validation circuit for improved noise immunity

Abstract

A switch controller for controlling a power switch includes a signal transformer to galvanically isolate a primary side from a secondary side and receive and transfer a transition signal to transition the power switch to an on or off state between the primary side and the secondary side. The transition signal pulses to a first value to indicate the power switch transitions to the on state, to a second value to indicate the power switch transitions to the off state, and remains at a third value when there is no transition. A transmission circuit is coupled to a primary winding to control a switch to generate the transition signal. The switch switches a substantially low impedance onto the primary winding when there is no transition. A receiver circuit is coupled to a secondary winding to generate a drive signal to control the power switch in response to the transition signal.