Protection for bi-directional switch

摘要

A bi-directional protection circuit employs a single comparator for detecting fault conditions. Diodes are coupled between a detection node and voltage dividers setting references for inverting and non-inverting comparator inputs, each diode forward biased during one of the positive and negative halves of the alternating current input signal cycle and coupling the detection node to a respective one of the inverting and non-inverting comparator inputs, and reverse biased during the other of the positive and negative halves and decoupling the detection node from the other of the inverting and non-inverting comparator inputs. Upon an overcurrent condition during the positive half, a voltage at the inverting comparator input is drawn above the reference voltage at the non-inverting input. Upon an overcurrent condition during the negative half, a voltage at the non-inverting comparator input is drawn below the reference voltage at the inverting input.