Patent ID: 7636227
Filing Date: 2009-12-22
Classification: H02H

Abstract:
1. A circuit for providing over-current protection, the circuit including a gate driver circuit for controlling a bridge circuit including a half bridge stage having high and low switches, the circuit comprising: a feedback loop circuit for counting over-current indicators sensed during one or more consecutive PWM cycles, wherein when an over-current indicator is sensed, the low switch is turned OFF for duration of a first time period after which the low switch is turned back ON, to enable determination of an over-current condition whereby false over-current conditions due to noise signals are rejected thereby preventing circuit shutdowns due to the false over-current condition, the feedback loop circuit comprising: a comparator circuit for generating a comparison signal when a first current exceeds a user provided preset threshold and a pulse generator circuit coupled to the output of the comparator circuit for generating a disabling signal, wherein, when the comparison signal is generated, the low switch is turned OFF for the first time period by the pulse generator circuit after which the low switch is turned back on; a counter circuit for counting a number of occurrences of the comparison signal, the number of occurrences of the comparison signal in excess of a predetermined number indicating an over-current condition; and a latch circuit for resetting the counter circuit when the comparison signal does not occur for a second time period.