Control circuitry in a DC/DC converter for zero inductor current detection

摘要

A converter controller for discharge of a coil used in a DC/DC converter including a voltage detector connected to monitor a state of a diode connected between the coil and ground and an offset comparator, having an adjustable offset, for causing a coil discharge path to be interrupted. The comparator is provided with an initial high offset so that for at least a first converter switching period, the coil will have sufficient charge when the coil discharge path is interrupted to cause the diode to become forward biased as determined by the voltage detector. The offset is periodically reduced until the coil is sufficiently discharged so that the diode is not forward biased, with that value of offset being optimum and thus used in subsequent switching periods.