Monolithic Power Systems, Inc.
Adaptive feedback control in LED driving circuits

Abstract:

A feedback control circuit in an LED driving circuit for driving a plurality of LED strings. Each LED string provides a headroom detecting voltage. The feedback control circuit has a status detecting circuit, a counting circuit and a modulating circuit. The status detecting circuit compares each headroom detecting voltage with a low headroom threshold voltage and a high headroom threshold voltage and generates an up self-status signal and a down self-status signal. The counting circuit counts or keeps unchanged and then generates a counting signal based on the up self-status signal and the down self-status signal. The modulating circuit generates a modulating signal based on the counting signal. And based on the modulating signal, the feedback control circuit generates a feedback control signal to regulate a bias voltage supplying the plurality of LED strings.