Patent ID: 8680781
Filing Date: 2014-03-25
Classification: H05B

Abstract:
1. A circuit for driving light emitting diodes, the circuit comprising: a first semiconductor switch and a freewheeling device coupled between a first supply terminal that provides a supply voltage and a second supply terminal that provides a reference potential, the first semiconductor switch being responsive to a driver signal; an LED and an inductor coupled in series between a common circuit node of the first semiconductor switch and the freewheeling device and either the first supply terminal or the second supply terminal; a current measurement circuit coupled to the LED, the current measurement circuit configured to provide a load current signal that represents a load current passing through the LED; a first feedback circuit including an on-off controller that is configured to receive the load current signal and a reference signal, to compare the load current signal with the reference signal, and to generate the driver signal dependent on the comparison; and a second feedback circuit configured to receive the load current signal, to determine an average load current signal, and to generate the reference signal supplied to the first feedback circuit dependent on the average load current signal and a reference value.