Patent ID: 8456106

Claim:
A circuit for powering of a Light Emitting Diode (LED) string comprising: a switching power converter; and a brightness control circuit coupled to the switching power converter; wherein the brightness control circuit has a logic control block coupled to a brightness control signal and to a device for generating an error signal when an error voltage is exceeded, the logic control block sending a signal to maintain a conductive state of a switch of the switching power converter until the error voltage monitored at a compensator network of the brightness control circuit is exceeded for maintaining a current magnitude in the LED string constant; wherein the logic control block comprises: a logic gate having a first input coupled to a current sense comparator of the brightness control circuit and a second input coupled to a PWM pulse generator of the brightness control circuit; and a flip flop, wherein an output of the logic gate is coupled to a clock input of the flip flop, an input of the flip flop coupled to the PWM pulse generator of the brightness control circuit, and an output of the flip flop coupled to a brightness control circuit logic gate.