Patent ID: 8680788

Claim:
A driver circuit operable to provide a current to a semiconductor light-emitting element, said driver circuit comprising: a DC-DC converter operable to provide current to the semiconductor light-emitting element from a DC power source, said DC-DC converter comprising an inductor, a freewheeling diode, and a power switch, wherein the power switch is configured to receive a pulse width modulated signal and cycle ON and OFF as a function of the pulse width modulated signal; a high frequency oscillating circuit operable to provide the pulse width modulated signal to the power switch of the DC-DC converter as a function of a reference voltage and a low frequency PWM signal and cycle the pulse width modulated signal between an ON state and an OFF state, wherein the high frequency oscillating circuit is further operable to maintain the pulse width modulated signal in the OFF state when the low frequency PWM signal is in an OFF state; an output sensor operable to provide a detection output indicative of at least one of the voltage of the semiconductor light-emitting element, the current provided by the DC-DC converter, or a power provided by the DC-DC converter; a dimming control circuit operable configured to receive a dimming control signal and provide a target value and the low frequency PWM signal as a function of the received dimming control signal; and a feedback controller operable to receive the detection output from the output sensor and the target value from the dimming control circuit and provide the reference voltage to the high frequency oscillating circuit as a function of the received detection output and the target value, wherein the feedback controller is operable to provide a minimum reference voltage when the received target value corresponds to a reference voltage less than the minimum reference voltage.