Patent ID: 7372883
Filing Date: 2008-05-13
Classification: H01S

Abstract:
1. A driving circuit comprising: a current sensing circuit coupled to one or more light emitting devices, the current sensing circuit adapted to sense driving current being supplied to the one or more light emitting devices, the current sensing circuit including an operational amplifier and a collection of resistors configured to sense a ripple in the driving current; an error amplifier circuit coupled to the current sensing circuit, and the current sensing circuit is adapted to supply a first voltage to the error amplifier circuit, the first voltage being related to the driving current and the ripple being supplied to the one or more light emitting devices; a pulse width modulation circuit coupled to the error amplifier circuit and adapted to modulate a pulse width of a control signal based at least in part on an output of the error amplifier circuit to compensate for the ripple sensed by the current sensing circuit, the control signal to be employed to adjust the driving current being supplied to the one or more light emitting devices; and a buck converter coupled to the one or more light emitting devices, the buck converter adapted to switch the driving current being supplied to the one or more light emitting devices by changing amplitude of the driving current based, at least in part, on the control signal.