US 7,321,203 B2
LED dimming control technique for increasing the maximum PWM dimming ratio and avoiding LED flicker
Mark W. Marosek, Sunnyvale, Calif. (US)
Assigned to Linear Technology Corporation, Milpitas, Calif. (US)
Filed on Mar. 13, 2006, as Appl. No. 11/373,266.
Prior Publication US 2007/0210725 A1, Sep. 13, 2007
Int. Cl. H05B 41/16 (2006.01)
U.S. Cl. 315—247  [315/246; 315/DIG. 4; 315/291; 315/209 R] 14 Claims
OG exemplary drawing
 
1. A system for driving a light-emitting diode (LED), comprising:
a switching regulator for providing power supply to drive the LED, the switching regulator including a switching circuit;
an oscillator for providing an oscillation signal to control switching of the switching circuit;
a dimming control input adapted to be supplied with a pulse-width modulation (PWM) dimming control signal to provide dimming control of the LED, the dimming control input being configured to apply the PWM dimming control signal to control switching of the switching circuit, and
a synchronizing circuit for synchronizing the oscillation signal to the PWM dimming control signal.