Circuits and methods for driving light sources

摘要

A circuit for powering a LED light source includes a converter and a controller. The converter provides an output voltage, and includes a first switch which is turned on and off alternately according to a driving signal to control a current. The controller generates the driving signal which is a periodic signal having a first state and a second state per time period. The first switch is turned on when the driving signal operates in the first state, and is turned off when the driving signal operates in the second state. The controller modulates a time period of the driving signal and a time duration of the first state, such that a quotient of the time duration squared and the time period is substantially independent of a change of the time period, and the current is substantially independent of the change.

主权项

1. A driving circuit for powering a light-emitting diode (LED) light source, said driving circuit comprising:
a converter, configured to provide an output voltage to power said light source; said converter comprising a first switch, wherein said first switch is turned on and off alternately according to a driving signal to control a current through said light source; and a controller coupled to said converter and configured to generate said driving signal, wherein said driving signal is a periodic signal having a first state and a second state per time period; wherein said first switch is turned on when said driving signal operates in said first state, and is turned off when said driving signal operates in said second state, wherein said controller modulates a time period of said driving signal and a time duration of said first state, such that a quotient of said time duration squared and said time period is substantially independent of a change of said time period, and said current is substantially independent of said change.