Patent ID: 7439945

Claim:
A Light-Emitting Diode (LED) driver circuit for controlling the brightness of light generated by a LED that is coupled between a first terminal and a second terminal of the LED driver circuit in response to an user supplied brightness control signal, said LED driver circuit comprising: constant current means for generating a constant current between the first terminal and the second terminal when the first terminal is connected to an external voltage source; shunt means connected between the first and second terminals; and brightness control means for generating a pulse signal having a duty cycle that is proportional to the user-supplied brightness control signal, wherein said shunt means is controlled by said pulse signal such that: said shunt means closes when said pulse signal is at a first voltage level, whereby the constant current is passed through said shunt means and said first and second terminals are maintained at a substantially common voltage, and said shunt means opens when said pulse signal is at a second voltage level, whereby the constant current is passed from the first terminal to the second terminal through said LED.