Patent ID: 7791584

Claim:
A system for powering and controlling an LED backlight, the system comprising: a control circuitry; a plurality of LED strings; a pulse width modulation functionality associated with said control circuitry and arranged to pulse width modulate a current flow through each of said plurality of LED strings; a plurality of current limiters responsive to said control circuitry, each of said plurality of current limiters associated with a particular one of said plurality of LED strings and arranged to limit current flow of said pulse width modulated current there-through to a value settable responsive to an output of said control circuitry; and a current sensor in communication with said control circuitry and arranged to output an indication of the current flow through each of said plurality of current limiters, said control circuitry arranged to: determine a thermal condition of at least one of said plurality of current limiters; reduce, in the event that the determined thermal condition of said at least one of said plurality of current limiters exceeds a predetermined limit, a duty cycle of said pulse width modulation functionality of said current flow through said at least one of said plurality of current limiters exhibiting said exceeded thermal condition; and compensate, responsive to said indication of current flow, for any inaccuracy in the amount of current flow through any of said plurality of LED strings by adjusting the appropriate PWM duty cycle.