Patent ID: 6107985
Filing Date: 2000-08-22
Classification: G09G,H05B

Abstract:
A backlighting circuit for a user interface of an electronic device, said backlighting circuit comprising:at least one light emitting diode optically coupled to the user interface wherein said at least one light emitting diode provides backlighting for the user interface;a current source electrically coupled in series with said at least one light emitting diode wherein said current source controls a current through said at least one light emitting diode; anda brownout detection circuit wherein said brownout detection circuit determines a brownout condition for the user interface responsive to said current through said at least one light emitting diode falls below a predetermined threshold wherein said brownout detection circuit determines a brownout condition using a comparison between a reference signal and a feedback signal from said current source; anda control circuit wherein said control circuit is electrically coupled to said brownout detection circuit and wherein said control circuit turns said current source off in response to a determination that a brownout condition has occurred.