Patent ID: 6256007
Filing Date: 2001-07-03
Classification: G09G,H05B

Abstract:
A radio communications device comprising:a housing;a transceiver in said housing for transmitting and receiving radio communications to and from a radio base station;a user interface on said housing;a backlighting circuit in said housing wherein said backlighting circuit includes,at least one light emitting diode optically coupled to said user interface wherein said at least one diode provides backlighting for the user interface, anda 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 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 falling 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.