Patent ID: 8073499

Claim:
A battery-powered portable electronic device comprising: a serial bus interface for providing serial communications to the electronic device via a connected serial cable having an information pin and a power pin; a turn-on circuit electrically coupled to the information pin and a power pin of the serial bus interface, wherein, in response to a non-standard signal received on the information pin, the turn-on circuit: (1) generates a mode signal for the electronic device, and (2) enables power to be supplied to the electronic device from the power pin; a comparator receiving a reference voltage at a first input of the comparator and an identification signal from the serial bus interface at a second input of the comparator, and generating a comparison signal on an output of the comparator when the identification signal is non-standard as indicated by a comparison to the reference voltage, wherein the output of the comparator is coupled to the electronic device that enters a unique mode of operation in response to receiving the comparison signal; and a voltage regulator receiving a power signal from the serial bus interface at a first input of the voltage regulator and being electrically coupled to the output of the comparator at a second input of the voltage regulator, wherein the voltage regulator is enabled to generate a power supply on an output of the voltage regulator in response to the comparison signal.