Patent ID: 8564448

Claim:
A portable computer system, comprising: a battery for providing a supply signal; a power switch electrically connected to the battery for receiving the supply signal; and a computer unit, comprising: an embedded controller (EC) for determining whether the battery satisfies a low power condition in response to the supply signal, wherein the EC further provides a driving supply signal when the battery satisfies the low power condition; a driver for determining whether the supply signal satisfies a first low voltage condition according to the driving supply signal, wherein the driver triggers a first alert event when the supply signal satisfies a first low voltage condition related to the level of the supply signal, the driver including a signal converter for generating a current conversion signal in response to the driving supply signal, a Wheatstone bridge for providing a first control voltage signal and a second control voltage signal, wherein the Wheatstone bridge determines a differential voltage signal between the first and the second control voltage signal in response to the current conversion signal, and the magnitude of the differential voltage signal is related to the driving supply signal, and a comparison circuit for determining whether the differential voltage signal is substantially larger than a threshold value so as to determine whether the supply signal satisfies the first low voltage condition, wherein the comparison circuit provides a first control signal to trigger the first alert event when the supply signal satisfies the first low voltage condition; and a user interface device for triggering a first user notification event in response to the first alert event; wherein, the power switch is turned on for providing the supply signal to power the computer unit in response to a first operation event; and wherein, the power switch is turned off in response to a second operation event, so that the battery and the computer unit substantially float, and the computer unit is put in a power cut-off situation.