Patent ID: 8239696
Filing Date: 2012-08-07
Classification: G06F

Abstract:
1. A power supply circuit for supplying electric power to a portable computer, the power supply circuit comprising: a main battery comprising a first output terminal and a second output terminal, the second output terminal being shorter than the first output terminal; a first control circuit, wherein the first control circuit includes a first and a second P-channel enhancement mode MOSFETs and a third N-channel enhancement mode MOSFET, the drain of the first MOSFET is electrically connected to the first output terminal of the main battery, the source of the first MOSFET is electrically connected to the source of the second MOSFET, the drain of the second MOSFET is connected to an electric output terminal of the first control circuit, the gate of the third MOSFET is electrically connected to the second output terminal of the main battery, the source of the third MOSFET is connected to ground, and the drain of the third MOSFET is electrically connected to the gate of the first MOSFET; a backup battery comprising a first output terminal and a second output terminal; and a second control circuit being electrically connected to the first and the second output terminals of the backup battery and the second output terminal of the main battery; wherein when the main battery is drawn out of the portable computer, a disconnection between the second output terminal of the main battery and the portable computer is effected earlier than a disconnection between the first output terminal of the main battery and the portable computer to thus establish a time difference between the two disconnections, and during the period of this time difference, the main battery is controlled by the first control circuit to change from supplying electric power to the portable computer to not supplying electric power to the portable computer, and the backup battery is controlled by the second control circuit to change from not supplying electric power to the portable computer to supplying electric power to the portable computer.