Abstract: A technique for detecting power demand to provide efficient power sharing. The technique is particularly but not exclusively concerned with providing a power sharing detector for use in a portable computer which requires battery charging to be done concurrently with computer usage, and preferably provides three different rates of charging. A power sharing detector is provided for use with this technique. The power sharing detector is used in a circuit which has a power supply which supplies power both to an auxiliary device and a battery charger. The detector has a voltage detection circuit which is connected to receive a voltage representative of the power supplied to the auxiliary device and to determine therefrom a state of the auxiliary device.

Abstract: An improved battery charging circuit provides a single circuit for charging both Ni-MH and Ni-Cd batteries. Separate circuits are provided for sensing an end of charge sequence for both battery types. Both circuits operate simultaneously, and one circuit will generate and end of charge signal when a battery corresponding to its type is fully charged. When either circuit signals that a sequence is complete, charging ends. This provides for charging either type of battery without the necessity for determining the type of battery being charged.