Low cell charge enable circuit

Abstract

A circuit and method of operating a circuit furnish a capability to connect a battery in a conduction mode to a battery pack and, therefore, to a charger. The circuit and method furnish this capability even when no power is available for driving normally active electronic circuits. The circuit includes passive-type components which sense for the presence of a charger and activate switches for connecting the battery to the charger. The circuit and method in these embodiments supply this capability by applying a voltage derived from the charger to a power switch connecting the battery to the battery pack. For example, for a battery pack utilizing a power switch including two power FETs connected back-to-back, the circuit pulls a gate potential of the power switch FETs as far as possible from the potential at the minus terminal of the power pack so that conduction through the FETs and battery accompanies attachment of the charger to the battery pack.

Dependencies are inferred from the claim text.