Voltage monitoring circuit for rechargeable battery

DETAILED DESCRIPTION A voltage monitoring circuit and method for use in monitoring the voltage of a rechargeable battery cell uses a time-multiplexed connection to the battery cell for alternately sampling the cell voltage and powering the voltage monitoring circuitry.
The cell voltage is sampled and held while the higher power consuming voltage monitoring circuitry is powered down.
The sampling circuitry is then disconnected, with the sampled cell voltage held therein, while the remaining circuitry is powered up to compare the sampled and held cell voltage against a reference voltage.
Accordingly, an error-free cell voltage is acquired for comparison to a known reference voltage.
In accordance with one embodiment of the present invention, a voltage monitoring circuit suitable for use in monitoring the voltage of a rechargeable battery includes battery connection nodes, a resistive circuit, a switching circuit, a voltage sampling circuit and a voltage measurement circuit.
The battery connection nodes are configured to connect to the terminals of a rechargeable battery.
The resistive circuit includes first and second terminals, with the first resistive circuit terminal being connected to the first battery connection node.
The switching circuit includes an input terminal and first and second output terminals, with the switching circuit input terminal being connected to the second resistive circuit terminal and the switching circuit being configured to: connect the switching circuit input terminal to the first switching circuit output terminal and disconnect the switching circuit input terminal tom the second switching circuit output terminal during a first time period; and connect the switching circuit input terminal to the second switching circuit output terminal and disconnect the switching circuit input terminal from the first switching circuit output terminal during a second time period.
The voltage sampling circuit is connected between the first switching circuit output terminal and the second battery connection node and is configured to sample a voltage between the first and second battery connection nodes via the resistive circuit and the switching circuit during the first time period and in accordance therewith provide a stored voltage corresponding to the sampled voltage