Battery pack with monitoring function utilizing association with a battery charging system

Abstract

A battery detect circuit ( ) is provided that is operable to dispose a sense resistor ( ) in series with the battery to determine whether the charge is being provided to the battery or being extracted from the battery. The voltage across the sensor resistor ( ) is sensed by a voltage/frequency converter ( ). The voltage/frequency converter ( ) is a differential structure comprised of two integrator structures ( ) and ( ) that are operable to utilize a switched capacitor configuration to drive comparators on the output thereof. Each of the integrator structures ( ) and ( ) has associated therewith passive elements and active elements. The integrators ( ) and ( ) have associated therewith integration capacitors ( ) and ( ). Additionally, there are two operational amplifiers ( ) and ( ) that provide the active components of each of the integrators ( ) and ( ). The various switched capacitor circuits ( ) and ( ) associated with the amplifiers ( ) and ( ) are provided to provide the integration operation. Both the amplifiers ( ) and ( ) and their associated switched capacitor circuits ( ) and ( ) are dynamically balanced such that they are switched between integrator ( ) and integrator ( ) on a periodic basis. This therefore allows the errors between the active and passive elements to be switched between the two integrators ( ) and ( ) such that no accumulative error occurs.