The bq2004 Fast Charge IC provides comprehensive fast charge control functions together with high-speed switching power control circuitry on a monolithic CMOS device. Integration of closed-loop current control circuitry allows the bq2004 to be the basis of a cost-effective solution for stand-alone and system integrated chargers for batteries of one or more cells. Switch-activated discharge-before charge allows bq2004-based chargers to support battery conditioning and capacity determination. High-efficiency power conversion is accomplished using the bq2004 as a hysteretic PWM controller for switch-mode regulation of the charging current. The bq2004 may alternatively be used to gate an externally regulated charging current. Fast charge may begin on application of the charging supply, replacement of the battery, or switch depression. For safety, fast charge is inhibited unless/until the battery temperature and voltage are within configured limits. Temperature, voltage, and time are monitored throughout fast charge. Fast charge is terminated by any of the following: Rate of temperature time (T/t) Peak voltage detection (PVD) Negative delta voltage (-V) Maximum voltage Maximum temperature Maximum time After fast charge, optional top-off and pulsed current maintenance phases are available.