The MAX2003/MAX2003A are fast-charge battery chargers (with conditioning) for NiCd (nickel cadmium) or NiMH (nickel-metal hydride) rechargeable batteries. The MAX2003A has the same features as the MAX2003 with an additional pulsed trickle-charge mode to prevent dendrite formation in NiMH batteries. Each can be configured as a switch-mode current regulator or as a gating controller for an external current source. Switch-mode current regulation provides efficient energy transfer, reducing power dissipation and the associated heating. Gating control of an external current source requires minimal components, saving space and cost. On-chip algorithms determine charge termination, so the MAX2003/MAX2003A can be used as stand-alone chargers. Fast-charge termination is accomplished by five methods: temperature slope, negative voltage change, maximum temperature, maximum time, and maximum voltage. As a safety feature, the start of fastcharge is inhibited until battery voltage and temperature are within safe limits. By selecting the appropriate charge-termination method, a single circuit can be built with the MAX2003/MAX2003A to fast-charge both NiMH and NiCd batteries.