The MAX1501 intelligent, constant-current, constantvoltage (CCCV), temperature-regulated battery charger charges a single lithium-ion (Li+) cell or three-cell NiMH/NiCd batteries. The device integrates the currentsense resistor, PMOS pass element, and thermalregulation circuitry, while eliminating the reverseblocking Schottky diode to create the simplest charging solution for hand-held equipment. The MAX1501 functions as a stand-alone charger to control the charging sequence from the prequalification state through fast charge, top-off, and charge termination for single-cell Li+ or three-cell NiMH/NiCd batteries. Alternatively, the MAX1501 collaborates with a host microprocessor to determine the best charging algorithm. Proprietary thermal-regulation circuitry limits the die temperature when fast charging or while exposed to high ambient temperatures, allowing maximum charging current without damaging the charger. The MAX1501 continually supplies a regulated output voltage under no-battery conditions, allowing battery changing. The device achieves high flexibility by providing an adjustable fast-charge current, top-off current, safety timer, and thermal-regulation setpoint. Other features include input power detection (ACOK) and input under-/ overvoltage protection. The MAX1501 provides activelow control inputs. The MAX1501 accepts a 4.5V to 13V supply, but disables charging when the input voltage exceeds 6.5V, preventing excessive power dissipation. The MAX1501 operates over the extended temperature range (-40C to +85C) and is available in a compact 16-pin thermally enhanced 5mm x 5mm thin QFN package with 0.8mm profile.