The ISL9220, ISL9220A is a cost-effective and versatile battery charger for 1-cell and 2-cell Li-ion and Li-Polymer based portable applications. The device features synchronous PWM technology, maximizing power efficiency, thus minimizing charge time and heat. The 1. 2MHz switching frequency allows use of small external inductors and capacitors. A simple charge current programming method is provided. External resistors program the fast charge and end-of-charge currents. The two status outputs can be used to drive LEDs, or can be connected to host processor. A programmable charge timer provides the ability to detect defective batteries, and provides a secondary method of detecting charge termination. A thermistor interface is provided for battery presence detection, and for temperature qualified charging conditions. Additional features include preconditioning of an over-discharged battery, automatic recharge, and thermally enhanced QFN package.