A fully integrated solar battery charger

This paper presents a solar charger ASIC for Nickel-based (NiCd or NiMH) batteries. The system is fully integrated and no external component is needed. The ASIC includes a voltage reference, a low-impedance switch, an oscillator, a power-on reset, and a digital control block. The circuit is fabricated in a fully digital 0.35 mum 3.3 V process. It features a low power consumption of 10 muA and operates with a low power supply voltage in the 0.6 V to 1.5 V range.