The LTC1731-8.2 from Analog Devices is a Li-ion Linear Battery Charger Controller that has been designed for 2-cell Lithium-ion batteries. It requires an input voltage of 8.8 - 12 V. This controller consists of N-channel MOSFETs, error amplifiers, resistors, current and voltage sources, control logic, switches, an oscillator, and a counter. It can also charge Nickel-cadmium (NiCd) and Nickel-Metal-Hydride (NiMH) batteries with constant current using an external compensation. This battery charger automatically enters a low current sleep mode when the input supply is removed, dropping the battery drain current to 15 µA. It uses an internal comparator to detect the end-of-charge condition while a programmable timer, using an external capacitor, sets the total charge time.

This charger controller automatically trickle charges fully discharged cells at 10% of the programmed current until the battery voltage exceeds 4.95 V. It is available in a surface-mount package that measures 3 x 3 mm and is ideal for programmable current sources, handheld computers, charging docks and cradles, and cellular mobile applications.