The LTC1732 is a complete constant-current/constantvoltage linear charger controller for lithium-ion (Li-Ion) batteries. Nickel-cadmium (NiCd) and nickel metalhydride (NiMH) batteries can also be charged with constant current using external termination. Charge current can be programmed with 7% (max) accuracy using external sense and program resistors. An internal resistor divider and precision reference set the final float voltage with 1% accuracy. The SEL pin allows users to charge either 4.1V or 4.2V cells. When the input supply is removed, the LTC1732 automatically enters a low current sleep mode, dropping the battery drain current to 7mA. An internal comparator detects the end-of-charge (C/10) condition while a programmable timer, using an external capacitor, sets the total charge time. Fully discharged cells are automatically trickle charged at 10% of the programmed current until cell voltage exceeds 2.457V.