Single Cell Lithium-Ion Linear Battery Charger Controllers

The LTC1731 is a complete constant-current/constant-voltage linear charger controller for single cell lithium-ion batteries. Nickel-cadmium (NiCd) and nickel-metal-hydride (NiMH) batteries can also be charged with constant current using external termination. The external sense resistor sets the charge current with 5% accuracy. An internal resistor divider and precision reference set the final float potential with ±1% accuracy. The output float voltage is set internally to 4.1V (LTC1731-4.1) or 4.2V (LTC1731-4.2).

When the input supply is removed,the LTC1731 automatically enters a low current sleep mode, dropping the battery drain current to typically 7µA. 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.

The LTC1731 is available in the 8-pin MSOP and SO packages.

Float Voltage

LTC1731-4.1

4.1V

LTC1731-4.2

4.2V

LTC1731-8.2

8.2V

LTC1731-8.4

8.4V

Applications

* Cellular Phones

* Handheld Computers

* Charging Docks and Cradles

* Programmable Current Source

* Complete Linear Charger Controller for 1-Cell Li-Ion Batteries

* 1% Voltage Accuracy

* Programmable Charge Current

* C/10 Charge Current Detection Output

* Programmable Charge Termination Timer