LTC1731-4.2

· Complete Linear Charger Controller for 1-Cell Lithium-Ion Batteries
· 1% Voltage Accuracy
· Programmable Charge Current
· C/10 Charge Current Detection Output
· Programmable Charge Termination Timer
· Space Saving 8-Pin MSOP Package
· Automatic Sleep Mode When Input Supply is Removed (Only 7mA Battery Drain)
· Automatic Trickle Charging of Low Voltage Cells
· Programmable for Constant-Current-Only Mode

The LTC®1731-4.2 is a complete constant-current/constant- voltage linear charge controller for 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 4.2V.

When the input supply is removed, the LTC1731-4.2 automatically enters a low current sleep mode, dropping the battery drain current to 5mA. 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 2.5V.

The LTC1731-4.2 is available in the 8-pin MSOP and SO packages.