Analog Devices Inc./Maxim Integrated

The LTC1730 is a complete pulse charger for 1-cell lithium-ion batteries. When charging a depleted cell, the internal MOSFET is fully on allowing the current limited input power source to provide charge current to the battery, virtually eliminating heat generation in the charger.As the battery accepts charge and approaches the programmed voltage, the internal MOSFET begins switching off and on with the duty cycle gradually decreasing as the battery approaches a fully charged condition. A programmable timer ends the charge cycle. The end-of-charge condition is indicated at theCHRGpin when the average charge current falls to C/10. Removing the input voltage puts the LTC1730 into a sleep mode, dropping the battery current drain to less than 1µA (maximum).An external sense resistor limits the maximum charge current as a safety precaution against a user connecting a wall adapter with the incorrect or no current limit. The internal MOSFET prevents reverse battery current from flowing if the input voltage is shorted to ground, eliminating the need for a blocking diode.The LTC1730-4 is available in the 16-pin SSOP package and the LTC1730-4.2 is available in the 8-pin SO package.ApplicationsStandalone Lithium-Ion Battery ChargerHandheld ComputersCellular Telephones

The LTC1732-8.4 is a complete constant-current/constant-voltage linear charge controller for lithium-ion (Li-Ion) batteries. Nickel-cadmium (NiCd) and nickel metal-hydride (NiMH) batteries can also be charged with constant current using external termination. Charge current can be programmed with ±7% accuracy using external sense and program resistors. An internal resistor divider and precision reference set the final float voltage with ±1% accuracy.When the input supply is removed, the LTC1732-8.4 automatically enters a low current sleep mode, dropping the battery drain current to 10µA. 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 battery voltage exceeds 4.9V.The LTC1732-8.4 begins a new charge cycle when a discharged battery is connected to the charger or when the input power is applied. In additon, if the battery remains connected to the charger and the cell voltage drops below 8.05V, a new charge cycle will begin.The LTC1732-8.4 is available in the 10-pin MSOP package.Float VoltageRecharge VoltageLTC1732-44.1V or 4.2V (pin select)3.8VLTC1732-4.24.2V4.05VLTC1732-8.48.4V8.05VApplicationsCellular PhonesHandheld ComputersCharging Docks and CradlesDigital Cameras and Camcorders