The LTC4052 is a complete standalone pulse charger with integrated MOSFET for 1-cell lithium-ion batteries. An external sense resistor provides overcurrent limiting 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. As the battery accepts charge and approaches the programmed float 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 terminates the charge cycle. The near end-of-charge C/10 condition is indicated at the CHRG pin when the average charge current falls to one tenth of the wall adapter current. Removing the input voltage puts the LTC4052 into a sleep mode, dropping the battery current drain to less than 1µA. The LTC4052 is available in a tiny 8-pin thermally enhanced MSOP package.
