Lithium-Ion Battery Pulse Charger with Overcurrent Protection

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.

Applications

* Handheld Computers

* Cellular Telephones

* Cradle Chargers

* Very Low Power Dissipation: 350mW at 1A

* Complete Standalone Pulse Charger for 1-Cell Lithium-Ion Batteries

* Requires No Microcontroller, MOSFET or Blocking Diode

* Sense Resistor Limits Maximum Current for Safety

* Programmable Charge Termination Timer for

Maximum Capacity Charging

* ±1% Float Voltage Accuracy

* Near End-of-Charge (C/10) Detection Output

* AC Wall Adapter Present Output

* Low Battery Drain when Input Supply Is Removed

* Automatic Trickle Charge for Low Battery

* Automatic Battery Refresh

* Thermal Shutdown Protection

* Tiny Thermally Enhanced MSOP Package