Standalone Li-Ion Switch Mode Battery Charger

The LTC4002 is a complete battery charger controller for one (4.2V) or two (8.4V) cell lithium-ion batteries. With a 500kHz switching frequency, the LTC4002 provides a small, simple and efficient solution to fast charge Li-Ion batteries from a wide range of supply voltages. An external sense resistor sets the charge current with ±5% accuracy. An internal resistor divider and precision reference set the final float voltage to 4.2V per cell with ±1% accuracy.

When the input supply is removed, the LTC4002 automatically enters a low current sleep mode, dropping the battery drain current to 10µA. An internal comparator detects the near end-of-charge condition while an internal timer sets the total charge time and terminates the charge cycle. After the charge cycle ends, if the battery voltage drops below 4.05V per cell, a new charge cycle will automatically begin.

The LTC4002 is available in the 8-lead SO and 10-lead DFN packages.

Applications

* Portable Computers

* Charging Docks

* Handheld Instruments

* Wide Input Supply Range:

* 4.7V to 22V – 4.2 Version

* 8.9V to 22V – 8.4 Version

* High Efficiency Current Mode PWM Controller with

500kHz Switching Frequency

* ±1% Charge Voltage Accuracy

* End-of-Charge Current Detection Output

* 3 Hour Charge Termination Timer

* Constant Switching Frequency for Minimum Noise

* ±5% Charge Current Accuracy

* Low 10µA Reverse Battery Drain Current

* Automatic Battery Recharge

* Automatic Shutdown When Input Supply is Removed

* Automatic Trickle Charging of Low Voltage Batteries

* Battery Temperature Sensing and Charge

Qualification

* Stable with Ceramic Output Capacitor

* 8-Lead SO and 10-Lead DFN Packages