4A, High Efficiency, Standalone Li-Ion Battery Charger

The LTC4007 is a complete constant-current/constant-voltage charger controller for 3- or 4-cell lithium-ion batteries. The PWM controller uses a synchronous, quasi-constant frequency, constant off-time architecture that will not generate audible noise even when using ceramic capacitors. Charging current is programmable to ±4% accuracy using a programming resistor. Charging current can also be monitored as a voltage across the programming resistor.

The output float voltage is pin programmed for cell count (3 cells or 4 cells) and chemistry (4.2V/4.1V). A timer, programmed by an external resistor, sets the charge termination time. Charging is automatically restarted when cell voltage falls below 3.9V/cell.

LTC4007 includes a thermistor input, which suspends charging if an unsafe temperature condition is detected. If the cell voltage is less than 2.5V, a low-battery indicator asserts and can be used to program a trickle charge current to safely charge depleted batteries. The FAULT pin is also asserted and charging terminates if the low-battery condition persists for more than 1/4 of the total charge time.

LTC4007

LTC4007-1

Low battery threshold 4.2V cell

2.5V

3.25V

Low battery threshold 4.1V cell

2.44V

3.173V

Restart

Enabled

Disabled

Package

SSOP-24

QFN-24

Applications

* Notebook Computers

* Portable Instruments

* Battery-Backup Systems

* Standalone Li-Ion Chargers

* Complete Charger Controller for 3- or 4-Cell Lithium-Ion Batteries

* High Conversion Efficiency: Up to 96%

* Output Currents Exceeding 4A

* ±0.8% Charging Voltage Accuracy

* Built-In Charge Termination for Li-Ion Batteries

* AC Adapter Current Limiting Maximizes Charge Rate

* Thermistor Input for Temperature Qualified Charging