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

The LTC4006 is a complete constant-current/constant voltage charger controller for 2-, 3- or 4-cell lithium batteries in a small package using few external components. The PWM controller is a synchronous, quasi-constant frequency, constant off-time architecture that will not generate audible noise even when using ceramic capacitors.

The LTC4006 is available in 8.4V, 12.6V and 16.8V versions with ±0.8% voltage accuracy. Charging current is programmable with a single sense resistor to ±4% typical accuracy. Charging current can be monitored as a representative voltage at the IMON pin. A timer, programmed by an external resistor, sets the total charge time or is reset to 25% of total charge time after C/10 charging current is reached. Charging automatically resumes when the cell voltage falls below 3.9V/cell.

Fully discharged cells are automatically trickle charged at 10% of the programmed current until the cell voltage exceeds 2.5V/cell. Charging terminates if the low-battery condition persists for more than 25% of the total charge time.

The LTC4006 includes a thermistor sensor input that suspends charging if an unsafe temperature condition is detected and automatically resumes charging when the battery temperature returns to within safe limits.

Applications

* Notebook Computers

* Portable Instruments

* Battery-Backup Systems

* Standalone Li-Ion Chargers

* Complete Charger Controller for 2-, 3- or 4-Cell Lithium-Ion Batteries

* High Conversion Efficiency: Up to 96%

* Output Currents Exceeding 4A

* ±0.8% Accurate Preset Voltages: 8.4V, 12.6V, 16.8V

* Built-In Charge Termination with Automatic Restart

* AC Adapter Current Limiting Maximizes Charge Rate*

* Automatic Conditioning of Deeply Discharged Batteries

* Thermistor Input for Temperature Qualified Charging

* Wide Input Voltage Range: 6V to 28V

* 0.5V Dropout Voltage; Maximum Duty Cycle: 98%

* Programmable Charge Current: ±4% Accuracy

* Indicator Outputs for Charging, C/10 Current Detection and AC Adapter Present

* Charging Current Monitor Output

* 16-Pin Narrow SSOP Package