Standalone 250mA Li-Ion Battery Charger in 2 × 2 DFN

The LTC4065L is a complete constant-current/constant-voltage linear charger for single-cell lithium-ion batteries. Its small size and ability to accurately regulate low charge currents make the LTC4065L especially well-suited for portable applications using low capacity rechargeable lithium-ion cells. Furthermore, LTC4065L is specifically designed to work within USB power specifications.

The CHRG pin indicates when charge current has dropped to ten percent of its programmed value (C/10). An internal timer terminates charging according to battery manufacturer specifications.

The LTC4065L-4.1/LTC4065LX-4.1 features a constant-voltage float voltage of 4.1V. This 4.1V version of the standard LTC4065L/LTC4065LX is intended for back-up or high ambient temperature applications. Under these conditions, a reduced float voltage will trade-off initial cell capacity for the benefit of increased capacity retention over the life of the battery. A reduced float voltage also minimizes swelling in prismatic and polymer cells.

When the input supply (wall adapter or USB supply) is removed, the LTC4065L automatically enters a low current state, dropping battery drain current to less than 1µA. With power applied, LTC4065L can be put into shutdown mode, reducing the supply current to less than 20µA.

The full-featured LTC4065L also includes automatic recharge, low-battery charge conditioning (trickle charging) and soft-start (to limit inrush current).

Float Voltage (V)

Charge Current Range

Pin 5 Is EN or ACPR?

Trickle Charge?

LTC4065

4.2V

40mA to 750mA

EN

Yes

LTC4065A

4.2V

40mA to 750mA

ACPR

Yes

LTC4065-4.4

4.4V

40mA to 750mA

EN

Yes

LTC4065L

4.2V

8mA to 250mA

EN

Yes

LTC4065LX

4.2V

8mA to 250mA

EN

No

LTC4065L-4.1

4.1V

8mA to 250mA

EN

Yes

Applications

* Charger for Li-Ion Coin Cell Batteries

* Portable MP3 Players, Wireless Headsets

* Bluetooth Applications

* Multifunction Wristwatches

* Charge Current Programmable up to 250mA with 5% Accuracy

* Complete Linear Charger in 2mm × 2mm DFN Package

* C/10 Charge Current Detection Output

* Timer Termination

* No External MOSFET, Sense Resistor or Blocking Diode Required

* Preset Float Voltage with 0.6% Accuracy:

* 4.2V for LTC4065L/LTC4065LX

* 4.1V for LTC4065L-4.1/LTC4065LX-4.1