■ Features

 Programmable Charge Current Up to 500mA

 No MOSFET, Sense Resistor or Blocking Diode

Required

 Complete Linear Charger in ThinSOT Package for

single Cell Lithium-Ion Batteries

 Constant-Current/Constant-Voltage Operation with

Thermal Regulation to Maximize Charge Rate

Without Risk of Overheating

 Charges Single Cell Li-Ion Batteries Directly from

USB Port

 Preset 4.2V Charge Voltage with 1% Accuracy

 Charge Current Monitor Output for Gas Gauging

 Automatic Recharge

 Charge Status Output Pin

 C/10 Charge Termination

 2A Supply Current in Shutdown

 2.9V Trickle Charge Threshold (LN2054)

 Soft-Start Limits Inrush Current

 Available in 5-Lead SOT-23 and SOT-89 Package

■ General Description

The LN2054 is a complete constant-current /constant

-voltage linear charger for single cell lithium-ion batteries.

Its ThinSOT package and low external component count

make the LN2054 ideally suited for portable applications.

Furthermore, the LN2054 is specifically designed to work

within USB power specifications.

No external sense resistor is needed, and no blocking

diode is required due to the internal MOSFET architecture.

Thermal feedback regulates the charge current to limit the

die temperature during high power operation or high

ambient temperature. The charge voltage is fixed at 4.2V,

and the charge current can be programmed externally with

a single resistor. The LN2054 automatically terminates the

charge cycle when the charge current drops to 1/10th the

programmed value after the final float voltage is reached.

When the input supply (wall adapter or USB supply) is

removed, the LN2054 automatically enters a low current

state, dropping the battery drain current to less than 2A.

The LN2054 can be put into shutdown mode, reducing the

supply current to 2μA.

Other features include charge current monitor,

under-voltage lockout, automatic recharge and a status pin

to indicate charge termination and the presence of an input

voltage.

■ Applications

 Cellular Telephones, PDAs, MP3 Players

 Charging Docks and Cradles

 Bluetooth Applications