■ Features

 Constant-Current/Constant-Voltage

 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

 3/10 Charge Termination

 25uA Supply Current in Shutdown

 2.9V Trickle Charge Threshold (XT4051)

 Soft-Start Limits Inrush Current

 Battery reversed protection

 6KV ESD(HBM) capability

■ General Description

The XT4051 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 XT4051 ideally suited for portable applications.

Furthermore, the XT4051 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 XT4051 automatically terminates the

charge cycle when the charge current drops to 3/10th the

programmed value after the final float voltage is reached.

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

removed, the XT4051 automatically enters a low current

state, dropping the battery drain current to less than 1uA.

The XT4051 can be put into shutdown mode, reducing the

supply current to 25μA.

When battery reversed,the internal protected the BAT pin

throughout about 0.7mA current from GND.Also,The BAT

pin has a 6KV ESD(HBM) capability.

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

■ Applications

 wearable devices

 Bluetooth Applications