1

Diode Required

Single Cell Lithium-Ion Batteries

Thermal Regulation to Maximize Charge Rate

Without Risk of Overheating

from USB Port

±1% Accuracy

Gauging

µA Supply Current in Shutdown

The KB 4540 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 KB4540 ideally suited for portable applications.

Furthermore, the KB4540 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 KB4540 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 KB4540 automatically enters a low current

state, dropping the battery drain current to less than 2

µA.

The KB4540 can be put into shutdown mode, reducing

the supply current to 25

µA.

Other features include charge current monitor, undervoltage

lockout, automatic recharge and a status pin to indicate

charge termination and the presence of an input voltage.

500mA Single Cell Li-Ion Charger

2k

4.2V

Li-Ion

BATTERY

KB4540-4.2

1

µF

4.5V TO 6.5V

BAT

4

3

5

2

PROG

GND

500mA

FEATURES

DESCRIPTION

KB4540

Kingbor Technology Co.,Ltd

TEL:(86)0755-26508846 FAX:(86)0755-26509052

Li-Ion Battery Charger

TYPICAL APPLICATION

I

V

R

CHG

PROG

PROG

=

X 1000

(V

=1V)

PROG

330

Ω

CHRG

1