Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB4540
Li-Ion Battery Charger
FEATURES
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DESCRIPTION
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 2µA.
The KB4540 can be put into shutdown mode, reducing
the supply current to 25µA.
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.
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Programmable Charge Current Up to 800mA
No MOSFET, Sense Resistor or Blocking
Diode Required
Complete Linear Charger in SOT 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
25µA Supply Current in Shutdown
2.9V Trickle Charge Threshold (KB4540)
Available Without Trickle Charge (KB4540X)
Soft-Start Limits Inrush Current
Available in SOT23-5 Package
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Cellular Telephones, PDAs, MP3 Players
Charging Docks and Cradles
Bluetooth Applications
TYPICAL APPLICATION
500mA Single Cell Li-Ion Charger
V
IN
4.5V TO 6.5V
1µF
330Ω
1
BAT
KB4540-4.2
CHRG
4
V
CC
3
500mA
5
2k
4.2V
Li-Ion
BATTERY
I
CHG
=
V
PROG
R
PROG
X 1000
(V
PROG
=1V)
PROG
GND
2
1
KINGBOR [ KINGBOR TECHNOLOGY CO ]
