LTC4054L-4.2
150mA Standalone Linear
Li-Ion Battery Charger in ThinSOT
U
FEATURES
DESCRIPTIO
■
Programmable Charge Current Range:
TheLTC®4054Lisacomplete, constant-current/constant-
voltage linear charger for single cell lithium-ion batteries.
Its small size and ability to regulate low charge currents
make the LTC4054L especially well-suited for portable
applications using low capacity rechargeable lithium-ion
coin cells. Furthermore, the LTC4054L is specifically de-
signed to work within USB power specifications.
10mA to 150mA
■
No External MOSFET, Sense Resistor or Blocking
Diode Required
Complete Linear Charger in ThinSOTTM Package for
Single Cell/Coin Cell Lithium-Ion Batteries
Constant-Current/Constant-Voltage Operation with
Thermal Regulation* to Maximize Charge Rate
Without Risk of Overheating
■
■
No external sense resistor is needed, and no blocking di-
ode is required due to the internal MOSFET architecture.
Thermalfeedbackregulatesthechargecurrenttoeliminate
thermaloverdesign.Thechargevoltageisfixedat4.2V,and
the charge current can be programmed externally with a
single resistor. The LTC4054L automatically terminates a
charge cycle when the charge current drops to 1/10th the
programmed value after the final float voltage is reached.
■
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 Max Supply Current in Shutdown Mode
2.9V Trickle Charge Threshold
Soft-Start Limits Inrush Current
Available in a 6-Lead Low Profile (1mm)
When the input supply (wall adapter or USB supply) is
removed, the LTC4054L automatically enters a low cur-
rent state, dropping the battery drain current to less than
2µA. The LTC4054L can be put into shutdown mode, re-
ducing the supply current to 25µA.
SOT-23 PackageU
Otherfeaturesincludechargecurrentmonitor,undervoltage
lockout, automatic recharge and a status pin to indicate
charge termination and the presence of an input voltage.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
*U.S. Patent No. 6,522,118
APPLICATIO S
■
Charger for Li-Ion Coin Cell Batteries
■
Portable MP3 Players, Wireless Headsets
■
Bluetooth Applications
Multifunction Wristwatches
■
U
TYPICAL APPLICATIO
Complete Charge Cycle (130mAh Battery)
100
90
80
70
60
50
40
30
20
10
0
4.4
4.3
4.2
4.1
4.0
3.9
3.8
3.7
3.6
3.5
3.4
90mA Li-Ion Single Coin Cell Charger
CONSTANT
CURRENT
CONSTANT
VOLTAGE
V
IN
4.5V TO 6.5V
1µF
4
V
3
5
CC
BAT
90mA
LTC4054L-4.2
4.2V
V
= 5V
CC
JA
PROG
COIN CELL
Li-Ion
BATTERY
θ
= 130°C/W
GND
R
T
= 1.69k
PROG
= 25°C
1.69k
A
2
4054l42 TA01
0
0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25
TIME (HOURS)
4054l42 TA01b
4054l42f
1