LTC4065L/LTC4065LX/
LTC4065L-4.1/LTC4065LX-4.1
Standalone 250mA Li-Ion
Battery Charger in 2 × 2 DFN
FEATURES
nn Charge Current Programmable up to 250mA with
5% Accuracy
nn Complete Linear Charger in 2mm × 2mm DFN Package
nn C/10 Charge Current Detection Output
nn Timer Termination
nn No External MOSFET, Sense Resistor or Blocking
Diode Required
nn Preset Float Voltage with 0.6% Accuracy:
4.2V for LTC4065L/LTC4065LX
4.1V for LTC4065L-4.1/LTC4065LX-4.1
nn Constant-Current/Constant-Voltage Operation with
Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating
nn Charge Current Monitor Output for Gas Gauging
nn Automatic Recharge
nn Charges Single Cell Li-Ion Batteries Directly from
USB Port
nn 20µA Supply Current in Shutdown Mode
nn Available Without Trickle Charge (LTC4065LX/
LTC4065LX-4.1)
nn Tiny 6-Lead (2mm × 2mm) DFN Package
APPLICATIONS
nn Charger for Li-Ion Coin Cell Batteries
nn Portable MP3 Players, Wireless Headsets
nn Bluetooth Applications
nn Multifunction Wristwatches
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents, including 6522118, 6700364.
DESCRIPTION
The LTC®4065L is a complete constant-current/constant-
voltage linear charger for single-cell lithium-ion batteries.
Its small size and ability to accurately regulate low charge
currents make the LTC4065L especially well-suited for
portable applications using low capacity rechargeable
lithium-ion cells. Furthermore, LTC4065L is specifically
designed to work within USB power specifications.
The CHRG pin indicates when charge current has dropped
to ten percent of its programmed value (C/10). An internal
timer terminates charging according to battery manufac-
turer specifications.
The LTC4065L-4.1/LTC4065LX-4.1 features a constant-
voltage float voltage of 4.1V. This 4.1V version of the
standard LTC4065L/LTC4065LX is intended for back-up
or high ambient temperature applications. Under these
conditions, a reduced float voltage will trade-off initial
cell capacity for the benefit of increased capacity retention
over the life of the battery. A reduced float voltage also
minimizes swelling in prismatic and polymer cells.
When the input supply (wall adapter or USB supply) is
removed, the LTC4065L automatically enters a low current
state, dropping battery drain current to less than 1µA.
With power applied, LTC4065L can be put into shutdown
mode, reducing the supply current to less than 20µA.
The full-featured LTC4065L also includes automatic
recharge, low-battery charge conditioning (trickle
charging) and soft-start (to limit inrush current).
TYPICAL APPLICATION
Standalone Li-Ion Battery Charger
VIN
4.3V TO 5.5V
C1
1µF
R1
510Ω
VCC BAT
LTC4065L
CHRG PROG
EN GND
100mA
+ 4.2V
Li-Ion
R3
BATTERY
2k
4065L TA01
Complete Charge Cycle (180mAh Battery)
LTC4065L and LTC4065LX
110
100
4.3
90 CONSTANT
80 CURRENT
70
CONSTANT
VOLTAGE
4.1
60
CHRG
3.9
50
TRANSITION
40
3.7
30
20
10
0
0
CHARGE
TERMINATION
3.5
VCC = 5V
RPROG = 2k
3.3
0.5 1 1.5 2 2.5 3 3.5 4 4.5
TIME (HOURS)
4065 TA02
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For more information www.analog.com
Rev. D
1
