LTC4065L/
LTC4065LX/LTC4065L-4.1
Standalone 250mA Li-Ion
Battery Charger in 2 × 2 DFN
FEATURES
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.
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Charge Current Programmable up to 250mA with
5% Accuracy
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Complete Linear Charger in 2mm × 2mm DFN Package
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C/10 Charge Current Detection Output
Timer Termination
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No External MOSFET, Sense Resistor or Blocking
Diode Required
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Preset Float Voltage with 0.6% Accuracy:
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.
4.2V for LTC4065L/LTC4065LX
4.1V for LTC4065L-4.1
Constant-Current/Constant-Voltage Operation with
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Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating
TheLTC4065L-4.1featuresaconstant-voltagefloatvoltage
of 4.1V. This 4.1V version of the standard LTC4065L is in-
tendedforback-uporhighambienttemperatureapplications.
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.
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Charge Current Monitor Output for Gas Gauging
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Automatic Recharge
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Charges Single Cell Li-Ion Batteries Directly from
USB Port
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20μA Supply Current in Shutdown Mode
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Available Without Trickle Charge (LTC4065LX)
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Tiny 6-Lead (2mm × 2mm) DFN Package
When the input supply (wall adapter or USB supply) is
removed,theLTC4065Lautomaticallyentersalowcurrent
state,droppingbatterydraincurrenttolessthan1μA.With
powerapplied,LTC4065Lcanbeputintoshutdownmode,
reducing the supply current to less than 20μA.
APPLICATIONS
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Charger for Li-Ion Coin Cell Batteries
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Portable MP3 Players, Wireless Headsets
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Bluetooth Applications
Multifunction Wristwatches
The full-featured LTC4065L also includes automatic re-
charge,low-batterychargeconditioning(tricklecharging)
and soft-start (to limit inrush current).
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L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6522118, 6700364.
Complete Charge Cycle (180mAh Battery)
LTC4065L and LTC4065LX
TYPICAL APPLICATION
110
Standalone Li-Ion Battery Charger
100
90 CONSTANT
CURRENT
4.3
4.1
3.9
3.7
3.5
3.3
100mA
V
IN
CONSTANT
VOLTAGE
V
BAT
LTC4065L
CHRG PROG
EN GND
80
70
60
50
40
30
20
10
0
CC
4.3V TO 5.5V
R1
510Ω
4.2V
C1
1μF
CHRG
TRANSITION
+
Li-Ion
BATTERY
R3
2k
4065L TA01
CHARGE
TERMINATION
V
= 5V
PROG
CC
R
= 2k
0
1
1.5
2
2.5
3
3.5
4
4.5
0.5
TIME (HOURS)
4065 TA02
4065lfb
1