LTC4059/LTC4059A
900mA Linear Li-Ion
Battery Chargers with
Thermal Regulation in 2 × 2 DFN
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FEATURES
DESCRIPTIO
The LTC®4059/LTC4059A are constant-current/constant-
voltagelinearchargersforsinglecelllithium-ionbatteries.
Their 2mm × 2mm DFN package and low external compo-
nent count make these chargers especially well suited for
portable applications. Furthermore, they are designed to
work within USB power specifications.
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Programmable Charge Current Up to 900mA
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Charge Current Monitor Output for Charge
Termination
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Constant-Current/Constant-Voltage Operation with
Thermal Regulation to Maximize Charging Rate
Without Risk of Overheating
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Constant-Current Source Mode for Charging
Nickel Batteries (LTC4059 Only)
ACPR Pin Indicates Presence of Input Supply
(LTC4059A Only)
No External MOSFET, Sense Resistor or Blocking
Diode Required
Operating Supply Voltage from 3.75V to 8V
Charges Single Cell Li-Ion Batteries Directly from
USB Port
Preset 4.2V Charge Voltage with 0.6% Accuracy
10µA Supply Current in Shutdown Mode
Tiny 6-Lead (2mm × 2mm) DFN Package
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No external sense resistor, MOSFET or blocking diode is
required. Thermal feedback regulates the charge current
tolimitthedietemperatureduringhighpoweroperationor
high ambient thermal conditions. The charge voltage is
fixed at 4.2V and the charge current is programmable.
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When the input supply (wall adapter or USB supply) is
removed,theLTC4059/LTC4059Aautomaticallyenteralow
currentstate,droppingthebatterycurrentdraintolessthan
1µA. With power applied, they can be put into shutdown
mode, reducing the supply current to 10µA.
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The LTC4059A features an open-drain status pin to indi-
cate the presence of an input voltage. The LTC4059 can be
used as a constant-current source to charge Nickel cells.
Other features include undervoltage lockout protection
and a current monitor pin which can indicate when to
terminate a charge cycle.
APPLICATIO S
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Wireless PDAs
Cellular Phones
Portable Electronics
Wireless Headsets
Digital Cameras
The LTC4059/LTC4059A are available in a 6-lead, low
profile (0.75mm) 2mm × 2mm DFN package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6522118.
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Complete Charge Cycle (800mAh Battery)
TYPICAL APPLICATIO
700
4.4
CONSTANT
CURRENT
CONSTANT
VOLTAGE
V
DD
50k
600
4.2
V
IN
4.5V TO 8V
500
400
300
200
100
0
4.0
3.8
3.6
3.4
3.2
3.0
ACPR
µP
V
CC
LTC4059A
EN
GND PROG
600mA
BAT
1µF
4.2V
Li-Ion
BATTERY
+
2k
V
= 5V
PROG
= 25°C
CC
4059 TA01
R
= 2k
T
A
0
0.5
1
1.5
2
2.5
4059 TA02
TIME (HOURS)
4059fb
1