LTC1733
Monolithic Linear
Lithium-Ion Battery Charger with
Thermal Regulation
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FEATURES
DESCRIPTIO
The LTC®1733 is a standalone constant-current/
constant-voltage linear charger for lithium-ion batteries
withanon-chippowerMOSFET.Internalthermalfeedback
regulates the charge current to limit die temperature
during high power operation or high ambient temperature
conditions. This feature allows the user to program a high
charge current without risk of damaging the LTC1733 or
the handheld product.
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Complete Linear Charger for 1-Cell Lithium-Ion
Batteries
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Thermal Regulation Maximizes Charging Rate
without Risk of Overheating*
No External MOSFET, Sense Resistor or Blocking
Diode Required
Up to 1.5A Charge Current
Preset Charge Voltage with 1% Accuracy
Programmable Charge Current with 7% Accuracy
Programmable Charge Termination Timer
Tiny Thermally Enhanced 10-Pin MSOP Package
Charge Current Monitor Useful for Gas Gauging*
C/10 Charge Current Detection Output
Automatic Recharge
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No external current sense resistor is needed and no
blocking diode is required due to the internal MOSFET
architecture. The charge current and charge time can be
set externally with a single resistor and capacitor, respec-
tively. When the input supply (wall adapter) is removed,
the LTC1733 automatically enters a low current sleep
mode, dropping the battery drain current to less than 5µA.
Thermistor Input for Temperature Qualified Charging
AC Present Logic Output
4.1V/4.2V Pin Selectable Output Voltage
The LTC1733 also includes NTC temperature sensing,
C/10 detection circuitry, AC present logic, 4.1V/4.2V pin
selectability and low battery charge conditioning (trickle
charging).
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APPLICATIO S
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Cellular Telephones
The LTC1733 is available in a 10-pin thermally enhanced
MSOP package.
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Handheld Computers
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Digital Still Cameras
Charging Docks and Cradles
, LTC and LT are registered trademarks of Linear Technology Corporation.
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*Patent Pending
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TYPICAL APPLICATIO
Charge Current vs Battery Voltage
Standalone Li-Ion Battery Charger
1200
T
A
= 0°C
CONSTANT
CURRENT
V
= 5V
IN
1000
800
600
400
200
0
T
= 40°C
8
2
A
T
= 25°C
A
SEL
V
I
= 1A
CC
BAT
9
7
CONSTANT
POWER
4.7µF
BAT
4.2V
LTC1733
TIMER
4
1-CELL
Li-Ion
PROG
CONSTANT
VOLTAGE
GND
NTC
6
BATTERY*
1.5k
1%
5
0.1µF
TRICKLE
CHARGE
V
= 5V
IN
1733TA01
θ
= 40°C/W
JA
2.5
3
4
4.5
2
3.5
*AN OUTPUT CAPACITOR MAY BE REQUIRED
DEPENDING ON BATTERY LEAD LENGTH
BATTERY VOLTAGE (V)
1733 TA01b
sn1733 1733fs
1