LTC1733
Monolithic Linear
Lithium-Ion Battery Charger with
Thermal Regulation
FEATURES
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DESCRIPTIO
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Complete Linear Charger for 1-Cell Lithium-Ion
Batteries
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
Thermistor Input for Temperature Qualified Charging
AC Present Logic Output
4.1V/4.2V Pin Selectable Output Voltage
The LTC
®
1733 is a standalone constant-current/
constant-voltage linear charger for lithium-ion batteries
with an on-chip power MOSFET. Internal thermal feedback
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.
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.
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).
The LTC1733 is available in a 10-pin thermally enhanced
MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
*Patent Pending
APPLICATIO S
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Cellular Telephones
Handheld Computers
Digital Still Cameras
Charging Docks and Cradles
TYPICAL APPLICATIO
V
IN
= 5V
Charge Current vs Battery Voltage
Standalone Li-Ion Battery Charger
1200
T
A
= 0°C
1000
CHARGE CURRENT (mA)
8
SEL
4.7µF
4
2
V
CC
BAT
9
I
BAT
= 1A
4.2V
1-CELL
Li-Ion
BATTERY*
800
600
400
200 TRICKLE
CHARGE
0
2
2.5
LTC1733
7
TIMER
PROG
GND
NTC
6
5
1.5k
1%
1733TA01
0.1µF
*AN OUTPUT CAPACITOR MAY BE REQUIRED
DEPENDING ON BATTERY LEAD LENGTH
U
CONSTANT
CURRENT
T
A
= 40°C
T
A
= 25°C
CONSTANT
POWER
CONSTANT
VOLTAGE
V
IN
= 5V
θ
JA
= 40°C/W
3
4
3.5
BATTERY VOLTAGE (V)
4.5
1733 TA01b
U
U
sn1733 1733fs
1
LINER [ LINEAR TECHNOLOGY ]
