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LTC1734L

1734lf

Lithium-Ion Linear

Battery Charger in ThinSOT

The LTC

constant-voltage Li-Ion battery charger controller. When

combined with a few external components, the SOT-23

package forms a very small, low cost charger for single cell

lithium-ion batteries. The LTC1734L is a lower charge

current version of the LTC1734.

The LTC1734L provides a fixed float voltage of 4.2V with

1% accuracy (for 4.1V and 4.15V float voltages, contact

LTC Marketing). Constant current is programmed using a

single external resistor between the PROG pin and ground.

Manual shutdown is accomplished by floating the pro-

gram resistor while removing input power automatically

puts the LTC1734L into a sleep mode. Both the shutdown

and sleep modes drain near zero current from the battery.

Charge current can be monitored via the voltage on the

PROG pin allowing a microcontroller or ADC to read the

current and determine when to terminate the charge cycle.

The output driver is both current limited and thermally

protected to prevent the LTC1734L from operating outside

of safe limits. No external blocking diode is required.

The LTC1734L can also function as a general purpose

current source or as a current source for charging nickel-

cadmium (NiCd) and nickel-metal-hydride (NiMH) batter-

ies using external termination.

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Low Profile (1mm) ThinSOT

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Programmable Charge Current: 50mA to 180mA

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No Blocking Diode Required

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No Sense Resistor Required

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1% Accurate Preset Voltage: 4.2V

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Charge Current Monitor Output

for Charge Termination

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Automatic Sleep Mode with Input Supply Removal

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Manual Shutdown

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Negligible Battery Drain Current in Shutdown

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Undervoltage Lockout

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Self Protection for Overcurrent/Overtemperature

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Cellular Telephones

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Handheld Computers

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Digital Cameras

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Charging Docks and Cradles

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Low Cost and Small Size Chargers

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Programmable Current Sources

, LTC and LT are registered trademarks of Linear Technology Corporation.

80mA Li-Ion Battery Charger

PROG Pin Indicates Charge Status

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

5V

1734 TA01

SINGLE

Li-Ion

BATTERY

10

µF

+

GND

PROG

DRIVE

BAT

2

4

6

5

LTC1734L

31

1

µF

4.7k

UMT4403

CHARGING

BEGINS

CHARGING

COMPLETE

1734 TA01b

5V

4V

3V

2V

1V

0V

1.5V

CONSTANT

CURRENT

CONSTANT

VOLTAGE

ThinSOT is a trademark of Linear Technology Corporation.