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LTC1732-4/LTC1732-4.2

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

Lithium-Ion Linear

Battery Charger Controller

The LTC

voltage linear charger controller for lithium-ion

(Li-Ion) batteries. Nickel-cadmium (NiCd) and nickel metal-

hydride (NiMH) batteries can also be charged with con-

stant current using external termination. Charge current

can be programmed with 7% (max) accuracy using exter-

nal sense and program resistors. An internal resistor

divider and precision reference set the final float voltage

with 1% accuracy. The SEL pin allows users to charge

either 4.1V or 4.2V cells.

When the input supply is removed, the LTC1732 automati-

cally enters a low current sleep mode, dropping the battery

drain current to 7

µA. An internal comparator detects the

end-of-charge (C/10) condition while a programmable

timer, using an external capacitor, sets the total charge

time. Fully discharged cells are automatically trickle charged

at 10% of the programmed current until cell voltage

exceeds 2.457V.

The LTC1732 begins a new charge cycle when a discharged

battery is connected to the charger or when the input power

is applied. In addition, if the battery remains connected to

the charger and the cell voltage drops below 3.8V for the

LTC1732-4 or below 4.05V for the LTC1732-4.2, a new

charge cycle will automatically begin.

The LTC1732 is available in the 10-pin MSOP package.

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Complete Linear Charger Controller for 1-Cell

Lithium-Ion Batteries

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Preset Charge Voltage with 1% Accuracy

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Programmable Charge Current

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C/10 Charge Current Detection Output

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Programmable Charge Termination Timer

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Small, Thin 10-Pin MSOP Package

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Select Pin Charges 4.1V or 4.2V Cells (LTC1732-4)

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Input Supply (Wall Adapter) Detection Output

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4.5V to 12V Input Voltage Range

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Automatic Sleep Mode When Input Supply

is Removed (Only 7

µA Battery Drain)

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Automatic Trickle Charge of Low Voltage Cells

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Programmable for Constant-Current-Only Mode

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Battery Insertion Detect

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4.05V Recharge Threshold for 4.2V Cells

(LTC1732-4.2)

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3.8V Recharge Threshold for 4.1V or 4.2V Cells

(LTC1732-4)

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Cellular Phones

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Handheld Computers

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Charging Docks and Cradles

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

Single Cell 4.2V Li-Ion Battery Charger

SENSE

DRV

R2

1k

R1

1k

0.2

Ω

19.6k

4.2V

Li-Ion

CELL

LTC1732-4

*SHUTDOWN INVOKED BY FLOATING THE PROG PIN

BAT

CHRG

9

8

2

MBRM120T3

10

µF

1732 TA01

1

µF

0.1

µF

Q1

Si9430DY

7

1

6

5

+

3

10

4

ACPR

TIMER

PROG

GND

SEL