LTC4002

1

4002f

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

All other trademarks are the property of their respective owners.

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

4.7V to 22V – 4.2 Version

8.9V to 22V – 8.4 Version

500kHz Switching Frequency

Qualification

Standalone Li-Ion

Switch Mode Battery Charger

The LTC

one (4.2V) or two (8.4V) cell lithium-ion batteries. With a

500kHz switching frequency, the LTC4002 provides a

small, simple and efficient solution to fast charge Li-Ion

batteries from a wide range of supply voltages. An external

sense resistor sets the charge current with ±5% accuracy.

An internal resistor divider and precision reference set the

final float voltage to 4.2V per cell with ±1% accuracy.

When the input supply is removed, the LTC4002 automati-

cally enters a low current sleep mode, dropping the battery

drain current to 10µA. An internal comparator detects the

near end-of-charge condition while an internal timer sets

the total charge time and terminates the charge cycle. After

the charge cycle ends, if the battery voltage drops below

4.05V per cell, a new charge cycle will automatically begin.

The LTC4002 is available in the 8-lead SO and 10-lead DFN

packages.

6.8µH

22µF

+

4002 TA01

NTC: DALE NTHS-1206N02

10µF

0.1µF

0.47µF

2.2k

68mΩ

Li-Ion

BATTERY

10k

NTC

SENSE

GATE

BAT

CHRG

LTC4002ES8-4.2

5V TO 22V

BAT

NTC

GND

COMP

2k

CHARGE

STATUS

T

1.5A Single Cell Li-Ion Battery Charger

INPUT VOLTAGE (V)

5

80

90

25

4002 TA02

70

60

10

15

20

100

(CURVES INCLUDE

INPUT DIODE)

Efficiency vs Input Voltage