LTC4001-1

1

40011fa

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

2A Synchronous

Buck Li-Ion Charger

5V wall adapters. It utilizes a 1.5MHz synchronous buck

converter topology to reduce power dissipation during

charging. Low power dissipation, an internal MOSFET and

sense resistor allow a physically small charger that can be

embedded in a wide range of handheld applications. The

LTC4001-1 includes complete charge termination circuitry,

automatic recharge and a ±1% 4.1V float voltage. Input

short-circuit protection is included so no blocking diode

is required.

This 4.1V version of the standard LTC4001 is intended

for applications which will be operated or stored above

approximately 60°C. Under these conditions, the reduced

float voltage will trade-off initial cell capacity for the benefit

of increased capacity retention over the life of the battery. A

reduced float voltage also minimizes swelling in prismatic

and polymer cells, and avoids open CID (pressure fuse)

in cylindrical cells.

Battery charge current, charge timeout and end-of-charge

indication parameters are set with external components.

Additional features include shorted cell detection, tempera-

ture qualified charging and overvoltage protection. The

LTC4001-1 is available in a low profile (0.75mm) 16-lead

(4mm × 4mm) QFN package.

2A Single Cell Li-Ion Battery Charger

Blocking Diode Required

Temperature Safety Margin

Termination

Charging

L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners.

Charging (PWM Mode)

3

0.75

1.00

1.25

4

40011 TA01b

0.50

0.25

0

3.25

3.5

3.75

4.25

2A CHARGER

+

PROG

EN

FAULT

NTC

CHRG

PGND

BAT

BATSENS

IDET TIMER

274Ω

0.22μF

10μF

40011 TA01a

4.1V

Li-Ion

10μF

4.5V TO 5.5V

0.1μF

SS

SW

SENSE

LTC4001-1

1.5μH

GNDSENS