LTC4075/LTC4075X

1

4075Xfa

that are capable of charging a single-cell Li-Ion battery

from both wall adapter and USB inputs. The chargers can

detect power at the inputs and automatically select the

appropriate power source for charging.

No external sense resistor or blocking diode is required

for charging due to the internal MOSFET architecture.

Internal thermal feedback regulates the battery charge

current to maintain a constant die temperature during high

power operation or high ambient temperature conditions.

The float voltage is fixed at 4.2V and the charge current

is programmed with an external resistor. The LTC4075

terminates the charge cycle when the charge current drops

below the programmed termination threshold after the

final float voltage is reached. With power applied to both

inputs, the LTC4075/LTC4075X can be put into shutdown

mode reducing the DCIN supply current to 20µA, the USBIN

supply current to 10µA, and the battery drain current to

less than 2µA.

Other features include automatic recharge, undervoltage

lockout, charge status outputs, and “power present”

status outputs to indicate the presence of wall adapter

or USB power.

Dual Input Battery Charger for Single-Cell Li-Ion

LTC4075

DCIN

USBIN

IUSB

IDC

BAT

ITERM

1.24k

1%

2k

1%

2k

1%

WALL

ADAPTER

USB

PORT

1

µF

1

µF

+

4.2V

SINGLE CELL

Li-Ion BATTERY

800mA (WALL)

500mA (USB)

4075 TA01

GND

Dual Input USB/AC

Adapter Standalone Li-Ion

Battery Chargers

TIME (HR)

0

4.2

200

0

400

800

600

1000

1.5

2.5

4075 TA01b

3.6

3.4

5.0

4.0

3.8

2.5

0

–2.5

0.5

1.0

2.0

3.0

CONSTANT VOLTAGE

USBIN = 5V

Complete Charge Cycle (1100mAh Battery)

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

All other trademarks are the property of their respective owners.

*Protected by U.S. patents, including 6522118, 6700364

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

Adapter and USB Inputs

Wall Adapter Input

Diode Needed

Without Risk of Overheating*

(0.75mm) 10-Lead (3mm

× 3mm) DFN Package