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Copyright © 2008 Active-Semi, Inc.

ActivePath

ACT3780

Product Brief, 29-May-08

Advanced Information―All Information Subject to Change

ActivePath

SIMPLIFIED APPLICATION CIRCUIT

FEATURES

Available Input Supply

System to Draw Maximum Load from AC/USB

Input

Interface

or TDFN3545-20 Packages

APPLICATIONS

GENERAL DESCRIPTION

The ACT3780 is a complete battery charging and

management solution for one cell Lithium-Ion or Lith-

ium-Polymer battery. The ACT3780 incorporates the

ActivePath

architecture which automatically selects

the best available input supply for the system.

When an external power source such as an AC

adapter or a USB port is connected in, the ACT3780

regulates the system voltage to 4.8V in addition to

providing charging current to the battery. If the exter-

nal input source is not present or the system load

current is more than the input source can provide,

the ActivePath supplies additional current from the

battery to the system.

The ACT3780 charger is a complete, thermally

regulated, stand-alone single cell linear Li+ charger

that integrates an internal power 12V MOSFET. The

battery regulation voltage is ±0.5% accurate, and is

factory programmed from 4.2V (other voltages avail-

able upon request).

The ACT3780 is available in an thermally enhanced

4mm x 4mm Thin-QFN and 3.5mm × 4.5mm Thin-

DFN 20-pin packages.

ACT3780

CHG_IN

ISET

To SYSTEM

STAT1

STAT2

BAT

Li-ion Battery

AC Adapter/USB

+

TM

Path

Path

Active

SYS

Active-Semi

Pb

Pb-free