REV. B

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties that

may result from its use. No license is granted by implication or otherwise

under any patent or patent rights of Analog Devices. Trademarks and

registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

www.analog.com

Fax: 781/326-8703

© 2004 Analog Devices, Inc. All rights reserved.

ADP3806

High Frequency Switch Mode

Li-Ion Battery Charger

FEATURES

Li-Ion Battery Charger

Three Battery Voltage Options

Selectable 12.525 V/16.700 V

Selectable 12.600 V/16.800 V

Adjustable

High End-of-Charge Voltage Accuracy

0.4% @ 25 C

0.6% @ 5 C to 55 C

0.7% @ 0 C to 85 C

Programmable Charge Current with Rail-to-Rail

Sensing

System Current Sense with Reverse Input Protection

Soft-Start Charge Current

Undervoltage Lockout

Bootstrapped Synchronous Drive for External NMOS

Programmable Oscillator Frequency

Oscillator SYNC Pin

Low Current Flag

Trickle Charge

APPLICATIONS

Portable Computers

Fast Chargers

FUNCTIONAL BLOCK DIAGRAM

–

gm2

+

SELECT

12.6/16.8

BOOTSTRAPPED

SYNCHRONOUS

DRIVER

CS+

OSCILLATOR

VREF + VREG

UVLO

BIAS

CS–

COMP

REF

AGND

BAT

SD

CT

SW

REG

PGND

VCC

BST

DRVH

DRVL

SYS+ SYS–

ISYS

ISET

LOGIC

CONTROL

LC

SYNC

LIMIT

VREF

2.5V

VREF

ADP3806

BSTREG

BATSEL

SD

IN DRVLSD

DRVLSD

–

gm1

+

+

–

+

–

+

–

AMP1

+–

AMP2

+–

–

+

GENERAL DESCRIPTION

The ADP3806 is a complete Li-Ion battery-charging IC. The

device combines high output voltage accuracy with constant

current control to simplify the implementation of constant-

current, constant-voltage (CCCV) chargers. The ADP3806 is

available in three options: The ADP3806-12.6 guarantees the

final battery voltage selected is 12.6 V or 16.8 V

± 0.6%, the

ADP3806-12.5 guarantees 12.525 V/16.7 V

± 0.6%, and the

ADP3806 is adjustable using two external resistors to set the

battery voltage. The current sense amplifier has rail-to-rail inputs

to accurately operate under low dropout and short-circuit condi-

tions. The charge current is programmable with a dc voltage on

ISET. A second differential amplifier senses the system current

across an external sense resistor and outputs a linear voltage

on the ISYS pin. The bootstrapped synchronous driver allows

the use of two NMOS transistors for lower system cost.