Switch-Mode Lithium-Ion

Battery-Charger

________________________________________________________________

Maxim Integrated Products

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

General Description

The MAX745 provides all functions necessary for

charging lithium-ion battery packs. It provides a regu-

lated charging current of up to 4A without getting hot,

and a regulated voltage with only ±0.75% total error at

the battery terminals. It uses low-cost, 1% resistors to

set the output voltage, and a low-cost N-channel MOS-

FET as the power switch.

The MAX745 regulates the voltage set point and charg-

ing current using two loops that work together to transi-

tion smoothly between voltage and current regulation.

The per-cell battery voltage regulation limit is set

between 4.0V and 4.4V using standard 1% resistors,

and then the number of cells is set from 1 to 4 by pin-

strapping. Total output voltage error is less than ±0.75%.

For a similar device with an SMBus™ microcontroller

interface and the ability to charge NiCd and NiMH cells,

refer to the MAX1647 and MAX1648. For a low-cost

lithium-ion charger using a linear-regulator control

scheme, refer to the MAX846A.

____________________________Features

o Charges 1 to 4 Lithium-Ion Battery Cells

o ±0.75% Voltage-Regulation Accuracy

Using 1% Resistors

o Provides up to 4A without Excessive Heating

o 90% Efficient

o Uses Low-Cost Set Resistors and

N-Channel Switch

o Up to 24V Input

o Up to 18V Maximum Battery Voltage

o 300kHz PWM Operation: Low-Noise,

Small Components

o Stand-Alone Operation; No Microcontroller

Needed

___________________________________________________Typical Operating Circuit

19-1182; Rev 2; 12/98

PART

MAX745EAP

-40°C to +85°C

TEMP. RANGE

PIN-PACKAGE

20 SSOP

EVALUATION

KIT MANUAL

FOLLOWS

DATA

SHEET

Ordering Information

Pin Configuration appears on last page.

________________________Applications

Lithium-Ion Battery Packs

Desktop Cradle Chargers

Cellular Phones

Notebook Computers

Hand-Held Instruments

MAX745C/D

0°C to +70°C

Dice*

*

SMBus is a trademark of Intel Corp.

(UP TO 24V)

REF

DCIN

BST

VL

DHI

DLO

LX

CS

BATT

CELL

COUNT

SELECT

SET PER

CELL VOLTAGE

WITH 1% RESISTORS

ON

OFF

VADJ

STATUS

SETI

CELL0

CELL1

CCI

PGND

GND

IBAT

CCV

N

N

VOUT

1–4 Li+ CELLS

(UP TO 18V)

MAX745

THM/SHDN