General Description

The low-cost MAX1873R/S/T provides all functions

needed to simply and efficiently charge 2-, 3-, or 4-

series lithium-ion cells at up to 4A or more. It provides a

regulated charging current and voltage with less than

±0.75% total voltage error at the battery terminals. An

external P-channel MOSFET operates in a step-down

DC-DC configuration to efficiently charge batteries in

low-cost designs.

The MAX1873R/S/T regulates the battery voltage and

charging current using two control loops that work

together to transition smoothly between voltage and

current regulation. An additional control loop limits cur-

rent drawn from the input source so that AC adapter

size and cost can be minimized. An analog voltage out-

put proportional to charging current is also supplied so

that an ADC or microcontroller can monitor charging

current.

The MAX1873 may also be used as an efficient current-

limited source to charge NiCd or NiMH batteries in mul-

tichemistry charger designs. The MAX1873R/S/T is

available in a space-saving 16-pin QSOP package. Use

the evaluation kit (MAX1873EVKIT) to help reduce

design time.

Applications

Notebook Computers

Portable Internet Tablets

2-, 3-, or 4-cell Li+ Battery Pack Chargers

6-, 9-, or 10-cell Ni Battery Pack Chargers

Hand-Held Instruments

Portable Desktop Assistants (PDAs)

Desktop Cradle Chargers

Features

o Low-Cost and Simple Circuit

o Charges 2-, 3-, or 4-Series Lithium-Ion Cells

o AC Adapter Input-Current-Limit Loop

o Also Charges Ni-Based Batteries

o Analog Output Monitors Charge Current

o ±0.75% Battery-Regulation Voltage

o 5µA Shutdown Battery Current

o Input Voltage Up to 28V

o 200mV Dropout Voltage/100% Duty Cycle

o Adjustable Charging Current

o 300kHz PWM Oscillator Reduces Noise

o Space-Saving 16-Pin QSOP

o MAX1873 Evaluation Kit Available to Speed

Designs

Simple Current-Limited Switch-Mode

Li+ Charger Controller

________________________________________________________________ Maxim Integrated Products

1

Ordering Information

19-2099; Rev 0; 7/01

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATIO

N KIT AVA

ILABLE

PART

TEMP. RANGE

PIN-PACKAGE

MAX1873REEE

-40°C to +85°C

16 QSOP

MAX1873SEEE

-40°C to +85°C

16 QSOP

MAX1873TEEE

-40°C to +85°C

16 QSOP

Selector Guide

PART

SERIES CELLS TO CHARGE

MAX1873REEE

2-Cell Li+ or 5- or 6-cell Ni Battery

MAX1873SEEE

3-Cell Li+ or 7- or 9-cell Ni Battery

MAX1873TEEE

4-Cell Li+ 10-cell Ni Battery Packs

MAX1873

GND

VADJ

REF

ICHG/EN

IOUT

DCIN

VH VL

CSSP

CSSN

SYSTEM

LOAD

VIN 9V TO

28V

(9V MIN

FOR 2-

CELLS)

4V OUT PER

EXT

BATT

CSB

CCI

CCS

CCV

2- TO 4-CELL

Li+

Typical Operating Circuit

Pin Configuration appears at end of data sheet.