AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and ordering information, please contact Maxim Direct

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

General Description

The MAX1551/MAX1555 charge a single-cell lithium-ion

(Li+) battery from both USB and AC adapter sources.

They operate with no external FETs or diodes, and

accept operating input voltages up to 7V.

On-chip thermal limiting simplifies PC board layout and

allows optimum charging rate without the thermal limits

imposed by worst-case battery and input voltage. When

the MAX1551/MAX1555 thermal limits are reached, the

chargers do not shut down, but progressively reduce

charging current.

The MAX1551 includes a POK output to indicate when

input power is present. If either charging source is

active, POK goes low. The MAX1555 instead features a

CHG output to indicate charging status.

With USB connected, but without DC power, charge cur-

rent is set to 100mA (max). This allows charging from

both powered and unpowered USB hubs with no port

communication required. When DC power is connected,

charging current is set at 280mA (typ). No input-blocking

diodes are required to prevent battery drain.

The MAX1551/MAX1555 are available in 5-pin thin SOT23

packages and operate over a -40°C to +85°C range.

Applications

PDAs

Wireless Appliances

Cell Phones

Digital Cameras

Features

♦ Charge from USB or AC Adapter

♦ Automatic Switchover when AC Adapter is

Plugged In

♦ On-Chip Thermal Limiting Simplifies Board

Design

♦ Charge Status Indicator

♦ 5-Pin Thin SOT23 Package

SOT23 Dual-Input USB/AC Adapter 1-Cell Li+

Battery Chargers

Ordering Information

19-2902; Rev 0; 7/03

PART

TEMP RANGE

PIN-PACKAGE

MAX1551EZK-T

-40°C to +85°C

5 Thin SOT23-5

MAX1555EZK-T

-40°C to +85°C

5 Thin SOT23-5

GND

DC

15

BAT

USB

MAX1551

(MAX1555)

THIN SOT23

TOP VIEW

2

34

POK

(CHG)

Pin Configuration

MAX1551

(MAX1555)

DC

USB

BAT

AC ADAPTER

3.7V TO 7V

USB

3.7V TO 6V

TO SYSTEM

LOAD

Li+

GND

TO LOGIC RAIL

CHARGE

CONTROL

POK

(CHG)

LOGIC

CONTROL

Typical Operating Circuit

Selector Guide

PART

TOP MARK

FEATURES

MAX1551EZK

ADRT

POK Output

MAX1555EZK

ADRU

CHG Output

MAX1551/MAX1555