General Description

The MAX1925/MAX1926 single-cell lithium-ion (Li+)

switch-mode battery chargers use an external PMOS

pass element step-down configuration. Charge current

is programmable, and an external capacitor sets the

maximum charge time.

Additional features include automatic input power

detection (ACON output), logic-controlled enable, and

temperature monitoring with an external thermistor. The

MAX1925 disables charging for inputs greater than

6.1V, while the MAX1926 charges for inputs between

4.25V and 12V.

The MAX1925/MAX1926 feature two precondition levels

to restore near-dead cells. The devices source 4mA to

a cell that is below 2V while sourcing C/10 to a cell

between 2V and 3V. Full charge current is then applied

above 3V. A CHG output drives an LED to indicate

charging (LED on) and fault conditions (LED blinking).

The MAX1925/MAX1926 are available in a 12-pin

the extended temperature range (-40°C to +85°C). An

evaluation kit is available to speed design.

Applications

Digital Cameras

Self-Charging Battery Packs

PDAs

Cradle Chargers

Features

o 4.25V to 12V Input Range (MAX1926)

o Overvoltage Lockout at 6.1V (MAX1925)

o ±0.75% Battery Regulation Voltage

o Set Charge Current with One Resistor

o Automatic Input Power Sense

o LED (or Logic-Out) Charge Status and Fault

Indicator

o Programmable Safety Timer

o Autorestart at Cell = 4V

o Thermistor Monitor Input

Switch-Mode 1-Cell Li+ Chargers

________________________________________________________________ Maxim Integrated Products

1

Ordering Information

MAX1925

MAX1926

IN

EN

INP

EXT

PGND

INPUT

4.5V TO 12V

LED

CT

CHG

ON

OFF

ACON

THRM

GND

BATT

CS

1-CELL

Li+

BATTERY

Typical Operating Circuit

19-2556; Rev 1; 10/02

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.

EVALUATION

KIT

AVAILABLE

PART

TEMP

RANGE

PIN-

PACKAGE

INPUT

CHARGING

RANGE

MAX1925ETC

-40

°C to +85°C

12 Thin QFN

4.5V to 6.1V

MAX1926ETC

-40

°C to +85°C

12 Thin QFN

4.25V to 12V

12

IN

11

INP

10

EXT

45

CT

6

CS

1

2

EN

3

9

8

7

THRM

PGND

GND

BATT

MAX1925

MAX1926

CHG

ACON

THIN QFN

Pin Configuration