_______________General Description

The MAX1642/MAX1643 are high-efficiency, low-voltage,

step-up DC-DC converters intended for devices pow-

ered by a single alkaline cell. They feature low quies-

cent supply currents and are supplied in the ultra-small

µMAX package, which is only 1.1mm high. The guaran-

teed start-up voltage is 0.88V.

Each device consists of an internal 1

Ω, N-channel

MOSFET power switch; a built-in synchronous rectifier

that acts as the catch diode; an oscillator; a reference;

and pulse-frequency-modulation (PFM) control circuitry.

Both devices feature an independent undervoltage

comparator (PFI/PFO). The MAX1642 also includes a

2µA logic-controlled shutdown mode. The MAX1643

offers a dedicated low-battery detector (BATTLO) in

lieu of shutdown.

The output voltage for each device is preset to 3.3V

±4%, or can be adjusted from +2V to +5.2V using only

two resistors.

________________________Applications

Pagers

Remote Controls

Pointing Devices

Personal Medical Monitors

Single-Cell Battery-Powered Devices

____________________________Features

o Built-In Synchronous Rectifier

o 0.88V Guaranteed Start-Up

o Ultra-Small µMAX Package: 1.1mm High

o 83% Efficiency

o 4µA Quiescent Supply Current into BATT Pin

o 2µA Logic-Controlled Shutdown (MAX1642)

o Two Undervoltage Detectors (MAX1643)

o 2V to 5.2V Output Range

o 20mA Output Current at 1.2V Input

o Reverse Battery Protection

High-Efficiency, Step-Up

DC-DC Converters for 1V Inputs

________________________________________________________________

Maxim Integrated Products

1

GND

PFO

FB

SHDN

1

2

8

7

OUT

LX

PFI

BATT

MAX1642

µMAX

TOP VIEW

3

4

6

5

GND

BATTLO

FB

PFO

1

2

8

7

OUT

LX

PFI

BATT

MAX1643

µMAX

3

4

6

5

_________________Pin Configurations

OUT

OUTPUT

3.3V

INPUT

0.88V TO 1.65V

100

µH

22

µF

22

µF

ON

LOW-BATTERY

DETECTOR INPUT

LOW-BATTERY

DETECTOR OUTPUT

OFF

PFO

BATT

LX

MAX1642

SHDN

PFI

GND

FB

__________Typical Operating Circuit

______________Ordering Information

PART

MAX1642C/D

MAX1642EUA

MAX1643C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

Dice*

8 µMAX

Dice*

MAX1643EUA

-40°C to +85°C

8 µMAX

EVALUATION

KIT MANUAL

FOLLOWS

DATA

SHEET

19-1183; Rev 0; 6/97

*

Note: To order these devices shipped in tape and reel, add a -T

to the part number.

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

For small orders, phone 408-737-7600 ext. 3468.