_______________General Description

The MAX1626/MAX1627 step-down DC-DC switching

controllers provide high efficiency over loads ranging

from 1mA to more than 2A. A unique current-limited,

pulse-frequency-modulated (PFM) control scheme

operates with up to a 100% duty cycle, resulting in very

low dropout voltages. This control scheme eliminates

minimum load requirements and reduces the supply

current under light loads to 90µA (versus 2mA to 10mA

for common pulse-width modulation controllers).

These step-down controllers drive an external P-chan-

nel MOSFET, allowing design flexibility for applications

to 12W or higher. Soft-start reduces current surges dur-

ing start-up. A high switching frequency (up to 300kHz)

and operation in continuous-conduction mode allow the

use of tiny surface-mount inductors. Output capacitor

requirements are also reduced, minimizing PC board

area and system costs.

The output voltage is preset at 5V or 3.3V for the

MAX1626 and adjustable for the MAX1627. Input volt-

ages can be up to 16.5V. The MAX1626/MAX1627 are

functional upgrades for the MAX1649/MAX1651.

________________________Applications

PCMCIA Power Supplies

Personal Digital Assistants

Hand-Held Computers

Portable Terminals

Low-Cost Notebook Computer Supplies

5V to 3.3V Green PC Applications

High-Efficiency Step-Down Regulation

Minimum-Component DC-DC Converters

Battery-Powered Applications

____________________________Features

o Low Dropout Voltage

o 100% Maximum Duty Cycle

o Soft-Start Limits Start-Up Current

o Efficiency >90% (3mA to 2A Loads)

o Output Power >12.5W

o 90µA Max Quiescent Current

o 1µA Max Shutdown Current

o Up to 300kHz Switching Frequency

o 16.5V Max Input Voltage

o Output Voltage: 5V/3.3V (MAX1626)

Adjustable (MAX1627)

o Current-Limited Control Scheme

5V/3.3V or Adjustable, 100% Duty-Cycle,

High-Efficiency, Step-Down DC-DC Controllers

________________________________________________________________

Maxim Integrated Products

1

MAX1626

V+

CS

SHDN

GND

3/5

ON/OFF

P

EXT

REF

OUT

OUTPUT

3.3V

INPUT

3.3V to 16.5V

__________________Pin Configuration

1

2

3

4

8

7

6

5

GND

EXT

CS

V+

REF

SHDN

3/5 (FB)

OUT

( ) ARE FOR MAX1627

SO

TOP VIEW

MAX1626

MAX1627

__________Typical Operating Circuit

19-1075; Rev 0; 6/96

PART

MAX1626C/D

MAX1626ESA

MAX1627C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

Dice*

8 SO

Dice*

EVALUATION

KIT MANUAL

FOLLOWS

DATA

SHEET

______________Ordering Information

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

MAX1627ESA

-40°C to +85°C

8 SO