_______________General Description

The MAX746 is a high-efficiency, high-current, step-down

DC-DC power-supply controller that drives external N-chan-

nel FETs. It provides 93% to 96% efficiency from a 6V supply

voltage with load currents ranging from 50mA up to 3A. It

uses a pulse-width-modulating (PWM) current-mode control

scheme to provide precise output regulation and low output

noise. The MAX746's 4V to 15V input voltage range, fixed

limit make this device ideal for a wide range of applications.

High efficiency is maintained with light loads due to a propri-

that minimizes switching losses by reducing the switching fre-

quency at light loads. The low 950µA quiescent current and

ultra-low 1.4µA shutdown current further extend battery life.

External components are protected by the MAX746's cycle-

by-cycle current limit. The MAX746 also features a 2V ±1.5%

reference, a comparator for low-battery detection or level

translating, and soft-start and shutdown capability.

The MAX747—discussed in a separate data sheet—

functions similarly to the MAX746, but drives P-channel logic

level FETs.

________________________Applications

5V-to-3.3V Green PC Applications

Notebook/Laptop Computers

Personal Digital Assistants

Battery-Operated Equipment

Cellular Phones

____________________________Features

o 93% to 96% Efficiency for 50mA to 3A

Output Currents

o 4V to 15V Input Voltage Range

o Low 950µA Supply Current

o 1.4µA Shutdown Current

o Drives External N-Channel FETs

o Fixed-Frequency Current-Mode PWM (Heavy Loads)

o Idle-Mode PFM (Light Loads)

o Cycle-by-Cycle Current Limiting

o 2V ±1.5% Accurate Reference Output

o Adjustable Soft-Start

o Undervoltage Lockout

o Precision Comparator for Power-Fail or

Low-Battery Warning

______________Ordering Information

* Contact factory for dice specifications.

High-Efficiency, PWM, Step-Down,

N-Channel DC-DC Controller

________________________________________________________________

Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

GND

V+

CP

HIGH

REF

SS

LBI

LBO

TOP VIEW

MAX746

EXT

AGND

CS

OUT

AV+

CC

FB

SHDN

DIP/SO

__________________Pin Configuration

CP

HIGH

SHDN

LBI

REF

EXT

OUT

V+

AV+

CS

OUTPUT

5V

LOW-BATTERY

DETECTOR OUTPUT

LBO

GND

AGND

FB

CC

SS

ON/OFF

LOW-BATTERY

DETECTOR INPUT

INPUT 6V TO 15V

40m

Ω

39

µH

440

µF

MAX746

__________Typical Operating Circuit

Call toll free 1-800-998-8800 for free samples or literature.

PART

TEMP. RANGE

PIN-PACKAGE

MAX746CPE

0°C to +70°C

16 Plastic DIP

MAX746CSE

0°C to +70°C

16 Narrow SO

MAX746C/D

0°C to +70°C

Dice*

MAX746MJE

-55°C to +125°C

16 CERDIP

MAX746ESE

-40°C to +85°C

16 Narrow SO

MAX746EPE

-40°C to +85°C

16 Plastic DIP

19-0192; Rev 1; 11/93

™Dual-Mode and Idle-Mode are trademarks of Maxim Integrated Products.