__________________General Description

The MAX730A/MAX738A/MAX744A are 5V-output

CMOS, step-down switching regulators. The MAX738A/

MAX744A accept inputs from 6V to 16V and deliver

750mA. The MAX744A guarantees 500mA load capa-

bility for inputs above 6V and has tighter oscillator fre-

quency limits for low-noise (radio) applications. The

MAX730A accepts inputs between 5.2V and 11V and

delivers 450mA for inputs above 6V. Typical efficien-

cies are 85% to 96%. Quiescent supply current is

1.7mA and only 6µA in shutdown.

Pulse-width modulation (PWM) current-mode control

provides precise output regulation and excellent tran-

sient responses. Output voltage accuracy is guaran-

teed to be ±5% over line, load, and temperature varia-

tions. Fixed-frequency switching allows easy filtering of

output ripple and noise, as well as the use of small

external components. These regulators require only a

single inductor value to work in most applications, so

no inductor design is necessary.

The MAX730A/MAX738A/MAX744A also feature cycle-

by-cycle current limiting, overcurrent limiting, undervolt-

age lockout, and programmable soft-start protection.

___________________________Applications

Portable Instruments

Cellular Phones and Radios

Personal Communicators

Distributed Power Systems

Computer Peripherals

________________________________Features

o 750mA Load Currents (MAX738A/MAX744A)

o High-Frequency, Current-Mode PWM

o 159kHz to 212.5kHz Guaranteed Oscillator

Frequency Limits (MAX744A)

o 85% to 96% Efficiencies

o 1.7mA Quiescent Current

o 6µA Shutdown Supply Current

o Single Preselected Inductor Value,

No Component Design Required

o Overcurrent, Soft-Start, and Undervoltage

Lockout Protection

o Cycle-by-Cycle Current Limiting

o 8-Pin DIP/SO Packages (MAX730A)

_________________Ordering Information

Ordering Information continued at end of data sheet.

*Contact factory for dice specifications.

5V, Step-Down,

Current-Mode PWM DC-DC Converters

________________________________________________________________

Maxim Integrated Products

1

TOP VIEW

1

2

3

4

8

7

6

5

V+

LX

GND

OUT

CC

SS

REF

MAX730A

MAX738A

MAX744A

DIP

SHDN

Pin Configurations continued on last page.

_________________Pin Configurations

MAX738A

MAX744A

INPUT

6V TO 16V

V+

LX

OUT

CC

GND

SS

REF

SHDN

ON/OFF

33

µH

OUTPUT

5V

100

µF

68

µF

__________Typical Operating Circuit

19-0165; Rev 2; 1/96

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

PART

TEMP. RANGE

PIN-PACKAGE

MAX730ACPA

0°C to +70°C

8 Plastic DIP

MAX730ACSA

0°C to +70°C

8 SO

MAX730AC/D

0°C to +70°C

Dice*

MAX730AEPA

8 Plastic DIP

MAX730AESA

-40°C to +85°C

8 SO

-40°C to +85°C

MAX730AMJA

-55°C to +125°C

8 CERDIP