Rainbow-electronics MAX744A Manual do Utilizador descarregar pdf (Página 1)

__________________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

♦ 750mA Load Currents (MAX738A/MAX744A)

♦ High-Frequency, Current-Mode PWM

♦ 159kHz to 212.5kHz Guaranteed Oscillator

Frequency Limits (MAX744A)

♦ 85% to 96% Efficiencies

♦ 1.7mA Quiescent Current

♦ 6µA Shutdown Supply Current

♦ Single Preselected Inductor Value,

No Component Design Required

♦ Overcurrent, Soft-Start, and Undervoltage

Lockout Protection

♦ Cycle-by-Cycle Current Limiting

♦ 8-Pin DIP/SO Packages (MAX730A)

_________________Ordering Information

Ordering Information continued at end of data sheet.

*Contact factory for dice specifications.

MAX730A/MAX738A/MAX744A

5V, Step-Down,

Current-Mode PWM DC-DC Converters

________________________________________________________________

Maxim Integrated Products

TOP VIEW

V+

GND

OUT

REF

MAX730A

MAX738A

MAX744A

DIP

SHDN

Pin Configurations continued on last page.

_________________Pin Configurations

MAX738A

MAX744A

INPUT

6V TO 16V

V+

OUT

GNDSS

REF

SHDNON/OFF

33µH

OUTPUT

100µF

68µF

__________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

1 2 3 4 5 6 ... 15 16

Resumo do Conteúdo

Página 1 - 5V, Step-Down

__________________General DescriptionThe MAX730A/MAX738A/MAX744A are 5V-outputCMOS, step-down switching regulators. The MAX738A/MAX744A accept inputs

Página 2

MAX730A/MAX738A/MAX744Asingle 100µH (MAX7__AC) or 33µH (MAX7__AE/AM)inductor. The inductor’s incremental saturation currentrating should be greater th

Página 3

Printed Circuit LayoutsA good layout is essential for clean, stable operation.The layouts and component placement diagrams givenin Figures 4, 5, 6, an

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MAX730A/MAX738A/MAX744A5V, Step-Down,Current-Mode PWM DC-DC Converters12 _____________________________________________________________________________

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