Rainbow-electronics MAX5071 Instrukcja Użytkownika Pobierz pdf

General Description

The MAX5070/MAX5071 BiCMOS, high-performance,

current-mode PWM controllers have all the features

required for wide input voltage range isolated/nonisolated

power supplies. These controllers are used for low- and

high-power universal input voltage and telecom power

supplies.

The MAX5070/MAX5071 contain a fast comparator with

only 60ns typical delay from current sense to the output

for overcurrent protection. The MAX5070A/MAX5070B

have an integrated error amplifier with the output at

COMP. Soft-start is achieved by controlling the COMP

voltage rise using external components.

The frequency is adjustable from 20kHz to 1MHz with

an external resistor and capacitor. The timing capacitor

discharge current is trimmed allowing for programma-

ble dead time and maximum duty cycle for a given fre-

quency. The available saw-toothed waveform at R

can be used for slope compensation when needed.

The MAX5071A/MAX5071B include a bidirectional syn-

chronization circuit allowing for multiple controllers to

run at the same frequency to avoid beat frequencies.

Synchronization is accomplished by simply connecting

the SYNC pins of all devices together. When synchro-

nizing with other devices, the MAX5071A/MAX5071B

with the highest frequency synchronizes the other

devices. Alternatively, the MAX5071A/MAX5071B can

be synchronized to an external clock with an open-

drain output stage running at a higher frequency.

The MAX5071C provides a clock output pulse

(ADV_CLK) that leads the driver output (OUT) by

110ns. The advanced clock signal is used to drive the

secondary-side synchronous rectifiers.

The MAX5070/MAX5071 are available in 8-pin µMAX

and SO packages and operate over the automotive tem-

perature range of -40°C to +125°C.

Applications

Universal Input AC/DC Power Supplies

Isolated Telecom Power Supplies

Isolated Power-Supply Modules

Networking Systems

Computer Systems/Servers

Industrial Power Conversion

Isolated Keep-Alive Circuits

Features

♦ Pin-for-Pin Replacement for UC2842 (MAX5070A)

and UC2844 (MAX5070B)

♦ 2A Drive Source and 1A Sink Capability

♦ Up to 1MHz Switching Frequency Operation

♦ Bidirectional Synchronization

(MAX5071A/MAX5071B)

♦ Advanced Output Drive for Secondary-Side

Synchronous Rectification (MAX5071C)

♦ Fast 60ns Cycle-by-Cycle Current Limit

♦ Trimmed Oscillator Capacitor Discharge Current

Sets Maximum Duty Cycle Accurately

♦ Accurate 5% Start and Stop Voltage with 6V

Hysteresis

♦ Low 32µA Startup Current

♦ 5V Regulator Output (VREF) with 20mA Capability

♦ Overtemperature Shutdown

MAX5070/MAX5071

High-Performance, Single-Ended, Current-Mode

PWM Controllers

________________________________________________________________ Maxim Integrated Products 1

OUT

GNDR

VREF

COMP

µMAX/SO

TOP VIEW

MAX5070A

MAX5070B

Pin Configurations

Ordering Information

19-3283; Rev 1; 6/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information continued at end of data sheet.

Selector Guide appears at end of data sheet.

PART TEMP RANGE

PIN-PACKAGE

MAX5070AASA

-40°C to +125°C

8 SO

MAX5070AAUA

-40°C to +125°C

8 µMAX

MAX5070BASA

-40°C to +125°C

8 SO

MAX5070BAUA

-40°C to +125°C

8 µMAX

Pin Configurations continued at end of data sheet.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

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MAX5070/MAX5071 1
PWM Controllers 1

Podsumowanie treści

Strona 1 - PWM Controllers

General DescriptionThe MAX5070/MAX5071 BiCMOS, high-performance,current-mode PWM controllers have all the featuresrequired for wide input voltage rang

Strona 2

MAX5070/MAX5071High-Performance, Single-Ended, Current-ModePWM Controllers10 _________________________________________________________________________

Strona 3

Detailed DescriptionThe MAX5070/MAX5071 current-mode PWM controllersare designed for use as the control and regulation core offlyback or forward topol

Strona 4

MAX5070/MAX5071Current-Mode Control LoopThe advantages of current-mode control over voltage-mode control are twofold. First, there is the feed-forward

Strona 5

VCCand StartupIn normal operation, VCCis derived from a tertiary wind-ing of the transformer. However, at startup there is noenergy delivered through

Strona 6

MAX5070/MAX5071To calculate the capacitance required, use the followingformula:where:IG= QGfSWICCis the MAX5070/MAX5071s’ maximum internal sup-ply cur

Strona 7

MAX5071A/MAX5071B/MAX5071CFeedbackThe MAX5071A/MAX5071B/MAX5071C are designed tobe used with either an external error amplifier whendesigned into a no

Strona 8

MAX5070/MAX5071Advance Clock Output (ADV_CLK) (MAX5071C)ADV_CLK is an advanced pulse output provided tofacilitate the easy implementation of secondary

Strona 9