Rainbow-electronics MAX5095A Manual de usuario descargar pdf

General Description

The MAX5094A/B/C/D/MAX5095A/B/C 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 volt-

age and telecom power supplies.

The MAX5094/MAX5095 contain a fast comparator with

only 60ns typical delay from current sense to the output

for overcurrent protection. The MAX5094 has an inte-

grated error amplifier with the output at COMP. Soft-

start is achieved by controlling the COMP voltage rise

using external components.

The oscillator frequency is adjustable from 20kHz to

1MHz with an external resistor and capacitor. The tim-

ing capacitor discharge current is trimmed allowing for

programmable dead time and maximum duty cycle for

a given frequency. The available saw-toothed waveform

at R

can be used for slope compensation when

needed.

The MAX5095A/MAX5095B 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 of all devices together. When synchronizing

with other devices, the MAX5095A/MAX5095B with the

highest frequency synchronizes the other devices.

Alternatively, the MAX5095A/MAX5095B can be syn-

chronized to an external clock with an open-drain out-

put stage running at a higher frequency.

The MAX5095C 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 MAX5094A/B/C are available in the 8-pin SO and

8-pin µMAX

packages. The MAX5094D and

MAX5095A/B/C are available in the 8-pin µMAX pack-

age. All devices operate over the automotive tempera-

ture 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 UCC28C43

(MAX5094A) and UCC28C45 (MAX5094B)

♦ 2A Drive Source and 1A Sink Capability

♦ Up to 1MHz Switching Frequency Operation

♦ Bidirectional Frequency Synchronization

(MAX5095A/MAX5095B)

♦ Advanced Output Drive for Secondary-Side

Synchronous Rectification (MAX5095C)

♦ Fast 60ns Cycle-by-Cycle Current Limit

♦ Trimmed Oscillator Capacitor Discharge Current

Sets Maximum Duty Cycle Accurately

♦ Accurate ±5% Start Voltage with 0.8V Hysteresis

♦ Low 32µA Startup Current

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

♦ Versions with 0.3V Current-Sense Threshold

MAX5094A/B/C/D/MAX5095A/B/C

High-Performance, Single-Ended, Current-Mode

PWM Controllers

________________________________________________________________ Maxim Integrated Products 1

OUT

GNDR

REF

COMP

µMAX/SO

TOP VIEW

MAX5094

Pin Configurations

Ordering Information

19-3864; Rev 0; 10/05

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.

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX5094AASA

-40°C to +125°C

8 SO S8-4

MAX5094AAUA

-40°C to +125°C

8 µMAX U8-1

MAX5094BASA*

-40°C to +125°C

8 SO S8-4

MAX5094BAUA*

-40°C to +125°C

8 µMAX U8-1

MAX5094CASA*

-40°C to +125°C

8 SO S8-4

MAX5094CAUA*

-40°C to +125°C

8 µMAX U8-1

MAX5094DAUA*

-40°C to +125°C

8 µMAX U8-1

MAX5095AAUA

-40°C to +125°C

8 µMAX U8-1

MAX5095BAUA*

-40°C to +125°C

8 µMAX U8-1

MAX5095CAUA*

-40°C to +125°C

8 µMAX U8-1

Pin Configurations continued at end of data sheet.

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

*Future product—contact factory for availability.

Ordering Information continued at end of data sheet.

1 2 3 4 5 6 ... 21 22

Indice de contenidos

Pagina 1 - PWM Controllers

General DescriptionThe MAX5094A/B/C/D/MAX5095A/B/C BiCMOS, high-performance, current-mode PWM controllers have all thefeatures required for wide input

Pagina 2

MAX5094A/B/C/D/MAX5095A/B/CHigh-Performance, Single-Ended, Current-ModePWM Controllers10 _____________________________________________________________

Pagina 3

Detailed DescriptionThe MAX5094_/MAX5095_ current-mode PWM con-trollers are designed for use as the control and regulationcore of flyback or forward t

Pagina 4

MAX5094A/B/C/D/MAX5095A/B/CCurrent-Mode Control LoopThe advantages of current-mode control over voltage-mode control are twofold. First, there is the

Pagina 5

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

Pagina 6

MAX5094A/B/C/D/MAX5095A/B/CTo calculate the capacitance required, use the followingformula:where:IG= QGfSWICCis the MAX5094/MAX5095s’ maximum internal

Pagina 7

MAX5095_FeedbackThe MAX5095A/MAX5095B/MAX5095C use either anexternal error amplifier when designed into a nonisolat-ed converter or an error amplifier

Pagina 8

MAX5094A/B/C/D/MAX5095A/B/CAdvance Clock Output (ADV_CLK) (MAX5095C)ADV_CLK is an advanced pulse output provided tofacilitate the easy implementation

Pagina 9