MAX8743(2004) 데이터 시트보기 (PDF) - Maxim Integrated

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MAX8743
(Rev.:2004)

Dual, High-Efficiency, Step-Down Controller with High Impedance in Shutdown

Maxim Integrated 

19-3318; Rev 0; 6/04

Dual, High-Efficiency, Step-Down

Controller with High Impedance in Shutdown

General Description

The MAX8743 is a dual pulse-width modulation (PWM)

controller configured for step-down (buck) topologies

that provides the high efficiency, excellent transient

response, and high DC output accuracy necessary for

stepping down high-voltage batteries to generate low-

voltage chipset and RAM power supplies in notebook

computers. The CS_ inputs can be used with low-side

sense resistors to provide accurate current limits or can

be connected to LX_, using low-side MOSFETs as cur-

rent-sense elements. High output impedance in shut-

down eliminates negative output voltages, saving the

cost of a Schottky diode at the output.

The on-demand PWM controllers are free running, con-

stant on-time with input feed-forward. This configuration

provides ultra-fast transient response, wide input-output

differential range, low supply current, and tight load-reg-

ulation characteristics. The MAX8743 is simple and easy

to compensate.

Single-stage buck conversion allows the MAX8743 to

directly step down high-voltage batteries for the highest

possible efficiency. Alternatively, two-stage conversion

(stepping down the 5V system supply instead of the bat-

tery at a higher switching frequency) allows the minimum

possible physical size.

The MAX8743 is intended for generating chipset, DRAM,

CPU I/O, or other low-voltage supplies down to 1V. The

MAX8743 is available in 28-pin QSOP and 36-pin thin

QFN packages.

Applications

Notebook Computers

CPU Core Supplies

Chipset/RAM Supplies as Low as 1V

1.8V and 2.5V I/O Supplies

Pin Configurations appear at end of data sheet.

Quick-PWM and Dual Mode are trademarks of Maxim Integrated

Products, Inc.

Features

♦ Ultra-High Efficiency

♦ Accurate Current-Limit Option

♦ Quick-PWM™ with 100ns Load-Step Response

♦ 1% VOUT Accuracy over Line and Load

♦ High Output Impedance in Shutdown

♦ Dual Mode™ Fixed 1.8V/1.5V/Adj or 2.5V/Adj Outputs

♦ Adjustable 1V to 5.5V Output Range

♦ 2V to 28V Battery Input Range

♦ 200kHz/300kHz/420kHz/540kHz Nominal Switching

Frequency

♦ Adjustable Overvoltage Protection

♦ 1.7ms Digital Soft-Start

♦ Drives Large Synchronous-Rectifier FETs

♦ Power-Good Window Comparator

♦ 2V ±1% Reference Output

Ordering Information

PART

MAX8743EEI

MAX8743ETX

TEMP RANGE

-40°C to +85°C

-40°C to +85°C

PIN-PACKAGE

28 QSOP

36 Thin QFN

6mm x 6mm

Minimal Operating Circuit

5V INPUT

OUTPUT1

1.8V

VDD

V+

VCC

UVP

ILIM1 OVP

ILIM2

ON1

ON2

BST1 BST2

DH1 DH2

LX1

LX2

DL1

DL2

TON

CS1

OUT1

PGOOD

REF

CS2

OUT2

SKIP

FB1

FB2

GND

BATTERY

4.5V TO 28V

MAX8743EEI

OUTPUT2

2.5V

________________________________________________________________ Maxim Integrated Products 1

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.

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