General Description

The MAX8543/MAX8544 current-mode, constant-fre-

quency PWM buck controllers operate from a 3V to

13.2V input supply and generate adjustable 0.8V to 0.9

adjustable switching frequency and synchronization for

noise-sensitive applications.

The MAX8543/MAX8544 can start with (or without) a pre-

existing bias on the output, without discharging the out-

put. This feature simplifies tracking supply designs for

core and I/O applications and redundant supply designs.

The MAX8543/MAX8544 use the DC resistance of the

output inductor as the current-sense element for loss-

less, low-cost current sensing. The current-sense

threshold can be set to four discrete levels to accom-

modate inductors with different DC resistance values.

The MAX8544 features a power-OK monitor and two

MAX8544 controllers that can operate at 180° out-of-

phase for dual-output applications.

Applications

Base Stations

Networks and Telecom

Storage

Servers

Features

♦ Prebias Startup/Monotonic

♦ 1% Output Accuracy

♦ Ceramic, Polymer, or Electrolytic Capacitors

♦ 200kHz to 1MHz Adjustable Frequency

♦ 160kHz to 1.2MHz Synchronization

♦ Lossless, Foldback Current Limit

♦ Overvoltage Protection

♦ Enable (On/Off)

♦ Adjustable Soft-Start

♦ MAX8544

Latch-Off/Autorecovery

Power-OK Monitor

Out-of-Phase Clock Output

Step-Down Controllers with Prebias Startup,

Lossless Sensing, Synchronization, and OVP

________________________________________________________________ Maxim Integrated Products

1

Ordering Information

MAX8543

ON

OPTIONAL

SYNCHRONIZATION

OFF

BST

VL

TO 5.5V

COMP

ILIM

FSYNC

EN

SS

PGND

GND

IN

DH

LX

DL

CS+

CS-

FB

INPUT 3V TO 13.2V

OUTPUT

UP TO 25A

POK (MAX8544)

Typical Operating Circuit

19-3155; Rev 0; 5/04

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.

EVALUATION

KIT

AVAILABLE

PART

TEMP RANGE

PIN-PACKAGE

MAX8543EEE

-40°C to +85°C

16 QSOP

MAX8544EEP

-40°C to +85°C

20 QSOP

Pin Configurations appear at end of data sheet.