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For small orders, phone 408-737-7600 ext. 3468.

General Description

The MAX1637 synchronous, buck, switch-mode power-

supply controller generates the CPU supply voltage in

battery-powered systems. The MAX1637 is a stripped-

down version of the MAX1636 in a smaller 16-pin QSOP

package. The MAX1637 is intended to be powered sep-

arately from the battery by an external bias supply (typi-

cally the +5V system supply) in applications where the

battery exceeds 5.5V. The MAX1637 achieves excellent

DC and AC output voltage accuracy. This device can

operate from a low input voltage (3.15V) and delivers the

excellent load-transient response needed by upcoming

generations of dynamic-clock CPUs.

Using synchronous rectification, the MAX1637 achieves

up to 95% efficiency. Efficiency is greater than 80%

over a 1000:1 load-current range, which extends bat-

tery life in system-suspend or standby mode. Excellent

dynamic response corrects output load transients

caused by the latest dynamic-clock CPUs within five

300kHz clock cycles. Powerful 1A on-board gate driv-

ers ensure fast external N-channel MOSFET switching.

The MAX1637 features a logic-controlled and synchro-

nizable, fixed-frequency, pulse-width-modulation

(PWM) operating mode. This reduces noise and RF

interference in sensitive mobile-communications and

pen-entry applications. Asserting the SKIP pin enables

fixed-frequency mode, for lowest noise under all load

conditions. For a stand-alone device that includes a

+5V VL linear regulator and low-dropout capabilities,

refer to the MAX1636 data sheet.

________________________Applications

Notebook Computers

Subnotebook Computers

Handy-Terminals, PDAs

____________________________Features

o ±2% DC Accuracy

o 0.1% (typ) DC Load Regulation

o Adjustable Switching Frequency to 350kHz

o Idle Mode™ Pulse-Skipping Operation

o 1.10V to 5.5V Adjustable Output Voltage

o Internal Digital Soft-Start

o 1.1V ±2% Reference Output

o 1µA Total Shutdown Current

o Output Overvoltage Crowbar Protection

o Output Undervoltage Shutdown (foldback)

o Tiny 16-Pin QSOP Package

Miniature, Low-Voltage,

Precision Step-Down Controller

________________________________________________________________

Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

CSH

SKIP

LX

DH

BST

PGND

DL

TOP VIEW

MAX1637

QSOP

CSL

FB

SHDN

CC

REF

SYNC

GND

__________________Pin Configuration

__________Typical Operating Circuit

19-1321; Rev 1; 2/98

PART

MAX1637EEE

-40°C to +85°C

TEMP. RANGE

PIN-PACKAGE

16 QSOP

EVALUATION

KIT

AVAILABLE

______________Ordering Information

Idle Mode is a trademark of Maxim Integrated Products.

MAX1637

SHDN

GND

DL

PGND

LX

DH

BST

CSH

CSL

FB

SKIP

SYNC

REF

CC

OUTPUT