General Description

The MAX1608/MAX1609 provide remote input/output (I/O)

expansion through an SMBus™ 2-wire serial interface.

Each device has eight high-voltage open-drain outputs

that double as TTL-level logic inputs, providing continuous

bidirectional capabilities. The open-drain outputs tailor the

MAX1608/MAX1609 for use in load-switching and other

level-shifting applications as well as general-purpose I/O

applications.

Two complete sets of registers allow the device and its

outputs to be toggled between two states using the

SMBSUS input, without the inherent latency of reprogram-

ming outputs over the serial bus. The eight I/O lines are

continuously monitored and can be used as inputs. Each

line can generate asynchronous maskable interrupts on

the falling edge, the rising edge, or both edges.

For load-switching applications, the MAX1608 is designed

to drive N-channel MOSFETs, and its outputs are low

upon power-up; the MAX1609 is designed to drive P-

channel MOSFETs, and its I/Os are high impedance upon

power-up. Other features of both devices include thermal-

overload and output-overcurrent protection, ultra-low sup-

ply current, and a wide +2.7V to +5.5V supply range. The

MAX1608/MAX1609 are available in space-saving 16-pin

QSOP packages.

Applications

Parallel I/O Expansion

Power-Plane Switching

Notebook and Desktop Computers

Servers and Workstations

Notebook Docking Stations

Industrial Equipment

Features

o Serial-to-Parallel or Parallel-to-Serial Conversions

o 8 General-Purpose Digital I/O Pins

(withstand +28V)

o SMBus 2-Wire Serial Interface

o Supports SMBSUS Asynchronous Suspend

o 9 Pin-Selectable Slave Addresses

o Outputs High Impedance on Power-Up (MAX1609)

o Outputs Low on Power-Up (MAX1608)

o 2.5µA Supply Current

o +2.7V to +5.5V Supply Range

o 16-Pin QSOP Package

Octal SMBus-to-Parallel I/O Expanders

________________________________________________________________ Maxim Integrated Products

1

19-1639; Rev 0; 1/00

PART

MAX1608EEE

MAX1609EEE

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE

PIN-PACKAGE

16 QSOP

16 QSOP

Ordering Information

Typical Operating Circuits

MAX1609

IO1

SMBUS

TO/

FROM

HOST

+2.7V TO +5.5V

V+

IO3

IO2

GND

LOAD1

LOAD2

LOAD3

ALERT

0.1

µF

P-CH

100k

100k

100k

SMBCLK

SMBDATA

SMBSUS

ADD

IO7

ADD1

Typical Operating Circuits continued at end of data sheet.

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

IO0

V+

SMBSUS

SMBCLK

ALERT

SMBDATA

ADD1

ADD0

GND

TOP VIEW

MAX1608

MAX1609

QSOP

IO1

IO2

IO5

IO3

IO4

IO6

IO7

Pin Configuration

SMBus is a trademark of Intel Corp.

For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.