REV. D

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a

ADG438F/ADG439F*

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2000

High Performance 4/8 Channel

Fault-Protected Analog Multiplexers

FUNCTIONAL BLOCK DIAGRAMS

S1

S8

A0

D

A1 A2 EN

ADG438F

1 OF 8

DECODER

A0

ADG439F

A1 EN

S1A

DA

S4A

S1B

S4B

DB

1 OF 4

DECODER

FEATURES

Fast Switching Times

Fault and Overvoltage Protection (–40 V, +55 V)

All Switches OFF with Power Supply OFF

Analog Output of ON Channel Clamped Within Power

Supplies If an Overvoltage Occurs

Latch-Up Proof Construction

Break Before Make Construction

TTL and CMOS Compatible Inputs

APPLICATIONS

Data Acquisition Systems

Industrial and Process Control Systems

Avionics Test Equipment

Signal Routing Between Systems

High Reliability Control Systems

GENERAL DESCRIPTION

The ADG438F/ADG439F are CMOS analog multiplexers, the

ADG438F comprising 8 single channels and the ADG439F

comprising four differential channels. These multiplexers pro-

vide fault protection. Using a series n-channel, p-channel, n-

channel MOSFET structure, both device and signal source

protection is provided in the event of an overvoltage or power

loss. The multiplexer can withstand continuous overvoltage

inputs from –40 V to +55 V. During fault conditions, the multi-

plexer input (or output) appears as an open circuit and only a

few nanoamperes of leakage current will flow. This protects not

only the multiplexer and the circuitry driven by the multiplexer,

but also protects the sensors or signal sources which drive the

multiplexer.

The ADG438F switches one of eight inputs to a common out-

put as determined by the 3-bit binary address lines A0, A1 and

A2. The ADG439F switches one of four differential inputs to a

common differential output as determined by the 2-bit binary

address lines A0 and A1. An EN input on each device is used to

enable or disable the device. When disabled, all channels are

switched OFF.

PRODUCT HIGHLIGHTS

1. Fault Protection.

The ADG438F/ADG439F can withstand continuous volt-

age inputs up to –40 V or +55 V. When a fault occurs due

to the power supplies being turned off, all the channels

are turned off and only a leakage current of a few nano-

amperes flows.

2. ON channel turns OFF while fault exists.

4. Fast Switching Times.

5. Break-Before-Make Switching.

Switches are guaranteed break-before-make so that input

signals are protected against momentary shorting.

6. Trench Isolation Eliminates Latch-up.

A dielectric trench separates the p- and n-channel MOSFETs

thereby preventing latch-up.

7. Improved OFF Isolation.

Trench isolation enhances the channel-to-channel isolation

of the ADG438F/ADG439F.

*Patent Pending.