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
t
ON
250 ns max
t
OFF
150 ns max
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.
3. Low R
ON.
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.
