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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.
REV. D
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use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
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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
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
t
t
Supplies If an Overvoltage Occurs
ON
OFF
250 ns max
150 ns max
Fault-Protected Analog Multiplexers
PRODUCT HIGHLIGHTS
1. Fault Protection.
2. ON channel turns OFF while fault exists.
3. Low R
4. Fast Switching Times.
5. Break-Before-Make Switching.
6. Trench Isolation Eliminates Latch-up.
7. Improved OFF Isolation.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
High Performance 4/8 Channel
S8
S1
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.
Switches are guaranteed break-before-make so that input
signals are protected against momentary shorting.
A dielectric trench separates the p- and n-channel MOSFETs
thereby preventing latch-up.
Trench isolation enhances the channel-to-channel isolation
of the ADG438F/ADG439F.
A0
DECODER
ADG438F
ON.
A1 A2 EN
1 OF 8
FUNCTIONAL BLOCK DIAGRAMS
ADG438F/ADG439F
World Wide Web Site: http://www.analog.com
D
S1A
S4A
S1B
S4B
© Analog Devices, Inc., 2000
DECODER
A0
ADG439F
1 OF 4
A1 EN
DA
DB