ADG438F_15 Datasheet, PDF (1/16 Pages) Analog Devices – High Performance, 4-/8-Channel, Fault-Protected Analog Multiplexers

High Performance, 4-/8-Channel,
Fault-Protected Analog Multiplexers
ADG438F/ADG439F
FEATURES
All switches off with power supply off
Analog output of on channel clamped within power supplies
if an overvoltage occurs
Latch-up proof construction
Fast switching times
tON 250 ns maximum
tOFF 150 ns maximum
Fault and overvoltage protection: −40 V to +55 V
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 and ADG439F are CMOS analog multiplexers, with
the ADG438F comprising eight single channels and the ADG439F
comprising four differential channels. These multiplexers provide
fault protection. Using a series n-channel, p-channel, and
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 with power
supplies off, the multiplexer input (or output) appears as an open
circuit and only a few nanoamperes of leakage current flows. 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 output
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. E
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FUNCTIONAL BLOCK DIAGRAM
ADG438F
S1
D
S8
1 OF 8
DECODER
A0 A1 A2 EN
Figure 1.
ADG439F
S1A
DA
S4A
S1B
DB
S4B
1 OF 4
DECODER
A0 A1 EN
Figure 2.
PRODUCT HIGHLIGHTS
1. Fault Protection. The ADG438F and ADG439F can with-
stand continuous voltage 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 nanoamperes flows.
2. On channel saturates while fault exists.
3. Low RON.
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-channel and n-channel MOSFETs thereby
preventing latch-up.
7. Improved Off Isolation. Trench isolation enhances the
channel-to-channel isolation of the ADG438F/ADG439F.
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