Datasheet

Page 21
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Multiplexer selection guide
Choose between the broad functionality of the 34901A, the
high speed scanning of the 34902A, or the single-ended
density of the 34908A. These three modules are the only
way to connect to the 34970A/34972A internal DMM. They
can be used to scan with external instruments as well.
All multiplexer modules employ break-before-make
scanning, ensuring only one closed channel (or channel
pair) at a time. Multiple channel closures are allowed on
the 34901A and 34902A modules when not configured for
scanning.
The 34908A does not allow multiple channel closures at
any time.
34901A
20-Channel General Purpose Multiplexer
– 60 ch/s scanning
– Two- and four-wire scanning
– Built-in thermocouple reference
junction
– 300 V switching
The Keysight 34901A is the most
versatile multiplexer for general
purpose scanning. It combines dense,
multifunction switching with 60-channel/
second scan rates to address a broad
spectrum of data acquisition applications.
Two- and four-wire channels can be mixed
on the same module. Two additional fused
inputs (22 channels total) route up to 1 A
of current to the internal DMM, allowing
ac and dc current measurements without
the need for external shunt resistors.
34901A 34902A 34908A
Number of channels 20 + 2 16 40
Max scan speed 60 ch/s 250 ch/s 60 ch/s
Number of contacts 2 or 4 2 or 4 1
Temperature
Thermocouple
● ● ●
2-wire RTD
● ● ●
4-wire RTD
● ●
Thermistor
● ● ●
dc Volts
● ● ●
ac Volts
● ● ●
2-wire Ohms
● ● ●
4-wire Ohms
● ●
Frequency
● ● ●
Period
● ● ●
dc current
●
ac current
●
Backplane switches
Internal
DMM input
01
10
Com
H
L
H
L
H
L
H
L
H
L
H
L
I
L
I
L
I
L
I
L
H
L
H
L
T
Com
(4W sense)
11
20
21
Current
channels
22
Com
(Current)
Fuse
Fuse
Internal
DMM input
(4W sense)
Internal
DMM input
(Current)
Reference
junction
sensor
Channel switches
Bank switch
Shunt switches