HP 34901A
20-Channel
General-Purpose Multiplexer
• 60 ch/s scanning
• Two- and four-wire scanning
• Built-in thermocouple reference
junction
• 300 V switching
The HP 34901A is the most versatile
multiplexer for general purpose
scanning. It combines dense,
multi-function 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
1A of current to the internal DMM,
allowing ac and dc current
measurements without the need for
external shunt resistors.
Multiplexer
Selection Guide
Choose between the broad
functionality of the HP 34901A,
the high speed scanning of the
HP 34902A, or the single-ended
density of the HP 34908A. These
three modules are the only way to
connect to the HP 34970A 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
HP 34901A and HP 34902A modules
when not configured for scanning.
HP 34901A HP 34902A HP 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
HP 34970A Data Acquisition/Switch Unit
HP 34902A
16-Channel
High-Speed Multiplexer
• 250 ch/s scanning
• Two- and four-wire scanning
• Built-in thermocouple reference
junction
The HP 34902A employs reed
relays to achieve scan rates up to
250 channels-per-second. Use this
module for high-throughput
automated test applications as
well as high-speed data logging
and monitoring tasks.
Sixteen two-wire inputs switch up
to 300 V. Two- and four-wire
channels may be mixed on the same
module. User provided shunt
resistors are required for current
measurements.
HP 34908A
40-Channel
Single-Ended Multiplexer
• 60 ch/s scanning
• Single-wire switching for
common-low applications
• Built-in thermocouple
reference junction
Use the HP 34908A for the greatest
density in common-low
applications, such as battery test,
component characterization, and
benchtop testing.
Each module switches 40 one-wire
inputs. All two-wire internal
measurements except current are
supported. The module low
connection is isolated from earth
and can float up to 300V.
Backplane Switches
Internal
DMM Input
01
08
Com
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
T
Com
(4W Sense)
09
16
Internal
DMM Input
(4W Sense)
Reference
Junction
Sensor
Channel Switches
Bank Switch
01
20
21
40
Com
Com
H
H
L
H
H
H
L
H
Channel Switches
Backplane
Switch
Bank Switch
Internal
DMM Input
Reference
Junction
Sensor
T
Loading...