11 | Keysight | 34980A Multifunction Switch/Measure Unit - Data Sheet
Table 3. Multiplexer selection table—speciꢁcations and characteristics
34921A
34922A
34923A
34924A
34925A
Channels/conꢀgurations
40 2-wire
20 4-wire
4-current
1.5 A Fused
70 2-wire
35 4-wire
80 1-wire
40 2-wire
20 4-wire
70 2-wire
35 4-wire
80 1-wire
40 2-wire
20 4-wire
Switch type
Armature
latching
Armature
latching
Reed
Reed
Optically
isolated FET
Input characteristics (per channel)
Max volts
± 300 V[1]
± 300 V[1]
± 150 V peak[2]
± 150 V peak [2]
± 80 V peak[2]
0.02 A [8]
Max current (DC, AC RMS)
Switch current
Carry current
1 A
2 A
1 A
2 A
0.5 A [5]/ 0.05 A [11]
1.5 A [5]/ 0.05 A [11]
0.5 A [5]/ 0.05 A [11]
1.5 A [5]/ 0.05 A[11]
Power (W, VA) [6]
60 W
108
60 W
108
10 W
108
10 W
108
1.6 W
107
Volt-Hertz limit
Initial closed channel res [3][12]
< 1.5 Ω
< 1.5 Ω
< 1.5 Ω [5]/200 [11]
< 1.5 Ω [5]/200 [11]
< 700 Ω
nominal
nominal
General speciꢀcations
Offset voltage [3]
< 3 μV
< 3 μV
< 50 μV
< 50 uV
< 3 μV
< 100 uV 1-wire
DC Isolation (ch-ch, ch-earth)
Leakage current [3]
T/C cold junction accuracy [3, 10]
>10 G Ω
N/A
>10 GΩ
N/A
>10 GΩ >
N/A
10 GΩ
N/A
>10 GΩ
20 nA [9]
N/A
< 1°C
N/A
N/A
N/A
AC characteristics
Bandwidth at terminal block [4]
45 MHz
25 MHz
45 MHz[5]/4 MHz
10 MHz 1-wire
25 MHz [5]/4 MHz [11]
1 MHz
Crosstalk at terminal block (ch-ch) [4]
300 kHz
–75 dB
–75 dB
–75 dB
–75 dB
Not recommended for
RF signal switching
1 MHz
20 MHz
45 MHz
–75 dB
–50 dB
–40 dB
–75 dB
–50 dB
–75 dB
–50 dB
–40 dB
–70 dB
–45 dB
Capacitance at terminal block
HI-LO
LO – earth
150 pF
150 pF
250 pF
200 pF
130 pF
120 pF
200 pF
170 pF
100 pF
300 pF (600 pF 1-wire)
[1] DC or AC RMS voltage, channel-to-channel or channel-to-earth
[2] Peak voltage, channel-to-channel or channel-to-earth
[3] Into analog bus. System errors are included in the internal DMM measurement accuracy specifications
[4] 50 Ω source, 50 Ω load, differential measurements verified with 4-port network analyzer (Sdd21)
[5] With input resistors bypassed. Bypassing resistors will reduce lifetime of relays. See the rated load relay life characteristics.
[6] Limited to 6 W of channel resistance power loss per module
[7] Speeds are for 2-wire ohms or DCV, 4 1/2 digits, delay 0, display off, autozero off, and within bank
[8] DC or peak AC current
[9] Ambient temperature < 30°C
[10] Includes 0.5°C temperature reference sensor and 0.5°C terminal block isothermal gradient error, measured under worst case loading of the mainframe; see User’s Guide for
information on supported external reference sensors
[11] With input protection resistors: 2 x 100 Ω ±5%; 0.5W ; TC = ±200 ppm/°C. The series resistance of the 34923/24/25 limits the use of the 100 Ω range.
[12] Channel resistance is typically < 1.5 Ω but can go as high as 50 Ω when a channel is used in measurement applications with < 10 mA load current. Increased relay channel
resistance for measurements with load currents below 10 mA can occur on cards that have been out of service or following relay inactivity for periods of greater than 1 week.
Switching relays for 2K cycles prior to use may reduce the variation in channel resistance. Applies to the 34921A and 34922A. Keysight recommends the use of 4-wire Ohms for
resistance measurements. For high accuracy voltage measurements, select the DMM input resistance setting of >10 G ohms to minimize the impact of relay contact resistance.
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