29 | Keysight | 34980A Multifunction Switch/Measure Unit - Data Sheet
Measurement characteristics with optional internal DMM
Measurement Consideration (Frequency and Period)
DC voltage
All frequency counters are susceptible to error when measuring low-volt-
age, low-frequency signals. Shielding inputs from external noise pickup is
critical for minimizing measurement errors.
Measurement method
Continuously integrating multi-slope
III A-D converter
A-D linearity
0.0002% of reading + 0.0001% of
range on 10 V range
DC current
Input resistance
100 mV, 1 V, 10 V ranges
100 V, 300 V ranges
Shunt resistance
5 Ω for 10 mA, 100 mA;
0.1 Ω for 1 A
Selectable 10 M Ω or > 10,000 M Ω
10 M Ω ± 1%
Input protection
1A 250 V fuse on 34921A module
Input bias current
Input protection
< 50 pA at 25°C
300 V all ranges
True RMS AC current
Measurement method
Direct coupled to the fuse and shunt.
AC coupled True RMS measurement
(measures the ac component only)
True RMS AC voltage
Measurement method
AC coupled True RMS—measures
the AC component of the input with
up to 300 VDC of bias on any range
Shunt resistance
Input protection
Thermocouple
Conversion
5 Ω for 10 mA; 0.1 Ω for 100 mA, 1 A
1A 250 V fuse on 34921A module
Crest factor
Maximum of 5:1 at full scale
Additional crest factor
errors (non-sinewave)
ITS-90 software compensation
Internal, ꢀxed, or external
Crest factor 1-2 0.05% of reading
Crest factor 2-3 0.15% of reading
Crest factor 3-4 0.30% of reading
Crest factor 4-5 0.40% of reading
Reference junction type
Open thermocouple check
Thermistor
Selectable per channel. Open > 5 k Ω
44004, 44007, 44006 series
a = 0.00385 (DIN) and a = 0.00392
AC Filter Bandwidth:
Slow
Medium
Fast
RTD
3 Hz - 300 kHz
20 Hz - 300 kHz
200 Hz - 300 kHz
Measurement noise rejection 60 (50) Hz [1]
DC CMRR
AC CMRR
140 dB
70 dB
Input impedance
Input protection
Resistance
1 M Ω ± 2% in parallel with 150 pF
Integration time Normal mode rejection [2]
300 Vrms all ranges
200 plc/3.33 s (4 s)
100 plc/1.67 s (2 s)
20 plc/333 ms (400 ms)
10 plc/167 ms (200 ms)
2 plc/33.3 ms (40 ms)
1 plc/16.7 ms (20 ms)
< 1 plc
105 dB [3]
100 dB [3]
95 dB [3]
90 dB [3]
85 dB
Measurement method
Current source
Selectable 4-wire or 2-wire ohms
referenced to LO input
Offset compensation
Selectable on 100 Ω, 1k Ω,
10k Ω ranges
60 dB
0 dB
Maximum lead resistance
10% of range per lead for 100 Ω
and 1k Ω ranges. 1k Ω on all
other ranges
[1] For 1 KΩ unbalance in LO lead
[2] For power line frequency ± 0.08%
Input protection
300 V on all ranges
[3] For power line frequency ± 1% use 75 dB or ± 2.5% use 60 dB
Frequency and period
Measurement method
Voltage ranges
Reciprocal counting technique
Same as AC voltage function
1 s, 100 ms, or 10 ms
Gate time
Measurement timeout
Selectable 3 Hz, 20 Hz, 200 Hz LF limit
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