User`s guide

11
Table 3. Multiplexer selection table—specifications and characteristics—continued
34921A 34922A 34923A 34924A 34925A
General characteristics
Relaylife,typical
Noload 100M 100M 1000M 1000M UnlimitedwithinFET
banks
10 V, 100 ma 10 M 10 M 10 M 10 M Unlimited within FET
banks
Ratedload 100k 100k 10k 10k UnlimitedwithinFET
banks
Scanning speeds
[7]
100 ch/sec 100 ch/sec 500 ch/sec 500 ch/sec 1000 ch/sec
Open/ close time, typical 4 ms/4 ms 4 ms/4 ms 0.5 ms/0.5 ms 0.5 ms/0.5 ms 0.25 ms/0.25 ms
Analog bus backplane connection Yes Yes Yes Yes Yes
[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 peri-
ods 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. Agilent
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.