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TS5A3166: Analog Switch for multiplexing 3 wire RTDs

Jayant Deshpande85
Prodigy 140 points
Part Number: TS5A3166

Hi,

Is the part TS5A3166DBV suitable for multiplexing 3 wire RTDs or Thermocouples?

Any better alternatives?

Thanks,

Jayant

  • 0
    TI__Mastermind 45495 points

    Jayant,

    To determine the correct switch for your system you need to know the voltage range of the signal from the Resistance Temperature Detectors (RTD) or thermocouple.  The TS5A3166 device will pass a voltage up to 5.5 V with little distortion with <1 ohm on state resistance and flat on state resistance across the voltage range.

    What are you trying to accomplish with the multiplexer?  Are you trying to interface multiple thermocouples to one ADC?  The TS5A3166 is a 1:1 SPST and will only turn on and off a signal path. 

    Thank you,

    Adam  

  • 0 in reply to Adam Torma
    Prodigy 140 points

    Hi Adam,

    Thanks for your reply.

    My intention is to use the part in between field sensors and the ADC. The maximum input voltage is 3V, but the sensors can be RTDs, Thermocouples or 24V powered current loops. "Break before make" operation and low ON resistance are vital for my operation. I read DG408 datasheet, but it had larger Ron..

    Will you help me in selecting the most suitable part?

    Thanks,
    Jayant

  • 0 in reply to Jayant Deshpande85
    TI__Mastermind 45495 points

    Jayant,

    Thank you for the more information on your requirements.  All of our signal switches will support 3V signals and we have devices with on-state resistance <1 ohm.  Since you mentioned the DG408, it looks like you want to interface up to 8 different sensors to one ADC.  Below I used our switch selection tool on TI.com and filtered our 1:8 switches and sorted them by on-state resistance from least to greatest.

     

    Let me know if you think if any of these devices are close to what you are looking for and we can refine our search further. 

    One issue with making muxes with increasing number of ports it can select like 1:8, 1:16, 1:32 is it increases the on-state resistance of the signal path.  You could look at using a device with less ports on the signal path like the 1:4 TS5A5017.  You could tie the inputs of the 2-channel 1:4 switch together and isolate them with a 1:1 TS5A3166 to effectively make a 1:8 switch with Ron ~15ohms.

     I look forward to your thoughts,

    Adam