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ADS114S08: off state leakage?

Lutz Naumann
Expert 6680 points

Part Number: ADS114S08
Other Parts Discussed in Thread: ADS124S08

Hi Team,

do we have specifications for the inputs / MUX of ADS124S08/114S08 in off-state? We want to understand for our application how much crosstalk we have to expect in a multi channel RTD application. The excitation may be done with voltage instead of using the internal current sources. I think knowing off-state leakage would be a good indication or isolation resistance.

many thanks

Lutz 

  • 0
    TI__Guru** 113765 points

    Hi Lutz,

    Separating out the various leakage components is difficult in that the current is measured externally and the current paths divide inside of the chip.  A lot of the leakage is through the ESD structures.  The mux itself is using t-gates which is incredibly high impedance.  The ADS1x4S08 is designed in such a way as to limit all leakage paths.  The action of the mux is break before make, so the effect on one input relative to another is going to be unmeasurable.  Channel to channel isolation is very high and there no reason to expect an impact on the performance in a multi-channel RTD application.

    Where we often hear the term 'crosstalk' is actually analog settling when switching input channels at fast data rates with what is essentially a dc measurement.  When switching mux input channels, the ADS1x4S08 digital filter is reset and the conversion restarted after a delay that is configurable by register setting used to eliminate this effect.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    TI__Expert 6680 points

    Hi Bob,

    I will discuss this and if we need further detail I'll come back to you.

    Thanks for now.

    Lutz