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TLV1543 Ref Inputs

Chris DeWitt
Prodigy 90 points
Other Parts Discussed in Thread: TLV1543

What is the internal connection of REF- in the TLV1543?  Is this part of a differential input or is REF- the Analog ground for the converter?  I need to know what relationship it needs to have with reference to the ground pin.

 

Thanks,

Chris

  • 0
    Prodigy 90 points

    Also, from an EMC immunity perspective what might happen if the connection between REF- and GND is made on a different board over a flex cable?

    Thanks,

    Chris

  • 0 in reply to Chris DeWitt
    TI__Expert 6925 points

    Hello Chris,

    Sorry for taking so long to reply. We were under the impression that this thread was already answered.

    The TLV1543 doesn’t have isolated grounds. All voltages are referred to pin 10 (GND).

    The REF- pin voltage is specified as 0V in the spec table or -0.1V as the absolute minimum. Thus, REF- must be grounded.

    REF- should be connected as close as possible to GND (pin 10) with a thick trace to have return currents across small resistance and inductance. If REF- is grounded in a different board, the cable or long traces will force the return currents across high resistance and inductance producing small voltage offsets and/or spikes, which can affect conversions even for this low resolution converter.

    Also, REF+ should be decoupled with a capacitor to GND (pin 10) to decouple the little currents produced during conversion. I recommend at least a 1uF capacitor.

    Let us know if this info answered your question.

    Best regards,
    Rafael

  • 0 in reply to Rafael Ordonez
    Prodigy 90 points

    Rafael -

    Thank you, that is what I expected.