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XTR111: xtr111 emc compliance

Prodigy 30 points

Replies: 5

Views: 919

Part Number: XTR111

Dear Team,

for my new project i use the xtr111 trasmitter.

I have to measure a differential pressure by NXP5010 and send 4-20ma via PIC16F1788 processor.

Have you a suggestion for XTR111 input filter and  emc compliance?

Best Regard

Manfreda Lino

EMME SERVICE

ITALY

  • Hi Manfreda,

    I'm not sure what you are trying to filter, but the XTR111 is a single-ended input, so you will certainly need an instrumentation amplifier to convert the pressure sensor signal. We do have some TI designs for 4-20mA loops that have been tested for emc compliance, you may want to start by looking at these: http://www.ti.com/tool/tipd126
    http://www.ti.com/tool/TIPD190

    Note these are designs with 2-wire devices, but you can do a similar design for the XTR111.

    Regards,

    Zak Kaye
    Precision Amplifiers Applications 

  • In reply to Zak Kaye:

    Dear Zak,

    i want tu use the pre-conditioned pressure sensor MPX5010. The sensor outpui is derectly connect to ADC pin of processor and DAC pin directly connect to XTR111 input pin.

    The sensor outpui is derectly connect to ADC pin of processor and DAC pin directly connect to XTR111 input pin. I use the processor fo store and traslate the kPa to mmH2O. The output of XTR111 must be proportional to the value of mmH2O.

    My question was related to the protection and emc of the xtr111 and its outputs.

    I don't have the schematic yet. We are at the planning stage.

    Best regard

    Lino

  • In reply to lino stefano manfreda:

    Hi Lino,

    the EVM contains a suited protection circuit:

    Kai

  • In reply to lino stefano manfreda:

    Hi Lino,

    The EVM that Kai has attached shows how to best protect the output of the XTR111. The current limit circuit (Q2 + R3) is highly recommended because the XTR111 does not have an internal current limit. If you are concerned about transients on the output, then the addition of the TVS (D3) and Schottky diode (D1) provide protection against this. You do need to be careful in choosing those components because whatever leakage current flows into those devices comes out of your loop current and can impact your accuracy, particularly across temperature.

    As far as EMC is concerned, this shouldn't really be too much of an issue because you are working with low frequency, low power current signals. The XTR111 does generate some noise spikes between 10KHz -100KHz as a result of the chopping in the current mirror, but these can be attenuated with a capacitor on the output. Running your signal and ground lines with twisted pair wire can also help reduce EMI if this is a concern.

    Regards,

    Zak Kaye
    Precision Amplifiers Applications 

  • In reply to Zak Kaye:

    Hi Zak,

    thank you for your suggestion.

    I follow the indication of the schematic

    Best Regard

    Lino

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