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XTR117: XTR117 output nosie level

Part Number: XTR117
Other Parts Discussed in Thread: XTR111, XTR115, XTR116, XTR110

What's noise level of XTR117 output at 500R load?

  • Hello Changhping,

    The noise at the load resistor of the XTR117 is dependent on the external components used in the two-wire loop. All the external components will have some influence on the noise: including the external transistor, bypass capacitors, cables/wiring used in the two wire loop, and other components present in the system. Therefore, it is difficult to provide a specification since this would be more of a system performance specification. The datasheet provides the XTR117 input referred noise of 0.6uVp-p.
    The best thing to do will be to perform a noise measurement at the load in your system.

    That said, it is important to highlight that 4-20mA current loops tend to be robust and have good immunity against external noise sources outside the system due to the low impedances involved, and are often used in applications to transmit signals across long distances.

    Thank you,

    Best Regards,

    Luis
  • Hi Changhping,

    usually the most noise comes from the sensor or bridge you connect to the input of XTR117. Compared to the noise the XTR117 creates by itself the sensor or bridge noise is totally dominant.

    Kai
  • Hello Luis

    Thanks for your prompt reply. I am making a chip selection for the 4-20mA current output with low noise. Would you please give some comment for it? XTR111 or XTR117? or others?

    Best Regards

    Roger Li

  • Hi Roger,

    Depends on the application requirement, you can choose between a 2-wire or a 3-wire transmitter.

    The main difference between 2-wire and 3-wire transmitters is how they are powered: 2-Wire transmitters are loop powered and are used in applications were the transmitter and sensor are remotely located, and local supply is not practical. 3-Wire Transmitters are locally powered where the transmitter is in close proximity to the power supply.

    The XTR111 (3-wire transmitter) is very accurate, having very good linearity and low offset drift. It relies on the dynamic matching of the current sources; however the trade-off of this architecture is a small ripple on the output that can be filtered by placing a capacitor in parallel with the load resistor.

    If your primary concern is noise, the XTR115, XTR116 and XTR117 belong to a family of 2-wire current transmitters; they are low noise, they all specify 0.6uVp-p (0.1Hz to 10Hz) input referred noise.

    Below is a list of 2-wire and 3-wire transmitters.

    Thank you,

    Best Regards,

    Luis

    2-Wire Current Converters:

    XTR115: is a 4-20mA output, 0uA to 250uA input range current transmitter with 2.5V reference and 5V regulator
    XTR116: is a 4-20mA output, 0uA to 250uA input range current transmitter with 4.096V reference and 5V regulator
    XTR117: is a 4-20mA output, 0uA to 250uA input range current transmitter with 5-V regulator.

    3-Wire Transmitters:
    XTR110: 0-20mA, 4-20mA and 5-25mA output and 0-5V, and 0-10V input 3-wire transmitter with adjustable reference.
    XTR111: 0-20mA, 4-20mA and 5-25mA output and 0-5V, and 0-12V input 3-wire transmitter with adjustable regulator.
  • Roger

    We haven't heard back from you so we assume this answered your question. If you need more help just post another reply.

    Thanks
    Dennis