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XTR105: XTR105 circuit protection

Part Number: XTR105
Other Parts Discussed in Thread: XTR108

HI Friends,

currently i'm developing RTD to 4-20mA converter using XTR105. this is loop powered IC so I'm worrying, what if someone make the connection in reverse direction. so I'm confused about what are the precautions should be taken at input side as well as at power supply side.

somebody please help me......provide some suggestions.



  • Hi Rupesh,

    The RTD just looks like a resistor that varies with temperature, so just like a normal resistor it makes no difference which way you connect it. On the power supply side, if you just want to prevent damage to the device then you can add a diode like D1 in the figure below. 

    Ideally, this diode should be sized to handle the reverse voltage of the power supply so you can just flip the connection and resume operation. If you want the device to operate regardless of how the supply is hooked up, you could add a bridge rectifier as shown in figure 4 in the datasheet. 

    This will detract from your compliance voltage though, so you will need to make sure you are not attempting to drop more voltage in the loop than you are supplying.

  • Hi,

    Thanks Zak Kaye. want to know what if i go with XTR108 instead of XTR105 .......?

  • lot of peoples says XTR105 is malfunctioning at site situation. Is it right ? is it susceptible to noise ?
  • Rupesh,

    The XTR108 is a very different device than the XTR105. Do you need the the flexibility offered by the digital circuitry of the XTR108? Without knowing anything about your application I can't comment on whether you'd benefit from using the XTR108. I am not aware of any quality issues with the XTR105 so I'm not sure what you are referring to.
  • Dear Zak,

    I want to use XTR108 in my design, as i am going to add EEPROM also. so please provide some reference design of XTR108. 

  • Rupesh,

    We do not have a reference design for the XTR108. We do offer an evaluation module that allows you to familiarize yourself with the device. You can find it here: It walks through the calibration procedure and demonstrates how to configure the various features. This design may serve as a good starting point for you, but keep in mind it is not a reference design and thus is not intended to be dropped into an industrial application as is. As you develop your design we can help with any questions you may have about the part.