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XTR108

Other Parts Discussed in Thread: XTR108

Hello, 

 

My name is Juliana and I'm working with a XTR108 but, unfortunately I'm having problems with this circuit. When I test it, the output through the Rload is always the same. We I change the temperature on the PT100, this voltage has to vary at the same proportion, but it's is not happening. The multiplexer is working. I already tested the MOSFET, and I think that the problem isn't in this device. So, I would like to ask about some possibilities. What can be wrong? Could some inputs/outputs of the XTR108 be burned? 

 

Any answer can help. Thanks in advance

Best regards, 

 

Juliana Silva

  • Hello Juliana,

    Thank you for your question regarding the XTR108.

    Are you using a 2-wire or 3-wire RTD connection? Are you using your own circuit to test the device? If so, can you provide a schematic of your circuit?

    In general, due to the complexity of the XTR108 we always recommend evaluating the part with our EVM (evaluation module) and its included software. Using this system you can quickly configure the device for your desired input temperature range and output current/voltage span, perform a full calibration, and verify its performance.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    High Performance Linear

     

     

  • Hello Ian, 

     

    Thanks for your answer. The circuit is already working, but now I have another problem. I'm using my own circuit and I don't know any alternative to program the EEPROM device without taking it off the circuit.

     

    Do you know about some possibilities which can I use to program the EEPROM? Can I use other device like a microcontroller? Are there any other possibilities to configurate the XTR registers?

     

    Thanks in advance,

    Best regards, 

     

     

    Juliana Campos

     

  • Dear Ian, 

     

    I also would like to know if there is other device that can replace the XTR108, with similar characteristics, but using different tecnology to serial interface, like I2C. 

     

    Thanks in advance,

     

    Juliana Campos Silva

  • Juliana,

    The EEPROM used in the XTR108 system can be programmed while still connected to the XTR108. There is no need to remove the device.

    If you look at Figure 1 on p. 8 of the XTR108 data sheet, you can see that the calibration system (can be a microcontroller or PC) is connected to the SDIO and SCLK pins of both the EEPROM and the XTR108. Also, you can see that the calibration system is connected to the CS1 (chip select 1) pin of the XTR108, but not CS2 which is connected to the EEPROM. This is because the XTR108 itself asserts the CS2 line when you need to read or write to the EEPROM.

    When you need to read or write to the EEPROM, first you must send an instruction byte of 0x7F (0b01111111) to the XTR108. Once this byte is written, the XTR108 will assert the CS2 line so that the calibration system can communicate with the EEPROM directly. The XTR108 also sets its SDIO pin to a high-impedance state so it will ignore any communication from the calibration system during this time.

    This information is explained in more detail in the "SERIAL INTERFACE" section on p. 15-18 of the XTR108 data sheet.

    For your most recent question, the XTR108 is the only digitally-programmable 4-20mA transmitter that we offer. There are no similar parts available from TI that use the I2C interface.

    Best regards,
    Ian Williams

  • Hello,

     

    My name is Zhongguang and I'm also working with  a XTR108,and have the same problems with Juliana .When I test it, the output through the Rload is always the same.The multiplexer is working.The circuit is myself designed,using 3-wire RTD connection.

     

    Any answer can help. Thanks in advance

    Best regards,

     Zhongguang

  • Hello Zhongguang,

    Please share your schematic so that I can assist you with troubleshooting your circuit.

    Best regards,

    Ian Williams