AD7682

I'm using an AD7682 and want to monitor the device temperature. This is available via the inbuilt temperature sensor, but whilst I can read the raw binary value ok, the datasheet does not explain the transfer function. How do I convert the binary to Degrees C ?



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[edited by: @skowalik at 1:34 PM (GMT 0) on 26 Sep 2019]
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  • +1
    •  Analog Employees 
    on Sep 10, 2019 2:24 AM

    AndyH,

    First of all my apologies for the delay in getting back to you.

    On page 23 of the datasheet there is a brief description that indicates that the output code of the temperature sensor is output in straight binary format.   The voltage generated is approximately 1mV for every degree K and the nominal output voltage at room temperature should be about 283mV (300K).    So at room temperature and for a reference of 2.5V we should expect an output code of 283e-3/2.5 * 65535 = 7418 decimal.

    Conversely if I were to say read an output code of 8500 decimal would be approximately 324mV (again with 2.5V reference) which would be equivalent to (324-283 = 41mV) 341 degrees K or 68 deg C.

    Hope that helps.

    Sean

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  • +1
    •  Analog Employees 
    on Sep 10, 2019 2:24 AM

    AndyH,

    First of all my apologies for the delay in getting back to you.

    On page 23 of the datasheet there is a brief description that indicates that the output code of the temperature sensor is output in straight binary format.   The voltage generated is approximately 1mV for every degree K and the nominal output voltage at room temperature should be about 283mV (300K).    So at room temperature and for a reference of 2.5V we should expect an output code of 283e-3/2.5 * 65535 = 7418 decimal.

    Conversely if I were to say read an output code of 8500 decimal would be approximately 324mV (again with 2.5V reference) which would be equivalent to (324-283 = 41mV) 341 degrees K or 68 deg C.

    Hope that helps.

    Sean

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