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[FAQ] REF54: Operating temperature range VS specified temperature range

Jackson Wightman
Expert 5740 points
Part Number: REF54

Tool/software:

The “C” version specifies 0°C-70°C in the device comparison table but the operating temperature in the datasheet is specified as -40°C to 125°C. What is the 0°C-70°C meant to represent if not the operating range?

  • 0
    TI__Expert 5740 points

    The REF54 datasheet includes two different types of temperature ranges:

    1. Operating ambient temperature

    This is the range at which REF54 will function as expected without the device being damaged. The operating temperature range is the same for all variants of REF54. Its purpose is to give the temperature range at which the customer can expect normal operation of the device.

            2. Specified temperature range

    This is the range at which we trim REF54 for temperature drift performance. REF54 has two grades: C (0°C to 70°C) and Q (-40°C to 125°C). C grade devices are specifically trimmed for the best temperature drift from 0°C to 70°C. This means, that if the temperature goes out of that range on a C grade device, REF54 will still operate with no issue, but the temperature drift will be worse than the Q grade, which is specifically trimmed for the best temperature drift from -40°C to 125°C.

    For example, if the ambient temperature of REF54250CDR would rise above 70°C and then return to below 70°C, the device would continue to behave as normal, and with the temperature drift spec of 0.8 ppm/°C as long as it remains in the 0°C to 70°C range. There would be no device damage. However, we do not guarantee the temperature drift spec of REF54250CDR above 70°C or below 0°C.

    Similarly, if you used REF54250QDR and it turns out the temperature of interest was 0°C to 70°C, the temperature drift spec would be 1.5 ppm/°C, not 0.8 ppm/°C like REF54250CDR, because REF54250QDR is not trimmed to the 0°C to 70°C temperature range.

    So, if the ambient temperature remains in the range of 0°C to 70°C, I would strongly suggest REF54xxxCDR. Otherwise, REF54xxxQDR is also a great choice.