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UCC2808DTR-1 temperature spec

Kwan
Intellectual 510 points

The datasheet for UCC2808DTR-1 indicated the operating temperature is 85degC max.  What is this referenced to?  
Is 85degC referring to max ambient temperature, case temperature or junction temperature?
Unfortunately, the datasheet is unclear; table 1 actually has a sentence "TA = TJ", which confuse me.

For UL Safety Test i need to provide the case temperature.  Anyone can advise the spec for max case temperature?  Else, pls advise what is the thermal resistances for the calculation.

  • 0
    TI__Mastermind 25130 points

    Kwan,

    Please contact the product information center in your region and they can input a thermal model request for you.

    John

  • 0
    TI__Mastermind 25130 points

    Kwan,

    Some addditional information on "TA =TJ"

    John

     

    The header of the specification table has the qualifier that for the tests defined in the table that TA=TJ, unless otherwise stated. In other words, these tests are valid for the part as long as the junction temperature remains within the specified limits for the part.

    This is derived from the packaged device testing that is performed.

    In this testing, the packaged device is mounted on a thermally controlled test set. The tests are then performed in a few milliseconds to verify the parameters. This test is performed in so short a time and with such low power that there is not sufficient time for the junction temperature to be materially affected.

    These tests are performed on the initial microcircuits at multiple temperatures to characterize the IC at various junction temperatures and from that information the drift with temperature of the various parameters are determined. This leads to a narrow window for each of the parameters that can be used for test limits at a nominal junction temperature so that if the part’s characteristics fall within that narrow window at the nominal junction temperature they will remain inside the much wider parameter window at the junction temperature extremes with some margin for lifetime shifts.

    This wider parameter window are the characteristics that are in the data sheet where it is stated that TJ=TA.

    This does not mean that for a part that has a range from -40°C to +85°C that the part will be out of spec at a junction temperature of +86°C. It may very well stay within spec right up to a junction temperature of +124°C for parts that have equivalent military parts. It just means that the part may start to drift out of spec at a junction temperature of +86°C.   

    In other words, the part will fail to meet some or all of its parameters somewhere between a junction temperature of +85°C and +125°C or between -40°C and -55°C.