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TL084I temp question.

Martin Wen
Prodigy 615 points

Hi Bro,

One of my customer tested our TL084I thermal performance and found that: 20℃ temp increase at Ambient temp 25℃.

In their product standard, the max working temp is 70℃ which means IC is 90℃.

From TL084I datasheet, the max ambient temp is 85℃. Because the critical factor affecting device reliability and functionality is the junction temperature, but we only have RθJA=97 which cannot calculate the junction temp. So the question is how can we calculate TL084I temp?  In addition 90℃ is higher than 85℃, does this has any risk?

Finally, we only found one 150 ℃ junction temp in the datasheet. So all the junction temp of TL084X are 150℃?

Thanks.

  • 0
    TI__Guru*** 140136 points
    Martin,

    97C/W is for TJA TL082ID; the TL084ID TJA is 86C/W.

    The die temperature can be calculated more accurately by measuring the top of case temperature.
    TJ = TC + PD * PSIJT
    TJ is die temperature, TC is case temperature, PD is power dissipation, PSI-JT is thermal factor, 3.7C/W for TL084ID.

    Because PSI-JT is so small, die temperature is just a little above case temperature.
    90C would be acceptable.

    150C is absolute maximum, the device would likely but may not function correctly at that temperature. Lifetime would be short.
    For every 25C reduction lifetime should increase by over 3X.
  • 0 in reply to Ron Michallick
    TI__Prodigy 615 points
    Hi Ron,

    Got it and thanks.