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SN74HC244: SN74HC244 operating temperature

Sunset
Genius 13385 points
Part Number: SN74HC244

Hello Team,

Looking to the SN74HC244  datasheet I do see that the absolute max Tj is 150C while the recommended operative temperature (ambient) is 85C.

I f the device is not loaded working at low frequency (2.5KHz at 3.3V and Iload <1mA).

The T increase from ambient should be low.

  • Would be possible to operate the SN74HC244  at 105C ambient? 
  • Do you have alternatives to the SN74HC244  that may operate at 105C and integrate ESD diodes?

Thanks

SunSet

  • 0
    TI__Guru* 96591 points
    Hi Sunset,
    No, the maximum junction temperature is an _additional_ constraint, not a free pass to violate the datasheet specs. That is to say, if the customer is operating the device within the d/s specs, and they manage to exceed the Tjmax, then the device will be damaged.
  • 0 in reply to Emrys Maier
    TI__Genius 13385 points
    Hello Maier,

    thanks for your feedback.
    The end application will not violate Tj max.

    The delta between the max operative ambient temperature and Tj max is quite high.
    Typically for devices that withstand Tj max 150C, have max T operative more in the range of 105C or 125C.

    Thus the question, why the SN74HC244 is only 85C?
    Can the SN74HC244 operate higher ambient operative be used (keeping Tj max 150C)?

    Thanks,

    SunSet
  • 0 in reply to Sunset
    TI__Guru* 96591 points
    Hi SunSet,
    The device is only rated for 85C because it was designed and characterized for 85C operation (about 30-40 years ago, I believe). Many of these devices have gone through a recharacterization to support 125C over the years, but apparently this one never did.

    As long as the datasheet lists 85C as the maximum ambient operating temperature, that is the highest temperature we can guarantee operation at. I repeat that TJ(max) does _not_ supercede other limitations in the datasheet.