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SN74HCT244: higher temperature range version

Howard Zou
Genius 12365 points
Part Number: SN74HCT244
Other Parts Discussed in Thread: UCC23513, , SN54HCT244, SN74HCT240, TMS320F28069, SN74LVC240A, SN74ACT244

Hi,

my customer is using this device to drive UCC23513's optocoupler input in solar inverter.

Now they need -40-105C version of SN74HCT244.

SN54HCT244's spec is enough but it's military rating.

Do we have or do we plan to have -40-105C version of SN74HCT244?

The same question apply to SN74HCT240.

  • 0
    TI__Mastermind 43360 points

    Hey Howard,

    Are TTL compatible inputs required?

  • 0 in reply to Dylan Hubbard
    TI__Genius 12365 points

    Dylan,

    the input is from TI's TMS320F28069 PWM pin.

  • 0 in reply to Howard Zou
    TI__Mastermind 43360 points

    Hey Howard,

    One more question: Are they wanting the output to be 5 V (are they trying to level shift up?)

    If not, then you can use the SN74LVC240A/244A as they have a wide operating temp range. They can also be powered from the same 3.3 V rails as the MCU unlike the previous device selected.

  • 0 in reply to Dylan Hubbard
    TI__Genius 12365 points

    Dylan,

    For the recommended operating conditions sector in datasheet,

    Operating free-air temperature is -40 to 85 for SN74ACT244.

    My question is:

    1. What's the recommended operating junction temperature for this device?

    2. For my knowledge, the real constraint for a device is the junction temperature. With different load and PCB layout, the corresponding Operating free-air temperature should vary, then why can we say that Operating free-air temperature is -40 to 85 for SN74ACT244?

    3. Is it possible that I use this device at ambient temperature>85C? What's the influence for such use case, will the device life be shorter? Do we have such statistics to show the device life versus. operating ambient temperature ?

  • 0 in reply to Howard Zou
    TI__Mastermind 43360 points

    Howard Zou said:

    1. What's the recommended operating junction temperature for this device?

    Please refer to the FAQ:https://e2e.ti.com/support/logic/f/151/t/716186?tisearch=e2e-sitesearch&keymatch=faq%3Atrue

    2. For my knowledge, the real constraint for a device is the junction temperature. With different load and PCB layout, the corresponding Operating free-air temperature should vary, then why can we say that Operating free-air temperature is -40 to 85 for SN74ACT244?

    Again, please refer to the FAQ.

    3. Is it possible that I use this device at ambient temperature>85C? What's the influence for such use case, will the device life be shorter? Do we have such statistics to show the device life versus. operating ambient temperature ?

    It can, it would be past our recommended operating temp with no guarantee of performance. There's failure rate info shown in the product folder quality tab, but this info is not something we have.