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ISOW1044: Temperature Derating

Trevor Cooper
Prodigy 10 points
Part Number: ISOW1044

Tool/software:

I am trying to calculate my effective operating temperature range for a ISOW1044.

I am operating the part on a 5V bus.

1.         Are the Isolation Characteristics Curves the temperature derating for the part?

           My read is yes but the nomenclature is non standard enough to make me ask.

          

2. Using the Supply Current Characteristics table

    For 5 Mbps @ 50% duty we get 136mA

    Cross referencing to the derating curve we get ~100C as the maximum operating temperature

   Is that correct?

   

Thanks in advance!

  • 0
    TI__Expert 7805 points

    Hi Trevor,

    Thanks for reaching out and providing clear details about your query. Please find my inputs below:

    The thermal derating curve dictates the derating of total current consumption allowed inside the device vs ambient temperature to limit the internal junction temperature(TJ) to 150C as per Absolute Maximum Ratings - breaching 150C TJ can damage the device permanently.

    Trevor Cooper said:
    For 5 Mbps @ 50% duty we get 136mA

    Here, this particular operation is guaranteed at 125C since on the CAN bus side, some of the current will be dissipated outside the device in the external load RL which can be calculated by VOD(DOM)/RL.

    Although if the DOM state period is >50%, then the max recommended operating temperature is 105C, mentioned in datasheet (snap below):

    Regards
    Varun