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TPS7A66-Q1: TPS7A6650QDGNRQ1 Junction temperature question

CHO SR
Expert 2935 points
Part Number: TPS7A66-Q1

Hi,

Customer asks temperature questions during TPS7A6650 review.

The data sheet temperature reference range is Junction temperature 150, shutdown 175, and 20 hysteresis.

The customer's circuit calculation shows that the junction temperature is above 150 degrees Celsius.

Junction temperature 156 is calculated and there is a margin until shutdown, but would it be a problem if the junction temperature actually exceeds the above?

  • +1
    TI__Genius 12511 points

    Hello Cho,

    The temperature range listed on datasheets are typically (-40C  125C), for automotive parts we increase the thermal performance and testing to higher temps as you see here with the (-40C   150C) rating. These values are the maximum values that we can guarantee the parts operation follows the EC table. If you operate outside these ranges we cannot be certain that the part will operate normally.

    For example at higher temps dropout may become too high to regulate Vout, It can cause slower response times in the feedback loop, or it can limit Iout below the Ioutmax. These are some of the consequences of outside standard temperature operation.

    Thermal shutdown is given a buffer before it trips so that during a load or line transient the part can still regulate for short bursts of over-temperature operation, without having to fully shutdown, and restart every time this happens, it is not there for operation to take place in this buffer zone, this makes shutdown a much more likely occurrence

    It is possible that the part could function under these operating conditions, however we do not recommend that they operate this device above temperature as failure is significantly more likely to occur, and operation is not guaranteed, as discussed above.

    Gerard Copeland's app note on ways to design the layout to increase the thermal performance of the LDO, would be able to get them to operate under 150C if they use the thermally enhanced layout.

    Hope this clarifies,

    John Schneider