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DAC60501: Short Circuit Duration

Greg
Expert 1961 points
Part Number: DAC60501

What is the absolute maximum spec for the duration of a short circuit of the output?  In particular I am interested in a short of VOUT to AGND, but I would be interested in knowing about VOUT to VDD as well.

Regards,

Greg

  • +1
    TI__Guru 52663 points

    Hi Greg,

    There is no maximum, and the device could stay in this condition indefinitely, with a few caveats:

    Short circuit condition usually means that there more power dissipation inside the device. These devices have a few temperature coefficients (look at the Thermal Information table), so depending on the wattage being dissipated and the ambient temperature, you could be heating the device up beyond its abs. max. rating).  The maximum power this device is able to dissipate is pretty limited, so you should be okay depending on the ambient temperature.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Expert 1961 points

    Thanks Paul.  That's good to hear.  I just looked at the Thermal Information table and followed the link to SPRA953.  That is a complicated App Report!  Too bad the standard equation for TJ and RθJA "results in extremely erroneous values".  The worst case power dissipation would be when Vout is at 5V and is shorted to ground.  The typical short-circuit output current would be 30 mA, resulting in 5 * 0.03 = 0.15W dissipated in the device.  That doesn't seem like a lot of power.  Assuming the DGS package and plugging the power into the TJ equation, at 70 deg C ambient TJ would be 95 deg C.  That is substantially lower than the maximum TJ for this device which is 150 deg C.  I feel comfortable that the device would survive that.  Under normal conditions the load current would be much lower than 30 mA.

    If you see anything wrong with what I wrote, please let me know.  Otherwise I fell comfortable that the device won't perish in a short-circuit condition.

    Thanks!

    Regards,

    Greg

  • 0 in reply to Greg
    TI__Guru 52663 points

    You understand this correctly, though note that while the abs max is 150°C, we only specify the performance to 125°C.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Expert 1961 points

    That's OK.  Thanks for the clarification.  Fortunately the circuit won't need to perform in the shorted condition.  Just survive it.

    I really appreciate your help in answering this question!

    Regards,

    Greg