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SN74LVCH16T245: How do the output drivers handle a short (current limited?)?

Lauren Mayfield
Expert 7915 points
Part Number: SN74LVCH16T245

Hi logic team,

I'm posting this question on behalf of my customer.

In one of our designs, we use a SN74LVCH16T245 as a digital buffer/level translator for some high speed data.  The part goes to a connector and then to another board within the system.  The cable is not polarized, and so if put in flipped, the outputs get shorted to ground (all the outputs on the buffer are shorted to ground).

My question is: How does the output drivers on this part handle a short?  Are the outputs current limited?  Can it sustain an indefinite output short on all channels?

We’re looking at ways here to prevent this from happening, but I’d like to get some feeling of how bad the situation would be if someone installed the cable flipped and buttoned the system all up before doing tests.

Thanks,

Lauren

  • 0
    Guru 316780 points

    There is no reasonable limit:

    The current can easily exceed the absolute maximum rating of 50 mA.

    One way to prevent this would be to add a pin on the connector that forces OE high if the cable is flipped.

  • 0
    TI__Expert 3450 points

    Hi Lauren, 

    I am assuming only the data output pins are being shorted (i.e. not VCC, DIR, OE). When an output is shorted to ground, the CMOS transistors in the output inverter stage on the SN74LVCH16T245 will saturate and output a continuous current well above the maximum output current rating for the device. The voltage on the output would fall to 0V. It is not recommended to sustain a current above the maximum rating; the extent of the damage caused by the current depends on what is connected to the output. 

  • 0 in reply to Gabriel Lake1
    TI__Expert 7915 points

    Thanks Gabriel, that helped.