Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

short circuit on IO

Hello everybody

What happens when I have a CycloneII IO pin physicaly connected to GND and I drive it with logic high, i.e. a short circuit.

Does this blow the FPGA or is there some protection against damage?

thanks for helping.

greets

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    For a LVCMOS output I don't think there is a protection.

    What happens is that the pull up circuit is forced in an unexpected steady condition of max voltage and max current.

    I think that this can destroy the device but wasn't able to find confirmation with a quick search of the documentation.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    There's no protection, and the current will most likely exceed the 25 mA rating for an output pin, unless you set the lowest drive strength. In so far, the device could be damaged. By experience, I can tell, there's a good chance that the FPGA survives shorting individual pins.