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Altera_Forum's avatar
Altera_Forum
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14 years ago

Arria II Max input voltage whilst powered down

First of all I hope this is the appropriate place to ask the question.

As the title explains. The absolute maximum rating of input voltage of 4V doesn't seem to have have reference to applied IO power supply voltage, or even if it's powered up.

I would like the option of a controlled power-up, where the Arria II may be unpowered, but where interface pins may have crucial 2.5V signals toggling away.

I assume from the absolute maximum rating that there is no protection diode between I/O and VCCIO, and that I can take a pin to 2.5V without it drawing current or causing any further reliability issues whilst the device is unpowered. Can anyone confirm and hopefully point me in the direction of documented evidence? I have searched but not found anything.

Many thanks in advance.

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    I would have hoped that someone may have helped, has no one here used the Arria II devices?

    Should I stear clear of them? :(
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    Hi Vidsol,

    I have not read the Arria II data sheet. However, I have used other Altera devices (Stratix, MAX II, FLEX10K, etc). All of these devices have a section of the data sheet talking about their 'Hot swap' capabilities. This is essentially what you are doing by driving I/O signals before the devices are powered.

    This works fine on all other Altera FPGAs, so I am sure it is fine on the Arria II devices. You should still try to avoid driving signals higher than the input voltage high value. But you comment that you will be driving 2.5V, and that will be fine.

    I have board designs where the data processing FPGAs are powered-up under software control. Those FPGAs have clocks driven onto pins and signals driven onto LVDS signals, and there are no issues.

    Cheers,

    Dave
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    Many thanks for your reply. It seems I was using the wrong keywords, namely "Hot Socketing", and I have found the datasheet clearly states that signals can be driven into Arria II parts before or during power-up.

    Many thanks again.