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Altera_Forum's avatar
Altera_Forum
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15 years ago

Cyclone II + Quickswitch = 5V PCI? How Reliable?

I am trying to build a 5V PCI card with a Cyclone II and i am probably going to follow AN330 instructions using quickswitchs. I am not worried about not being fullly PCI compliant but what worries me...
Altera_Forum's avatar
Altera_Forum
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15 years ago

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Do you know the 5V PCI spec? It's TTL based on TTL levels, Voh,min is 2.4V.

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It's minimum 2.4 to compensate for imperfect output and input stages (on real TTL) and loses from propagation, it gives you a safe windows if you are driving with 4.5-5V . If you are driving it with 3.3V the loses in the signal line may be enough to give you occasional hiccups or intermittent bugs. In principle it should work, but I would test it thoroughly before using it in anything serious.