Re: Expansion board decoupling specs

["Monish Shah" <monish@poboxes.com>]

>Hello:
>
> I am currently designing a 64 bit/66MHz PCI expansion board and have a
>question regarding the decoupling requirements stated in section 4.4.2.1
>of the PCI Spec rev 2.2.
>
> In section 4.4.2.1, there is a statement regarding decoupling of unused
>power pins to ground via 0.01uF per Vcc pin. On our board we are only
>using the +5V power pins, and thus have many unused power pins (all 3.3V
>and all VI/O pins)....

Huh?  66 MHz is supported for 3.3V signalling only.  I don't think you can
implement that without connecting to 3.3V and VI/O.

As for the original question, yes, you do have to decouple them, as Ivor
Bowden noted.

>--
>Craig Rich
>Senior Systems Engineer         mailto:craig_rich@sundanceti.com
>Sundance Technology Inc.        http://www.sundanceti.com
>1485 Saratoga Avenue            tel: 408 873 4117 x107
>Suite 200                       fax: 408 996 7064
>San Jose, CA, USA  95129


Monish Shah
Ascent Software