Re: +3.3V should be created on the PWB using a regulator

[Ivor Bowden <ivor@peritek.com>]

>At 12:02 PM 6/28/00 -0700, you wrote:
>>At 08:24 AM 6/28/00 -0700, Mike Dini wrote:
>> >I would like to comment that we do not believe a PCI board designer can
>> >guarantee that +3.3V is provided from the backplane in any PCI-based system
>> >that is not 66MHz.  The motherboard may have the connections, and be v2.2
>> >compliant, but it still is quite possible that the manufacturer of the
>> >computer didn't attache a power supply to the motherboard.
>>
>>Isn't it true that EVERY PCIv2.2 system MUST have 3.3V on the backplane?
>
>This isn't the right question.  The fact is that most PCI system
>shipped today do not have +3.3V on the backplane. A PCI
>product should account for this by creating +3.3V locally.

SAD, BUT TRUE!

>>So if you state your card will only run in a PCI v2.2 system, or v2.x if
>>3.3V is present on the backplane you should be OK. But if you are targeting
>>the commercial market it would probably be a good idea to have the regulator
>>to support all the old PCs out there.
>>
>> >For the present and into the near future, all PCI designs that are not
>> >66MHz should create +3.3V from +5v/+12v using a regulator.
>> >
>> >Mike Dini
>> >
>> >
>> >
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