up to PCI revision 2.1, supplying 3.3V on 5V PCI
slots was optional. Supplying 3.3V in any PCI environment is madatory since PCI
So, it's common practice to use a LDO regulator to
derive 3.3V from the 5V supply to make sure taht your PCI board works even in
some of these "old" PCs.
----- Original Message -----
Sent: Thursday, December 06, 2001 5:26
Subject: deriving 3.3V from 5V ..
Sub: Universal PCI card
I have referred a number of universal PCI card
designs. One point I have noticed is, none of the cards are using the 3.3V
supply from the slot - instead deriving the 3.3V from 5V by putting a
regulator.But even 5V PCI slots are provided with 3.3V supply rails. Is there
any solid reason for this ??
thanks in advance