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I believe that the PCI specifications do not say anything
about the signals of the local bus.
As far as bus PCI refers, a fully 5V tolerant
device means that this device can use 5V signals like 3.3V
signals
In the PCI connector you have:
- 3.3Vcc pins for 3.3V power suply
- 5Vcc pins for 5V power suply
all these pins are independent of the PCI signaling
enviroment. (For example, you can suply a 3.3V board
unsing only the 5Vcc pins).
The PLX devices support both 5V and 3.3V PCI signaling but the devices need
to "know" what kind of valtage levels they must use. For this purpose thay
have implemented the Vio pin.
This pin have the same function that the same pin in the universal PCI
connector, to signal to the PCI device what kind of PCI signals (3.3V or
5V) must use the device at every moment.
Iņigo Alvarez Ximenez de Embun
e-mail: patxipatxi@jazzfree.com |