Re: About PCI power supply

Robert Baer <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> oxy wrote:
> > 
> > Robert Baer <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> > >   I do not know about the PCI spec, have not looked at it.
> > >   But, if one of the pins is speced at 3.3V, then one might assume that
> > > it could be used as a power source.
> > >   Just limit the current to 100 mA if possible, with a 500mA absolute
> > > max surge.
> > 
> > Yesterday,I got news about 3.3v pins in PCI 2.0~2.3 from my teacher(he
> > got the news from MB Manufactor).
> > He said that if MB is PCI 2.x,so user can use 3.3v power supply from
> > 5v slot.
> > And Imax=4.5A.
> > But my boss and teacher tell me that we have to place 2 regulators to
> > transfer 3.3v & 1.8v.
> > So......it's terrible news for me.....oh!!god!!
> 
>   There aint no PCB contacts that can reliably handle 4.5 *amps* !!
>   In fact i would not trust a single contact with any current over
> 500mA, and it would have to be a multiple contact, *NOT* a single point
> like some Molex connectors.
>   Work on the basis of a contact resistance of 10 milliohms.
>   Yes, the typical may less, but if there is ever any fault that makes a
> contact go higher, then one certainly does not want I*R heating to
> aggrivate the problem.

My company decides to use 3.3v pin to support all component in PCI
add-in Card.
So i have to find a power regulator to transfer 3.3v to 1.8v, but the
IC isn't easy to buy in material store.
But i don't think it difficult to search.
The point is how to compute total current in a component (ex. Flash
ROM,EEPROM,PHY....).
Although I have spec about all component,but i still don't know how to
konw total current(it means a component that i need to supply max
current)
Can or Could any one help me to answer this stupid question?thanks.