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Re: How does 3.3V 5V PCI buffers are toggeled.
- To: Mailing List Recipients <pci-sig-request@znyx.com>
- Subject: Re: How does 3.3V 5V PCI buffers are toggeled.
- From: Andy Ingraham 17-Sep-1996 1047 <ingraham@wrksys.ENET.dec.com>
- Date: Tue, 17 Sep 96 10:57:59 EDT
- Apparently-To: pci-sig@znyx.com, yehuda@chipx.co.il
- Cc: pci-sig@znyx.com, ingraham@wrksys.ENET.dec.com
- Resent-Date: Tue, 17 Sep 96 10:57:59 EDT
- Resent-From: pci-sig-request@znyx.com
- Resent-Message-Id: <"jPg8r3.0.bg1.Q9iFo"@dart>
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> Is there a signal in the spec and/or de-facto signal on the PCI boards
> which tells the chips its 3.3V OR 5V. This information is needed for turning
> on/off an extra drivers for 3.3V PCI compliance compared to 5V compliance.
There are five special I/O power pins (11 on a 64-bit PCI card)
defined on the PCI connector. All these "+Vi/o" pins will have +5V in
a 5V PCI bus, or +3.3V in a 3.3V PCI bus. See the center column of
Table 4-13 in the PCI spec, pin A10 for example.
You can make use of this voltage to alter the characteristics of your
chip.
Regards,
Andy Ingraham
Ø Å