Re: Bidirectional Pad with 5.0V tolerant input

Hello David:

   My comments below, prefixed with --

            Regards,
            Stephen Peters
            Intel Corp.

> IBIS Users:
>
> I had created an IBIS model for one of our devices that have 5 volt tolerant
> I/O pads. This specific I/O pad is capable of driving to 3.3V but can
> tolerate input voltages up to 5V. Voltage sweep ranges (ie. table entries)
> are shown in 1) below.
> I had also set "[Voltage Range] 3.300V 2.9700V 3.6300V"
> for this specific pad. However, I'm concerned with using [Voltage Range] for
> this pad and feel as though the "Reference" voltage parameters should be
> used. However, I'm at a loss on how to use these "Reference" parameters
> listed in 2) below.
>
> 1) Are the appropriate voltage sweep ranges appropriate?
> [GND_clamp] -5V -> 5V
> [POWER_clamp] -5V -> 0V
> [Pulldown] -5V -> 10V
> [Pullup] -5V -> 10V

   -- per the IBIS cookbook the sweep ranges are correct. Basicly, you
   -- want to cover the entire range of what the pad (input) could see.

> 2) What values should be applied to the following?
> [Pullup Reference]
> [Pulldown Reference]
> [POWER Clamp Reference]
> [GND Clamp Reference]

    -- if this device drives 3.3v (nominal) and there is no separate
    -- voltage rail for the clamp diodes, the there is no reason to
    -- use the extra keywords, the [Voltage Range] keyword will do.

>
> Thanks for your help

   -- no problem :)
>
> David Makihara
> PMC-Sierra Inc.
> Burnaby, BC
> Canada
Received on Sun Jun 14 17:54:13 1998