Subject: RE: GND/PWR Clamp Data Collection

From: "Ingraham, Andrew" <[email-masked]>
Date: Tue, 23 Oct 2001 11:04:20 -0400

> I have noticed slight differences in ground clamp curves for 3-state
> buffers dependent on whether the data was gathered when the device is
> driven high or low ( output hi-Z ).  I have found the same to be true
> for
> power clamp curves.
> 
You can only gather GND Clamp data when the device is (externally)
driven Low; and you can only gather POWER Clamp data when the device is
driven High; right?  I am not sure I understand your question.

For 3-state devices, the GND and POWER Clamp curves should be taken with
the device in the hi-Z state.  The Clamp curves are the only ones used
to represent the device when simulated in the hi-Z state, so they need
to be accurate.

It may be true that the GND Clamp characteristic change when the device
is enabled and drives High, or that the POWER Clamp characteristics
change when the device is enabled and drives Low.  But since the device
spends very little, if any, of its time in these regions, I think those
differences can always be ignored.

Regards,
Andy