Re: [IBIS-Users] Confused about clamp data in pull-up/down

From: Andrew Ingraham <a.ingraham_at_.....>
Date: Tue Jun 21 2005 - 08:10:30 PDT
If the device has only two states (High and Low), then the clamp data will be in the Pullup and Pulldown curves.  There is no way to separate them.

If the device is capable of being in a high-impedance state, then all the clamp data should be in the separate clamp curves and none of it in the pullup and pulldown curves.

This can give you pullup and pulldown data that doesn't look like a clamp.  But sometimes the extra current due to turning on the pullup or pulldown transistor, includes current that greatly increases in the clamp regions, so they too may be shaped similarly to the clamp curves in these regions.

Also, it should be noted that the data in these regions may be a small difference between two very large numbers (clamp current with output tri-stated, and with output driving).

There may be no way to tell whether those curves are correct or not, except by comparing them with the original data.

Regards,
Andy



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Received on Tue Jun 21 08:10:33 2005

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