30
E5400-Pro Series Soft Touch User’s Guide
2
Mechanical Considerations
If you ever plan on upgrading from a 40- pin to a 90- pin
logic analyzer to take advantage of higher state speed and
differential probing on the clock channel, some steps should
be taken so that the original footprint will work for both the
E5404A and the E5406A probes.
•
If you are driving only single- ended clocks into A7
(CK1+) and B21 (CK2+), then you should ground A8
and B20. A8 and B20 are where CK1- and CK2- are
driven in the E5406A probe. Grounding these pads will
allow the user- defined threshold in the analyzer to be
used as in normal single- ended operation.
•
If you are using differential clocks, route the Odd pod
clock such that the positive side of the pair goes to A7
(CK1+) and the negative side of the pair goes to A8
(CK1- ). Similarily, route the Even pod clock such that
the positive side of the pair goes to B21 (CK2+) and
the negative side of the pair goes to B20 (CK2- ). When
using the E5404A probe, A8 and B20 are unused.
However, when using the E5406A probe, A8 and B20
are where the probe connects to the negative sides of
the clocks' differential pair.
