LayoutReviewDec2016
Remarks and Outcome
1) Remove RL2
Probing on the bus side of the transformer could potentially damage the
board.
Removing it will remove the possibility of diagnosing errors on the
transformer, but those are not frequent (one transformer error in the 10
years of WorldFIP has been reported).
The removal could also ease the rerouting described in point 2 below.
2) Improve routing of the differential WorldFIP signal from the front
connector to the FielDrive.
Despite the fact that the WorldFIP signal is slow and on V1 (where
routing is far from symmetrical) we have not faced issues in the testing
environment, better rooting would result in a more robust design; the
removal of RL2 would ease the rerouting.
3) Change the behavior of the relay that connects the ADC:
from: "highZ": relay OFF; "0" : relay ON; "1" relay OFF
to: "highZ": relay OFF; "0" : relay OFF; "1" relay ON.
3) L3: island of 3V3 surrounded by -5V; is it needed?
4) Add test points for power supplies +5V, +5V_SW, -5V, 1V8.
5) Differential pair ADC_IN1 is not length matched by 3 mm.
In principle it is not critical, as the signal to sample is not fast.
6) Why are you using so big vias?
Increasing the vias was the outcome of the V1 review; bigger vias could
decrease the overall board cost (see
issue)
7) What are the parameters of the signal you are measuring with the ADC
(range, bandwidth)?
See https://www.ohwr.org/project/fmc-worldfip/wikis/ADC