SN55LVTA4-SEP: bypass capacitors

Hi David,

David Nakasone said:

for figure 8-4, want to confirm device and placement (don't see device). I think it is >10uF bulk, 1nF at VCC pin, then put 100nF in between?

Yes that is correct. If the 10uF were shown in that image it would be to the left of the 0.1uF, and if the device were shown it would be right next to the 0.001uF. 

David Nakasone said:

for figure 8-2, note A says to put the 0.1uF/100nF as close as possible. want to see if this is specific to 5V on diode drop or if figure 8-4 is the way to go. Also, will there be a significant loss in performance if I swap the Z5U/mica/poly dielectric for X7R or C0G?

Follow figure 8-4 if you're not doing the 5V supply with the diodes as shown in that setup. Using an X7R or C0G in that configuration is fine as well.

David Nakasone said:

equations 1 and 2 work out 1nF for the bypass capacitor, should I consider different rise times, worst-case change in supply, or currents?

You can if you would like. The rise time (200ps) and step change in supply (1A) used in that equation already are pretty conservative, but if you expect different supply noise in your system you can certainly adjust for it. 

Best Regards,
Brandon Fisher