General
Review and verify the following for the custom
schematic design:
- Reviewed Section 1.1.4.1 of the user's guide
- Use of bulk and high frequency capacitors.
- Number of capacitors used, package and value.
- Voltage rating of the capacitors used.
Schematic Review
Follow the below list for the custom schematic
design:
- All processor power rails use bulk and high frequency decoupling capacitors.
The critical power domains that require the focused attentions are the low
voltage, high current domains (VDD_CORE, VDDR_CORE).
- As a starting point, the recommendation is to follow the validated SK or
EVM, or PDN application note. When there is difference between the SK or EVM
and PDN, the recommendation is to follow the PDN. When information is not
available in the PDN, follow the SK or EVM implementation.
- The recommendation is to use Low-ESL capacitors connected with short traces
to minimize the PCB trace loop inductance.
- The recommendation is to verify each of the power rail pins has a decoupling
capacitor and each of the supply rail group has a bulk capacitor.
- Voltage rating of the capacitors used (> twice the worst-case applied
voltage is a commonly used guideline).
Additional
- In case difference is observed
between the SK or EVM and the PDN application note on the capacitor number
recommendation and value, the recommendation is to consider the recommendations
in the PDN application note
- While optimizing the capacitors, the recommendation is to perform static and dynamic PDN analysis to verify that the Reff, Cap LL, and Impedance targets are met
- In some situations, the SK or EVM uses 3-terminal capacitors, due to low inductance packaging. Make sure the 3-terminal capacitors connections are not implemented as an in-line or filter component
- The recommendation is to show the connections of the capacitor near to the relevant pin for ease of placement and routing