AM4378: Limiting CPU frequency for EMC reasons

Hello Ankur,

Thank you for the query.

Please share additional details on the development you are using.

Ankur Patel3 said:

he hardware team recommends running the processor and associated DDR3 at 100 MHz

Please elaborate the requirement

Ankur Patel3 said:

to meet the EMC testing requirements and pass the in-house tests

Did you run the tests on the current board and see any issue?

Is the required analysis to confirm that the device operating at 100M as mentioned above will meet the functional requirements.

Regards,

Sreenivasa

Thank you Sreenivasa,

Based on HW team, our inhouse chamber supports up to 1GHz test range. Hence for a product to do inhouse we can go with 10 times lower based on the spec. 

They are currently checking if there are any external labs available in the city to test if we run at AM4378 at full speed.

Kallikuppa Sreenivasa said:

Is the required analysis to confirm that the device operating at 100M as mentioned above will meet the functional requirements.

Good question, as we too have same question and with product evolving in future, they may have to run at full speed. It is in the discussion phase.

Another thing, is the CPU can only scale to one of the predefined below frequencies: 

300000 600000 720000 800000 1000000

Regards,

Ankur

Hello Ankur,

Thank you.

Please refer to the below selection table.

https://www.ti.com/lit/ds/symlink/am4372.pdf

Figure 6-1. Device Nomenclature

Not sure if this answers the query?

Regards,

Sreenivasa

Hello Ankur,

You could also refer the below section for the OPP

5.4 Operating Performance Points

The below thread could help

(+) AM4372: the main frequency of CPU - Processors forum - Processors - TI E2E support forums

Regards,

Sreenivasa

Hello Ankur,

Please refer additional inputs from the expert:

It is recommended to use only OPP frequencies.  You could technically pick other frequencies, but these have not been tested and could cause failures.

Regards,

Sreenivasa