I can’t seem to find the overall power requirements for the module in the datasheet or other documentation. Are the overall electrical characteristics given anywhere?
Currently, we do not have power consumption numbers. The modules are currently equipped with alpha silicon SoC. The final production SoC will be updated in many aspects, which probably have impacts on the power consumption. The current software is still in an early state. Also this has impacts on the actual power consumption of the module.
Are there any guidelines on the size (current capability) of the 3.3V supply that should be designed for a carrier board?
The original Apalis Evaluation Board is featuring a TPS51120 which limits the current output at the 3.3V rail to 5A. This buck converter is limiting quite fast. This means if the peak current reaches 5A just for a short time, the converter reduces the output voltage which then causes the Apalis iMX8 to reboot. With the 5A limit, we have seen this issue very rarely with the Apalis iMX8 and only under extreme load situations.
However, we wanted to avoid issues with the 5A current limit and decided to modify the carrier boards that have been delivered with the Apalis iMX8 early access kit. We intended to increase the current limit but by accident did the opposite of it. We actually decreased the current limit to around 3.2A. The did not see that issue, since in most situations, the module was even able to run with this current limit. More information to this issue including a workaround, you find in this errata document.
Nevertheless, we are currently working on a new revision of the Apalis Evaluation board as well as the Ixora. We are manly replacing the TPS51120 with a different buck converter which has a higher current limit. We are going to use the AOZ2261QI-11 form Alpha and Omega. This integrated solutions provides up to 8A which is more than enough for the Apalis iMX8 and the peripherals on the carrier board.
We made some preliminary power consumption measurements for Apalis iMX8QM 4GB WB V1.0A.
NOTE: The measurements were done using A0 silicon stepping as well as early/non-optimized software on a single SoM. Don’t take the numbers as official/final numbers and don’t base your design on these numbers!
Do you have updated power requirements for the Apalis i.MX8 modules? The current datasheet lists TBD.
Our latest measurements show slightly lower power consumption compared to the ones posted in November 2018. The newer silicon version consumes less than the A0 silicon. However, the software is still not able to fully use the two graphical cores. Therefore, the final peak consumption numbers could be still higher.
We are not publishing the numbers in the datasheet until we get the final silicon version and have all the graphical cores fully running.