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I am wondering If I can Run RPI4 or RPI CM4 by external 3.3V, 1.8V, 1.2V (x2) connected to board removing Mxl7704 and Chokes. and I may have to pull up RUN signal to RPI. located at MxL7704's 20th pin. (after removing MxL7704)

In this manner the I2C pin is remain empty.(not connected to main chip) so I worry about this can cause no boot.

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    Simple - just design your own ASIC to activate power in sequence. You will also need to write your own kernel. – Milliways Oct 27 at 8:44
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    It would be interesting to know why? What are you trying to achieve? – joan Oct 27 at 9:00
  • Sure it will work, if you provide the right voltage in the right sequence. I2C is not mandatory to have at boot (you can always blacklist it in modprobe.conf if it's causing problems). – Dmitry Grigoryev Oct 27 at 10:58
  • Some audiophiles has had good effect from separating powers to RPI3B in which case it is easy. someone sell a power board for that. ("mezzanine board"). From 3B+ onwards, however, as MXL appeared, only cases of failure to separating powers were known. When I analyzed the circuit diagram and board, I found that they(failure) did not apply a pullup voltage to the RUN pin. – Daeyeol Lee Oct 27 at 11:02
  • with RUN, do you mean RUN_PG? If so, why then not just add the pull up on J1, pin 3? (datasheets.raspberrypi.org/cm4io/cm4io-datasheet.pdf, page 10 for if others want to understand this) – Ljm Dullaart Oct 28 at 10:33

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