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Troubleshooting • Re: Replacement DA9091 PMIC

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I was talking to someone who is more active in the "Right to Repair" movement than I am, and they said it's not just having the right to repair that is required; having the ability to repair is essential in that. That includes -
  • Manufacturers making spares available with short delivery times and reasonable pricing.
  • Manufacturers providing enough documentation to allow a repair to be carried out.
  • Manufacturers having to appoint official repair service providers or undertake repairs in-house, at reasonable cost, with repairs carried out within a reasonable time frame.
Basically it means ensuring all those things manufacturers don't want to do when their goal is to see product replacement rather than repair.

The argument for providing datasheets on components under "Right to Repair" is to allow a component to be replaced with something else when that component is no longer available or difficult to obtain.
1st Nobody needs a datasheet for doing the replacement of a faulty chip
2nd The time of interchangeable components has basically ended, since QFN, BGA, and other complicated packages became widespread, and no one is actively designing with part interchangeability in mind because it's stupid...
Especially while being in a highly competitive/low-profit-margin market.
Even if you have the datasheet for such a component, I am 99% sure you will never find a suitable replacement with the exact same package, because in most cases, if you design a custom component, you also design a custom package and footprint for it...

Best case scenario for the example of DA9091 - You have the datasheet, you find a replacement which magically has the exact same footprint, pinout, etc. The chip has hard hard-coded I2C address, and if you don't know that, you can't change the PMIC address to which the SoC would want to speak in order to know if the power is ok or not.
So to make (in theory) the perfect drop-in replacement work, you will need an adapter featuring another chip (microcontroller) that should answer to the I2C address that the SoC expects the genuine PMIC to answer to.
And that's complete BS if you ask me.

BY THE WAY - That was the case with DA9090 and MXL7704-P4, they have mostly the same footprint (yeah, it needs some modification on the PCB side, but let's say it's the same for the sake of this conversation), they have the exact same pinout, even the default output voltages are supper close, but they have a different hardcoded I2C addresses and as a result if you swap them around (I actually tried this before the DA9090 was released for purchase) the Pi will never boot (it would give ACT LED code of power failure or something) if there isn't an additional MCU to mimic the original PMIC responses on the correct I2C address...

Like, is it better to have a 50p OEM part or to have a 1$ "fitting replacement" with a 15-pound adapter to make it work?!?!
I just don't get it.

You clearly don't understand in detail how these things work, so please stop arguing...

What's the verdict on all of that?
- We DON'T actually need the datasheet for the chip to fix a Pi with a fried PMIC.
- It's more than enough that they will make the part available at a reasonable price.
- Would it be nice if they released the datasheet? - Yes.
- Do we actually need it to resolve the problem we started with? - Definitely not.

Statistics: Posted by MadEDoctor_YT — Fri Apr 04, 2025 7:19 pm



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