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What kinds of application-specific things would it do? Have a weird pinout? Have slightly different voltage thresholds? Have a strange sequencing between dif

by kragen 1y ago

What kinds of application-specific things would it do? Have a weird pinout? Have slightly different voltage thresholds? Have a strange sequencing between different power supplies? None of that is rocket science; you could program an off-the-shelf microcontroller to do any of that (maybe with a breakout board and a couple of bodge wires).

InitialLastName 1y ago
All of the above, plus implement the control interface expected by the driver and maybe control loops to keep the voltages in range at the point of load. You probably could do it with a breakout board, but good luck getting the right voltage drops to the chip (or fitting it in a cellphone case).
- kragen 1y ago
  I mean you can put an 0.1mm flat flex board between the board and your chosen microcontroller to get the power and ground pins in the right place.
Aurornis 1y ago
It's far more complicated than that. You are not going to replace an iPhone PMIC with a microcontroller and some bodge wires. Even if you could nail all of the logic, the bodge wires alone would be an order of magnitude more loop inductance than the tightly designed PCB and it just would not work. The PMIC for a modern SoC is tightly integrated with the SoC. It handles power management, supply sequencing and timing, transitions between power states, standby modes, battery charging, and communication with the SoC. There is digital communication between the SoC and the PMIC to control all of this. This isn't something you kludge together with a microcontroller and some off the shelf parts.
- kragen 1y ago
  Except for the digital communication, inductance mostly helps you here, not hurts. You don't want submicrosecond rise times on your power rails. I haven't seen modern SoCs with tightly integrated PMICs like you're describing, but they could certainly exist. But if they're not using an off-the-shelf chip, why don't they just integrate their power management functions into the SoC? Not enough balls?

by kragen 1y ago

InitialLastName 1y ago

All of the above, plus implement the control interface expected by the driver and maybe control loops to keep the voltages in range at the point of load. You probably could do it with a breakout board, but good luck getting the right voltage drops to the chip (or fitting it in a cellphone case).

kragen 1y ago
I mean you can put an 0.1mm flat flex board between the board and your chosen microcontroller to get the power and ground pins in the right place.

Aurornis 1y ago

It's far more complicated than that. You are not going to replace an iPhone PMIC with a microcontroller and some bodge wires. Even if you could nail all of the logic, the bodge wires alone would be an order of magnitude more loop inductance than the tightly designed PCB and it just would not work. The PMIC for a modern SoC is tightly integrated with the SoC. It handles power management, supply sequencing and timing, transitions between power states, standby modes, battery charging, and communication with the SoC. There is digital communication between the SoC and the PMIC to control all of this. This isn't something you kludge together with a microcontroller and some off the shelf parts.

kragen 1y ago
Except for the digital communication, inductance mostly helps you here, not hurts. You don't want submicrosecond rise times on your power rails. I haven't seen modern SoCs with tightly integrated PMICs like you're describing, but they could certainly exist. But if they're not using an off-the-shelf chip, why don't they just integrate their power management functions into the SoC? Not enough balls?