Digital outputs at 12v

Official Hardware Pro Solutions Portenta Machine Control
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I note that the PMC uses TPS4H160AQPWPRQ1 high side switches and has separate power supply rails for the digital and programmable outputs. Docs say these are not galvanically isolated but if I use two power supplies (24v for board, 12V for the digital output VINs) that have their grounds tied together, will this work? The TPS4H160AQPWPRQ1 works from 3.4v to 40V.

My thought process is that there would not be a separate VIN for the digital outputs unless it was meant to work this way ... Just looking for some confirmation before I go apply some power.

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My comments:

  • MCU drives GPIO pins with 3V3 logic. So, logic "high" is 3V, logic "low" is maybe 0.2V
  • You can have an external board connected, running with 12V, but the interface signals remain the same from MCU to this board: 3V3 logic
  • You HAVE - to connect the GND between all boards (they all need the same GND, as common reference)
  • but if your external board will see signal levels (GPIO, interface) as 5V even 12V logic - it will not work:
    You have to "level shift", translate the signal voltage levels when not 3V3 is epxpected

Just one point to consider:

  • your external board can run with 12V, via a separate power supply
  • the GND is common and connected (all GNDs go together)
  • but if your external board has PULL-UPs to 12V on external board - it will kill your MCU pins:
    most MCU accept just 3V3 input on GPIOs (or they are 5V tolerant) but 12V pull-ups will kill you MCU

You should check:

  • what are the logic value levels on digital signal inputs?
    (can they take 3V3 logic, 5V, or do they require a 12V logic level)
  • if signal levels need 12V logic: you need a "level shifter"
  • are there pull-ups for signals, directly connected to MCU, driving 12V into MCU?
    If so: DON'T connect!

Supply Power and digital interface signals (their voltage) - are two different topics.
The external device supply voltage can be anything, as long as MCU and external boards are powered separately.
But the digital communication signals matter, if they are in the same voltage level range.
If not: signal "level shifters" are needed.
Check for Pull-Ups, if a higher voltage is "driven back", provided on MCU pins.

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Thx for replying tjaekel, but perhaps you've misunderstood my question or the function of the high side switch? The Portenta Machine Control breakout board employs five TPS4H160AQPWPRQ1 switches - they take the 3.3v logic of the H7 and run it through power FETs that are fed with a separate VIN to create a 0-VIN waveform that follows the original 0-3.3v waveform. They have some extra function, like current sense and overload protection.
A comment in the Pinout_machineControl_Latest.pdf from the docs site:
"DIGITAL OUTPUT PIN +24V IN IS NOT CONNECTED TO POWER SUPPLY +24V IN AND IS NOT CONNECTED TO OTHER +24V PINS. PROVIDE POWER EXTERNALLY"
seems to imply this would work with any voltage from 3.4V to 40V as per the Texas Instruments data sheet. I'm certainly not gonna try my luck with anything over 24v but just wanted to see if anyone else had tried < 24V.

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Here for the same question. Did you try it (providing digital outputs with 12V instead of 24V to output 12V?)