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USB-C PD laboratory power supply

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David Hess:

--- Quote from: MaTkEOxjC on February 16, 2019, 10:30:44 pm ---
--- Quote from: David Hess on February 16, 2019, 09:03:39 pm ---At most I would rely on the microcontroller for detecting a fault in the analog control loops.  Under normal conditions, I would generate analog voltage and current signals for the analog control loops to use and get feedback of actual voltage and current.  Inserting the microcontroller into the control loop is a hazard, extra complexity, and potentially limits performance.
--- End quote ---

That's actually quite a good safety related consideration.
So I need some sort of analog mux, to either re-direct the analog signal from voltage or current measurement to the DC/DC controller.
--- End quote ---

No, only one analog control signal across the isolation barrier is required.  Output voltage and current are monitored and feedback from both are combined before crossing the isolation barrier.

MaTkEOxjC:

--- Quote from: David Hess on February 18, 2019, 01:24:47 am ---No, only one analog control signal across the isolation barrier is required.  Output voltage and current are monitored and feedback from both are combined before crossing the isolation barrier.

--- End quote ---

Ah, got it. I wasn't sure how to feed both back over the same channel (and giving user info about both values). Thanks!

(image from https://www.eetimes.com/document.asp?doc_id=1278790)

So microcontroller on secondary would allow for direct measurement of V and I (just for user information) and the analog loop would not be compromised. Also using the microcontrollers DAC for setting the output V and I should be possible.
The only thing that seems pricey is an ADUM3160 with 5-6€. Just the USB-PD controller needs to stay on primary, but this would only require an I2C isolator (~2€).

Anyways, next step for me is to simulate, build and test the flyback circuit alone. Possibly at first without isolation.
Adding the microcontroller should be possible afterwards. Just trying to separate the project into steps which make sense.

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