Apple 140W USB-C PD 3.1 EPR Power Adapter, Part 1 – How It Charges a 16-Inch MacBook Pro 2021

TL;DR:

The USB-C to MagSafe 3 cable acted as a special PD EPR trigger.

  1. USB-C plug attached to power adapter
  2. Cable requested 5V @ 0.1A
  3. MagSafe 3 connected to MacBook
  4. MacBook requested 20V @ 4.7A
  5. Entered EPR Mode
  6. MacBook requested 28V @ 4.71A
  7. MacBook requested 28V @ 5A
  8. MagSafe 3 disconnected from MacBook
  9. Hard Reset
  10. Cable requested 5V @ 0.1A

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