fbrozovic

To add to this: the keyboard matrix scan controller on laptops is usually located inside the Super I/O chip and connected to the CPU/southbridge via LPC or eSPI. Since LPC/eSPI peripherals are mapped to I/O ports, implementing an 8042 controller means that the keyboard can work even without setting up a much more complicated USB host stack.

Also works with non-synchronous buck converters, Maxim has an app note here with a schematic: https://www.maximintegrated.com/en/design/technical-document...

Your beard trimmer is likely missing the 5.1k resistors to GND on the CC pins, which enables the USB-C charger to output 5V. I had several devices (mostly flashlights with integrated battery chargers) that would only charge using A-C cables. After adding the resistors, C-C cables also work.