The chip uses the 1-Wire protocol, which is a clever system for connecting low-speed devices through a single wire (plus ground). The 1-Wire system is convenient here since the Mac can communicate with the Magsafe through the single adapter sense pin.
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http://www.righto.com/2013/06/teardown-and-exploration-of-ma...
Magsafe 3 with USBC makes this even easier https://www.reddit.com/r/UsbCHardware/comments/11309f3/comme...
The Lightning comms protocol is interesting too https://hackaday.com/2015/02/14/reverse-engineering-apples-l...