Recommended · for some experience
EEVblog #831 - Power A Micro With No Power Pin!
Why people recommend it
Demonstrates a microcontroller running through the protection diodes on its I/O pins with the supply pin disconnected; cited whenever a supposedly unpowered chip keeps working.
Watch for: signals back-powering an unpowered chip
In their words
You may be interested in EEVBlog's video about powering an MCU without connecting the power pins.
tangrs on electronics.stackexchange.com, Mar 2017. CC BY-SA.
For more extensive explanation, watch this video by Dave from the EEVBlog.
Bimpelrekkie on electronics.stackexchange.com, Mar 2021. CC BY-SA.
The internal protection diodes will conduct and the chip can be powered on from this.
rdtsc on electronics.stackexchange.com, Jul 2021. CC BY-SA.
