This circuit emulates the functionality of the classic 555-Timer IC. It was designed using open-source tools and was taped-out in the Skywater 130nm CMOS process through TinyTapeout on April 19th 2024 ...
A low pulse on this pin (below 1/3 of VCC) sets the internal flip-flop and makes the output go HIGH. When the voltage on this pin reaches 2/3 of VCC, it resets the flip-flop, and the output goes LOW.