What do you get when you take 8,192 CH570 MCUs, put them on custom PCBs, and write firmware for this interconnected gaggle of ...
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.