I did a poor job of soldering and forgot to solder the pull-down resistor on the input to the buffer. My mistake for posting a question too soon.
I built a circuit to read a button with a single board computer. Wanting to protect the input of the computer, I used a TI 74HC4050 buffer with a diode on the output to avoid any consequences if the SBC's input pin was mis-configured as an output.
I'm confused about the behavior of the buffer at the anode of the diode. It goes from 0V to 5V, but does not return back to 0V. Removing the diode seems to solve the issue (and anyways the resistors limit current enough to protect misconfigured pins), but I still want to understand why this was happening.
The datasheet description for the buffer says that it is a CMOS non-inverting buffer, so I imagine that there is a pull-up network and a pull-down network. Why doesn't the pull-down network successfully clear the voltage at the input of the diode?
This is my understanding of how the buffer looks on the inside. I understand that there may also be some ESD protection circuits attached, but I don't see how those could be causing issues.