4 ms·

Thanks! The pin out on page 2 has no ground, so what are they pulling down to? That’s my question. I can imagine a couple of ways to do make the TTL levels so

by egsmi 6y ago

Thanks! The pin out on page 2 has no ground, so what are they pulling down to? That’s my question. I can imagine a couple of ways to do make the TTL levels so I’m curious which way it was actually done.

pwg 6y ago
According to the diagram of the output buffer on pdf page 15, they pull down against Vdd (the negative supply). What is left unstated is that the pulldown transistor has likely been designed with a Vt such that when "on", and pulling down against Vdd, the output goes quite close to zero volts.