- Jan 1, 1970
On Mon, 26 Feb 2007 08:03:19 -0700, Jim Thompson
[snip]Ooops! Strike that second suggestion :-(
Dang, you beat me to it.
But you can do a tapped divider and use the mux to ground taps on a
series-string divider, sort of like what you suggest.
But why do these chips do this? How does the esd diode current find
its way into the output? Incidentally, the effect is almost perfectly
symmetric for high and low clmping.
GND is the substrate (NMOS bodies _are_ the substrate).
VDD has all the PMOS bodies tied to it.
There is nothing there to keep currents from going all over hell and
back when ESD is forward-biased.