=20
> And unless I'm missing something...  a zener/TVS tied to
> ground/vdd will clamp at its rated voltage, and a couple of
> volts or less below zero

What is your acceptable -ve voltage ? You mentioned Schottkeys,
with the lower Vf @ 1A vs the TVS, higher Vf @ 50A. My
admittedly limited experience is with small ESD devices like the
DALC208SC6 for data line protection

www.st.com/stonline/books/pdf/docs/6477.pdf

They are recommended by the manufacturer of the modem modules
I use, and examples are given in the d/s of using them to protect
interfaces which may have exposure to discharges
--=20
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