Ken Smith wrote...
I'll deny it.
Almost all CMOS chips have ESD protection. Many DMOS parts have no
ESD protection because they don't want to give up any performance.
Right, 2n7000 are not protected, and are probably more fragile than
a typical CMOS logic chip. However the gate's input capacitance is
much higher than that of a logic gate, and provides some protection.
For example a typical logic gate has 2 to 5pF of capacitance, which
compares to 40 to 50pF for a 2n7000 at zero volts bias. Nonetheless,
you can easily zap the 2n7000 straight to kingdom come, as they say.
In the early 70s I always used a Supertex VN01 type that came with a
gate zener. When they discontinued the zener version, I called and
complained. An engineer there told me they had more failures of the
protective zener than they had from the unprotected gate alone, so
they discontinued it. There are still MOSFETs available with zeners,
but in considering them I think back to the Supertex guy's claim. In
using about 3000 pieces of 2n7000 in recent years, I have encountered
only about 4 damaged ones. This is a bit on the high side compared
to CMOS gates, but it's not too bad. If one uses good static-control
procedures, a much lower failure rate should ensue.
