Fred Bartoli wrote...
Boki wrote,
Yes.
Welcome to the electronics design _real_ world.
So, boki, accept the fact that any given 2n7000 you
purchase may be anywhere within that min-max range,
or if it's beyond the range, which it could be, then
and only then may you return it for a refund. This
reality means that we come up with designs that can
live with the full range of variation, in order to
insure that all manufactured production units will
operate the first time and every time, without any
further attention or tweaking.
That said, most parts do not show such a wide range
of operation, and sometimes critical designs do rely
on that fact, employing pre-production sorting, etc.,
to work with a tighter tolerance. In AoE figure 3.14
we show the full measured variation of Vgs vs Id over
a 9-decade drain-current range, for 20 MOSFETs from
four different production runs spread over two years.
Boki, you should study this graph. The VN01 part we
used in the graph is very similar to the 2n7000. One
thing, if you were to evaluate 2nd-source parts from
different manufacturers, you'd probably see a *much*
wider tolerance range than we observed. Now and then
a manufacturer changes his fab facility, etc., and we
see a step shift in his tolerance-distribution mean.
