Bob Camp wrote:
Hi
Simply a few stories I thought I would share.
Simulate design. Use manufacturer's published models. Build design. Note differences.
Call manufacturer. Answer - switched die three years ago, Ft is now " much better
" ( now 3x old parts ).
Odd they never mentioned that to people who work for the same company.
Simulate design, Build design, verify design, ship it for a few years. Odd things start
to happen. Look at some parts. Package looks different. Ask around..... Line got moved to
other side of big ocean. Process got " tweaked" beta is now 4x what it was.
Again all inside the same company. Both cases were excused by industry standard
specs that had no upper limit.
We had whole departments devoted to tracking this sort of stuff. It still happened on a
regular basis. 30 years later the specs on the devices and their published models are
still the " old version " ones.
there are also designs that depend on "non-data-sheet" performance of
particular devices. There's a very low noise, very low leakage fet
popular in charge amplifiers. It has a JEDEC 2N number (which I can't
remember off hand), but only the ones from one particular company (in
England) actually work in the circuits, and even then, there's some hand
selection involved.
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