Re: alll possible permutation switching device
- From: mzenier@xxxxxxxxxx (Mark Zenier)
- Date: Mon, 26 Dec 2005 04:31:04 GMT
In article <11qrn2jb809u041@xxxxxxxxxxxxxxxxxx>,
Abstract Dissonance <Abstract.Dissonance.hotmail.com> wrote:
>
>Ok, I think this might be what I'm talking about or very close. I'm not so
>much interested in the logic part of it but just the switching(i.e. for
>analog).
>
If you're working on this universal device programmer, either you have
to restrict the universe or deal with some voltage/current levels that
are more extreme than you seem to expect. Old UV EPROMS will have at
least 25 volts, and old bipolar PROMS and PALS can have currents in the
100 milliamp range that have to switch from 0 to about 12 volts in
10 to 100 nanoseconds (the old AMD PAL programming spec, in this case).
You'll find that you only really have a few special voltages for any one
part, (most are either logic, static power, or ground). So you can get
by with, at each pin, switches to a few programmable voltage supplies along
with a logic low, a logic high (both also settable, but not dynamic like the
other voltages), and a really stiff ground.
Hardest to deal with are various specs that specify a source resistance,
a limited slew rate, or timing down to a microsecond or so. And an
analog comparator to read the outputs back that is both fast and won't
get fried.
Mark Zenier mzenier@xxxxxxxxxx
Googleproofaddress(account:mzenier provider:eskimo domain:com)
.
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