TK50Z-GA EPROM

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Mon Jan 18 11:34:47 1999

>>The main difference is the power consumption. The CMOS version takes a
>>much lower supply current (even when selected).
>>
>>There may also be differences in the access time (but fast enough CMOS
>>EPROMs exist) and the programming algorithm (but that only matters to the
>>programmer).
>>
>>They are essentially pin/function compatible.
>
> Erm, correct me if I'm wrong ('cause I may very well be) but at least in
> comparison with 4xxx CMOS vs. 74xx TTL, not only do the require less
power
> to do their job, but they can also *provide* less power on their outputs
to
> other chips' inputs, right?


Hmm. You're comparing CMOS with TTL. The traditional EPROMs are not TTL
but NMOS - very similar components (at the transistor level) to CMOS, but
fewer different sorts available. NMOS uses enhancement mode FETS and
depletion mode FETS of N-channel polarity. CMOS uses enhancement mode FETS
of both sorts. In theory, depletion mode FETS could be fabricated by the
CMOS process, but I've never heard of it being done except perhaps for
NMOS-compatible outputs etc.

So I don't envisage a difficulty here. The newer designs of CMOS parts
should compensate for any inherent disadvantages with CMOS technology.

Philip.
Received on Mon Jan 18 1999 - 11:34:47 GMT