linear IC suffixes

[Rich Nelson]

CGS2510.SEP.STUDENT.UCA at CUB.UCA.EDU wrote:

> C is commercial, I is industrial, etc.  Some are company lettering...
> The difference usually is the temperature rating and for op amps the
> dc offset and stuff like that.  I am of the opinion since I don't
> live in Antarctica or anything  and usually am not worried about a
> small DC bias to just go with the CN suffix.  Generally, anyway.
> 
This is _sometimes_ the case, although... Signetics uses the suffix "P"
for a dip and "T" 
for an SO package, RCA uses "E" for a dip package, etc. ->


> That may be a missprint perhaps since the 1458 is a very common op
> amp and really stinks compared to more modern op amps (its a dual
> 741).  If it is an op amp, it is very conceivable that it was used
> where the convenience of an op amp was desired, but the prices back
> then were prohibative for using fancy stuff in all but the signal
> path.  Many things use 1458's and such for CV controls and the like.
> In ALMOST EVERY case, a direct replacement with a TL072 or whatever
> should work.  Look at the schematic and see if there is anything
> going on that prohibits the use of another variety op amp (current
> drive and that kind of thing) and pick a different one if you feel so
> inclined.
\
Not always true... the higher GBP and input Z of TL or LF type opamps
make them more 
susceptible to spurious oscillation... and the slower slew rate of "old
fashioned" 
741 types is often desirable.  For instance, they are the best choice in
a saw to 
triangle converter (at audio freqs) since the slower slew squelches the
crossover glitch.

741 types are by no means obsolete, and it is not correct to say that
741 types "stink" 
in comparison to more recent opamp designs... in fact they are the
appropriate choice in
many circuits.  Unless one has an understanding of parts substitution,
and some experience 
in physical layout, it is usually a good idea to stick with the opamp
specified by the circuit 
designer.

And why pay more for a higher performance opamp when 1458s are available
for 25 cents each?

rich