Equivalent to CA3240

[aless2056]

Hello guys, my friend needs the CI CA3240, but this item is missing from distributors (Farnell, Mouser, Digikey,...).

What would be the option to replace this CI in DPID format?

 

[Aussie Susan]

When you say 'missing' do you really mean it is on back-order?
I'm sure there are many manufacturers sites where you could do a parametric search for an equivalent.
Susan

 

[FvM]

Presume there's no exact replacement. Parametric search presupposes that you know the actual application requirements:
- supply voltage
- input common mode range
- output voltage swing
- input current
- precision (offset and drift)
- GBW, slew rate
- noise

 

[danadakk]

Ebay has them if you just need to repair something.

If production just search TI, ON, ST for RRIO OpAmps to help you start
the selection process.

Not knowing what the circuit requirements look like this part a little unusual in its input
CM range is .5 V outside its supply rails. So be careful when using search tools and
qualifying the parameters for selection, unless you know the circuit does not need this
capability.


Regards, Dana.

 

[d123]

I just read here that it can replace LM741, so maybe vice versa. When I saw Jurassic CA3240, LM324 sprang to mind - rightly or wrongly.

 

[danadakk]

CA3240 input bias and offset current an order of magnitude lower
that the LM324, one possible reason, depending on design re-
quirments, why thats not a good substitution.

LM324 :

Regards, Dana.

 

[d123]

Hi,

Okay, admittedly a terrible suggestion after having had a look at CA3240, whoops. Sorry.

FWIW, a search for CA3240 brought up:

CA3240 replacement thread on another forum

Main suggestions and search results mentioned:

LF353
AD712
OPA2604
and
TL072

Hope any of them actually are appropriate.

 

[danadakk]

Just a thought, we really need to know more about the circuit as there are other
differences. Like the CA3240 will operate down to just +5V, whereas the LF353 cant
do that. But the TL072 can....

Just too many unknowns to do a good recommendation.


Regards, Dana.

 

[dick_freebird]

Major semiconductor vendors used to take the time to make
cross-reference / substitution tables, to enable their parts to
"steal sockets". A few paper databooks I looked at, didn't.

TI's online cross reference shows only Renesas (<Intersil<Harris<RCA)
CA3240. This part would have been built in fabs they no longer
operate (most likely Findlay OH) and it's probably a die bank
situation with very little motivation. Or inventory.

TI general search turns up the LM148/248/348 datasheet when
you look for CA3240, yet that keyword seems not to appear in
the datasheet. Maybe not a good enough fit to claim anything
but worth the MarCom people burying a closest-fit keyphrase
somewhere in the fine print?

Harris / Intersil may have offloaded die bank products to
Rochester, worth a look if you need it bad and don't mind the
money.

 

[d123]

Just a thought, we really need to know more about the circuit as there are other
differences. Like the CA3240 will operate down to just +5V, whereas the LF353 cant
do that. But the TL072 can....

Just too many unknowns to do a good recommendation.


Regards, Dana.

Hi there Dana,

My thoughts as well, particularly what is highlighted in bold. I posted the links to those parts a) because it was suggested in that other forum thread (link in previous post) that they are reasonable substitutes and b) because I would imagine the thread poster is familiar with the dull chore of comparing multiple datasheets and understands caveat emptor .

 

[Audioguru]

The antique CA3240 has Mosfet inputs that have a limited input voltage range and the dual opamp produced the most noise than any other dual opamp.

 

[danadakk]

The antique CA3240 has Mosfet inputs that have a limited input voltage range and the dual opamp produced the most noise than any other dual opamp.

Only a little bit more than a ua741 era part, Neither exactly an audio class part.....

1Khz 100 ohms

CA3240 30 - 40 nV/rootHz
741__________ 23
351__________ 15 JFET
Regards, Dana.