Author Topic: Finding Equivalent Op-Amp (National Semiconductor Part)  (Read 365 times)

0 Members and 1 Guest are viewing this topic.

Offline The13thParish

  • Contributor
  • Posts: 18
  • Country: us
Finding Equivalent Op-Amp (National Semiconductor Part)
« on: June 08, 2021, 08:20:34 pm »
Dear all,

I'm trying to replace two op-amps in a Phillips Scientific Wideband Amplifier that was good up to 1 GHz (Model 6954). An issue I am facing is that this company seems to have disappeared last year so I cannot find a datasheet online. I wish I'd saved it previously, but alas . . .

The op-amps are National Semiconductor ones in an SOIC-8 package with the numbers 1678 on one line and 742 on the second line of the package. Both op-amps have identical part numbers. I understand that NS was bought out by Texas Instruments in 2011. Does anyone know what an equivalent part number would be? It seems like a stab in the dark here . . .

All the best,
Ryan
 

Offline fzabkar

  • Frequent Contributor
  • **
  • Posts: 945
  • Country: au
Re: Finding Equivalent Op-Amp (National Semiconductor Part)
« Reply #1 on: June 08, 2021, 08:34:38 pm »
Are you sure it's an NS part?

https://www.analog.com/media/en/technical-documentation/data-sheets/16789fs.pdf
https://www.mouser.ca/datasheet/2/286/upc1678-1186874.pdf
https://www.ti.com/lit/gpn/OPA1678 <-- this is an audio amp, so it is probably the wrong fit for your application

Edit:

I think that uPC1678 is the only good fit for a wideband amplifier.
« Last Edit: June 08, 2021, 09:45:30 pm by fzabkar »
 

Offline The13thParish

  • Contributor
  • Posts: 18
  • Country: us
Re: Finding Equivalent Op-Amp (National Semiconductor Part)
« Reply #2 on: June 08, 2021, 08:37:54 pm »
The package has the squiggly N logo of National Semiconductor. I don't think I could have misidentified it for the LT logo.

If indeed you have found the ones I am after, what does the '742' refer to on second line of the package I have? Do I not also need this to match up with the part numbers you have found?
« Last Edit: June 08, 2021, 08:39:45 pm by The13thParish »
 

Offline fzabkar

  • Frequent Contributor
  • **
  • Posts: 945
  • Country: au
Re: Finding Equivalent Op-Amp (National Semiconductor Part)
« Reply #3 on: June 08, 2021, 09:18:39 pm »
what does the '742' refer to on second line of the package
It's normally a YWW (Year/Week) date code, ie week 42 of 2017 or 2007 or 1997. You should find similar codes on the other chips. Some may be in YYWW format.

Here is a repository of NS databooks:
https://mirrorservice.org/sites/www.bitsavers.org/components/national/_dataBooks/
« Last Edit: June 08, 2021, 09:36:00 pm by fzabkar »
 
The following users thanked this post: The13thParish

Offline fzabkar

  • Frequent Contributor
  • **
  • Posts: 945
  • Country: au
Re: Finding Equivalent Op-Amp (National Semiconductor Part)
« Reply #4 on: June 10, 2021, 08:48:00 pm »
I'm trying to replace two op-amps in a Phillips Scientific Wideband Amplifier that was good up to 1 GHz (Model 6954). An issue I am facing is that this company seems to have disappeared last year so I cannot find a datasheet online.

https://confluence.desy.de/download/attachments/129394950/6954ds.pdf?version=1&modificationDate=1566481777124&api=v2
 

Offline The13thParish

  • Contributor
  • Posts: 18
  • Country: us
Re: Finding Equivalent Op-Amp (National Semiconductor Part)
« Reply #5 on: June 29, 2021, 01:26:22 am »
fzabkar,

I wanted to say thanks: the UPC1678 op-amp was the one that I needed and the pre-amplifier now works again like a charm.

All the best,
Ryan
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf