Author Topic: quad op amp pin outs?  (Read 944 times)

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Offline loki42Topic starter

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quad op amp pin outs?
« on: July 01, 2019, 06:34:01 am »
Are there quad op amps, if possible similar or better noise performance to the TL074 that have a switched pin out with the inverting and not inverting input pins switched? I need it in a SOIC format. Currently I'm reworking the boards to fix my mistake but it'd be a lot faster to swap the chips.
 

Offline David Hess

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Re: quad op amp pin outs?
« Reply #1 on: July 01, 2019, 11:26:11 am »
I am not aware of any with the inverting and non-inverting pins swapped.

Most quads use the LM324 pinout but there are exceptions like the RC4136.
 

Offline GK

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Re: quad op amp pin outs?
« Reply #2 on: July 01, 2019, 11:41:10 am »
Bzzzzt. No longer care, over this forum shit.........ZZzzzzzzzzzzzzzzz
 

Offline loki42Topic starter

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Re: quad op amp pin outs?
« Reply #3 on: July 01, 2019, 11:42:07 am »
Not sure if this is the easiest option but I've just thought of something that might have been obvious to others... how about I make a board that has a SOIC format on the bottom and a TSSOP format on the top and put new op amps on? I guess I could have SOIC on both but then I think I'd have to hot air the PCB on the solder the top ones? Maybe still pretty quick.
 

Offline David Hess

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Re: quad op amp pin outs?
« Reply #4 on: July 01, 2019, 12:22:13 pm »
Incidentally, there is some reasoning behind operational amplifier pinouts.  The outputs are placed closer to the inverting inputs than the non-inverting inputs to prevent positive feedback through capacitive coupling.  Comparators want the opposite leading to the very different LM339 quad comparator pinout.  Dual comparators copy the dual operational amplifier pinout which is not optimal for them.

 
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Offline loki42Topic starter

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Re: quad op amp pin outs?
« Reply #5 on: July 01, 2019, 12:28:09 pm »
Looking at the prices of castellated holes it seems a lot quicker and easier to just use it basically as a QFN style package, with all the leads underneath and solder the top one. Would it work to put down paste, heat a small adapter PCB with hot air to solder it onto the main PCB and then hand solder the op amp on the adapter? I assume the enough heat would get to the paste to liquefy it without damaging the adapter board but maybe castellated is safer.
 


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