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I need help understanding how to work with a dual op amp using all 8 pins.

I downloaded a spice model for the RC4558 from TI's website, but it only has pins 1, 2, 3, 4(-) and 8(+). In my audio projects, I use a schematic that has the op amp split into two graphics, UA and UB. UA has pins 1, 2, 3, 4(-) and 8(+) and UB has pins 5, 6 and 7. I am pretty new to LTspice and can't seem to find any info beyond just the one half, UA, of the 4558 or TL072, etc.

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    \$\begingroup\$ Are you specifically looking to model the (very small) crosstalk/interaction between the two halves? \$\endgroup\$
    – nanofarad
    Commented Jun 30, 2022 at 19:26
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    \$\begingroup\$ Use 2 separate op amps.. \$\endgroup\$
    – Hedgehog
    Commented Jun 30, 2022 at 19:49
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    \$\begingroup\$ In LTspice they're mainly interested in the functioning of the circuit, not the layout, so they don't usually bother to model multiple device packages. You just use 2 separate opamps to do your simulation and worry about the pinouts in your board layout software. It is possible to do it if you want to get into editing the packages, but it's not generally worth it for the intended purpose of LTspice. \$\endgroup\$
    – GodJihyo
    Commented Jun 30, 2022 at 20:11

1 Answer 1

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Note that even when the datasheet explicitly mentions a shared circuit between the integrated opamps:

enter image description here

It may be the case that the model doesn't bother to represent this very small interference:

* fetched on 2015/3/15 from http://www.ti.com/lit/zip/sloj043
* LM324 OPERATIONAL AMPLIFIER "MACROMODEL" SUBCIRCUIT
* CREATED USING PARTS RELEASE 4.01 ON 09/08/89 AT 10:54
* (REV N/A)      SUPPLY VOLTAGE: 5V
* CONNECTIONS:   NON-INVERTING INPUT
*                | INVERTING INPUT
*                | | POSITIVE POWER SUPPLY
*                | | | NEGATIVE POWER SUPPLY
*                | | | | OUTPUT
*                | | | | |
.SUBCKT LM324    1 2 3 4 5

For the two models mentioned (without explicit reference to shared circuitry) it is clearly the case that independent opamp models are being assumed.

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    \$\begingroup\$ That is exactly what I needed to know, thanks everyone! \$\endgroup\$
    – Rick Kelly
    Commented Jun 30, 2022 at 21:13

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