Add symbol/component/device for SN6501 push-pull transformer driver

[eduardosm]

SUMMARY

Adds symbol, component and device for SN6501 push-pull transformer driver

Typical application:

DATASHEETS / REFERENCES

https://www.ti.com/lit/ds/symlink/sn6501.pdf

CHECKLIST

• I have read and followed the library conventions¹.
• For packages, I followed IPC7351C (see details in library conventions).
• For modified elements, I bumped their version number².
• I already used the new library elements in a design and verified their correctness (optional).
• I'm the copyright owner of the added content (i.e. the changes are made by myself, not copied/imported from somewhere else).
• I agree to publish all my changes under the CC0 Public Domain License³, allowing everyone to use and modify the content without any restrictions.

¹ Library Conventions: https://docs.librepcb.org/#libraryconventions
² Minor version bump if only metadata was modified (e.g. "0.1" -> "0.1.1"), major version bump if functional changes were made (e.g. "0.1" -> "0.2")
³ CC0 Public Domain License: https://en.wikipedia.org/wiki/CC0

[ubruhin]

We already have that symbol in the libraries, so that one should be reused instead of adding a new one - just look for "Generic IC 4-Pin".

One thing that bothers me a bit - for me it feels not intuitive to have D2 above D1, I feel like it would look cleaner to swap those pins. Or is there any reason not to swap them? Those pins are equivalent in function, right? 🤔

Btw, changing the symbol is a breaking change, so to avoid issues on your side, I'd recommend to duplicate the component (to get a new UUID) and remove the current one.

[eduardosm]

One thing that bothers me a bit - for me it feels not intuitive to have D2 above D1, I feel like it would look cleaner to swap those pins. Or is there any reason not to swap them? Those pins are equivalent in function, right? 🤔

In this particular case, having D2 above D1 allows a cleaner schematic.

Swapping D1/D2 would require crossing the wires on the schematic, which would look like this (or crossing traces on the board, which is much worse)

In push-pull transformers, pin 1 (top left) is usually the "positive" of the primary winding

https://www.we-online.com/components/products/datasheet/760390014.pdf

https://www.coilcraft.com/getmedia/4ec07077-995f-40dc-869e-e8eda6407197/ua825x.pdf

[ubruhin]

Swapping D1/D2 would require crossing the wires on the schematic

Hmm really? I mean, isn't the polarity of D1/D2 irrelevant? The circuit looks symmetric to me, but I am asking because I have no experience with transformers 🙈

So, would this circuit be wrong or not?

(and btw, even if the polarity matters, one could mirror the transformer symbol in the schematic to avoid wire crossings - but I agree that would a bit ugly)

In push-pull transformers, pin 1 (top left) is usually the "positive" of the primary winding

That is not relevant - the location of pins in the schematic is not related to the location of pads on the package.

[eduardosm]

Hmm really? I mean, isn't the polarity of D1/D2 irrelevant?
So, would this circuit be wrong or not?

The circuit would not be electrically wrong, but PCB routing would be far worse, at least with a typical push-pull transformer

That is not relevant - the location of pins in the schematic is not related to the location of pads on the package.

But pins should be arranged such as schematics looks cleaner, right?

one could mirror the transformer symbol in the schematic to avoid wire crossings

That would be more acceptable than crossing wires, but I'd still avoid it if possible.

[ubruhin]

But pins should be arranged such as schematics looks cleaner, right?

That's right, but actually without considering the package of a part. I mean, from the SN6501 component point of view, we don't know what transformer the user will use, so we don't know its package neither. IMHO it doesn't matter if "usually" transformers have pin 1 at the top left. Additionally we also don't know how the user will mount those devices on the PCB. He might want to mount the transformer on bottom side and the SN6501 on top side, which might even end up with a simpler wiring with swapped D1/D2 pins. So in the end, we should not make any assumptions about packages in the schematic.

Therefore I think I'd go with mirroring the transformer in the schematic. But let's make an exception for this specific part now :) In this particular case, it also makes it easier to draw a schematic that matches the application example in the datasheet.

So I'll merge as-is, thanks for contributing it!