Connected internal components - schematic & footprint?

Hi everybody,

working on a pcb which incorporates wo stepper motor drivers I integrated a reverse current diode array to protect the drivers.
First shot was to have 2x8 single Schottky diodes on the pcb. To ease soldering etc. I came across with a special Schottky diode array from Texas Instruments (= UC3610).

Now my challenge is to create a schematic symbol plus a footprint for this device. But I have no idea how to design a symbol which represents 1:1 the diode array on the schematics of the pcb and the corresponding footprint. Issue: the diodes come already internally pre-connected, so I can’t break it up like a 7400 or other “internally independent components” of a package.

For a better understanding see the attached schematics of the UC3610 diode array.
My today’s workaround is, to have the symbol designed just as a “black box” with labelled pins which then can be used in the footprint adequately.

So - does somebody have an idea how to have a detailled schematics including the diode array and the corresponding footprint?

I see no problem to split this network to one component with 8 parts. Select “Edit pins per part” and go on…
uc3610.zip (617 Bytes)
Of course you have to be more careful when choosing particular parts during capturing your schematic.

EDIT: Sorry, I forgot to check very important option for this component: All units are not interchangeable. Check this option if you plan to use automatic annotation tool!

2 Likes

Thank you very much.
I could successfully create the pcb schematics, create a footprint and a pcb layout with your suggestions.

Just of interest:
What if the internal connections of a package were not accessible on external pins?

Could you give any example?

Here you go (especially in the audio IC environment, there are dozens of these integrated circuits); I suppose that in these cases you can only use “dummy” circuits which only handle the externally available pins, can’t you?

Well. I see neither the reason nor possibility to split this kind of circuit to the three separate parts. They are not independent.

IMO this is the better example: http://www.datasheetlib.com/datasheet/645189/ul1102_unitra-cemi.html
Six transistors in two bare differential amplifier circuits. We can not split this for the 6 transistors, but we can create two complete parts with 3 transistors per each.
In case of UC3610, we had a better situation. This diode network can be treated as 8 separate diodes, but to make it more legible, the network should be treated as 4 protection units (clamping diodes).

I won’t argue what is the better example and what not.
Both examples are alike having internal connections with no external pins available. So I think the best workaround is to just look at the outside of the pins and create the adequate symbol/footprint.

On the overall schematics side one should then reference to the internal circuit of the component(s). Imho a screenshot of the datasheet circuit and attached as picture to the schematics will do.

Andy,

I agree. Being a semi-pro / hobbyist for me it’s helpful to have all the information of a project in one place.

So what I will do is, following your suggestion, not to care about the “internals” too much, but attach the adequate data sheet(s) to the schematics to have everything in one place.