OrCad Capture power pins

Hi Malcolm, You are using Capture, right? If so, you can just make the power pins visible, and attach them to the different rails. That makes it pretty apparent.

Of course, if you are using PSpice, only some of the parts have the ability to use different power supply rails, spec. only the CMOS based parts usually have the option...

Hi,

I can't seem to find a good way of having logic gates on different rails.

My options seem to be:

Edit part to change power name for each part. Make power pins passive and thus visible on all gates and connect.

Both seem naff to me. Is there another way?

--

Malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK ( snipped-for-privacy@fullcircuit.com, snipped-for-privacy@fullcircuit.co.uk or snipped-for-privacy@iee.org). Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:

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In article , Malcolm Reeves wrote: [...]

In the DOS Orcad, you could make passive pins that appeared only on one part in the package. Such schematics import into capture ok so I assume you can do the same in capture, but this may not be true. I've discovered that some things that are quick and easy to do in the DOS version don't seem posible in the windows software.

Rubbish :-) Hidden power pins are a complete PITA to a service tech. When you come to service the product, the circuit MUST show which supply each chip is connected to. And preferably on the chip not in some hand-typed table... Geo

In article , Malcolm Reeves writes: |> Hi, |> |> I can't seem to find a good way of having logic gates on different |> rails. |> |> My options seem to be: |> |> Edit part to change power name for each part. |> Make power pins passive and thus visible on all gates and connect. |> |> Both seem naff to me. Is there another way?

Well, I don't think you would want the first option. That would hide the power connections so that you would not be able to see what rails they are connected to.

In Capture, you can select the part, and then right click and select "Edit Properties". At the bottom of the dialog box, check "Power Pins Visible". Then you can wire the pins to whatever rails you want. I THINK (check this) that this will have the desired effect of overriding the power name on the pin. Alternatively, it might cause you to interconnect all your power buses, but I don't think it does that.

The bad thing about this is that many of the Orcad parts have zero length pins for the power pins, and the pins may not be located on the part body where you would like to see them. I suppose that this is because they forgot that someone might actually want to make these pins visible. The work around, of course, is to make your own library of parts on which you want sane power pins. This is what I usually do.

Thanks to all for their suggestions but let me address this point.

I would agree that hidden power pins are a pain, but then so is power pins on all 6 gates. The best method I have seen is where a part has

In my circuit I have opted for editing the gate to two different parts. One with the label VCCa connecting to VCCa and one VCCb. That way I can pick the appropriate part for the right rail and annotate won't assign the wrong gate to the wrong package. The labels are shown in on each part of course.

The alternative of power pins visible I'd have to do for all gates to ensure they all packaged right. Since I only have two ICs my method seems more tidy.

Malcolm, Here is the way I do it with my individual logic parts within I/Cs...

Mylib.slb : INVERTER Pin Data U? VP X Y E R C# Name invert_a VN 0 20 i 1 A 50 20 o 2 Y 30 0 x 3 VP 30 40 x 4 VN Symbol Data: Description = Inverter Type = p Bbox = (0 0) (50 40) Origin = (0 20) Attributes PART = INVERTER REFDES = U? TEMPLATE = X^@REFDES %A %Y ?GLOPWR|$G_@VPLUS $G_@VNEG|%VP %VN|@MODEL MODEL = invert_a GLOPWR = VPLUS = PWRP VNEG = PWRN

This is, of course, with Schematics, not Capture, which you seem to have switched to ;-)

...Jim Thompson