connecting power to gates

[stressed_user]

Hi,

I don't use logic (74HC and other HCT... CMOS) gates that often, but when I use them they're not always connected to the same ground and supply.

When putting gates on my schematic, there is no power connection visible, so I can not connect it myself.

as an example, I have a board with two parts devided with optocouplers, lets call the an input and an output part.

The input part has its own 5V supply, and so does the output part.

When I place a HC138 on the input, and one on the output, how to spilt their supplies (in an easy way)?

Johan

[kittmaster · Accepted solution]

Right click on any gate, properties, pins, you'll see the VCC and GND in the cell layouts, click in cell and type in the net name like +5V or whatever your power nets are there.  It will then connect them as you require.  Its a lousy system, but it works.  There should be a power gate shown, but for some reason NI doesn't do it this way, and it is very annoying and in PCB land, can be a paramount mistake if care is not taken to this "minor" detail.  Regards,

[stressed_user]

Thanks,

That works fine for the layout... 

It is indeed rather lousy, since from the schematics you can never see what supply is used for which gate...

That is no problem now, but after a while when opening an old design, it is not easy to find out wat's supplied by what...

Also, customers checking the schematic/layout may have problems understanding....

I'll send them to NI 🙂

I think i'll just add text to the schematic, just to help in the future when reading the schematic...

thanks a lot

Johan

[kittmaster]

Well I do believe that there is a way to make the power pins visible if you move it to the footprint editor and unhide the two power pins.  I haven't had to do it for a while, but it is still a huge pain the ass.  I am pretty much using pads lately and using the control and left click method cycles through gate A - X until it hits the package power gate which is remoted to another area on the same page to the power nets.  NI should take this cue for this since the digital gates and custom package and power sources nets never seem to match.  I've been burned hard on a few designs that used inverters and logic and I forgot to assign the power pins to the nets in hardware.  My mistake, but would have easily been avoided if I had a visual on the connection points........oh well live and learn.