Stats

  • Replies 9
  • Subscribers 161
  • Views 14346
  • Members are here 0
More Content

4 Terminal PCB Footprint

MikeSD

I have a component (MOSFET) that is a 3 terminal device, in TO-92.  In a surface mount, it's 4 pins (3 pins and a tab).

 

I'm not sure the best way to deal with this.  On the datasheet, each connection is D, G, S and D(tab).  But on the footprint it's numbered (1, 2, 3, 4).

I have two options.

1) Make the footprint 4 pins (each differently numbered, 1, 2, 3 and 4).  But this requires adding a 4th pin on my component in the schematic capture, which looks strange. Most transistors are only 3 pin devices.

2) Make a footprint that has 3 pins with the center pin large to include the tab area.  But this removes routing options under the componet.

I initially tried 4 pins with numbers 1, 2, 3 and 2 for the tab but got an error becuse two pins had the same number.

 

What is the best or most appropriate way of handling this?

Parents

  • Whoops,

    I didn't know you needed to connect the tab to a net when I suggested using a mechanical pin.  For a pin to connect to a net normally, it needs to be a connect pin in the physical symbol.  Also, the pin needs to be assigned to the net in the schematic or the logical symbol.  Unfortunately, I also am not familiar with how to do that in Capture.  Of course, you always have non-elegant solutions like putting in a static shape over the mechanical pin and assigning a net to the shape, then waiving the DRC; but then if you have to move the symbol or change the net name, it's more work.  Hopefully, you can figure out how to assign the net in Capture.

    Good luck.

Reply

  • Whoops,

    I didn't know you needed to connect the tab to a net when I suggested using a mechanical pin.  For a pin to connect to a net normally, it needs to be a connect pin in the physical symbol.  Also, the pin needs to be assigned to the net in the schematic or the logical symbol.  Unfortunately, I also am not familiar with how to do that in Capture.  Of course, you always have non-elegant solutions like putting in a static shape over the mechanical pin and assigning a net to the shape, then waiving the DRC; but then if you have to move the symbol or change the net name, it's more work.  Hopefully, you can figure out how to assign the net in Capture.

    Good luck.

Children
No Data
Cadence Guidelines

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.