I was looking at a this CUI power jack connector and I noticed that it has a switch which is NC, and I think goes open when a connector is plugged in (pin 2/3).

There's no clear distinction I can make out between which pin (pin 2 or 3) which is actually electrically hooked up to the outer housing (in my case ground since my adapter is center positive).

Which pin should I connect my ground to? If I don't need to detect if the jack is plugged in, can I just short out the two pins and not worry about the issue?


The pin numbers of the connector are identified in the data sheet that you linked, both on the small schematic and on the footprint/hole diagram.

Here is an annotation of the connector schematic.

enter image description here

As drawn the connector barrel pushes down on the contact and opens the point switch contact to pin 3.

  • \$\begingroup\$ I can't tell from the schematic which is which. \$\endgroup\$ – helloworld922 Jan 17 '13 at 21:26
  • \$\begingroup\$ The pin numbers of the connector are labeled in the drawing on nearly every view. In the schematic the connector view for pin 2 shows the actual connection that contacts the outside barrel contact. I'll add a picture to my answer. \$\endgroup\$ – Michael Karas Jan 18 '13 at 0:29

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