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DC power jack design decision: 2.1mm ID or 2.5mm ID?????

Former Member

Hello there!

We are designing a family of consumer devices that will require an input DC power barrel connector on our PCB.  It will be for +12vdc of various power levels.  We will be able to purchase "off the shelf" UL-listed wall warts depending on the application.  My question is, as I design our PCB to work with a PCB mount DC barrel jack, which is more common?  2.1mm ID or 2.5mm ID for DC power jacks with 5.5mm OD???  So far it looks like they both are "standards".  So, which do I design for if I want to be most forward compatible?  Does one of the options work with both plug types, but not vice-versa?

 

Switchcraft 2.1mm ID, 5.5mm OD $1.61 @ qty=1k

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=SC1330-ND

 

CUI 2.1mm ID, 5.5mm OD $0.19 @ qty=1k

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CP-102A-ND

 

CUI 2.5mm ID, 5.5mm OD $0.19 @ qty=1k

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CP-202B-ND

 

Thank you for any suggestions!!.... changing after we make several thousand will be much more difficult!

Respectfully,
Steve  French
814.584.1220.office
814.730.0003.cell
 
President, Volt  Vision
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  • 0

    I know this is a very, very old thread resurrected but bizarrely I was looking into this question myself on Saturday.  I think 2.1mm and 2.5mm is very common.  What you need to be aware of is the voltage and current specs on available jacks (female sockets):

     

    • 2.1mm with 12V capable jacks, even up to 5A, are as common as hydrogen molecules.  Try finding one that takes 15V though - hen’s teeth.  I was looking for a 2.1mm jack to take 15V, 0.5A.  No chance, not on Farnell, CPC, RS components.
    • 2.5mm can go to higher voltages with jacks but are more expensive for some reason. 

     

    Note that the jacks are not defined by power, i.e. a 12V 5A is not a 60VA socket so that 15V 0.5A is acceptable: the two specs are separate.  The current spec defines the power handling capability based on the connector resistance (typically <50mOhm); the voltage spec defines the insulation capability.

     

    TBH I don’t think there would be a problem with 15V 0.5A in a 12V 5A jack but the latter isn’t specced for it.  If you are looking to build your own board connector solution, check that you can get the right plug and socket combination.

  • 0 in reply to Andrew J

    That's an interesting observation @andrewj - I wouldn't have thought the size different to be significant to voltage but the thicker pin should enable higher currents.

     

    Speaking of which, a 2.1mm jack capable of more than 12V isn't entirely unknown of -

     

    But you're right - there's not many choices out there.

     

    - Gough

Reply Children
  • 0 in reply to Gough Lui

    Yep, more choice in PCB mount but not that many.  I wanted a 3-pin, panel mount one that would give me more flexibility in positioning a PCB inside a case and given I already have a 2.1mm 15V wall wart which I've designed around, I've decided to risk a 12V 5A panel connector rather than paying through the nose for a 15V 2.5mm jack and a replacement wall wart or, more likely, a 2.1mm to 2.5mm adapter.  If it does breakdown in the future at least I only have easy-to-change parts to deal with!  Assuming the house doesn't burn down of course image

  • 0 in reply to Andrew J

    I'm sure it will be fine, as long as you're not connecting/disconnecting under load too frequently - the arcs could damage the contacts and increase the contact resistance before the connector reaches its "rated" contact cycles. Perhaps the rating is conservative for that reason. I'd be much more suspect using a plug adapter ... as sometimes you don't know what parts are used to make them!

     

    It should be remembered that connectors as small and fine-pitched as USB-C are rated to carry 20V at up to 5A ... and the barrel jack is likely to have quite a bit more metal and plastic.

     

    - Gough