DFN 3 & 4-Pin Numbering and JEDEC MO-236C Standard

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   Hello.  We've noticed that the DFN 3-Pin doesn't follow the pin number order as defined in JEDEC MO-236C by default.  Most manufactureres seem to use the JEDEC pin numbering that we've come across.

PCB Libraries has the large pad assigned as pin 1 where JEDEC has that as pin 3.  The JEDEC pin numbering follows the same pin order as a SOT-23 would.

Pin order on the 4 pin version also doesn't follow this standard. In the default orientation pin 1 would be in the upper left, with pin 2 on the lower left.

Is there a reason for this or is this a bug?  By default I think the numbering should follow the JEDEC standard.

Thanks,

Chris

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GrungyRemnant Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 17 Oct 2013 Status: Offline Points: 91	Post Options Post Reply Quote GrungyRemnant Report Post Thanks(0) Quote Reply Topic: DFN 3 & 4-Pin Numbering and JEDEC MO-236C Standard Posted: 20 Jun 2014 at 8:16am
	Hello. We've noticed that the DFN 3-Pin doesn't follow the pin number order as defined in JEDEC MO-236C by default. Most manufactureres seem to use the JEDEC pin numbering that we've come across. PCB Libraries has the large pad assigned as pin 1 where JEDEC has that as pin 3. The JEDEC pin numbering follows the same pin order as a SOT-23 would. Pin order on the 4 pin version also doesn't follow this standard. In the default orientation pin 1 would be in the upper left, with pin 2 on the lower left. Is there a reason for this or is this a bug? By default I think the numbering should follow the JEDEC standard. Thanks, Chris



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 20 Jun 2014 at 9:05am
	The DFN pins can easily be renumbered any way you want them. All of the "Reference" parts are real genuine component manufacturer parts that we simply pulled for the 227,000 part numbers on www.pcblibraries.com/pod Once we created an FPX file with every JEDEC component family and their dimensions. Then we downloaded 5,000 component manufacturer's datasheets and entered all those component dimensions. The Library Expert will pop-up a warning if you try to import an identical footprint name with the same exact dimensions. The results were that the program allowed us to import every component mfr. dimensions and not once did the "Part Already Exists" notice pop-up. This means that no component manufacturer is using JEDEC dimensions. Please post on this forum one component manufacturer datasheet and the exact matching JEDEC standard where the dimensions match 100%. It doesn't exist.
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GrungyRemnant Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 17 Oct 2013 Status: Offline Points: 91	Post Options Post Reply Quote GrungyRemnant Report Post Thanks(0) Quote Reply Posted: 23 Jun 2014 at 8:27am
	[1]Hi Tom. Thanks for the feedback. I understand there is a quite a bit of variability in these package types. I’m not really concerned about the package dimensions but the default pin order. Here are 2 devices that are on my current design that match the M0266C-AA spec very closely. http://www.nxp.com/packages/SOT883.html http://www.onsemi.com/pub/Collateral/NTNS3A65PZ-D.PDF I understand you can change the pin order (great feature) but basically every time we will create a footprint for these families we’ll have to change the pin order. I was simply suggesting the default order follow the spec. We’d prefer people creating the parts follow the tool defaults as much as possible. Thanks, Chris

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 23 Jun 2014 at 11:05am
	We're going to try to change the default pin order for the 3-Pin DFN to match JEDEC. I have to run some tests on the .05 pre-release installation to see if it messes up any existing parts in FPX files. That's the downside of making a change like this, but I hope everything works out where the "reference" default does not affect existing parts. If everything works out OK and you would like a V2014.05 pre-release with this update, let me know.
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Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5717	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 26 Jun 2014 at 7:53am
	OK, we changed the 3-pin DFN to this default pin assignment. But Pin Rename can change it to what ever the user requires. 1 3 2 We are going to release V2014.05 this weekend with several new features.
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