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SMPC (TO-277A) made out of DFN standard
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zentekfr View Drop Down
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    Posted: 23 Feb 2022 at 3:57am
Hello,

In the process of building a footprint for a SMPC component (standardized against JEDEC TO-277A), I found that a 3-pin DFN could do the job. The obtained land pattern is very close to the manufacturer's recommended footprint. Of course the pins should be reordered/renamed.
Is my idea of building this part out of a DFN3 good? Not advisable? And why?


Thanks!
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zentekfr View Drop Down
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Points: 83 		Post Options Post Options   Thanks (0) Thanks(0)   Quote zentekfr Quote  Post ReplyReply Direct Link To This Post Posted: 23 Feb 2022 at 6:06am
I add the drawings and datasheet for reference: https://www.vishay.com/docs/89335/ar4pm.pdf
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Tom H View Drop Down
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Points: 5716 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 23 Feb 2022 at 9:45am
The Vishay TO-277A Case Code is not a 3-pin DFN component family. 

This footprint must be created in FP Designer.  

There are 34 Vishay part numbers on www.pcblibraries.com/POD that have the TO-277A Case Code. 
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zentekfr View Drop Down
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Points: 83 		Post Options Post Options   Thanks (0) Thanks(0)   Quote zentekfr Quote  Post ReplyReply Direct Link To This Post Posted: 24 Feb 2022 at 12:58am
Hello Tom,

Of course it's not a DFN. But as soon as I use the FP Designer, I'm losing much of the features of Footprint Expert (3-tier density system, rounded rectangle pads, pad shapes drawing, Master options for batch generation, ...).
That's why I considered building it from a known standard package.

Thanks for your answer Wink
Justin
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Tom H View Drop Down
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Points: 5716 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 24 Feb 2022 at 10:42am
In FP Designer you have 100% control of the pad stacks like Rounded Rectangle Pads and Pad Shapes. 

All non-standard package footprints should be created in FP Designer. 

This is not a 3-Tier Density footprint. Only the mfr. recommended pattern will work correctly. 

If you need FP Designer training, we can do a quick webcast so I can show you some great features. 
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zentekfr View Drop Down
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Points: 83 		Post Options Post Options   Thanks (0) Thanks(0)   Quote zentekfr Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2022 at 10:22am
So I probably missed the rounded rectangle option.
Then a webcast is welcome! I will send you an e-mail.
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