[TriEmbed] TriEmbed Digest, Vol 25, Issue 43

Chip McClelland chip at mcclellands.org
Fri Jun 26 08:23:51 CDT 2015 

Shane, 

Thank you for taking a look - I know the dimensions for this part are a little different than the standard SOIC as it seems the package body is smaller and the legs are more extended.  I created my footprint to match the data sheet not the standards SOIC - Looking at this though, it seems that both would likely work.

As for extending the pads, Pete and I experimented with this when we were learning how to solder QFN devices and they lead to issues with bridging - perhaps worth a look here as the pins are more spaced out.

From what I can see, from the Power FET design image you shared here <http://triembed.org/lib/PowerFetSOIC8-1/PowerFetSOIC8-1-brd.png>, I don’t need to connect any pins on the footprint but will add some big “pours” when I lay out the board.  I am thinking this is most important for the high-side P MOSFET switch that will switch on and off the supply to the test-section of the board.  

I will create a second part in the library for the N-MOSFET for the other part you recommended on your blog.  Thanks again for helping us mere mortals comprehend the power and wonder of these devices.  Drawing that MOSFET device in EAGLE is a pain but, I think it helps..

Chip



> On Jun 25, 2015, at 2:09 PM, Shane Trent <shanedtrent at gmail.com> wrote:
> 
> Chip,
> 
> Great idea on building and sharing devices for Eagle. I would like to get better at this myself. I have a bunch of old designs that will not open in Eagle 7 because of a glitch with some device definitions I built and used in the older version of Eagle (5 something). Perhaps there would be an interest in getting a few people together to share ideas/experiences on defining new parts.
> 
> For comparison to your P-FET device, I dropped in the only SOIC I found in my Eagle resources, the NDS8434 N-FET from SparkFun-DescreteSemi. The image below shows both devices on a schematic and a board. I like how your device shows the intrinsic body diode (it's easy to forget about it). It looks like the SparkFun footprint includes longer pads which I would THINK would give you more room for margin of error on your solder paste and placement. But you and Pete have much more experience with working with SMD parts. 
> 
> <SOIC Footprint.jpg>
> 
> I am not sure about joining the common Drain pins or the common Source pins. Even the high-current 7-pin MOSFETs (like IRF2804S-7) appear to have separate pads for each pin on their footprint. I presume joining the common pins and adding heat spreading copper under the device are left to design choices during board layout. 
> http://www.irf.com/product-info/datasheets/data/irf2804s-7p.pdf <http://www.irf.com/product-info/datasheets/data/irf2804s-7p.pdf>
> 
> On a related note, does anyone know if there is a thermal advantage to connecting heat spreading copper under an SOIC device to the Source verses the Drain? Does one work better than the other or does it make no difference?
> 
> Shane
> 
> On Thu, Jun 25, 2015 at 10:29 AM, Chip McClelland via TriEmbed <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
> To all, 
> 
> Sorry for not getting this right on the first two attempts.  Here is a link <https://www.dropbox.com/sh/9qdzturvffr66do/AAAv0D0bogqsjLA9GiF5-DD6a?dl=0> to my dropbox where the PDF and the EAGLE custom MOSFET library are stored: 
> 
> Also, I am toying with the idea of contributing some of my custom footrprints to this ambitious project to share footprints for surface mount parts.- SnapEDA <http://www.snapeda.com/home>  So far, I have not been impressed with the designs I have seen but, it could grow up to be a cool solution and reduce the amount of time I have to spend designing custom libraries like the one linked to above.  
> 
> Thanks,
> 
> Chip
> 
>> On Jun 25, 2015, at 10:20 AM, triembed-request at triembed.org <mailto:triembed-request at triembed.org> wrote:
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>> Today's Topics:
>> 
>>   1. Re: TriEmbed Digest, Vol 25, Issue 42 (Chip McClelland)
>> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Thu, 25 Jun 2015 10:20:08 -0400
>> From: Chip McClelland <chip at mcclellands.org <mailto:chip at mcclellands.org>>
>> To: triembed at triembed.org <mailto:triembed at triembed.org>
>> Subject: Re: [TriEmbed] TriEmbed Digest, Vol 25, Issue 42
>> Message-ID: <C5FEC22C-496D-42FC-BCFC-49CAA530C1EF at mcclellands.org <mailto:C5FEC22C-496D-42FC-BCFC-49CAA530C1EF at mcclellands.org>>
>> Content-Type: text/plain; charset="us-ascii"
>> 
>> Shane and Pete and all, 
>> 
>> Thank you for the recommendations on the Surface Mount MOSFETS.  Since they were not in EAGLE, I have started creating a custom library for each part.  Here is the MOSFET library where I have made the first part (IRF9310P) and will add the N-MOSFET next.  Please take a look and let me know if I should do something differently, For example, should I have just one continuous PAD across all the source and drain pins?  I figured using a custom footprint rather than the standard SOIC-8 would allow for some better connection or thermal tweaks.
>> 
>> Thanks,
>> 
>> Chip
>> 
>> Here is a link to the data sheet I used to define the footprint - http://www.irf.com/product-info/datasheets/data/irf9310pbf.pdf <http://www.irf.com/product-info/datasheets/data/irf9310pbf.pdf> <http://www.irf.com/product-info/datasheets/data/irf9310pbf.pdf <http://www.irf.com/product-info/datasheets/data/irf9310pbf.pdf>>
>> 
>> 
>>> On Jun 24, 2015, at 1:00 PM, triembed-request at triembed.org <mailto:triembed-request at triembed.org> wrote:
>>> 
>>> Send TriEmbed mailing list submissions to
>>> 	triembed at triembed.org <mailto:triembed at triembed.org>
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>>> 
>>> Today's Topics:
>>> 
>>>  1. Re: Recommended SMD Logic-Level MOSFETs for prototyping
>>>     (Shane Trent)
>>>  2. iOS developer needed part-time (Jon Wolfe)
>>>  3. Re: iOS developer needed part-time (Robert Gasiorowski)
>>> 
>>> 
>>> ----------------------------------------------------------------------
>>> 
>>> Message: 1
>>> Date: Tue, 23 Jun 2015 15:52:39 -0400
>>> From: Shane Trent <shanedtrent at gmail.com <mailto:shanedtrent at gmail.com>>
>>> To: Pete Soper <pete at soper.us <mailto:pete at soper.us>>
>>> Cc: TriEmbed Discussion <triembed at triembed.org <mailto:triembed at triembed.org>>
>>> Subject: Re: [TriEmbed] Recommended SMD Logic-Level MOSFETs for
>>> 	prototyping
>>> Message-ID:
>>> 	<CAAFjd3ps+0LewCRG17EnKu1MqksoPiXDE0ank8Cj3sB0MVN4SQ at mail.gmail.com <mailto:CAAFjd3ps%2B0LewCRG17EnKu1MqksoPiXDE0ank8Cj3sB0MVN4SQ at mail.gmail.com>>
>>> Content-Type: text/plain; charset="utf-8"
>>> 
>>> Pete,
>>> 
>>> I like the board. I think a library of helper boards could be helpful for
>>> prototyping. The engineers at Pololu have the best examples I have seen for
>>> high-current PCB layout with surface mount MOSFETS. This board uses SOIC8
>>> transistors in a motor driver H-bridge rated for 18 volts and 15 amps. I
>>> like their multipurpose details on the high-current terminals. They use all
>>> the copper they can for the terminal pads while allowing the use of screw
>>> terminals or direct soldering of two different sizes of wire. Beautiful
>>> design.
>>> 
>>> https://www.pololu.com/product/755 <https://www.pololu.com/product/755>
>>> Top image - https://www.pololu.com/picture/view/0J1025 <https://www.pololu.com/picture/view/0J1025>
>>> Bottom image  - https://www.pololu.com/picture/view/0J1026 <https://www.pololu.com/picture/view/0J1026>
>>> 
>>> Shane
>>> 
>>> On Tue, Jun 23, 2015 at 1:45 PM, Pete Soper via TriEmbed <
>>> triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>>> 
>>>> Great writeup.
>>>> I found myself searching for "beefy breakouts" for SOIC-8 packages and
>>>> couldn't find one. I just knocked this out in Eagle and would like comments
>>>> or criticism:
>>>> 
>>>> http://triembed.org/images/b1.png <http://triembed.org/images/b1.png>
>>>> 
>>>> (the Eagle files are the same URL but ending FAT-SOIC8.{brd,sch})
>>>> 
>>>> This is a dead-simple board except there are redundant traces on the
>>>> bottom to vias that are in turn connected to the chip pads. So there are
>>>> two .024" traces for each pin. The vias have relatively large holes I
>>>> guestimate to have a circumference three times the trace width.
>>>> 
>>>> The biggest question is whether this is redundant. If there's an
>>>> unburdened Eagle file out there that I could upload to OSHPark I might be
>>>> able to get some boards made in time for the next meeting. This board would
>>>> cost 47 cents. But the boards I've found so far online have laughably
>>>> narrow traces for multiple amps.
>>>> 
>>>> I notice that the N channel chip you point to can handle pulses over 100
>>>> amperes. Wow.
>>>> 
>>>> -Pete
>>>> PS Is just crazy some times. A fraction of the time it flagged net
>>>> connections when I added wires from the via chip pads or else refused to
>>>> acknowledge the connection. So I'm only 92% sure there would be copper in
>>>> some cases and the first version of this board might really only have
>>>> single traces for some of the pins.
>>>> 
>>>> 
>>>> On 06/23/2015 11:22 AM, Shane Trent via TriEmbed wrote:
>>>> 
>>>> Someone else asked for recommendations on logic-level MOSFETs so I wrote
>>>> it up as a blog post.
>>>> 
>>>> 
>>>> http://fettricks.blogspot.com/2015/06/prototype-friendly-smd-logic-level.html <http://fettricks.blogspot.com/2015/06/prototype-friendly-smd-logic-level.html>
>>>> 
>>>> 
>>>> Shane
>>>> 
>>>> --
>>>> A blog about some of my projects.  http://fettricks.blogspot.com/ <http://fettricks.blogspot.com/>
>>>> 
>>>> 
>>>> _______________________________________________
>>>> Triangle, NC Embedded Computing mailing listTriEmbed at triembed.orghttp://mail.triembed.org/mailman/listinfo/triembed_triembed.org <http://mail.triembed.org/mailman/listinfo/triembed_triembed.org>
>>>> TriEmbed web site: http://TriEmbed.org <http://triembed.org/>
>>>> 
>>>> 
>>>> 
>>>> _______________________________________________
>>>> Triangle, NC Embedded Computing mailing list
>>>> TriEmbed at triembed.org <mailto:TriEmbed at triembed.org>
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>>>> TriEmbed web site: http://TriEmbed.org <http://triembed.org/>
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>>>> 
>>> 
>>> 
>>> -- 
>>> A blog about some of my projects.  http://fettricks.blogspot.com/ <http://fettricks.blogspot.com/>
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>>> 
>>> ------------------------------
>>> 
>>> Message: 2
>>> Date: Tue, 23 Jun 2015 18:15:17 -0400
>>> From: Jon Wolfe <jonjwolfe at anibit.com <mailto:jonjwolfe at anibit.com>>
>>> To: TriEmbed Discussion <triembed at triembed.org <mailto:triembed at triembed.org>>
>>> Subject: [TriEmbed] iOS developer needed part-time
>>> Message-ID: <42515d35b99fbe8b0a406aee87154f72 at anibit.com <mailto:42515d35b99fbe8b0a406aee87154f72 at anibit.com>>
>>> Content-Type: text/plain; charset="us-ascii"
>>> 
>>> 
>>> 
>>> This isn't embedded electronics related, so if you aren't into iOS, you
>>> can stop reading now ;) 
>>> 
>>> I alluded to it at the last meeting, but things are starting to
>>> solidify, and it looks like I'm going to need to hire an iOS developer. 
>>> 
>>> If you are interested in some part time or side work developing an
>>> iPhone app. Let me know. It's a pretty straightforward app, a few forms
>>> and menus, that uses REST calls to interact with a server, with possibly
>>> some camera and SMS interaction. There's no graphics programming needed.
>>> I will have the server side component and an Android version developed
>>> in tandem. 
>>> 
>>> I'm still working out a few details, such as rates, timeline, etc, but I
>>> would prefer someone local to RTP that I could meet with on occasion.
>>> You would need to provide your own equipment for development. 
>>> 
>>> Anyways, if you have any interest, contact me. 
>>> 
>>> Now back to your regularly scheduled program :) 
>>> -- 
>>> 
>>> Jon Wolfe
>>> Anibit Technology LLC.
>>> 
>>> https://anibit.com <https://anibit.com/>
>>> 
>>> 
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>>> 
>>> ------------------------------
>>> 
>>> Message: 3
>>> Date: Tue, 23 Jun 2015 21:09:04 -0400
>>> From: Robert Gasiorowski <rgresume at gmail.com <mailto:rgresume at gmail.com>>
>>> To: Jon Wolfe <jonjwolfe at anibit.com <mailto:jonjwolfe at anibit.com>>
>>> Cc: TriEmbed Discussion <triembed at triembed.org <mailto:triembed at triembed.org>>
>>> Subject: Re: [TriEmbed] iOS developer needed part-time
>>> Message-ID:
>>> 	<CAEU50hXPUoEuycAsJKLTe=OoBSHi3i+gJ_UMOKp6a+2H24SucQ at mail.gmail.com <mailto:OoBSHi3i%2BgJ_UMOKp6a%2B2H24SucQ at mail.gmail.com>>
>>> Content-Type: text/plain; charset="utf-8"
>>> 
>>> Have you considered using Ionic/Cordova to develop your mobile apps? You
>>> develop one app and build/deploy to multiple platforms.
>>> 
>>> In any case, I would love to get involved in your project, but I am not
>>> sure I will have enough time to spare.
>>> 
>>> Rob.
>>> 
>>> On Tue, Jun 23, 2015 at 6:15 PM, Jon Wolfe via TriEmbed <
>>> triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>>> 
>>>> 
>>>> 
>>>> This isn't embedded electronics related, so if you aren't into iOS, you
>>>> can stop reading now ;)
>>>> 
>>>> 
>>>> 
>>>> I alluded to it at the last meeting, but things are starting to solidify,
>>>> and it looks like I'm going to need to hire an iOS developer.
>>>> 
>>>> If you are interested in some part time or side work developing an iPhone
>>>> app. Let me know. It's a pretty straightforward app, a few forms and menus,
>>>> that uses REST calls to interact with a server, with possibly some camera
>>>> and SMS interaction. There's no graphics programming needed. I will have
>>>> the server side component and an Android version developed in tandem.
>>>> 
>>>> I'm still working out a few details, such as rates, timeline, etc, but I
>>>> would prefer someone local to RTP that I could meet with on occasion. You
>>>> would need to provide your own equipment for development.
>>>> 
>>>> Anyways, if you have any interest, contact me.
>>>> 
>>>> Now back to your regularly scheduled program :)
>>>> --
>>>> 
>>>> Jon Wolfe
>>>> Anibit Technology LLC.
>>>> https://anibit.com <https://anibit.com/>
>>>> 
>>>> 
>>>> _______________________________________________
>>>> Triangle, NC Embedded Computing mailing list
>>>> TriEmbed at triembed.org <mailto:TriEmbed at triembed.org>
>>>> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org <http://mail.triembed.org/mailman/listinfo/triembed_triembed.org>
>>>> TriEmbed web site: http://TriEmbed.org <http://triembed.org/>
>>>> 
>>>> 
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> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org <http://mail.triembed.org/mailman/listinfo/triembed_triembed.org>
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> 
> -- 
> A blog about some of my projects.  http://fettricks.blogspot.com/ <http://fettricks.blogspot.com/>

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