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MrOnion's OnionBoard - GP IO/Power PCB (requires CPU board) 
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Congratulations, but let's save the chatter about that for the real thread ;-)

Neat picture! DIY to the core/for life! :-)

Fred.

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Mon May 27, 2013 10:05 pm
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viewtopic.php?f=55&t=2145 < this one, this one!!! :-)

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Mon May 27, 2013 11:04 pm
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I have done some driving with the onionboard and so far it has been working ok. A little setback happened as I used the board with a separate mains power supply at home and overheated the regulator a few times. This is most probably caused by oscillation that is happening because of too small capacitors and/or capacitors being too far from the regulator. The home supply might have given some voltage spikes that drove the regulator insane as I haven't had any problems in the car.

To correct the issue I tweaked the proto pcb a little. I removed the 0.1uF ceramic cap after the regulator and soldered it straight to the regulator legs. I also lied to you a little (blog text) and had an 10uF cap after the reg (datasheet said it should be enough) so I installed a 22uF cap where the ceramic was. If I still get problems 47uF would be the next choice.

So far no more overheating. I also changed the pcb layout so that the caps are near the regulator as possible. This made me use surface mount caps (as Andy already suggested earlier ;)) and rotate the regulator 180 degrees. Also the solder pads for the power supply cables are arranged differently. So no major changes.

Image

So, if any of you power supply wizards see any false magic being practised here please give me a shout ;).

Need to order a few boards soon as I want to make another ECU for the FreeEMS and keep that in the car.


Wed Jun 26, 2013 1:29 pm
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LQFP112 - Up with the play

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Hi MrOnion,

Do you have a list of specific manufacturer's (or distributor's) part numbers for the components you plan on using for the power supply circuitry? Thanks


Thu Jun 27, 2013 4:14 am
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Hi TonyS,

The regulators that I use are:

Micrel MIC29150-5.0BT
http://www.micrel.com/_PDF/mic29150.pdf
or
National LM2940CT-5
http://www.ti.com/lit/ds/symlink/lm2940-n.pdf

10/22uF Tantalum caps are from Vishay:
http://www.vishay.com/docs/40002/293d.pdf
Package is size E, 35V and ESR is about 0.6ohm.

100nF (0.1uF) Ceramics from Murata:
http://psearch.murata.com/capacitor/product/GRM31C5C1E104JA01%23.pdf
Package is 1206, 25V, NP0.

I guess NP0 versions are better for this application than X7R:s?

The polyfuses RXE020/030 are from Tyco and the MOV is a S20K20 from Epcos.


Thu Jun 27, 2013 6:46 pm
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Ok,

Did a final change to the vegetableboard and reorganized the solderpads so molex minifit connectors can be used if desired...

Image

Few boards are now ordered so will see how they look when they arrive... :)


Mon Oct 07, 2013 10:16 pm
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:-o oh oh oh!!! :-) :-D

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n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Mon Oct 07, 2013 11:49 pm
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LQFP144 - On Top Of The Game
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image link is broken :-S


Tue Oct 08, 2013 3:56 am
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works4me

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DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 08, 2013 8:50 am
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LQFP144 - On Top Of The Game
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ok they are all working now? weird?


Tue Oct 08, 2013 1:13 pm
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