Raspberry PI2 turns off when hit with a Xenon Flash Light

Raspberry PI2 turns off when hit with a Xenon Flash Light
Posted by soaringmonchi on 08 Feb, 2015 13:20
Hey Dave,

I was taking a photo of my Raspberry PI2 today and it powered off immediately. Interestingly, it was very reliable to reproduce, also from other people on the webs: http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=99042

It would be fantastic to see a blog from you measuring and explaining what is going on there!

Take care,

Pascal

#1 Reply
Posted by ivan747 on 08 Feb, 2015 13:38
Yep, it's being talked about somewhere else on the forum. It's quite amazing and would make for a good video (maybe with a lot of views, Dave!!!). Besides, a RasPi is only $35 US bucks and he has mailbag monday, which is a nice way of trying to convince Dave of what to do.

#2 Reply
Posted by dave_k on 08 Feb, 2015 13:41
Sounds like EMF or some interference from your flash is causing it .. could be hard for someone else to replicate if they don't have your exact flash unit...

#3 Reply
Posted by plazma on 08 Feb, 2015 13:43
In one device I fixed a similar problem. There was a light sensitive flip chip LDO. The LDO was replaced with an encased model and the problem was fixed.

#5 Reply
Posted by soaringmonchi on 08 Feb, 2015 13:55
Sorry guys, I didn't see the other thread.

Apparently it boils down to the SMPS chip being photo-sensitive, but I'm sure it could still be an interesting video about photosensitivity in general and different methods of debugging such issues (including EMI :-)).

#6 Reply
Posted by electr_peter on 08 Feb, 2015 19:42
Quote from: c4757p on 08 Feb, 2015 13:44
The chip appears to be an NCP6343, which is a WLCSP "package" - ie, solder balls stuck to the bottom of a die. The back is translucent...
And typical PCB is translucent as well (to some degree). I have seen cheap cameras to produce the output image with shadow of ball grid and tracks because other side of the PCB was in semi translucent plastic case (not shielded from light).

#7 Reply
Posted by EEVblog on 08 Feb, 2015 23:44
Quote from: soaringmonchi on 08 Feb, 2015 13:55
Sorry guys, I didn't see the other thread.
Apparently it boils down to the SMPS chip being photo-sensitive, but I'm sure it could still be an interesting video about photosensitivity in general and different methods of debugging such issues (including EMI :-)).

Yes, looks like a basic photosensitivity issue. From one photo I saw the chip was a non-encapsulated bare died flip chip or something similar?

#8 Reply
Posted by Stonent on 10 Feb, 2015 14:20
That makes me wonder about FCPGA and FCBGA chips in general.

For much of the late 90s and early 2000s, higher end video cards tended to have a big flip-chip RAMDAC chip on them.

I know flip chip devices are still common but typically they seem to be used when heat transfer is important, so you can't really test them with a flash without risking overheating first.

#9 Reply
Posted by CRCasey on 19 Feb, 2015 02:36
Posted this elsewhere,

But why not use this to explain what would happen with a true EMP both solar or human caused.