A Very Compact Christmas Display - Part 037

RE: A Very Compact Christmas Display - Part 037

mmohit00007 — Thu, 09 Jan 2014 07:51:48 GMT

cool

RE: A Very Compact Christmas Display - Part 037

rodreig89kishore — Sun, 22 Dec 2013 21:47:29 GMT

Nice [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-ce897a58-d56d-429f-b9fc-4bf40354a38f/contentimage_5F00_2516.png:16:16]

RE: A Very Compact Christmas Display - Part 037

DAB — Sun, 22 Dec 2013 20:55:40 GMT

Hi Monte,

When I looked at the datasheet, there was a statement that warned about over voltage on the LEDs.

Evidently you can put a short voltage spike on the line and it will destroy the LED in femtoseconds.

You might try a voltage limit circuit, possibly a zener diode to suck up any short voltage spikes, though it might cause some issues with your timing.

DAB

RE: A Very Compact Christmas Display - Part 037

michaelkellett — Sun, 22 Dec 2013 09:58:19 GMT

I'm interested in your reliability issues - these parts are pretty cheap and it could be that they are just not very good but 0.3% failure rate after a week or so of intermittent use seems very bad (although it wouldn't shock me for the DOA rate). A more reasonable figue would be down between 10 and 100 ppm which would mean that even at the high end you should only have about 1/3 of a dead one.

It might be worth looking at your supply and signal rails very carefully with a reasonable scope while the system is operating - you have a lot of fast switching and plenty of inductance so you may be overvolting parts from time to time - according to exactly how you drive them.