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Subject: Re: Automotive electronics
Date: Sun, 13 Oct 2002 19:48:18 -0700
Organization: XS4ALL Internet BV
NNTP-Posting-Date: 13 Oct 2002 17:45:32 GMT
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
I would include a reverse polarity protection diode and after that an
overvoltage protection diode. The latter a transzil/tranzorb/plain zener
The first diode must be able to withstand the current the LEDs draw of
For what I know LEDs are not really good at withstanding reverse polarity
conditions, and high voltage spikes will gradually break them down, reducing
life considerably, and that's why you choosed LEDs in the first place for,
for their longlife...
"DaveC" wrote in message
> On Sun, 13 Oct 2002 15:40:11 -0700, Jeroen wrote
> (in message ):
> > Take a look at ST's website. There are some app notes there discussing
> > very subject.
> > Basically you need to protect every in/output with a transil/tranzorb
> > especially the powersupply. I once made a
> > with a 555, that literally exploded when I cranked the engine. Just a
> > reverse polarity protection doesn't work.
> What would be smart design to protect LED brake light? I'm assembling a
> 36-LED array (4 in series w/220 ohm resistor, 9 strings total). Should I
> concerned about protection here?
> Suggestions? (Please give component values or p/n's; I'm no good at
> "correct" components without engineer's input.)
> Note that my return address is corrupted in an attempt to reduce spam. If
> choose to e-mail me, please correct my address as described below.
> Dave Carpenter
> Sound Logic
> Remove the numbers to reply via e-mail
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