X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com X-TCPREMOTEIP: 173.48.170.224 X-Authenticated-UID: jpd AT noqsi DOT com From: John Doty Content-Type: multipart/alternative; boundary="Apple-Mail=_DC79CAF5-54AF-46B4-B7E6-3A90F4D57BE0" Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [geda-user] [off-topic] 24V automotive (truck) design issues Date: Mon, 26 Nov 2018 11:56:15 -0500 References: To: geda-user AT delorie DOT com In-Reply-To: Message-Id: X-Mailer: Apple Mail (2.3273) Reply-To: geda-user AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: geda-user AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk --Apple-Mail=_DC79CAF5-54AF-46B4-B7E6-3A90F4D57BE0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Lots of info out there, google "load dump protection=E2=80=9D. > On Nov 26, 2018, at 10:58 AM, Richard Rasker (rasker AT linetec DOT nl) [via = geda-user AT delorie DOT com] wrote: >=20 > Hello, >=20 > Apologies for this off-topic question, but I found that quite a few = people here have a lot of expertise in specialized electronics subjects. >=20 > My issue: I was asked to build a relatively simple LED lighting = application for use in trucks (24V). >=20 > I built a handful of prototype boards for testing, based on an = LMR14206 step-down device (see attachment), and while these work = perfectly fine on the workbench, even up to 50 volts, I had already two = failing when testing on an actual truck for several days. >=20 > I suspect that voltage spikes may be the cause, maybe in conjunction = with lack of a sufficiently large buffer capacitor on the input. But not = having much experience in the area of automotive-quality design, I don't = really know what to expect and how to handle this -- I did use a TVS = suppressor diode, but perhaps I should take some extra measures, like a = large cap across the supply input. >=20 > =46rom what I can find on the Internet, it would appear that the 24V = supply may have spikes of up to 200 volts, which of course can wreak = havoc with anything designed for a few dozen volts max. >=20 > Any thought on this? Or could someone point me to design guidelines, = or perhaps example schematics of actual electronic devices for = applications like this? No doubt, there must be pertinent information = out there, but I have trouble locating it. >=20 >=20 > Thanks in advance, >=20 >=20 > Best regards, >=20 > Richard Rasker > John Doty Noqsi Aerospace, Ltd. jpd AT noqsi DOT com --Apple-Mail=_DC79CAF5-54AF-46B4-B7E6-3A90F4D57BE0 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Lots of info out there, google "load dump protection=E2=80=9D.<= div class=3D"">

On Nov 26, 2018, at 10:58 AM, Richard Rasker = (rasker AT linetec DOT nl) = [via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:

Hello,

Apologies for this = off-topic question, but I found that quite a few people here have a lot = of expertise in specialized electronics subjects.

My issue: I was asked to build a relatively simple LED = lighting application for use in trucks (24V).

I built a handful of prototype boards for testing, based on = an LMR14206 step-down device (see attachment), and while these work = perfectly fine on the workbench, even up to 50 volts, I had already two = failing when testing on an actual truck for several days.

I suspect that voltage spikes may be the = cause, maybe in conjunction with lack of a sufficiently large buffer = capacitor on the input. But not having much experience in the area of = automotive-quality design, I don't really know what to expect and how to = handle this -- I did use a TVS suppressor diode, but perhaps I should = take some extra measures, like a large cap across the supply input.

=46rom what I can find on the Internet, it = would appear that the 24V supply may have spikes of up to 200 volts, = which of course can wreak havoc with anything designed for a few dozen = volts max.

Any thought on this? Or could = someone point me to design guidelines, or perhaps example schematics of = actual electronic devices for applications like this? No doubt, there = must be pertinent information out there, but I have trouble locating = it.

Thanks in advance,

Best regards,

Richard Rasker
<GL_MA= N_M.png>

John Doty = Noqsi = Aerospace, Ltd.

jpd AT noqsi DOT com

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