From: Joseph Legris
X-Mailer: Mozilla 4.77 [en]C-SYMPA (Win95; U)
Subject: Re: Automotive electronics
Date: Fri, 11 Oct 2002 12:15:47 -0400
NNTP-Posting-Date: Fri, 11 Oct 2002 12:09:45 EDT
Organization: Bell Sympatico
Bob Wilson wrote:
> In article , Family.Groell@t-online.de
> >Dear all,
> >I am looking for design tips for automotive controllers like seat
> >controllers, body controllers and automotive electronics in general.
> >How have digital inputs for switches to be designed? Waht kind of
> >protection, reverse polarity, short circuit, open load and so on.
> >How are power supplies to design?
> >How are analog inputs to design?
> >Any references, links and/or tips about this field?
> The 10-year old (but still excellent) Daimler-Benz specs that I got when I
> was working for an associated company in Stuttgart, required (among other
> things) that the load must withstand 1 Joule of energy discharged from both
> a +200V and also a -200V source, dumped onto the load once per second for a
> period of several hours. Somewhat brutal.
> This is pretty simple to rig up, and is all you need to know to make your
> electronics bulletproof.
> Viel Spass!
In Motorola's Application note AN843 - A Review of Transients and Their
Means of Suppression, there is a discussion of automotive issues.
The mother of all transients is the so called "load-dump transient"
which can produce upwards of 10 Joules @ 125 Volts peak in a single
shot. Is it necessary to allow for this or is it already suppressed at
the alternator? Motorola (On Semi) makes a gigantic suppression diode,
the MR2535, which is intended for precisely this application. One would
expect one to be installed in every vehicle at the factory. Is it so?