Subject: Re: Automotive electronics
Date: Sun, 13 Oct 2002 15:40:11 -0700
Organization: XS4ALL Internet BV
NNTP-Posting-Date: 13 Oct 2002 13:37:27 GMT
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Take a look at ST's website. There are some app notes there discussing this
Basically you need to protect every in/output with a transil/tranzorb and
especially the powersupply. I once made a fake-'alarm-activated'-blinklight
with a 555, that literally exploded when I cranked the engine. Just a
reverse polarity protection doesn't work.
Also bear in mind that automotive is not only a harsh environment
electricly, but also mechanically. Low and high temps, vibrations etc. Try
not to use electrolytic capacitors, use automotive temperature range
components, no sockets, pay attention to what your design does in low
battery conditions; especially when using microcontrollers. For example:
I once made a power windows controller that controlled the windows with
relays. The processor held its output high when in reset, and the relays
were activated when the outputs were high.
When the battery was low once, the processor was held in reset state but the
relays became energized, but not all, because of tolerances. Result: windows
that went down uncontrollably. Cure: the relay should be energized when the
output of processor is *low* (it was an AT89C2051)
Also wise to include a watchdog, should the processor go mad.
"Andreas Groell" wrote in message
> 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?