The LM2941 series are designed as automotive regulators - they handle
reverse polarity, load dump - take a look at the National web site.

I've been using one in a PIC-based circuit on my sailboat which has an
ancient old gasoline engine - so far so good. It too is a low-dropout
regulator, requiring a hefty low ESR (read tantalum) capacitor - they
recommend 47uf or more - I use 2x47 uf tantalum in parallel.

Larry

At 04:26 PM 1/8/2003 -0500, you wrote:
>At 01:31 PM 1/8/03 -0500, you wrote:
>>To be honest, I don't know. I bought some JW versions as well as some OTP's
>>for an automotive product, but didn't get around to doing anything yet. I
>>think they were designed with automotive functions in mind, but don't know
>>for sure!
>
>They seem to have been, but they also seem to be orphaned chips, with only
>a single member in the family, like the PIC14000.
>
>Automotive supplies have a lot of nasty transients, check the relevant
>standards for the exact requirements, but +/-24V 5 minutes jump start,
>and 125V 200-500ms 10J load dump, and the 300V-80V 1J 320usec inductive
>transients, -100V 1J alternator field decay etc (at each shut off), etc.
>I think the standards are something like ISO 7637 and SAE J1113.
>
>It's not hard to meet them if your circuit just draws a bit of current,
>you just put lots of series impedance and a hefty shunt zener or TVS
>in there. Some regulators like the LM2940 have *some* protection built-in
>but be careful about the output capacitor, they are only stable for
>some values and some ESRs. If your cap is too big, too lousy, too small
>or too *good* you get an oscillator.
>
>Best regards,
>
>Spehro Pefhany --"it's the network..."            "The Journey is the reward"
>speff@interlog.com             Info for manufacturers: http://www.trexon.com
>Embedded software/hardware/analog  Info for designers:  http://www.speff.com
>
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Larry Bradley
Orleans (Ottawa), Ontario, CANADA

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