Hi All,
I have developed a MCS51 based product with the a 12VAC input. The product is working fine and without any problems.
Now the end-user wants to use the same product in Automobiles that have 12DC or 24VDC Supply.

Now I have placed all the necessary protection for Noise/EMI in the power Supply for industrial applications. Such as inductor based PI filter, decoupling capacitors, Reverse diode for protecting the 7805, catered to heating issues of 7805, etc, etc. And the product is working fine in industrial environment.
But can this product (power supply) really work in Automobiles? This idea of using the product in Automobiles struck the marketing guys after few lots have already been sold. (I hate it when they do this. They want to change the structural design of the Ground Floor when the whole building is complete.)

I have downloaded a pdf file a long time back (about June2006) that has the following header:

DAIMLERCHRYSLER CORPORATION PERFORMANCE STANDARD   NO: PF-9326
Vehicle Engineering
Approved Source List Required: No Change: D
Volume: L Section: 5-l Page: 9326

ELECTRICAL & ELECTROMAGNETIC COMPATIBILITY SPECIFICATIONS FOR ELECTRICAL &
ELECTRONIC MODULES AND MOTORS 
 

I really do know the source where it came from, but it sure does talk about power supply for electronic products in Automobiles. It talks about +100 V for a duration of about 2 milliSeconds and such pulses at repetitive rates.

As of now I am not interested to go for certification for my product (later on I might). I Just want a power supply that can work reliably well in the Automotive world.

Can anybody throw some light on this matter, as to what changes I might need to do in the regular power supplies so that it works in the Automotive world very very reliably.


Thanks for reading the post.
From Kiran V Sutar
Mumbai, INDIA.