> Date: Mon, 12 Nov 2007 10:50:33 -0000
> From: "Picbits Sales" <sales@picbits.co.uk>
> Subject: [EE] Interesting Automotive transient/overvoltage regulator
> 	circuit
> To: "Piclist" <piclist@mit.edu>
> Message-ID: <00f901c82519$d9a10e00$0302a8c0@compaq>
> Content-Type: text/plain;	charset="iso-8859-1"
> 
> The recent posts about the overvoltage/transient suppressor discussion
> made me dig up the following link that I found a while ago - looks very
> promising for automotive protection of circuits.
> 
> http://www.automotivedesignline.com/showArticle.jhtml;jsessionid=ZTTET2TKQ
> 1EKUQSNDLPSKHSCJUNN2JVN?articleID=192500568&queryText=load+dump
> 
> Hope this helps
> Dom
> 

Very similar to what I use. You may need the TVS on the output side if the
FET doesn't switch fast enough to catch the really quick spikes. Like the
article says, some impedance (filtering) on the input helps a lot. A vehicle
battery has a very low source impedance and can supply a lot of current. The
scope capture in that article shows a rise time to 27V of around 0.5mS, not,
IMHO, particularly fast.
Cheers
James


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