At 05:00 PM 3/9/2010, Xiaofan Chen wrote:

>I see. If it is pure 50/60Hz AC, another poorman's DC/DC
>converter can be used. Supertex used to make two ICs,
>SR036 and SR037 which use the same mechanism to
>use the AC crossing as the base of switching regulator.
>http://www.futurel.bg/datasheets/4/SR03.pdf
>You can make your own based on discrete components
>as well.

That's interesting - I've been using a very similar circuit in other 
products since 1999 or so.  Mine is done with discrete components and 
the performance is not as good as the Supertex version since I have 
only half-wave AC available instead of full-wave.

I wasn't aware of the Supertex version but I had seen the ST version 
in the early 2000's.  I didn't bother going with any of the 
integrated versions that I saw - the cost for my version was just too 
low (less than $1 in hundreds).

But the capacitive supply I'm using in this particular product was 
chosen for other reasons.

dwayne

-- 
Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

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