Re: Current Transients -- Choke?

john jardine wrote:
"Joerg" <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:bnIXj.543$mh5.32@xxxxxxxxxxxxxxxxxxxxxxx

blanko wrote:

I am modulating power to a pump (power on and off) and when I am doing
this I am seeing dips in the input voltage to my power regulators
(Vin) on other parts of my board.

What is the best approach to guarantee that my Vin won't dip during
these current transients caused by my pump? I added some larger input
and output capacitors that helped a little but didn't fix the
problem. Should I be adding an inductor/choke to help with this? How
should I be calculating what type of inductor to use?

Thanks in advance for any info!


Yes, an inductor can help. But not really if the on/off cycles are
longer than a few hundred msec. And be careful since inductors generate
nasty spikes upon a load dump.

You can use this tool to see the effect of various sizes of inductors:
http://schmidt-walter.eit.h-da.de/smps_e/hgw_smps_e.html

Just pretend the transformer isn't there. Or throw your circuit onto
LTSpice. Another trick is to tap the heavy motor current off before the
regulators to the other parts of the board.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.


Handy site!.
I'm just sorting a 6V pos earth, to 12V neg earth, switcher design for a
friend who deals in old car radios. Repetitive calcs to home in on a decent
wire size and core are not my area of fun, so was a pleasure to just click
the buttons and see the results. An ETD44 showed in the list (I've piles of
'em :) and it seems I now need a few more turns :(.


Just remember that the old tube 6V car radios used positive as well as negative ground (chassis) depending if they were made for the US or for Europe.
.