(repost, I don't think the first one went though due to a bad subject
line)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I picked up a couple of NJM2360 DC-DC converter IC's and started
messing around with them over the weekend.  So now I'm confused and did
a google search but can't seem to get the answers I'm looking for, so
back to the piclist well I go . . .

First:  I put the docs (and a couple of pictures) at:

http://jrem.webhop.org/ee

Q1) I been goofing with the app #2, the step down converter, and
although I have ~5v (per the DMM in the pic), I'm not sure exactly how
I got there.  I would think that the R2/R1 divider gives the comparator
the input signal, but the value of R2 is meaningless.  I have 17v
input, and a 22k from pin 5 to ground gave me the 5v out.  Can someone
please advise if I'm on track here or out in the blue?

Q2) What does Rsc do?  I don't have the values listed on the app sheet,
so I used a 1ohm (I have lots of them, they're handy for determining
the ma draw, i.e., put in in series, the voltage drop is the current
draw).  Putting two 1ohm's in parallel didn't affect anything as far as
I can tell.

Q3) What does the value of the inductor do?  I realize that the larger
inductor will have more current when collapsing, but to power a 5v pic,
what's the difference between a 10uh and a 220uh inductor in this
circuit?  I had a couple of values I tried out, and even made one by
wrapping some wire around a steel core, but don't see any difference on
the output.

Q4) What does changing the timing cap (Ct) do to the circuit?  I mean I
can change it and watch the timing change on the scope, but what does
that do to the output?  I'm thinking it changes the input power
requirements or current draw or something . . .

Sorry if this all seems intuitive to you guys or too noobie or
long-winded something, but I like to know how this stuff works and not
just that "it works", if you know what I mean.

Regards, John.



		
__________________________________ 
Do you Yahoo!? 
Meet the all-new My Yahoo! - Try it today! 
http://my.yahoo.com 
 

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist