well I'm embarrassed to report I had a resistor on the wrong pin.  It
helps to get the circuit right.  Sorry for wasting bandwidth.



--- jrem <jrem123@yahoo.com> wrote:

> (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
> 



		
__________________________________ 
Do you Yahoo!? 
Yahoo! Mail - Helps protect you from nasty viruses. 
http://promotions.yahoo.com/new_mail
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist