Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wasatch!cs.utexas.edu!uunet!ncrlnk!ncrwat!swdev!tp2!howard
From: howard@tp2.Waterloo.NCR.COM (Howard F. Steel)
Newsgroups: sci.electronics
Subject: Re: want help with power supply
Message-ID: <425@tp2.Waterloo.NCR.COM>
Date: 6 Jul 89 12:16:37 GMT
References: <113785@sun.Eng.Sun.COM>
Reply-To: howard@tp2.UUCP (Howard F. Steel)
Organization: NCR Canada Ltd, Waterloo, Ontario, Canada.
Lines: 47


In article <113785@sun.Eng.Sun.COM> rom@xor.Sun.COM (Achyutram Bhamidipaty)
writes:

>The power supply has the following connectors on it:
>
>label	my guess on its purpose
>pf	????

Power Fail signal; usually an active low signal that gives you a few msec
warning that the supply has dropped below a specific level. Allows your
processor time to clean-house before the power actually is gone.

>+s1	??
>-s1	???
>+s2	???
>-s2	???
>So the question: what are the sn and pf connections?

+/-s is the Sense Line. The + side is connected to the load at the same place
as the + side of the V out that corresponds to it and likewise for the -s;
like so:

------------			   	  -------------
Power	   |				  |
Supply	   -s2--------------------------\ |  LOAD
	   |				 |-
	   -V2__________________________/ |
	   |				  |
	   +s2--------------------------\ |
	   |				 |-
	   -V2__________________________/ |
___________|				  |____________

The sense line lets the power supply compensate for line losses by comparing
the voltage at the load to the output voltage. If the the load is heavy
the voltage drop in the lines leading to it could be significant and result in
low voltage situations. If the sense lines are not going to be used (if for 
example your load is small in comparison to the rated output of the supply,
or you don't particularly care if the voltage drops a bit with varying loads)
then connect the -sn terminal directly to the -Vn terminal at the power supply
(same for the + lines). Don't operate the supply with terminating the sense
lines.

-- 
Howard.Steel@Waterloo.NCR.COM  :-(  	I Think, Therefore I AM,
aka: Howard "The Duck" Steel   :-) 		I think