"Stacked" Power Supplies - any thoughts?

[Don Tillman]

   From: "Stopp,Gene" <gene.stopp at telematics.com>
   Date: Tue, 19 May 1998 15:10:00 -0400

Hey man!

   a VC commutating filter 

I've always wondered... what the hell do these sound like?

   Anyway, I'm looking into my power supply options. The PC motherboard
   will have its own supply. As for the analog side, I can always build one
   from scratch. However, I have a box full of Power-One +5/-5 supplies

   My question is about regulation stability - can this be an issue? 

Yeah.  The "contract" of a power supply is to maintain a constant
voltage between points A and B, and degrade gracefully from that under
stress.  (Since they use feedback loops, and feedback loops need to be
compensated for, one form of degradation is how the unit handles
sudden current transients.)

In your proposed setup, the power supply is no longer providing the
+15V line, it's supplying the difference between that and the +10v
line (which is likely a value you care less about).  So any induced
noise on the +5v or +10v lines will show up on the +15v line.  Given
that you're likely using the +5v line for digital logic, I think this
would be a bad thing.

  -- Don