Quote:
Originally posted by bigben2k
This might be a foolish idea... What if I took the 12V and 5V regulating lines from the PSU, and hooked them up together, passed the MOSFET?
I'll be pondering this today.
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I'd written a fairly long response to this earlier, but due to some BS that Hotmail does, I lost it.
I assume you mean "What if I hook the output sense lines up to the common output power bus of the system?"
I see three big problems with this.
The first and biggest, is whether the PSU's will start up correctly with this kind of setup. The first PSU to come up will be pulling the sense lines of the other PSU's up. Nasty things might happen because of that. I wouldn't even guess what is likely to happen without seeing a schematic of the PSU's.
The second problem would be, that with all of the sense lines tied together at the output bus, all of the PSU's might be trying to regulate that point to a slightly different value. It's quite possible that oscillation would occur as different PSU's alternated outputting more or less power trying to regulate the output to their individual setpoints. You could use an RC so that at high frequency each PSU is sensing its own output and at low frequency each PSU is sensing the output at common bus. This would eliminate the possibility of oscillation at the cost of degrading the systems response to load transients. Added capacitance on the output bus could make up for the degraded transient response, but it would be somewhat costly.
Finally, sensing at the output bus pretty much defeats the load sharing capabilities of the setup. The sense line effectively makes the MOSFET resistance a nonfactor, but you were relying on the MOSFET resistance to ensure sharing of the load.