|
[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]
Paul,
The power on led could be run from any of the outputs. Usually it would run
from the +5V output but the +3.3V output would be ok. The design of
AT/ATX/etc. power supplies require a minimum load to ensure regulation of the
outputs. The AT style needed 1.0A minimum on the +5V line. The +12V, -12V &
-5V lines were regulated by the by the feedback from the +5V line and the
transformer design. The original ATX supplies more or less added the soft
on/off and +3.3V outputs to the AT design. The original spec for ATX called
for a min load of 1.0A @ +5V & 0.3A @ +3.3V. The latest spec for the ATX
supplies specifies a min load of 0.3A for both +5V & +3.3V. The spec is
available from www.formfactors.org (along with the motherboard specs and
various other formfactor specs). I missed the min load on the +3.3V line
earlier. If you only intend to check the outputs to see if a voltage is
present, you can use a switch to provide PS_ON# (the ground to pin 14) to
turn on the supply. After rereading the spec I relized the PS_ON# signal is
supposed to be debounced by the power supply so hooking a switch by itself
should be okay. In addition pin 11 should be tied to Pins 1 & 2 (it's a
voltage sense line for the +3.3V line). The voltages probably won't be right
without the loads but the supply shouldn't be damaged if you run it for 5 -
10 minutes like this. If you intend to power something )i.e. hard drives,
etc.) you need the min loads on the +5V & +3.3V outputs to prevent the supply
from burning out a component & to prevent whatever is attached from burning
out a component.
On Thursday 16 January 2003 23:59, Paul wrote:
> To which pin would you connect the power-on LED?
<snip>
I hope this didn't get too long winded!
Tom
_________________________________________________________________________
Philadelphia Linux Users Group -- http://www.phillylinux.org
Announcements - http://lists.netisland.net/mailman/listinfo/plug-announce
General Discussion -- http://lists.netisland.net/mailman/listinfo/plug
|
|