Power LED voltage?

Messiah Khan · 30 Sep 2006 at 00:57

Anyone know the voltage of a power LED on ATX cases? is it 5v or 12v?

Amidar · 30 Sep 2006 at 09:07

The one's i used to replace my Lian-Li's are 5mm 3v.

Day03 · 30 Sep 2006 at 09:21

I would assume that they are just standard 2-3V LEDs

Messiah Khan · 30 Sep 2006 at 10:20

So the the power led headers on the motherboard feed 3 volt then?

Amidar · 30 Sep 2006 at 10:26

Yes it's either 3v or 3.3v.

Messiah Khan · 30 Sep 2006 at 11:34

Ok, cheers.

Dr.EM · 30 Sep 2006 at 12:08

The mobo doesn't exactly supply a voltage, it has a current limiting resistor built in, or possibly a constant current output. The LED takes the voltage it needs (specified as VF in it's specs) and any additional voltage remains accross the mobo current limiter. Providing the mobo output voltage (as measured by a DMM with no LED connected) is higher than the LED VF, there should be no problems (it is possible white, blue or UV LEDs take too much voltage to work, but I expect modern boards accomodate them). The LED outputs on the mobo should be specified as a current which remains constant or varies depending on the LED VF, but not specified as a voltage. LED current should be around 10-20mA.