hi, a question about current and reading PC PSU spec.
i have 60 meters of led strip i want to fade using PWM. i have the circuit working on small cutouts of this strip. this 60m are devided between 11 PWM pins of arduino mega. (based on my 5Amp rated bench power supply) each meter of leds draw 12v/0.3Amp so each tip120 should handle (60/11)0.3=1.6Amp*
now my question - i want to run it all using an ATX power supply. on the ATX it can handle up to 470W, so my understanding it can handle 470W/12V= 40~ amp but there is spec on the ATX specifing that you can draw up tp 18Amp from 12v. i suspect this from each RAIL/wire. am i correct?
The ATX12V 2.x and EPS12V power supply standards defer to the IEC 60950 standard, which requires that no more than 240 volt-amps be present between any two accessible points. Thus, each wire must be current-limited to no more than 20 A; typical supplies guarantee 18 A without triggering the current limit. Power supplies capable of delivering more than 18 A at 12 V connect wires in groups to two or more current sensors which will shut down the supply if excess current flows. Unlike a fuse or circuit breaker, these limits reset as soon as the overload is removed.