i am using a mega 2560 to read 16 analogue 5V proximity sensors every 500ms. if the arduino is powered via usb - everything is fine. if the arduino gets the power from a 12v power supply the voltage converter (next to the power plug) gets really hot - but also the pcb on the other side gets hot.
after a few minutes the arduino stops responding. the proximity sensors use 30mA (average current).
is this a known problem or do i something wrong? in my view the converter is a bit small.
thanks for help.
I suspect your just fighting physics. Your 16 sensors drawing 30ma represents a 480ma current draw from the regulator. Add another 50-80ma for the boards 'overhead' consumption and you are well over 500ma. So 12v input to regulator means a 7 volt voltage drop across the regulator at 500ma means the regulator is dissapating 3.5watts of heat, that's a lot and if the regulator gets hot enough it will automatically shutdown into a protection mode. Your best chance to powering this total load is to find an external power source of 8vdc, then the device would only have to dissapate 1.5 watts of heat and may be able to maintain that.