Arduino mega 2560 Voltage Converter gets hot

Hi,

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.

regards, tom

baseless: Hi,

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.

regards, tom

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.

Lefty

And please just don't use an el-cheapo wall-wart. Invest a little more and get a small regulated power supply. They're not expensive at all. Most of them can also be set to different output voltages and most importantly, they NEVER spit out a higher-than-expected voltage at small loads.

I sugest you to just power it with a power supply 8-9 Volts.In a normal situation to a regulator work fine it need to have in the input a +3 V of the output.(5V +3V = 8V) This way you will still have a linear output 5 V and it generate less heat since the voltage drop on it is less. In my arduino I use a 8 Volts supply and works fine.The heat is less I also think the onboard regulator when working with 12 V is working on a very danger zone because of the heat he generate.This can be checked on datasheet of it ...

Yes, get a decent wallwart and drive the 5V pin directly http://www.dipmicro.com/store/DCA-0510

or the barrel jack with a lower voltage if you can't access the 5V power header due to the shield http://www.dipmicro.com/store/DCA-07510

hi all

thanks a lot. this is what i expected. one last question. why not use the usb-port as a power"supply". is there any advantage in connecting a 8 Volt ps to the separate power port than power the board via usb?

regards, tom

It keeps working when the PC is off. Good enough?

Also you won't have to worry about whether the usb ports actually adhere to the standard and really supply up to 500mA or not. Some small laptops had (and may still have) problems with that. Have you ever wondered why some usb disks come with 2 usb plugs?

i would use a power supply with a usb port delivering 5V/1 or 2 A.