RGB Lighting with MEGA2560


I am using the MEGA2560 board doing RGB lighting. I use RGB LED strips and it works fine.
I have connected two Strip Lights in series. Each strip light is 2 feet long. Everything works
Please note that I am NOT providing +12VDC to the LED strip lights through the MEGA2560.
The LED strip light get power straight from the +12VDC power supply.

My question is how many of these strip light can I use. What is the capability of the MEGA2560.
It is my understanding that the number of Strip lights is limited to the +12V power supply that
provides power to the Strip lights. And the regulators I have used for the RED, GREEN, BLUE
outputs of the MEGA2560.

Please checkout my circuit design and advise.



The "Absolute Maximum" current rating for the TIP120 is 5 Amps.

Check the current requirement for your LED strips. It may be listed as mA per foot or mA per meter, etc. And check that per-color, because obviously each transistor is only driving 1/3rd of the LEDs.

I would "de-rate" the transistor and maybe try to keep the current to half of that, and you may need heatsinks. A good rule-of-thumb is, if you can hold your finger on the device, it's not overheating. If it's too hot to touch, you may be overheating it and it might burn-up. (Wet your finger before you touch it, just in case it is too hot to touch. :wink: )

If they are getting to hot or if you burn-up your transistors, you can use multiple driver circuits or you can try making a [u]MOSFET driver[/u]. As a rule, you get less of a voltage drop across a MOSFET which means less power dissipation (less heat). But, make sure to use a "logic" MOSFET because a regular MOSFET won't fully turn-on with 5V (and that causes overheating).


Thank you.