Arduino Micro and SMT LED Power

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HammerArt
 
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Arduino Micro and SMT LED Power

Post by HammerArt »

I'm using a Arduino Micro powered with 9V power source and would like to power between 7 and 14 "SMT Cool White 5050 LED’S 6500-7000K" off of the 7 PWM pins on the board, 2 lights per pin.

Question1: Is the 1/4 watt 33ohm resistor in my diagram correct? when setup in parallel

Question2: Can I use 2 "SMT Cool White 5050 LED’S 6500-7000K" on each of the 7 available PWM pins?

Question3: Is running the LED's in parallel or series the best choice for this setup?
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led_diagram.jpg
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adafruit_support_bill
 
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Re: Arduino Micro and SMT LED Power

Post by adafruit_support_bill »

That is too much current per pin (40mA max), and too much total current for the processor (50mA max).
You could add a transistor per PWM pin to drive the LEDs. Or you could use a constant-current driver and eliminate the need for the resistors:
http://www.adafruit.com/products/1455
http://www.adafruit.com/products/1429

HammerArt
 
Posts: 13
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Re: Arduino Micro and SMT LED Power

Post by HammerArt »

Thanks, I will go with the breakout board.

Does this mean that each (SMT LED) with the 6 leads on the back will need wiring to all 6 leads? In the tutorials I've seen only one lead is wired on each side. I know the SMT has 3 diodes inside and wondering if I need to treat each diode as regular LED setup. So if the lights are setup in series off the breakout board does each SMT account for 3 lights?

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adafruit_support_bill
 
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Re: Arduino Micro and SMT LED Power

Post by adafruit_support_bill »

The wearables tutorials only use 1 of the leds because 3 would be blindingly bright. But you can treat them as 3 identical leds, side-by-side. You can wire them in series and power from 1 channel of the driver breakout (you would need about 7.5v min).

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