im making my first string of leds using 13 PL9823 RGB leds with integrated chips so i can program them with only one Arduino pin. i already solder them on parallel circuit.
I know from the datasheet that they need 5.5v and 20mA to run properly. Since Arduino only throws 40mA max per pin, im assuming it wont be enough to power the 13 leds right? to my surprise, when i plugged them directly to the 5v pin on the arduino they work fine.
i have some questions
A-Why are they working fine since the arduino’s output is 40mA max? how to calculate how much current i need for the 13 leds?
B-I tried to put a 100oms resistor between the 5v and the leds but it made the leds work wrong, randomly blinking. Are the leds in danger because im not using a resistor?
C-if i want to power them with a 9v Battery, how can i lower the voltage so the leds receive only 5.5volts?
thank you very much!
PL9823 leds Datasheet