I have a fairly good understanding of how LED matrices work, and I've worked with them more than several times. However, one thing still puzzles me. According to standard calculation of current draw for a LED hooked to 5V and 220Ohm resistor, it's current it about 20mA. However, hooking the same LED…

Current in LED matrix

CrossRoads April 28, 2014, 11:39pm 11

(5V-2.2V (typical Vf for Red))/220ohm = 12.7mA
What is Vf of the LEDs?

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