Hi I've got an 8x8 LED matrix driven by the Arduino Mega and 8 74HC595's. There is no resistor between the 74HC595 and the LEDs. I measured the current and they receive ~20mA at peak brightness which is exactly what the data sheet suggests. This is when I have just one LED on in the shift register. …

Help with increasing 8x8 LED Matrix brightness

johnwasser April 30, 2012, 1:57am 2

Perhaps your power supply can't handle the combined current draw? 64 * 20 = 1280 mA = 1.2 A What is your power supply rated for?

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