Hi,

Developing the software that drives a 7 segments LED displays I've noticed that the brightness of the display is a bit dimmed, but let's go in sequence:

1) Every segment of a single digit is connected via a 1K resistor to an I/O pin of the AVR1280 of my Arduino Mega, and the common anode (in my design) is connected directly without any resistor. In this case we have a drive voltage of 5 volts.

2) There are 4 digits in my refrence display

3) Every digit has 5 milliseconds of "persistence", this value is the higher value that allow a good display of all 4 digits without any flapping, longher values do a visible flap effect on my 4 digit display.

Now, with a 10 or 20 milliseconds persistence the single digit is very very more bright but the flap is really annoying.

The question is: if I lower the value of the resistor could I achieve a better brightness without damaging the segments of the LED digit display (always with a 5 milliseconds driving period) ?

Thanks a LOT as usual.

Ciao.

Fabio.

Hi Fabio,
yes, you can increase the current in each segment.
Usually LEDs can handle a current of 20-30mA without problems. In case the current pulse is very short, the current can be higher, but you have to check the display datasheet for this.

Also check on the ATmega1280 datasheet if the pins can supply the current when all the segments are lit.