How can I connect nearly 450 LEDs to an arduino without drawing too much current?
First you should consider changing your whole idea so that your LEDs don't draw nearly 10A.

I am assuming that for each segment you have 14-20 LEDs wired in parallel, each with its own current limiting resistor. That is very wasteful.

Instead you should be grouping the LEDs in chains of series LEDs which you then place in parallel.

Assuming you have normal red LEDs with a forward voltage of around 2V and a typical current draw for maximum brightness of 20mA, you can connect them up in chains of, say, 5 LEDs with one current limiting resistor, and power them from 12V not 5V.

3 chains of 5 LEDs (15 LEDs) would be 3x20mA = 60mA per segment. 4 chains of 5 LEDs (20 LEDs) would be 4x20mA = 80mA.

With 08:08 displaying that's 26 segments plus dots. Assuming each segment has 20 LEDs that's a total of 26x4 = 104 chains of 5 LEDs, totalling 520mA.

And then you should do away with the resistors as well, and use constant current LED sinks, such as the TLC59116, which can handle the higher input voltage.

If you don't want to do that, then more transistors will be needed:







simulate this circuit &ndash; Schematic created using CircuitLab

I have only showed 2 digits, 2 segments, 2 chains per segment, and 2 LEDs per chain to save space.

To drive it you need 1 GPIO per segment in one digit and 1 GPIO per digit. So for 4 digits at 7 segments that's 11 GPIO.