Big LED segment display --> hw suggestions

Hi.

This is update to my last post regarding to LED display.

Shortly:
Am in the process of creating schematics for 7 segment LED display.
The segment of display will have 6 ultra bright LED's per segment and
in the end display will have this format --> 11:11:11

The LED works from 2-2,6V and draws around 20mA

Is there some ready made controller that i can hook up to arduino mega ?
Of course, it should be enough to power all LED's

LED:

Arnix

If you can drive the segments with 5 volts, there are several controllers you could use with multiplexing. Otherwise you need high side digit drivers and open collector segment drivers and software multiplexing, or direct drive.

Hmm. i can connect those 6 LED from one segment, in parallel.
So that the voltage would be around 2.5V for whole segment.
Would this work ?

The device will not be used all the time but,
i have to gave some guarantee that it will work for at least years or two.

Arnix2:
Hmm. i can connect those 6 LED from one segment, in parallel.
So that the voltage would be around 2.5V for whole segment.
Would this work ?

The device will not be used all the time but,
i have to gave some guarantee that it will work for at least years or two.

It will only work properly if the LEDs are cherry picked from the same production batch. That is how the big array designers get away with it. Otherwise the currents and therefore the brightness will be different in each LED. There is no danger of burnout if the current doesn't exceed the maximum allowable for a single LED, but it might look like scat. You could use low value current limiting resistors on each individual LED to balance the load.

6 LED/segment x 20mA/LED = 120mA/Segment, 840mA overall. Lot of current.
Could you instead run the LEDs as 3 pairs of 2 LEDs from 5V sources, and reduce the current to 60mA/Segment, 420mA overall?
Then use a high current sink capable shift register like TPIC6C595 to control the digit.
MultiLED 7 segment.jpg

If they are very efficient LEDs you might not need or want them to run at full rated current/brightness. If not, then you have more design freedom. If you use shift registers, you have to either multiplex digits in software, or direct drive every segment of every digit.

10,000 and 15,000 mcd LEDs are really bright!
I think part of that comes from not having diffused lenses.
Blinding. I have some white ones from Dipmicro.com and MPJA.com, I had to tone them down to 1 or 2mA when used as across the room indicators.