# How does AS1130 132-channel LED driver work?

I was just checking out the AS1130 and I was wondering how you are able to drive a 12x11 array of LEDs using only 12 wires? Could anyone explain this to me?

## 1 Answer

It works by what they wrongly call "Cross plexing", see Figure 24 in the datasheet. An excerpt of this figure is shown here, which demonstrates 3 pins driving 6 LEDs.

What it should really be called is "Charlieplexing".

With Charlieplexing $n$ pins can drive $n^2-n$ LEDs.

So 12 pins can drive $(12*12)-12 = 132$ LEDs.

Wikipedia has a page all about it:

http://en.wikipedia.org/wiki/Charlieplexing

• That is exactly what I was looking for. I kept searching for cross plexing and couldn't find anything. Thanks! – Tarmon Oct 7 '11 at 20:21