LED matrix array sink and source?

Looking at  matth3w instructable https://www.instructables.com/id/LED-Umbrella-with-Arduino/ , as a rough guide line for hardware setup, He is just sourcing the rows with MIC2981 driver but has nothing to sink the current except the arduino.

Should I also use something to sink the current like a ULN2803 or HEF4794 to protect the arduino if all the LEDs in a column are on?

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He actually SAYS he didn't use the MIC2981 !!

It would be MUCH better to drive the thing with decent drivers. The 2981 will do as a source, and the humble ULN 2803 would work well as a sink.

belliedroot (author)  steveastrouk7 years ago
Thanks for your response! I am just getting started with LED matrix arrays, so I am not too familiar with using drivers.

I had questions about matth3w's instructable because of the indepth details and that it revolved around the fact that he was going to use the MIC2981 but just didn't have the part at the moment.

I started to think about how much current would be sunk if all the LEDs were on at the same time and not much protection leading back the the arduino pins.

I thought, If I can do this with one chip, then great, but it looks like I will need more.
belliedroot (author)  belliedroot7 years ago
I hooked up a couple of the ULN2803 for a sink on the columns. Works, no smoke! Now to figure out some code(the hard part for me).
Yes, driving lots of LEDs can cause major headaches !

He points to this though https://www.instructables.com/id/LED-matrix-using-shift-registers/step3/The-control-hardware/ - I missed that on the first look.

lemonie7 years ago

Doesn't his "high-current source driver array" deal with this?

belliedroot (author)  lemonie7 years ago
At first I assumed it would, but I can't figure out from the data sheet to be certain and don't want to fry the arduino. I saw alot of things incorporated a sinking IC. This made me wonder since I plan on using a separated 5v power source for the driver and LEDs, grounding everything back to the arduino.