After a few small scale arduino projects I'm in the preperation of making a LED matrix for a project.
I've done some research and basicly I think the plan is the follow:
From what I understand this will let me turn on the led's one by one.
My question is first of all will these driver array's survice for sinking the current (and are they arduino compatible firstmost)?
And second, I'm looking for an IC to source the current (same way as the ULN2803's sink it) so I could use and external power supply. And correct me if I'm wrong this will make me turn on the matrix per row, thus speeding up up the process and allowing me for brighter light.
Use cd74AC164 instead of 74CH595 as the anode drives of your matrix.
Has 24mA output capability vs just 8mA for HC595.
12 x .02 = 240mA, ULM2803 can handle that. Or, use TPIC6A595 for combined shift register/current sink and cut a couple parts out of the design. Shift data to them just you would HC595.
Hans420:
Not really getting how 24 mA output capability would be enough for the 240mA I need to lilt the row of LEDs?
CrossRoads is saying that the '164 could provide up to 24mA per led. 2 x '164 could provide 20mA for each of the 12 leds in the columns.
Hans420:
Wouldn't a sourcing transistor array (is this a thing?) be the best solution? (incl ext power supply)
Yes, but hard to find and all seem to have quite a large voltage drop. Better to have the transistors on the "sinking" side (the cathode columns). This is what the tpic chips mentioned would provide.
What's the difference? Rotate your matrix by 90 degrees and columns become rows. But its easier to find chips that will allow you to scan by one group of cathodes at a time.
Hans420:
the resistor will then go on the anode* side of the matrix right?
If you are talking about sourcing current for the anodes with the 74hc165 and sinking from the common cathodes with the tpic6b595, then yes, put the series resistors on the '165's outputs.
This is 16x16, build up less for 16x12. Anodes driven by cd74AC164 (24mA outputs), cathodes by TPIC6B595 (150mA outputs). Each column turned on for
(1/30 sec)/# of columns.
Say 2mS for 16 columns for flicker-free operation (2000uS).
Expand as needed.
No, its not as good. Look at the "Absolute Maximum Ratings" page of the data sheets for those 2 chips. You will see that the "AC" version has much higher current ratings compared to the "HC" version.
