Despite my Computer Systems Engineering degree, I haven't played with electronics for over a decade, and I'd like to get back into it.
I have a project idea, and I think I've got all the design leg work done. However before I commit money to this project, I would like a second opinion. My assumption is that I'm completely out of touch and no longer know what I am doing, so please take a look.
I believe the digital parts of the project to mostly be a nonissue. My biggest problem is powering 2048 LEDs that require that I deliver 640W over 5V, so a 128A current draw.
I've written up what I intend to do (and how I came upon the Idea) here.
In short, and in terms of power supply: I intend to have 512 LEDs, each drawing max. 60mA in parallel. Thus a total of 32A @ 5V. I will then connect 4 of these these in series. Thus 32A @ 20V achieving my 640W supply for 2048 LEDs. Thus avoiding DC-DC converters and yet more heat.
I plan to deal with connecting the logic parts of the circuit to the floating grounds using some form of Digital Isolator IC.
I need to ensure that each of the floating 5V power rails stay at 5V. Remember each LED has its own PWM and so current draw will fluctuate very rapidly. After some searching I landed on the idea of using a Zener diode to provide the base current to a power transistors . I need to look at possible transistors. I think I will probably pepper more then one across each rail to keep current and heat (in any one area) down.
Some capacitors would probably also help.
Is this a reasonable solution? Or is there a better way? Should I arrange the circuit differently somehow? e.g. dividing through 40V (8 x 256 LED strips) to keep the current down even further? Can I get 40V from a ATX PSU or will I have to use some other supply?