What is this page for?
This page contains research into updating the lights boards for MSXV.
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Aesthetics count for points
General Notes from reading
We will likely be using parallel led strings (this is pretty common in lights now days) so we need a good way to deal with this. We want to balance led strings. One example would be if there are leds in parallel and they have a forward voltage of 3.3V, since there is up to 20% variation it could be a huge difference in the voltage needed. Additionally, the lower voltage draws more current than expected compared to the higher voltage string.
In general, if temp goes up, the forward voltage will drop and it will draw a lot more current → we should mount on a common heat sink (I believe this is being done in the current boards)
We can use a current mirror (this is being done in the current boards) for regulating current
We will need over-voltage protection for the current mirror (don’t think this is in place?)
Potential upgrades
Use independent opamps for each string instead of a current mirror, might have extra voltage but the current level should be good. More effective, less efficient, other considerations include needing a FET in a power package and that the switching frequency will be lower
Potential Ideas
https://youtu.be/oFdsiRMZZWk?t=145
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There are some RC filters which delay the "ON" signal sent from power distribution, making the voltage on each of the nodes increase one after the other (you can see on the probes). The NMOS should be on each node but is just on one for illustration. the diode models an LED (which would be technically on another board - space might be constrained so we have separate boards for driver + LEDs)
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Useful Resources
https://www.edn.com/overcome-the-challenges-of-driving-parallel-led-strings/
Relevant Confluence Pages