Good Evening,

I have ventured down a rabbit hole and want to make sure I have properly selected components for a dc-dc buck converter using the AP63205WU chip. Typically, I use an LM7805 for power regulation on my projects, but this particular project has too many integrated WS2812B LEDs which would more than max out the LM7805 and uses a power source that would have to be stepped down too much to use the LM7805 efficiently. Max power draw of just the LEDs (32 in total) is right around 1.6-1.9 amp, so I had to use a different regulator set up than I have used before. I read through the documentation and I think I have this configured appropriately, but wanted to check the parts selection for this circuit before I order boards. The schematic is below as well as component data. I have hyperlinked the product page to each component for ease of review.

I know the remainder of the components on the board will also consume power, but this is used on a barebones Arduino set-up, so the LEDs are easily the biggest power draw and the remaining components are negligible. At any given time, only 1/2 of the LEDs will be illuminated, so I have enough wiggle room in amperage that I can power the rest of the circuitry without issue.

This will be powered with 12-25V Li Ion battery packs (i.e. power tool battery packs).

C42: 35V 10uF
C43: 50V 100nF
C44 and C45: 10V 22uF
L1: 4.7uH 5.5A
U2: AP63205WU



I am certainly not partial to this power regulation set-up and I am open to suggestions. This just looked to be one of the simplest solutions for the amperage I needed.

 

Just Power the LEDs separately with something like this Circuit ...........
With separate Regulators there's less chance of getting Noise into you Micro-Controller.
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Just Power the LEDs separately with something like this Circuit ...........
With separate Regulators there's less chance of getting Noise into you Micro-Controller.
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.
View attachment 312539
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This is fine for simple LEDs, but the WS2812B isn't just a LED, it incorporates a serial interface to variable current RGB drivers. So the part requires a constant voltage supply for the logic to work.

 

Whenever implementing a buck switching supply one needs to be careful of the current pulses reflected back to the source. In this application the current pulses could be up towards a 2A swing. Is C42 going to be OK with that? The self-heating needs to be kept to a reasonable amount. Is C42 alone adequate to prevent the current pulses being thrown back at the source supply? Radiated as EMI to the outside world? You might need an LC filter to reduce the noise reflected to the source.