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QUIET 5V Converter
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Please be positive and constructive with your questions and comments.

QUIET 5V Converter

by GoremanX on Thu Feb 06, 2020 3:46 pm

I'm building a music player that contains an Arduino Uno with Music Maker shield. My project contains a lithium ion battery pack (14v to 9v depending on remaining charge), a 12v buck/boost converter (to power the separate speaker amp) and a 5v buck converter to power USB-powered Bluetooth accessories and the Uno itself (using the USB jack). I run the 5v converter straight from the battery pack's output, not from the 12v buck/boost converter's output. I've tried a bunch of 5v converters, and I've found that they generate varying amounts of noise in the audio produced by the Music Maker. Some are horrendously bad, while others are noticeable but not awful. Drawing power straight from my Anker desktop USB hub generates absolutely no noise whatsoever in the audio, it's flawless.

Does anyone have suggestions for a small, efficient 5v converter that can run off the battery pack's output and won't generate a ton of noise in the audio?

Incidentally, I tried a bunch of Arduino Uno board, too, and the Adafruit Metro328 has been the quietest by far. No audible noise in the audio from the Music Maker shield at all when hooked up to a good power supply.

GoremanX
 
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Re: QUIET 5V Converter

by GoremanX on Thu Feb 06, 2020 3:52 pm

Forgot to mention, I'll never need to draw more than 1 amp total from this converter, if even half that. 1 amp would give me plenty of overhead.

GoremanX
 
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Re: QUIET 5V Converter

by zener on Sun Feb 09, 2020 3:46 pm

I left this one alone since I didn't have a specific recommended product in mind. Someone might chime in if they know of something in particular, but "low noise switching regulator" is fundamentally a contradiction in terms, but not ultimately impossible. It is a matter of degree of course. When I did this search:

https://search.yahoo.com/search?p=filtering+noise+from+a+switching+regulator&fr=yfp-t&fp=1&toggle=1&cop=mss&ei=UTF-8

There was a ton of great hits. Yeah that's proper grammar... Filtering can get you very far and there are a lot of different approaches to take. Some switcher outputs have a really "sharp" spike - high-frequency component that can be snubbed well with a ferrite type filter. Murata has a ton of little filters. Panasonic does also.

https://www.murata.com/en-us/products/emc/emifil/audio/solution2

An LC filter can help a lot. Another approach is feed the output of the switcher into a linear LDO. Linear regulators can have good noise rejection. You wouldn't have much loss of efficiency with a LDO.

That's all I got. Good luck.

zener
 
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Re: QUIET 5V Converter

by GoremanX on Sun Feb 09, 2020 4:27 pm

I was considering running 6v switched power into this 5v linear regulator to smooth out the power:
https://www.mouser.com/Semiconductors/P ... yuZ1z0wa29

Would such a regulator need a cap before and/or after?

GoremanX
 
Posts: 30
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Re: QUIET 5V Converter

by zener on Sun Feb 09, 2020 6:41 pm

It depends on the specific part and what the manufacturer specifies for it. However sometimes they do, although often it is very small like .1uF. For example the TI data sheet for the LM78xx series regulators states "All characteristics are measured with a 0.33-µF capacitor across the input and a 0.1-µF capacitor across the output." and that is shown in all their circuit examples. Some data sheets say it is only if you need noise rejection. I would personally try some ceramics on the input and output, around 1uF but ultimately I would rely on what the data sheet says about it.

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Re: QUIET 5V Converter

by GoremanX on Sun Feb 09, 2020 7:49 pm

Thank you!

GoremanX
 
Posts: 30
Joined: Sat Jan 04, 2020 6:42 pm

Please be positive and constructive with your questions and comments.