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softerhardware / Hermes-Lite

Deprecated project!!! See Hermes-Lite2 at main web site
http://www.hermeslite.com
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Hardware: Better power supply #48

Open softerhardware opened 9 years ago

softerhardware commented 9 years ago

The current v1.2 series has a very open power supply interface. Ideally, I'd like one 12-13.8V input and then have low noise switching regulation down to 5 and 3.3V. I've read some articles about using switching power supplies with high-speed ADC and the trick is to design a good filter. See this and this. Such a power supply would be included on v2.0 but could be easily prototyped, tested and used with v1.2.

AC9HY commented 9 years ago

Need some parameters, Steve

  1. What is the foreseeable 5V current demand?
  2. For 3.3V, how much current? Not much, I guess.

Thought are to build a small swizzle board with some regulators similar to LT3470, and run it from a single 12-14v source. May include a PCB mounted circuit breaker. Should we regulate the 12V rail also? Re-purposed laptop power supplies usually run 19-20V at a solid 2-3 amps. 12v regulation would need to be optional, since most shacks provide 12v or 13.8V.

John - AC9HY

AC9HY commented 9 years ago

I like this one better - efficiency is real good and the cost is $.70 at Digikey.

AOZ1280

http://aosmd.com/res/data_sheets/AOZ1280CI.pdf

AC9HY commented 9 years ago

What ripple spec should I design for?

softerhardware commented 9 years ago

Thanks John for looking at this. You parts look like good possibilities. I have no ripple spec in mind. I would check the AD9866 datasheet and look around at what others or doing. The Hermes and HiQSDR groups may have some good feedback. I was expecting it would take 3-4 experimental tries with different regulators and configurations to find something with low noise. Take a look at the two links in the original issue post. Also, measure the current on your Hermes-Lite to get a feel for the final requirements.