Question about switching regulators for portables

Discussion in 'General Discussion' started by hazardousracerx, Jul 26, 2019.

  1. hazardousracerx .

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    I'm working on a PS2 portable, still designing the case but already purchasing components.

    I have a quick question about switching regulators for powering the project. I have found the TI PTH08080 modules on digikey, but I already have several UBECs used for RC vehicles to separate the ESC power from the video TX power. Would it be advisable/possible to use one of the UBECs as a replacement for the PS2 7900X on board regulator?

    I want to be able to power a RasPi and the monitor off the same supply and the PTH08080 only puts out 2.25A which isn't quite enough without the RPi giving me undervoltage/undercurrent warnings. Found that out while building a RPi portable using a USB power pack rated to output 2.5A.

    One of the UBECs I have is listed below:
    https://smile.amazon.com/gp/product/B01MUAGOAP/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
     
  2. cheese the tallest memer in town Staff Member . . .

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    Yes, but...

    You'll want to double check the output voltage, and make sure you aren't overloading your UBEC. As long as it's putting out ~5v and it can provide enough amps, you *should* be good...
     
  3. hazardousracerx .

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    Thanks. Ill verify the current capability, but I can confirm it provides 5V from a 2S pack.

    The primary unknowns at this point are the dropout voltage and how much noise it will create during operation. Noise can be countered with some bypass caps and/or an LC filter. If it will still function when the batteries get to 3V per cell then it would be a great replacement for the PTH08080 boards, even though it is slightly more expensive.

    I don't currently have an O-scope to measure noise but I'll run some tests and find out the working voltage range to post here.
     
  4. cheese the tallest memer in town Staff Member . . .

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    You shouldn't have to worry much about noise, both the display and pi have regulators onboard that drop the voltage lower, a bypass cap should be enough.
     
  5. hazardousracerx .

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    Thanks. The UBEC is working fine for the screen and RPi in tests.

    It outputs 5.28V no load and 5.25V under load.
     
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