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Thread: Powering custom Teensy 3.2 from 9v 500ma wall adapter

  1. #1
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    Powering custom Teensy 3.2 from 9v 500ma wall adapter

    I have a custom Teensy design using a MCP1825S-3302E/DB as a power regulator. I have a request from customers to allow the device to be powered from a 9v 500ma wall wart, which is typical for audio gear.

    I searched the forums here but couldn't really find anything. Anyone have any idea how I should drop that 9v down for interfacing with the MCP1825? Should I be looking for a different regulator? Any tips or schematics would be great.

    Rob

  2. #2
    Senior Member Constantin's Avatar
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    All comes down to the power needed. If you need the 500mA that the MCP1825 can allegedly produce (with an ideal PCB layout and so on) then have at least 2 choices:

    1) Find a more suitable voltage regulator that can handle the higher input-output voltage delta (i.e something like the LD 1117 series). Pay attention to heat management though.
    2) A DC-DC switchmode power supply like the Recom ROF-78xx series, which can either take you down to 3.3V directly (if your application can handle the ripple) or 'just' 5VDC and then the MCP1825 can take over.

  3. #3
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    Maybe something like this? Not sure about the caps. Probably have more than I need.

    Click image for larger version. 

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  4. #4
    Senior Member Constantin's Avatar
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    That's certainly one way to do it. However, I wonder if you have the polarities on the power jack reversed. Most jacks are positive on the inside, GND on the outside.

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