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Thread: ap7313 voltage regulator on audio board

  1. #1
    Junior Member
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    ap7313 voltage regulator on audio board

    there is a ap7313 voltage regulator on the audio board. what is it for?

    It draws from my teensy 3.2's 3.3v (max 250ma). i hope to use this 3.3v for other things (xbees). what current should i expect the audio portion is using?

    thanks!

    -matt

  2. #2
    Senior Member Frank B's Avatar
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    Hi, this is the schematic:


    And this is the datasheet:
    https://www.pjrc.com/teensy/SGTL5000.pdf

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by mpinner View Post
    there is a ap7313 voltage regulator on the audio board. what is it for?
    The SGTL5000 requires 1.8V power for its internal digital logic circuitry.

    what current should i expect the audio portion is using?
    That depends on whether you use a SD card and/or headphones at high volume.

    As a quick check, I just programmed a Teensy 3.2 with File > Examples > Audio > Synthesis > Guitar, using 96 MHz and all the default settings. Here's some quick current measurements, done by powering the board from a 5V lab bench power supply and reading the current right from the power supply's display (reasonable, but not as accurate as going to the trouble of connecting a multimeter inline).

    40 mA, Just running without any audio shield at all

    56 mA, with the audio shield, no SD card, no headphones

    56 mA, with the audio shield, no SD card, with Bose headphones

    58 mA, with the audio shield, with Sansung 32GB SD card (unused), with Bose headphones

    To check how much the SD card uses, I reprogrammed it with File > Examples > Audio > WavFilePlayer

    61 mA, with the audio shield, with Sansung 32GB SD card, with Bose headphones, default (0.5) volume

    65-91 mA, with the audio shield, with Sansung 32GB SD card, with Bose headphones, max (0.8) volume

    The current probably peaks higher than 91 mA in this last test. I just powered the whole thing from VIN & GND and watched the numbers on my power supply's fairly slow display.

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