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mpinner
06-19-2016, 08:47 PM
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

Frank B
06-19-2016, 10:33 PM
Hi, this is the schematic:
https://www.pjrc.com/store/schematic_audio2.gif

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

PaulStoffregen
06-22-2016, 09:48 AM
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.