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Thread: Running the teensy prop shield with 3.7v

  1. #1

    Running the teensy prop shield with 3.7v

    Trying to run a project off of 3.7v instead of 7.4v to save space any advice on picking the right converter w/ regards to current output?

    Running:
    teensy 3.6
    PWN for more 4 or more led's depending
    neopixels (not sure of the setup yet or how many i will be using exactly)
    Blufruit LE SPI
    prop shield w/motion
    (dont need to power the temp sensor or the altimeter. Since i'm running neopixels instead of apa102's i wont be using the led driver i will be using the 2w amp, maybe the flash memory, and the motion sensors.)

    I know the led driver runs 5v...I assume the 2w amp does...if it doesn't does that mean then that the only thing i am running that needs the 5v would be the neopixels? Do i need to run power to 5v on the prop shield if i am not using the led driver and 5v buffers? Or do i still need it for the Amp....

    Need advice, suggestions.

    Grimmdus

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Nov 2012
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    15,709
    Don't connect the battery directly to Teensy's 3.3V power. That's very risky!

    You can probably connect 3.7V to the VIN pin and let the regulator make 3.3V. Just make sure you cut the VUSB-VIN apart, so you don't short 5V power directly onto your battery when the USB cable is connected.

  3. #3
    Thanks for the quick reply, you are always on top of things. I would definitely be connecting via the Vin, sorry i didn't make that clear. Thanks for the reminder on the USB. Running just off of 3.3v from from the teensy how will that affect the 2w amp on the prop shield?... or will it affect it at all?
    Last edited by Grimmdus; 03-20-2017 at 09:59 PM.

  4. #4
    Senior Member Ben's Avatar
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    Jul 2013
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    Germany
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    This is the amp on the prop shield:
    https://www.pjrc.com/store/lm48310.pdf
    it is rated from 2.4V to 5.5V. On page 7 you can see the diagrams for THD+N vs Output Power, it shows about 1W into 4 Ohms and 0.6W into 8 Ohms at 3.6 Volts supply voltage. A little more if you are willing to accept higher levels of distortion due to clipping.

  5. #5
    Thanks Ben just what i needed

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