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Thread: Is a decoupling capacitor necessary for 5v in on the Teensy 4.0?

  1. #1

    Is a decoupling capacitor necessary for 5v in on the Teensy 4.0?

    Hello! I'm working on a project using the Teensy 4.0. I will be powering it via the 5v in port attached to a 5v power bank. The Teensy will be the only thing powered by this powerbank. Is a decoupling(I think that is the right word) necessary on the power supply? Thanks for taking a look at my question!

    I attached an image if I wasn't clear enough. "5IN" is the connection to the powerbank.

    Click image for larger version. 

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  2. #2
    Senior Member
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    there is a 2.2 ufd on the T4 board on that pin - that is probably enough - leave room in your artwork for
    and external 10-22 ufd but you probably won't need it.

  3. #3
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    Best to have a 100nF close to pin 20 of the shifter.

  4. #4
    Sounds good. Thanks a bunch for taking a look and the recommendations!

  5. #5
    Quote Originally Posted by skpang View Post
    Best to have a 100nF close to pin 20 of the shifter.
    I agree. At least look at the data sheet and see what they recommend.

    Also, the 1,000 F cap raises an eyebrow. What are you using for the supply?

    Typically I use a 10 F cap in parallel with a .1 F cap.

    The 10 F will reduce power supply ripple and the .1 F reduces noise. They are two different things.

  6. #6
    Thanks for the reply I didn't know noise and ripple were different things I'll have to check it out. Good call on the little cap. I've added it to my schematic.

    The project powers 1680 WS2812 style LEDs. The 1000uf is on the 5V power line for those. Most guides for WS2812 style LEDs recommend a 1000uf cap on the power supply for the lights. I'm assuming that it's to level out voltage when you rapidly change LED brightness.

    Does that gel with your understanding?

  7. #7
    Quote Originally Posted by MSO View Post
    Thanks for the reply I didn't know noise and ripple were different things I'll have to check it out. Good call on the little cap. I've added it to my schematic.

    The project powers 1680 WS2812 style LEDs. The 1000uf is on the 5V power line for those. Most guides for WS2812 style LEDs recommend a 1000uf cap on the power supply for the lights. I'm assuming that it's to level out voltage when you rapidly change LED brightness.

    Does that gel with your understanding?
    I think it does. We'll let others comment on that. Generally, the stuff Ido doesn't have that kind of loads.

  8. #8
    Awesome. Thanks for weighing in.

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