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Thread: Teensy Capacitor Ratings

  1. #1
    Junior Member
    Join Date
    Jun 2019

    Teensy Capacitor Ratings

    Hi there.

    I am in the middle of a project that will use a custom Teensy 3.2 at its core.

    Before I go ahead and get my prototype made and order some parts, I wanted to know what kind of caps are used in stock teensy boards? Looking for information like volrtage rating and tolerances, ideally I'd know the actual parts I want to know so I have a bit more of a chance of getting something that works.

    I did have a little search on here but couldn't find anything.

    Many thanks.

  2. #2
    Senior Member brtaylor's Avatar
    Join Date
    Mar 2016
    Portland, OR
    Here's a link to a Teensy 3.2 reference board clone:

    It has a shared cart on Mouser that you can view. Honesty though, all of the caps are just decoupling capacitors - the tolerances aren't very important and you should know the expected voltages. For my Teensy-based custom boards, I typically just sprinkle 0.1 uF caps at each voltage input and then put a few 2.2 uF to 10 uF caps to create a local power plane. Typically use X7R rated caps in a 0402, 0603, or 0805 package.

  3. #3
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    If you make a custom board which will be powered by USB, keep in mind the USB spec imposes a maximum USB power decoupling capacitance (without special current limiting features) of 10 uF. If you go over this recommendation, you risk startup problems when hot plugging into USB hubs.

    Some sites, particularly Adafruit, throw around recommendations to use very large capacitors across power supplies as a sort of "cure all" for unknown power problems. While this sometimes can help, and probably does get some projects working with the cheap power supplies Adafruit sells, know that the downside to larger capacitance is felt at startup when the available power has to charge the capacitor.

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