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Thread: Teensy LC - Additional decoupling if powering via 3V pin?

  1. #1
    Junior Member
    Join Date
    Jul 2018
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    Teensy LC - Additional decoupling if powering via 3V pin?

    Hi all,

    I'm working on putting together a project using a Teensy LC project that is powered via an external 3.3v power supply as it is being paired with an ESP8266 which is beyond the capability of the Kinetis on-chip regulator to power.

    I feel like this is a silly question, but I'm about to order PCB prototypes and would rather by safe than sorry... in this scenario, do I need to add additional decoupling capacitors the 3V3 pins, or should the decoupling already on the Teensy board still be sufficient? Asking since the ESP-WROOM-02 datasheet recommends adding 0.1uF and 10uF at the 3.3v input even though the board schematic on the datasheet shows on-board decoupling capacitors as well.

    Thanks!

  2. #2
    In general, a big capacitor should be placed by the source (regulator) and a smaller one(s) by the load(s) (ESP/Teensy).
    Read the regulator datasheet, and it should say if it needs any external capacitance, and if has a maximum capacitive load. As long as your total capacitance is between these two values all is well.

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