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Thread: Multiple 3.3v and Gnd connections to PCB

  1. #1

    Multiple 3.3v and Gnd connections to PCB

    Is there any advantage to connecting all of the 3.3v and Gnd connections on the Teensy to the ground and 3.3v planes on a PCB?

  2. #2
    Redundancy maybe. All 3.3v pins are all connected to each other, and not coming from separate voltage regulators.

  3. #3
    Senior Member
    Join Date
    Mar 2013
    Reducing the resistance with multiple connections is always a plus.

  4. #4
    Senior Member Epyon's Avatar
    Join Date
    Apr 2013
    The 3.3V pin below AGND is closest to the LDO. It's best to connect and place components drawing large currents closer to that pin, especially if only using one 3.3V pin. Connecting all GND pins to one low-impedance groundplane on your PCB is almost always a good idea .

  5. #5
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Multiple ground & power connections will lower high frequency noise when the digital signals switch. When a digital pin changes voltage, a high frequency current flows for a brief moment as the stray capacitance of the pin, wires and any other pins or connected parts is changed. Ultimately the current flows through ground wires, which form a loop. The larger the area of the loop, the higher its inductance is. Rapidly changing current through an inductor causes a brief voltage spike. This can be seen as ringing or other artifacts if viewed on a high bandwidth oscilloscope.

    By default most pins on Teensy 3.x are configured with slew rate limiting, which greatly helps reduce high frequency noise and lessen the need for low-inductance ground connections. But some faster signals like SPI and I2S clocks are used without slew rate limiting, because of the impact it has on their speed. Closer and redundant ground connections help most in those cases.

  6. #6
    Thanks everyone for the replies. I needed more room to route the traces, so not using the end pins on the Teensy 3.2 opens up a lot of space. Fortunately the power requirements are quite low. Basically just signal pins.

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