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Thread: Teensy 3.6 and external power: recap

  1. #1

    Teensy 3.6 and external power: recap

    Hi,

    I have read several threads about external power supply of Teensy 3.6, but I have not yet a clear idea on this point.
    My goal is to power externally the Teensy 3.6 and, if necessary, use the USB port to program the Teensy or to debug the sketch. Now the questions are:

    1. Is it better to power Teensy with 5v or 3.3v? I suppose I have to power via the Vin pin, right?
    2. Do I have to cut the trace between VUSB and VIN on the back of Teensy?
    3. I have read that someone have put a capacitor between reset and ground, but why?

    Thank you very much (and sorry for my poor English...)

  2. #2
    Senior Member
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    In order, for anything except very careful battery supplied use running 5.5-3.7 volts into VIN is the most robust way to power a Teensy.

    You don't have to cut the trace, but if you don't you need to come up with your own plan to avoid USB power and your VIN power interacting in bad ways. For example if your VIN is 5.5 volts (by accident or design) you will end up driving 5.5 volts into your computer. If you have the design right, or are very careful to only have only one power source at a time you can leave the link in.
    The Cap to ground is around powering from 3.3V regulators other than the one on board, which appear to have a different ramp up profile that doesn't get the boards cleanly restarting. The cap to reset appears to stabilise things a touch more and allow a clean start.

  3. #3
    Senior Member+ Frank B's Avatar
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    1. VIN 3.6 .. 6 Volt - does not matter.
    2. Yes, cut it.

    Personally, i think, it's more flexible to use a usb-cable (with power only - a charging cable, maybe.) I've cut a cable.

    3. The capacitor is needed in rare cases, when the Teensy does not start properly. In this case, the power-supply has a too slow rising power when switching on.

  4. #4
    Junior Member
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    Quote Originally Posted by Frank B View Post
    3. The capacitor is needed in rare cases, when the Teensy does not start properly. In this case, the power-supply has a too slow rising power when switching on.
    What capacitor value and where is it being connected to on the 3.6? I have a slow rising power supply and it's causing me issues.

    Thanks

  5. #5
    Senior Member PaulStoffregen's Avatar
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    I've committed a fix for the crash on Teensy 3.6 when the power ramps too slowly.

    https://github.com/PaulStoffregen/co...a9dd9e14a0daf0

    Any chance you could give this a try on your Teensy 3.6 with the MIC803 chip disconnected from the reset pin?

  6. #6
    Junior Member
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    In my project I have the problem of starting crash with external power source. I have applied the patch and now it works correctly. No extra electronics needed.

    Thanks Paul!

  7. #7
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    We solved it with hardware.

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