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Thread: Teensy 3.6 linear regulator problem

  1. #1
    Junior Member
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    Teensy 3.6 linear regulator problem

    Hello,

    Here is the thing :

    As said in the title, i have a teensy 3.6 witch i use to generate PWM signal.
    The teensy is on a PCB which is alimented in 12V DC but there is a regulator that send 5V to my teensy.
    The pwm signal is for a LED driver that delivers current between 0 and 1 A.

    here is a photo of the PCB and an electrical diagram
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    Problem is that i accidentaly shorted the LED + (bottom right) pin that is the out of the driver and the teensy immediatly stopped working.
    Further investigation seems to indicate that teensy's regulator is done for.

    I need to know two things :

    1 - Is there a way to make the teensy work without the regulator?
    2 - as I really can't find it anywhere, does anyone know where to find/ have the datasheet for thee regulator?

    Bonus : might my teensy just be completely dead and the only thing i can do is buy another one ?

    Thank you in advance for your help :)

  2. #2
    Senior Member PaulStoffregen's Avatar
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    First the easy question. You can get the regulator's datasheet here:

    http://www.ti.com/product/LP38691

    If the problem is only the regulator, and it's not failed in a way that drags down the 3.3V line, you could just apply external 3.3V power.

    If any digital or analog pin on the Teensy 3.6 accidentally touched 12V, even for a brief moment, the whole board is dead. 12V kills the chip pretty much instantly.

  3. #3
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    Thank you for the quick answer,
    Quote Originally Posted by PaulStoffregen View Post
    First the easy question. You can get the regulator's datasheet here:

    If the problem is only the regulator, and it's not failed in a way that drags down the 3.3V line, you could just apply external 3.3V power.
    Do you mean that 3.3V should be applied to the Vin pin insteead of the 5V i'm / I was feeding it ?

    Quote Originally Posted by PaulStoffregen View Post
    If any digital or analog pin on the Teensy 3.6 accidentally touched 12V, even for a brief moment, the whole board is dead. 12V kills the chip pretty much instantly.
    Well that might very well be the case though I have yet to understand how it happend.

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by lathyk View Post
    Do you mean that 3.3V should be applied to the Vin pin insteead of the 5V i'm / I was feeding it ?
    No. If you believe the regulator is damaged, but the rest of the board may be ok, you can try applying 3.3V directly to the 3.3V pin without anything connected to the VIN pin.

    But it's pretty rare for the regulator on Teensy 3.6 to fail this way. The odds of this working are slim, but if you have any other power supply with regulated 3.3V it's quick and easy to try.

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