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Connecting external 5v to the Stellaris LM4F120 demo board

Tim Coddington
Intellectual 440 points

I was unable to find an answer to this question searching the forum....

I want to run the Stellaris lm4f120 demo board from a 5V source, i.e. not powered by USB connection.  There's a VBUS+ connection point near SW1, lower left corner of the board.  Is this a good place to connect my external 5V?

If not, please point me or provide constructive suggestions regarding how I can do this.

Thanks

  • 0
    Guru 117855 points

    You seek both, "constructive suggestion" and a pointer?

    Key here - my belief - is that you not introduce 5V - mistakenly - upon the 3V3 regulated line.  (Monsieur Le Disaster then visits - quickly, destructively...)

    Your VBus+ finding looks good - and my quick review of your board's schematic notes "H23" as a potential entry point.

    Again - suggest/URGE that you ohm-out your proposed, "5V attachment point" prior to any 5V power-up!  Insure that you truly are introducing this 5V into 3V3 Reg's input - not output.  Board markings sometimes are improper - extra caution (as outlined) should safeguard...

  • 0
    TI__Expert 3555 points

    Tim Coddington said:
    There's a VBUS+ connection point near SW1, lower left corner of the board.  Is this a good place to connect my external 5V?

    Hi Tim,

      Yes this is a good location to connect an external 5V and use one of the GND point next to it as well for the supply ground. 

      If you are going to connect the debug usb cable while supplying external 5V, be sure the power switch is set to device so you are not supplying power back into your debug system.

    - Ken