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Powering Tiva C Series with out USB

Dimitrios Pantelis
Prodigy 150 points
Other Parts Discussed in Thread: TM4C123GH6PM

Hello all,

I have a Tiva C series LaunchPad - TM4C123GH6PM. I want to power it with out using any of the two USB ports. After I upload my code, all I need is to give it 3.3 Volt between it's "+3.3V" pin and "GND" pin?

  • 0
    Guru 47900 points

    NO, NO, NO! Don't do that!  (such will likely "kill" the 3V3 regulator - resident - that board)

    Instead - look closely at J3 (2nd header column, top pin).   Note that its labeled VBus - and seeks a 5VDC power input.   That header pin (properly) routes to the input of your 3V3 regulator (expected now to survive) and enables your "avoidance" of either of the 2 USB ports.

    We had the same requirement - I can "first hand" report the success of this method.   Ideally your 5VDC supply should be 300mA (minimum) and w/in ±5% of 5V.

  • 0 in reply to cb1
    Guru 20670 points
    To note that if you kill your 3v3 regulator then you will most likely also kill the MCU next time you plug it through USB as well the programmer/debugger.

    If you use a 5V regulated supply it can also give advantages. This way you get the 2 most common voltages for sensors/ICs/etc, 5V and 3.3V, without having the need for the extra 3.3V regulator.
    I do that all the time with the lauchpads since all MCUs in the launchpad enviroment are 3.3v
  • 0 in reply to Luis Afonso
    Guru 47900 points

    Luis Afonso said:
    without having the need for the extra 3.3V regulator.

    Might some caution accompany that suggestion?   The on-board 3V3 regulator is not especially robust - taxing it further - with "off-board" accessory powering - may not lead to long/safe operation!  

    Yes - it can be used to power (some) other devices/small boards - but attention must be paid to the current/power demands of each added attachment ...