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Max current output of the MSP432 launchpad

Jonathan Morr6
Prodigy 60 points
Other Parts Discussed in Thread: TPS735

Hi!

I bought myself a nice TFT Display lately and am working on controlling it with the MSP432 launchpad. But before running it, I have a question regarding the power the lauchpad can supply. The datasheet of the Display states that the maximum current consumption of the panel including the backlight is 450 mA (at 3,3V). I've read that the USB 3.0 port, on which the launchpad is (without a hub) directly connected can provide up to 900 mA. In the datasheet of the launchpad is no maximum current defined, but this Thread states that the XDS110-ET can provide up to 500 mA. This figure  of the launchpad datasheet states that the left header is directly connected to the power supply of the XDS110-ET, hence could provide the required 450 mA. I know, this is just a sketch of the schematic, but I couldnt find any other information regarding this. Would you say I can connect the Display to that header safely or are there any power related issues to consider? I would run it  with only half the brightness max possible to make sure all the other peripherals and the CPU get enough current.


Alternatively, there is a 3.3V supply on the XDS110-ET side of the launchpad. I have not measured it yet but is supplying the display from that pin a better option?

Thanks for you answers in advance

Jonathan

  • 0
    Guru 46710 points
    If user's guide says so, then you shall count on it. Thou I would double-check temperature of LDO regulator sourcing 500mA because at 1.7V drop it is lot of heat to dissipate for such an small IC. Reading datasheet of regulator will not hurt either
  • 0 in reply to Ilmars
    Guru 74080 points

    The voltage regulator for generating 3.3V on the MSP-EXP432P401R LaunchPad is a TPS735. It can deliver up to 500mA and it's output current is internally limited. As Ilmars already said, 1.7V @ 500mA is quite much - it depends on the cooling area if this small IC can dissipate all the heat to continuously deliver 500mA and I doubt the LaunchPad is not meant to do so.

    But give it a try - simply connect a load to the 3.3V rail and look if it stays stable over time.

    Dennis

  • 0
    Prodigy 60 points
    Ok thank you guys. I tried it, it works and with half the brightness possible it seems as if everything is running stable.
  • 0 in reply to Jonathan Morr6
    Guru 74080 points
    Half the brightness of the LCD's backlight to stay under the current limitation? Did you measure the current consumption?

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