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TMS320F280025C: Micro-Controller Heating up - with 3.3V Power Supply

Divya Tarana
Prodigy 50 points
Part Number: TMS320F280025C

Dear All 

I am using On-Board Micro-Controller of C2000 of the given part number, for a BLDC Motor Drive. I haven't populated the Power Section yet. I populated only the shown Resistors and Capacitors on board and connected to 3.3V Power Supply. I verified layout and solder errors. Is there anything I'm missing? What else should I diagnose ?

  • 0
    Prodigy 50 points

    What could be the possible issues that the micro-controller is heating just on the power supply? Can someone please suggest any diagnosis ?

  • +1 in reply to Divya Tarana
    TI__Guru* 80520 points

    Divya,

    The F280025 is a dual rail MCU, with an IO rail(VDDIO) powered to 3.3V and a core rail(VDD) powered to 1.2V nominal.  For the VDD pins we have an internal VREG that will derive the 1.2V automatically from the 3.3V supply.  Only decoupling caps to ground(VSS) are needed on these pins

    From your schematic it looks like the VDD pins are incorrectly connected to the 3.3V bus.  You should just float these pins with the appropriate decap to ground and the 1.2V will get generated automatically.

    This is why the device is getting hot, and likely damaged.  I would recommend replacing the device after you have corrected the schematic.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Prodigy 50 points

    Thank you for the response! I have seen the same after comparing it with the launchpad schematic and understood the mistake. Board is working fine now.  

  • +1 in reply to Divya Tarana
    TI__Guru* 80520 points

    Divya,

    Glad to hear it!  Can I ask if there was anything you identified as potentially confusing or unclear in our documentation that we could improve that would have helped you avoid this?  While we have had devices with internal VREG before and dual rail, this is the first device w/o an enable/disable so wanted to make sure things are clear in the docs.

    Appreciate any feedback you have to offer.

    Best,

    Matthew

  • 0 in reply to MatthewPate
    Prodigy 50 points

    Hi Matthew 

    Since I have referred to Launchpad Schematic of TMS320F280025C and User Manual, a 0-ohm resistor would've helped me to avoid such mistakes easily between VDD Sense Test point and Pins after realizing the mistake in Schematic instead of cutting tracks. Also, VDD nomenclature makes it susceptible to be assumed as 3.3V as VDDIO and VDDA are Input Voltage Pins.