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Original question:

TMS320F28069M: Launchpad shuts off immediately after connecting

TMS320F28069M: Launchpad shuts off immediately after connecting

Prashant Mishra
Prodigy 100 points
Part Number: TMS320F28069M


Hello, 

I just damaged another F28069 unfortunately. Mistakenly a jumper wire touched pin 21 and 22. Pin 21 seems to be 5V pin and 22 seems to be GND. I'm still not convinced that such a minor accident could damage the board. But suddenly the board got shut off. Not its behaving the same as in my previous post. (Linked with this one). Is there any way to make this board run again?

Thanks!

  • 0
    TI__Mastermind 45606 points

    Hi Prashant,

    How long did you make the 5V/GND short circuit for? If shunt JP3 was populated when the short occurred I could see it damaging the regulators on the board. Reason being that JP3 completes the connection for the 3.3V --> 5V boost, so the short may stress the 3.3V converter too much.

    Can you check the voltage rails of the F2806x device with a multi-meter (VDDIO / VDD)? Should see 3.3V and 1.8V respectively.

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    Prodigy 100 points

    Thank you for your response Kevin. 

    The short might have been of around 2 seconds. I also checked the voltage. I checked the voltage rails on Pin 21 (5V) and Pin 1(3V) on Lauchpand. The image below shows what happens on both. First plot corresponds to 5V pin and the second corresponds to the 3V pin. 

    Also all three pins , +3.3,+5 and GND are placed at the same point. I am not even confident which one got shorted. I think it was 5V to GND. It was an accident, so I don't know for sure.


    Thank you!

    Regards,
    Prashant

  • 0 in reply to Prashant Mishra
    TI__Mastermind 45606 points

    Hi Prashant,

    Is this waveform of the 3.3V and 5V rails on board power-up? And then you later remove the power cable?

    What voltage do 3.3V and 5V rails get to at the start? And what voltage do they settle at? It's hard for me to tell in the plot, but it looks like the 3.3V rail goes above 3.3V and then settles around 1.8V.

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    Prodigy 100 points

    Hello Kevin, 


    The waveforms correspond to 5V rail and 3.3V rail. It shows what happens when I plug in the board to my computer and power it up. In the entire plot I have not unplugged the board.

    The first plot in the image corresponds to the 5V pin. At the instant of powering up, it gives 5V output but as you see, it suddenly falls down to around 1.8V after a few seconds. It does not remain at 1.8 as well. The plot does not show that clearly, but it keeps falling from 1.8V slowly.

    The second plot (orange) corresponds to the 3.3V pin/rail. At the instant of powering up, it hits around 3.1V and quickly falls to zero. 

    The lower two plots are just the zoomed version of the first two plots. 


    Thanks, and regards, 
    Prashant 

  • 0 in reply to Prashant Mishra
    TI__Mastermind 45606 points

    Hi Prashant,

    Thanks for the further description. Something is clearly wrong, the 5V and 3.3V rails should maintain their respective voltages. Some parts are damaged on the Launchpad, likely the supply ICs. You could try ordering / sampling some replacement ICs and replace them on your board, assuming you have the capabilities to solder them on. Or you will need a new LaunchPad.

    Best,

    Kevin