LAUNCHXL-F28379D: Part Hot and Unable to connect

Hi Minhtuan,

Sorry to hear you're having this issue with the board you received.

Was the board working OK sometime before or was it always having this issue? Can you try the below and tell me what happens:

1. Remove JP1, JP2, and JP3 to isolate the USB side from the F2837xD side of the board
2. Plug the USB cable into the LaunchPad.
3. Does Green LED D4 light up?
4. Can you see 'XDS100 Class USB Serial Port (COM#)' when you open Device Manager on your PC?

Best,

Kevin

Hi Kevin,

We are back to the lab and able to follow your suggestions.  Here is the result:

1. Remove JP1, JP2, and JP3 to isolate the USB side from the F2837xD side of the board (Done)
2. Plug the USB cable into the LaunchPad. (PC recognized the board)
3. Does Green LED D4 light up? (Yes)
4. Can you see 'XDS100 Class USB Serial Port (COM#)' when you open Device Manager on your PC? (Yes)

What would be the next thing to check?  

Thanks,

Minhtuan

Hi Minhtuan,

OK this means that the USB / XDS100 side of the board is working as intended. If there's an issue with the board it must be on the F2837xD side.

Do you have a current limiting power supply available? If so it would be good to check if the F2837xD side of the board hits a 500~600mA current limit.

1. Remove JP1, JP2, and JP3 to isolate the USB side from the F2837xD side of the board
2. Connect power supply to 3.3V and GND connections on the F2837xD side
3. Configure current limited power supply to 3.3V and 500~600mA cap
4. Is the current cap being hit?
   1. If so, there must be a bad device or short somewhere on the F2837xD side of the board.
   2. Can discuss next steps after checking this

Best,

Kevin

Hi Kevin,

Thanks for following up with us.  I connected a limited-current power supply to JP1 (3.3V) and JP2 (GND) on the controller's side as you suggested, and set the current limit on power to 500mA.  The result is.

- Without USB connection, current on an external power supply also reached to the limit (500mA), and the F28379D was hot at the moment it was powered up.

- With USB connection, LED D4 was lid up and PC recognized the DXS100.  Current on the external power supply also reached to the limit (500mA), and the F28379D was hot for the first second.  I left it on for a few more seconds, and the temperature was very hot and F28379D was untouchable.

- Power off everything.

What would be your next suggestion, Kevin?

Thank you very much.

Regards,

Minhtuan

Hi Minhtuan,

Thanks for checking this. I assume there are no external connections to GND on the F2837xD board side (i.e. jumpers / connectors), but mentioning just to confirm.

The F2837xD side of the board sounds defective, likely due to a damaged part or a short to GND somewhere. It will likely be time consuming and difficult to narrow down the specific part (or parts) in issue and sufficiently replace them.

I'd suggest you apply for a replacement LaunchPad using the customer returns page below and reference this E2E post in the request:

https://www.ti.com/support-quality/additional-information/customer-returns.html

Best,

Kevin

Hi Kevin,

I will apply for a replacement.  Thanks you very much for your helps.

Regards,

Minhtuan

Hi Minhtuan,

Great, sorry for the inconvenience on receiving a defective board.They get functionally tested after production, so I'm not exactly sure what went wrong.

Once you receive your new board please see the User's Guide linked below. Specifically section 4 "Getting Started With the LAUNCHXL-F28379D" for the demo application and additional operating instructions to make sure it's working as intended.

https://www.ti.com/lit/sprui77

Best,

Kevin