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TMS320F28334: TMS320F28334 does not start up

Part Number: TMS320F28334

Dear team,

we would need your help to look into the following case where 

The problem description is the following; signal XCLKOUT is missing at any time and they believe that uC has no clock.

They do not have idea what the problem is. It looks that uC is broken.

They produced 4 prototypes, and all are not working where power supplies start up and values are correct.

They tried use external 1.9V oscillator without any progress. They also tried to supply other uC 28335 on the external board from 3.3V and 1.9V. Startup is OK, and board works fine.

They  shared rtg of BGA and picture of system start up with 1,9V, 3,3V and /XRS measured time diagram. (Provided those separately)

Kind regards,

Giuseppe

  • I reviewed the schematic and nothing stood out as wrong. This device has a dedicated XCLKOUT pin, so if the power-supplies are good and there is a valid clock input to the device, you definitely *should* see some activity on the XCLKOUT pin. No code required in the flash. Since you have a 30 MHz crystal, you should see 3.75 MHz output on the XCLKOUT pin (assuming the flash is erased). Do you see a clock on the X1/X2 pins? Also, is the device warm to the touch (which could indicate some kind of shorting).

  • they tried use external 1.9V oscillator without any progress.

    By this, do you mean they disconnected the crystal and instead fed a 1.9v level clock into the X1 pin? Assuming this is what was done, do you have an oscilloscope capture of both the X1 pin and the XCLKOUT pin?

    They also tried to supply other uC 28335 on the external board from 3.3V and 1.9V. Startup is OK, and board works fine.

    By this, I presume what you mean is that the 1.9v & 3.3v generated by the LDO on this board was fed to another board with a 28335 and it worked fine. Assuming this is what you meant, what we know is that the generated voltages are correct, but what we don’t know is that whether those voltages reach the balls under the device correctly.
  • I haven't heard anything and presume this issue is resolved.