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TMS320F28388D: Dev Board Issues Rails Shorted

Nathan Hilbish
Prodigy 10 points
Part Number: TMS320F28388D
Other Parts Discussed in Thread: TMDSCNCD28388D

We have a project using the TMDSCNCD28388D Control Card board. We keep having problems and have tracked it down to shorted VDD_3V3 and VDD_1V2 rails. The VDDA_3V3 is not shorted.

The only DIO we are currently using are 15 PWM output signals to drive Infineon 1EDC30I12MHXUMA1 gate driver ICs. 

We have gone through 6 boards, and have not been able to figure out what the issue is. 

I did notice some of the analog inputs max out around 3.8V, but I think the TPD4E001QDBVRQ1 on the DEV board would clamp them to 3.3V. 

The Firmware engineer has noted the board has failed a few times (rails shorted) during or right after flashing. We are using the onboard programmer. 

  • 0
    TI__Mastermind 42195 points

    Are all the boards failing in the same way?

    Please note that the TPD4 device is not designed to clamp over-voltage events, just very small current ESD events. It does provide *some* protection against over-voltage events, but that is not its intended purpose. Other diodes can be used for this purpose. Please note that if you're using an input filter it is best to put the series resistor between the over-voltage diodes and the C2000 device. Any non-zero resistor value will then help ensure that most of the current will be routed through the external diode, not through the internal clamping diode.

    As for failing after flashing. I would ensure that you've removed any hazardous voltage from the system before programming, a lot of these systems have significant capacitance leading to voltage that could damage the board even with the power supplies off. It is possible that the board was not put into a safe state before programming the flash, which leads to the damage. Alternatively there could be EOS events which is slowly damaging the device, then once flash programming occurs these weakened circuits finally fail due to the high currents seen while flash the device.

    Candidly, these system level device failures are typically very difficult to debug and require intimate system knowledge. If it helps your debug I have not seen undamaged TMDSCNCD28388D boards fail during or after flashing.

    Regards,
    Cody