Part Number: TMS320F28335 Hello everyone. I'm part of a research group and our area is Power Electronics. We decided to incorporate the DSP as a component once we needed access to the XINTF bus to establish communication with an FPGA. In this process we have experienced situations in which the DSP was electrically damaged and we're now trying to figure out what could be the root causes for the issue. 1st Occurrence: The equipment was turned off after a successful test exercise. The C2000 J-Tag programmer was left connected between the PC USB Port and the DSP J-Tag pins. In the following day, when the equipment was turned on, the DSP was no longer working and the 1.8V and 3.3V power inputs were draining more current than normal. The DSP was replaced and the equipment returned to normal operation. We established a new power-off procedure which consisted in disconnecting both, the C2000 J-Tag and the FPGA J-Tag programmers cables. This procedure seemed to work well for some time until we had the 2nd Occurrence. 2nd Occurrence: This situation was similar to the first one. In other words, we turned off after normal operation and, again, the DSP was not working when the equipment was turned on. Of, course, this time the programmers cables were disconnected. Symptoms were also the same, both power inputs drained more current than normal and the DSP was completely dead. Replacement of the DSP solved the problem. As an additional safety measure, although the digital circuit is galvanically isolated from the AC power line, we decided to disconnect the equipment from the power outlet after turned off. Since then, the DSP has been operating well and no further issues have been observed. 3rd Occurrence: The PCA was completely assembled following the same processes and procedures used in the first PCA (reflow soldering). As we started the bring-up procedures, during the first turn-on step, we observed over-current in the 1.8V power input. Disconnection of the power pins from the PCA circuit eliminates the over-current situation and the rest of the board goes back to normal operation. As an additional information that may help: - The DSPs used in the first board are samples provided by Texas. The DSP used in the second board was purchased from an authorized distributor. - Power to the DSP is provided by Texas LDOs (LM1117DT-1.8 and LM1117DT-3.3). No DC-DC converters. - We based our circuit in the reference guide supplied by Texas. We would like to understand: - Is this DSP more sensitive than average components of the same category? - Have you observed similar situations in other implementations using this component? - The electric safety measures we have taken are really necessary? Would you recommend anything different? - As far as the assembly process are there specific precautions, limits that we need to observe in order to avoid esd, thermal or mechanical stress. Thank you all.
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