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Damage to isolated JTAG of TMDSCNCD28069MISO while interfacing with TMDSHVMTRINSPIN

Part Number: TMDSCNCD28069MISO
Other Parts Discussed in Thread: TMDSHVMTRINSPIN


While testing on TMDSHVMTRINSPIN development kit using TMDSCNCD28069MISO the Isolated JTAG was damaged.

Before connecting to the Mains, the development kit was connected to a VARIAC and a circuit breaker. The VARIAC was set to 0 VAC before closing the breaker. As soon as the Breaker was closed, the JTAG got damaged.

It appears that the Development kit has not been damaged as the power supply is still working and the Rectifier and IPM are still intact.

My question is how did an isolated Control Card with an isolated JTAG get damaged considering that the USB cable was connected to the Isolated JTAG?

Besides this what other test should I perform on the Development kit to check its integrity before using it again?


Rishabh P.

  • You might take a look at the user's guide of the high voltage kit. The high voltage kit can accept power from the AC Mains/wall power supply, only uses the live and neutral line from the wall supply, the protective earth is unconnected (floating). The power ground is floating from the protective earth ground, all of the ground planes are the same. Hence appropriate caution must be taken and proper isolation requirements must be met before connecting scopes and other test equipment to the board. Isolation transformers must be used when connecting grounded equipment to the high voltage kit.

    So recommend that it's better to use isolation AC source or transformer as power supply for the high voltage kit and connected equipment.