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TPS7A78EVM-011: test set-up

Part Number: TPS7A78EVM-011
Other Parts Discussed in Thread: TPS7A78


we plan to perform some hot-plug and +/-1kV surge tests on TPS7A78EVM.

May you confirm resistors R5 / R6 / R7 are for surve immunity performance improvement?

Should we adjust their values to guarantee a < 2.5A current through AC+/- pins (as for table 6.3 in DS)?

Thanks a lot in advance



  • HI Vincenzo,

    The critical resistor is either R5 or R6. The Values on the EVM are sized to per the maximum clamp voltage of RV1. As you correctly state above, thsi is what ensures that the surge current into the device is kept under 2.5A for a line transient/surge. For Hot Plug, the maximum peak voltage would be much lower so if there is no concern for input line transient or surge, you can use the peak AC Voltage/2.5A to determine the total resistance in the path from C15 to the TPS7A78.

    R7 is there to prevent damaging the device if someone accidently connects a grounded scope to the ouptut while in full-bridge mode. This is definitely not recommended but we acknowledge that it can happen. 

    I hope this answers your question.