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THVD1400: Require TVS diode protection circuit for THVD1400 or not

Hideki Hayashi1
Genius 10330 points

Part Number: THVD1400
Other Parts Discussed in Thread: ESDS552

HI team,

Customer have a question regarding the TVS diode protection circuit proposed on page 19 of the THVD1400DRLR datasheet.
[Question] Regarding the protection circuit using the recommended TVS diode, would it still be necessary to include the diode in a scenario such as the following?
  • Scenario: Terminal A is connected, but Terminal B is accidentally left disconnected (open).
In such a case, would the TVS diode still be required to provide effective protection?
 
Best regards,
Hayashi
  • 0
    TI__Mastermind 30452 points

    Hi Hayashi,

    A TVS or ESD diode doesn't necessarily apply in this scenario. It helps with quick transients that are present on the A or B lines. Having only a single line connected does not affect the transient performance. THVD1400 and any other RS-485 transceiver will not be damaged in this scenario.

    The act of physically disconnecting the B terminal might cause some transients if a human/machine operator is touching the line. In this case, some level of ESD protection is necessary. THVD1400 already has good ESD protection (12kV IEC contact), but if more is needed I'd recommend the ESDS552. 

    Best,

    Ethan