This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

THVD2450V-EP: Can I Use TPD1E0B04DPL Instead of SMAJ30A with THVD2450VDRCREP?

Tool/software:

In my design with the THVD2450VDRCREP RS-485 transceiver, the datasheet suggests using SMAJ30A for surge protection.

Can I replace the SMAJ30A with TPD1E0B04DPL instead?

Will the TPD1E0B04DPL provide adequate protection in this application?

Any advice or experience on this substitution?

  • The TPD1E0B04DPL clamps to ±3.6 V, which is likely to affect the signals on the RS-485 bus. The SMAJ30A allows signals up to 30 V. You have to choose a component that allows your signals through, and this depends on what the actual voltages on your bus are. (If there is no ground shift between the nodes, then the range will be 0 V…VCC.)

    Also, the protection component must be able to handle the transient voltage that you expect to happen.

  • Hi Mamatha,

    As Clemens pointed out, for the RS485 facing pins (A/B), if you want to try to clamp the voltage then the clamping should occur before the abs max of the pin which those pins support +/-70V. If you're operating/working within let's say 20V common mode range then you would want to clamp above 20V but before 70V. It depends on your system.

    Clamping too early will affect your signal going out like Clemens said. If you clamp at 3.6V and our output signal is 5V then you will clamp the voltage too early (during normal operation).

    -Bobby