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.

ISO1500: ZD for bus protection

Part Number: ISO1500

Hi team,


In 9.2 typical application, bi-directional ZD is placed for bus protection.

Could you recommend what ZD you can recommend  ?


Thank you and best regards,


  • Hi Michiaki,

    Thanks for reaching out.

    The protection diode used on the RS-485 bus is the transient voltage suppressor (TVS) diode. The most commonly used TVS diode for RS-485 bus protection is the SM712 which is delicately designed for RS-485 bus protection. Along with the TVS diode, we recommend you to use 10Ω series resistor on RS-485 bus pins between device pins and the TVS diode. Please see below reference design and its design guide for reference schematic, PCB layout and a detailed EMC test data with various protection devices. Thanks.

    Koteshwar Rao