• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 33 subscribers
  • Views 2073 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

SN65HVD10 TVS Application

Seishin
Genius 4135 points

Hello,

I have a question about TVS application.

www.ti.com/.../sn65hvd10.pdf

I think that the recommended value of this series resistance is between 10Ω and 20 Ω.

However, my customer uses 100 Ω.

Is there a possibility that cannot communicate normally?

Best regards,
Seishin

  • 0
    TI__Guru 62920 points
    Hi Seishin,

    Yes, 100 Ohms is too large of a series resistance. Since the RS-485 bus should have 120-Ohm termination at both endpoints, the effective bus loading will be 60 Ohms (120 Ohms || 120 Ohms). Having 100 Ohms in series on both lines would cause the transmitted signal to be attenuated by a factor of about 77%. Resistances in the 5 Ohm to 10 Ohm range would be more appropriate.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    Genius 4135 points
    Hello Max,

    Thank you for your prompt reply.

    Understood.

    I'll tell my customer to change the resistance value.

    Thank you very much.
    Seishin