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.

  • Resolved

THVD1452: Transmission Distance

Expert 1255 points

Replies: 4

Views: 443

Part Number: THVD1452

Hello,

I have a question about transmission distance of RS-485.

Is there a correlation for the transmission distance and Vcc voltage of THVD1452?
Is the following recognition right?

   Transmission distance(@Vcc=5V) > Transmission distance(@Vcc=3.3V)

Or, is it related to the signal level?


Best Regards,
itabi

  • Genius 10585 points
    Itabi,

    You're right. A higher supply voltage makes the driver of THVD1452 'stronger'. For example, if the resistive load is the same, THVD1452 generates higher output voltage with 5V than that with 3.3V. Please let me know if you have more questions.

    Regards,
    Hao
  • In reply to Hao L:

    Hello Itabi-san,

    Adding on to Hao's comment, you might be interested in this application note that presents some practical results with respect to the THVD1450 transmitting and various rates over different lengths of cabling:

    www.ti.com/.../slla431.pdf

    One thing to note is that while lower-frequency operation tends to be limited by the signal amplitude (by DC losses creased by the series resistance of the cabling), higher-frequency operation tends to be limited by timing concerns (e.g., the jitter that is introduced due to higher-frequency losses in the cabling distorting the signaling waveforms). Increasing the differential signaling amplitude will provide less of a benefit for these higher-speed links compared to the lower-speed ones.

    Best regards,
    Max

  • In reply to Max Robertson:

    Hello Hao-san, Max-san,


    Thank you for your reply.

    Do you have any data of cable length for THVD1452 at Vcc=3.3V?

    We're using SN65HVD35 at present.
    If it was exchanged for THVD1452, can we extend the transmission distance?


    Best Regards,
    itabi

  • Genius 10585 points

    In reply to itabi:

    Itabi-san,

    What's the data rate of your application? THVD1452 has larger typical Vod (2.4V with 54Ohm) than that of SN65HVD35 (2V with 54Ohm). In general it should help extend the transmission distance. But I think it would be better that the side to side comparison is done in the real system. The samples of THVD1452 is available on ti.com. Please let us know if you have more questions.

    Regards,
    Hao

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.