• TI Thinks Resolved

THVD1452: Transmission Distance

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

  • 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