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THS6222: Range extension for RS485

Prayag Sahoo
Expert 5145 points
Part Number: THS6222
Other Parts Discussed in Thread: THVD8000, , THVD1500, THS6232

Tool/software:

Hi Team,

My customer is using THVD8000 and below are the achieved ranges -

                  Test case 1: on CAT6 cable which works for 1.2 Km

                  Test case 2: on Signalling cable (6.2 ohm for 100 meters) which works for 300 meters only

In order to send the data for long distance they want to use THS6222 Line Driver. In Design and Development page of Texas Instruments it is used for Solar Power Line communication.

But, in their application they need to transfer data but, not power and it is not multi node communication. (i.e; node =2)

Please Suggest the suitable Hardware design for our Application.

If there is any other solution please suggest.

  • 0
    Guru 316780 points

    What data rate and distance do you need?

  • 0 in reply to Clemens Ladisch
    TI__Expert 5145 points

    Data rate :  >75 kbps.

    Distance: 1.5 km. (better if   > 1.5 km)

  • 0 in reply to Prayag Sahoo
    Guru 316780 points

    A common limit quoted for RS-485/RS-422 is 1200 m. This assumes 24AWG conductors and a maximum signal loss of 66 % with a 100 Ω termination.

    If you use full duplex signals (i.e., two differential signal pairs, one for each direction), you need a termination resistor only at the receiver. And at very low speeds, you do not need a termination resistor.

    If you use cables with a lower resistance (e.g., 22 or 20 AWG or even lower), you should be able to extend the distance. But note that it is unlikely that you will be able to reach speeds above 75 kbps at high distances.

    All this assumes normal RS-485 transceivers (e.g., THVD1500). Other devices are unlikely to help because what limits you are the distortions caused by the cable resistance/capacitance.

  • 0
    TI__Mastermind 22654 points

    Hello Prayag,

    The THS6222 line driver is not tied or forced to support only a single PLC modulation scheme.  If you find your application requires a more complex modulation scheme, such as FSK, ASK, or OFDM, you may still use THS6222 to drive these line signals.  With your data rate and distance needs, your project may be improved if you consider the THS6232 as well, which can operate on 40V supply.

    You should also know that we observe customers using THS6222 and THS6232 in pairs for parallel output driving, such as two THS6222 devices in parallel to provide greater output current.  You could also use two THS6232 devices in parallel for increased current drive at a higher supply voltage than THS6222.

    There are different ways to meet your distance requirement, I can assist with the line driver circuitry.

    Best,

    Alec