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THVD8000: Coupling Transformer

Brian Wang0928
Genius 14000 points
Part Number: THVD8000

Recently, customer found the transmission line load would need to be compatible with PLC's transformer otherwise the differential signals would be decay and leading to the signal error or doesn't work normally.

In general, the differential signals is delivery though couple transformer and capacitor between Rx and Tx as below diagram. That is ok in application.

When there is a load with low impedance(solar inverter) is added on the transmission line as show below, the signals won't transmitter to the side of the Rx/PLC. the signals will go to low impedance loop. 

 

Here you can find one of the PLC transformers in the market. Customer would like to know if THVD8000 has compatible transformer you can suggest?

HomePlug®_PLC Transformers_磁性元件_網通_產品應用 | 聯寶電子股份有限公司官網 (linkcom.com.tw)

  • 0
    TI__Guru 51882 points

    Hi Brian,

    So if you are driving transformers with a solar inverter on the other side - we do not recommend the THVD8000 alone - it will need an additional line driver to overcome the low impedance loading. Luckily we do have an app note on how to do this (it has part recommendations)  - https://www.ti.com.cn/cn/lit/an/slla590/slla590.pdf?ts=1691425301940 please note that it says AC outlet - but the general architecture is used for both AC Mains and higher voltage solar inverter systems (down to effectively 1 ohm of loading is what was tested) 

    The transformer we recommend is tuned for 125KHz modulation - but if you need a different modulation frequency then a different transformer would need to be chosen. 

    Essentially:

    1. We don't have a rec. transformer for the THVD8000 to drive - you need an additional line driver as THVD8000 follows RS-485 loading limits which is why additional drive strength is necessary 

    2.  We do have a recommended transformer - but its best at 125KHz modulation frequency (in app note description)

    Please let me know if you have any other questions!

    Best,

    Parker Dodson