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THVD8000: Data transmission over an 50KHz AC power line

Miguel Aguirre
Prodigy 60 points
Part Number: THVD8000

Tool/software:

Hello!

We are working on an application were the power line must be a square or sinusoidal wave between 50KHz to 100KHz (under development yet), that is then rectified in the receiver to supply a DC load of 10V 1A.

Since no other cable is available, we need to send and receive data (half duplex is ok) over that high frequency AC power line.

My concern is that the rising and falling edges of the power signal could affect the communications. We were planning to use 5MHz as carrier with a slow transmission rate (about 14400 Bauds will be great)

1- Is it possible to use a THVD8000?

2- If not... Could you please provide us with any suggestions on other devices?

Best regards!

Miguel

  • 0
    TI__Guru 57720 points

    Hi Miguel,

    Miguel Aguirre said:
    We are working on an application were the power line must be a square or sinusoidal wave between 50KHz to 100KHz (under development yet)

    The THVD8000 has a bandpass filter on its receiver, so if you do use the 5MHz carrier frequency then the receiver should be able to filter out the 50khz~100kHz frequencies with it's high pass filter. I believe the lower end of the filter at 5MHz would have a cut off around 2.5MHz for the lower frequency's so the attenuation from the 50Khz~100KHz should be good enough to block it. 

    Miguel Aguirre said:
    My concern is that the rising and falling edges of the power signal could affect the communications. We were planning to use 5MHz as carrier with a slow transmission rate (about 14400 Bauds will be great)

    And yes, using a baud rate of 14400 with a 5MHz carrier frequency should work since you are more than 10x the fundamental frequency of your data. 

    Miguel Aguirre said:
    that is then rectified in the receiver to supply a DC load of 10V 1A.

    The THVD8000 has around a ~25 ohm driver. The impedance of your circuit is about 10 ohms under a 1A load (10V/1A=10ohms). I still suspect the THVD8000 could drive through this load though you may need to use a redriver to ensure it can drive through the load properly. 

    We have 2 design guides on how to use a redriver with THVD8000 here: https://www.ti.com/lit/ug/tiduf48a/tiduf48a.pdf?ts=1727468487733&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FTIDA-010935

    https://www.ti.com/lit/an/slla590/slla590.pdf?ts=1727468653238&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTHVD8000

    Just to verify, what is the max cable length you are trying to support? Using a higher carrier frequency would lower the max distance you can support. 

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 60 points

    Hello Bobby, thanks for your answer... it'll take me a while to analyze everything.

    The cable will be between 1 and 2 meters long, so there shouldn't be any issues regarding reflected waves and parallel impedance.

    Best regards!

    Miguel 

  • 0 in reply to Miguel Aguirre
    TI__Guru 57720 points

    Hi Miguel,

    1~2 meters of cable should definitely be short enough that our device can drive it without worrying about distance attenuating the signal (and reflections being minimal). 

    We do have an evaluation module for the device on the ti store and digikey. You would need 2x of them to test with but if you're interested in prototyping it, I would suggest trying it out with just the THVD8000 (without the redriver) to see if it can drive through your power line loading during max current draw conditions.

    -Bobby