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AFE032 FCC Application schematic

Karthikeyan Sivasambu
Prodigy 100 points
Other Parts Discussed in Thread: AFE032, AFE031, AFE030

I intend to use AFE032 for FCC band PLC Modem system, on a 24V DC line. How similar will the schematic be, having the DC PLC Reference Design for AFE031 as the reference.

Will the line coupling circuits be the same?


Please mention other considerations which has to be accounted for.

  • 0
    TI__Genius 9975 points

    Hello Karthikeyan Sivasambu,

    You can use the same schematic used in the DC PLC Reference Design for AFE031 (http://www.ti.com/tool/TIDA-00067).

    Yes, the line coupling circuits can be the same. You could consider using the series LC filter (600 nH and 470 nF ) recommended in the AFE032 datasheet (pag. 68) if you find that the noise present in the power line where you are transmitting increases your bit error rate.

    Best regards,

    Jose

  • 0 in reply to Jose Duenas
    Prodigy 100 points

    Jose,

    Thankyou for the response.

    Combining the information from AFE032 datasheet and DC PLC Reference Design document, I have come up with the circuits below. Could you please go through this and confirm if it will work for the FCC band (10kHz - 490kHz) application.?

    The inductor L8 (1uH) was not present in the Reference design, but is present in AFE032 datasheet. What is it's function and is it mandatory? If yes, could you please mention other parameters for this inductor (tolerance, max. DC current, DC resistance etc). I have chosen 74479876210 from Wurth for this part.

    Also, could you mention if there are any special considerations for L1, L6 and L7.

    These are my choices:

    L6 - ELJ-FA270JF

    L1, L7 - CBC3225T102KR

    I have had a couple of bad experiences with inductor selection, particularly due to the many other parameters to consider, hence asking for a check. Hope you understand. Thanks.

    Regards,


    Karthikeyan

  • 0 in reply to Karthikeyan Sivasambu
    TI__Genius 9975 points

     

    Hello Karthikeyan,

     

    The schematic looks good. My first suggestions would be to change C28 from 100 pF to 10 nF in order to prevent cutting off your received signal when using high RX_PGA1 gains.

    The inductor L8 (1uH) was not present in the reference design because the 24 VDC power line targeted for such design is fairly clean and well regulated. The purpose of that inductor in an AC power line design is to slow down surge currents that may be injected by the power line into the PLC modem (the main difference is that AC lines have power delivery capabilities that far exceed those of the 24 VDC line considered in the DC PLC Reference Design for AFE031).

    The tolerance of L8 is not a key parameter, its max. DC current and DC resistance are a function of the maximum current you need to inject into the power line and the maximum voltage drop across L8 that your application can withstand.

    The only consideration applicable to L1, L6 and L7 is their AC response. The self resonant frequency of your choices seems adequately high to me.

    Hope this helps and let me now if you have any further questions.

    Best regards,

    Jose

  • 0 in reply to Jose Duenas
    Prodigy 100 points

    Hi Jose,


    Thank you for the detailed response.

    As suggested I will replace C28 with 10nF and remove L8 (as my application is not going be on AC power line).

    Now I can place the order for the parts with relief.! :-)


    Regards,

    Karthikeyan

  • 0 in reply to Jose Duenas
    Intellectual 770 points

    Hi Jose.

    I am also planning to use the AFE030  to implement a simple PLC system sing a 24 volt 60Hz bus connecting 50 animal feed bins.

    The plan is to send out a 1 second "heartbeat" broadcast to all slave nodes to force RTC synchronisation and then scan all 50 nodes within 1 second period to retrieve feed consumptions clocked by opening and closing of the individual animal access gates.

    The 24 volt line is low noise and the protocol does not give rise to collisions  so the use of PC-Lite/G3/Prime seems an overkill option.  I would like to use the PLC as a straightforward MODBUS link where the response comes only from a slave appropriately numbered and the broadcast to all nodes likewise achieved by the appropriate MODBUS address.

    Ultimately I may have to uses the T.I. TMS320CX2000 excellent  modem options but the application is simple and secure and MODBuS RS458 seems a simple connection between the feed management computer and multiple feeder transformer groups.

    I suspect there may be problems in defining the carrier level/modulation  signals and I favour FSK

    Do you have any knowledge of   MODBUS implementation of a PLC ?

    Or major research feeding installations are T.I. LFRFID based after an upgrade three years ago and are proving very reliable in their mainly  American market ( I designed the original system in 1969)

    I apologise if this query breaks in to an inappropriate thread.  I am not fluent in this forum and could not find a clear home for my interest.

    Many thanks,

    Colin  Edinburgh - Scotland.