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AFE031: PLC design without AFE

Raviteja chukkapalli
Prodigy 140 points
Part Number: AFE031

Hi,

I don't get the use of AFE in DC PLC design. (it is also used in the 24 V DC PLC reference  design from TI)

i came across a post saying that AFE is used because it has a DAC and analog filtering , PGA and  power amplifier that can help put out high peak-to-peak PLC signals to the power line.

1)what is meant by "peak- to- peak signals to the power line."?

2) why do i need analog filtering when all AFE does is put my "MODULATED"  data over the power line (master side) and extract "MODULATED" data and give the same to the micro controller (slave side) , clearly is not doing demodulating. (MCU does demodulation, doesn't it?)

3) AFE031 data sheet says it has zero crossing detectors also, but doesn't say what is their use , i doubt why does it need them when demodulation is not happening in AFE?

4) Digital communication in binary level (0,1) is less error prone while decoding is what i think and DAC adds more levels (more than 2 symbols symbols) , how is this profitable? (is this what he meant by saying peak-to-peak in question 1 )

Thanks in advance

  • 0
    TI__Expert 5830 points

    Hello,

    I have answered your questions below in bold.

    1)what is meant by "peak- to- peak signals to the power line."?

    From the TI design, DC Power Line Communication Reference Design,  the AFE031 transmit power amplifier operates from a single-supply in the range of 7V to 24V.  At a maximum output current, a wide output swing provides a 12Vp-p (IOUT=1.5A) capability with 15V supply. This is what "high peak-to-peak PLC signals to the power line" is referring to.

    2) why do i need analog filtering when all AFE does is put my "MODULATED"  data over the power line (master side) and extract "MODULATED" data and give the same to the micro controller (slave side) , clearly is not doing demodulating. (MCU does demodulation, doesn't it?)

    It is true that the MCU implements the demodulation.  The AFE03x devices were designed for e-metering applications which have specific standards.  The filters on board are there to help pass emissions testing such as CISPER 16. 

    3) AFE031 data sheet says it has zero crossing detectors also, but doesn't say what is their use , i doubt why does it need them when demodulation is not happening in AFE?

    The zero crossing block consists of two independent zero crossing detectors.  These components are used for detecting the AC mains signal when crossing zero voltage.  Applications such as power line communcations typically need this type of information or signal to properly synchronize.  Only one zero crossing detector is generally used; however, in two-phase or three-phase applications, multiple zero crossing detectors can be used.

    4) Digital communication in binary level (0,1) is less error prone while decoding is what i think and DAC adds more levels (more than 2 symbols symbols) , how is this profitable? (is this what he meant by saying peak-to-peak in question 1 )

    Digital communication in binary level could be used, however, the data rates are much less that using OFDM communication standard.  

    Best regards,

    Errol Leon

    Texas Instruments

    Precision Op Amp Applications