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LMH0384 configuration

William Mair
Prodigy 30 points
Other Parts Discussed in Thread: LMH0384, DS15EA101, LMH0394

Hello

I'm planning to use the LMH0384 to interface to a differential video source. The datasheet shows a typical configuration for a single-ended input, would this be adequate circuitry for use on both input channels for differential signals (with some additional form of termination impedance between the two lines)?

thanks for your help

  • 0
    TI__Expert 5175 points

    Greetings -

    Sorry for the holiday delay in response.  The network shown is for the SMPTE return loss network that is commonly used with coax media.

    If you use the EQ with a differential input, usually that line is terminated in 100 Ohms and then AC coupled to the EQ inputs.  In some applications, the cable is AC coupled and the 100 Ohm is across the inputs to the EQ.  An example of this connection can be seen in the generic DS15EA101 data sheet for reference.  The EQ is AC coupled to its source, as it's inputs provide the bias point.

    John Goldie
    DPS APPS / SVA / www.ti.com

     

  • 0
    TI__Genius 13475 points

    William

    John's reply is correct, but I'd like to add one more thing:

    The LMH0384 deternines how much equalization to apply to the signal by measuring the energy of the signal at the input.   This requires that it make an assumption that the amplitude at the source is a certain value - which is what the SMPTE standards specify - namely 800mV.   If you drive the LMH0384 differentially, you need to make sure that the amplitude of your driver is such that with very short cables, the differential voltage going into the LMH0384 is 800mV,

  • 0 in reply to Mark Sauerwald88474
    Prodigy 60 points

    Hi

    As my query also related to configuration of LMH0384/LMH0394  I am posting in to this Thread only.

    i am using the above parts in our design, i am not using the SPI interface and Connected SPI_EN pin directly to GND.

    i just want to Know In which Mode these devices will operate as Default (SDI/ HD/3G), in datasheet this Information is not mentioned.

    I want to use in HD Mode so please let me know in which mode it will operate or it will automatically selects the Mode depends in Input data??

    Thanks in Advance

    Reddy

  • 0 in reply to ranga reddy
    TI__Expert 4400 points

    The LMH0384 and LMH0394 3G/HD/SD SDI Adaptive Cable Equalizers automatically adapt to the input signal, and will equalize signals with data rates from 125 Mbps to 2.97 Gbps by default.  These equalizers do not need to be configured for a specific data rate.