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LMH1219: LMH1219: Output not work when 12G fiber input given on IN1

Malav Patel
Prodigy 35 points
Part Number: LMH1219
Other Parts Discussed in Thread: TIDA-00428, LMH1218, USB2ANY

Hello,

We  have configured12G fiber 100-ohm differential input at IN1±(10GbE) channel and 100-ohm differential fiber output OUT1± channel in LMH1219.

We have used reference schematic of "'TIDA-00428'' and also find below screenshot of the our schematic design and setup block diagram.

When we used 6G in the same setup its work fine but when we used 12G at that time video came not came out properly.

We have also tried to override 10GbE with SMPTE video rate using few resisters write through SPI but still video not came out on 12G. 

RAW    FF    05    07    //Enable EQ core
RAW    31    20    30    //Power up OUT0
RAW    33    20    30    //Power up OUT1
RAW    FF    04    07    //Enable lmh1218 core
RAW    3F    04    04    //Override reference rate
RAW    2F    00    C0    //Enable CDR lock to SMPTE rates
RAW    3F    10    10    //Override IN_OUT_SEL pin
RAW    31    03    03    //Select IN1 to OUT0 and OUT1
RAW    3F    08    08    //Override OUT_CTRL
RAW    09    00    20    //Disable independent output control
RAW    1C    08    0C    //If locked OUT0/1 reclocked data else raw data
RAW    0A    0C    0C    //Reset CDR
RAW    0A    00    0C    //Release Reset

Could you tell me what is going wrong? Is it required any update in the schematic design or need to add more registers in the LMH1219 configuration?

Thank You.

MALAV Patel

 

  • 0
    Prodigy 35 points

    Hi all,

    We have read the LMH1219 datasheet and we found that we have to add 4.7uF capacitor when we used PCB equalizer but we have not added this capacitor. So, Do you think that this is the reason to not work on 12G?  

    Thank You.

    Malav Patel

  • 0 in reply to Malav Patel
    TI__Guru* 93670 points

    Hi Malav,

    Yes we need to be AC coupled on the input(either IN) or IN1). Additionally we should be AC coupled as well. Otherwise, this could cause signal integrity and cause the device to not lock. At lower rate, signal degradation may not high to cause a problem.

    Also, please use LMH1219 GUI with your board. You can get a USB2ANY box so GUI can communicate with your board. Then using GUI, you can easily control and set different settings(please note below):

    Regards,,Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 35 points

    Hello Nasser,

    Okay We are adding those AC coupled 4.7 capacitor and check.

    We have also tried to override 10GbE with SMPTE video rate using few resisters write through SPI but still video not came out on 12G.

    So we need LMH1219 programming guide or LMH1219 INIT sequence. So, Could you please sent us?

     Any changes required in the schematic design which I have sent you just above? 

    Thank you.

  • 0 in reply to Malav Patel
    TI__Guru* 93670 points

    Hi Malav,

    Please send me a friend request along with your company email address. These documents are on a secured folder and we need to provide you with access to these documents.

    Regards ,,Nasser