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LMH0002 / RREF resistor

S.Satoshi
Guru 21685 points
Other Parts Discussed in Thread: LMH0002, LMH0302, LMH0303

Hi, Team,

I know that the newer devices like LMH0302 or LMH0303 recommend to use only 750ohm and specify the VSDO with only RREF = 750ohm 1%. However LMH0002 specify the VSDO with RREF = 590ohm 1% in addition to 750ohm. When should the customer need to use 590ohm to set VSDO to 1000mVpp?

Best Regards,

Sonoki

  • 0
    TI__Genius 13475 points

    Sonoki-san

     

    For video applications, the SMPTE standards specify an output voltage swing of 800mV p-p, and to get this level, Rref must be 750Ohms.   There is an older european telecom standard which uses a similar cable, but a slower data rate, and requires a 1000mVp-p output voltage swing - and to achieve this output swing, Rref must be 590Ohms.

    Because the older telecom standard is not used in new equipment any more, with the newer releases, we have not characterized the parts, nor designed them to support a 1000mV p-p swing, so this is not mentioned in the datasheet.

    Mark Sauerwald

     

  • 0 in reply to Mark Sauerwald88474
    Guru 21685 points

    Hi Mark-san,

    Thank you for your quick response. I clearly understand that the 1000mVpp should be used for older telecom standard and so it will not be used for new design from now.

    Best Regards,

    Sonoki