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SN65LVDT101's common voltage

Other Parts Discussed in Thread: SN65LVDT101, SN65LVDS101

Customer use SN65LVDT101 to LVDS buffer, firstly customer use 0V common voltage , and then there is big BER issue , and then they use dc couple and provide 0.18V common voltatge, it is better, just few chips has BER issue.  what range is the common voltage of SN65LVDT101 (LVDS)? which voltage is best common voltage?

 

  • Hello Longchang Chen,

    To answer your question:

    Longchang Chen said:
    what range is the common voltage of SN65LVDT101 (LVDS)?

    I'd like to ask for some information, so that we can help you to find a good solution to this problem.

    Since this device is a buffer, there are two common mode voltages, one on the input side, V_IC and one on the output side, V_OC.

    • Is it correct, that we are talking about V_IC?
    • How big is the differential input voltage V_ID? And how big is V_IB and V_IA in the current setup?
    • Is the input terminated with the correct termination resistor?

    In short, the input voltages should be in the range of 0V to 4V, and therefore the common mode voltage should be in this range too.

    Longchang Chen said:
    Which voltage is best common voltage?

    The best common mode voltage is 1.2V, as specified in TIA/EIA-644. The differential input voltage V_ID should be bigger than +-100mV.

    The following table shows input voltages and the resulting output, this might give you a feeling about the device.

    Please let me know if this answer helps and what voltages are applied in the current setup.

    Best Regards

  • Hi Long,

    The SN65LVDS101 supports a common mode voltage range from 0 to 4-V so I am a bit confused over where the errors are coming from. Could you please provide me with an idea of the circuit design (i.e. termination) as well as waveforms of the input waveform and output waveform during normal operation conditions?