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LMK00301: Confused with Driving Pins

Part Number: LMK00301
Other Parts Discussed in Thread: LMK01000,

LMK00301 has 10 differential outputs and one single ended output according to the datasheet. While creating the clock tree how many pins are required to pass to the next stage. For example, if it is a differential output (LVPECL) do I need 2 pins to drive say a LMK01000 after it or do I need 1 pin. What is the general rule for all TI parts?

  • Hello Shikhar,

    If the upstream buffer has a differential output and the downstream buffer supports a differential input then the two pins from the differential pair will be used.

    If the upstream buffer has a single-ended output and the downstream buffer supports a single-ended input then one pin will be used.

    If the upstream buffer has a single-ended output and the downstream buffer has differential inputs then in most cases a single-ended input can be used with the unused input pin of the downstream buffer tied to GND, or left floating (depending on the particular device). The single-ended inputs typically have higher swing, for example LVCMOS 3.3 V and may not be directly compatible with the differential input, however it is possible to use some passives to adjust the swing.

    If the upstream buffer has a differential output and the downstream buffer has a single ended input, again it is possible to use a single input from the differential pair to drive the downstream buffer. However, you must be careful to ensure the differential signal can meet the single ended inputs voltage requirement.

    In this particular case since the LMK00301 has differential outputs and the LMK01000 has differential inputs. I would use two input pins from a differential pair.

    Thanks,

    Vibhu

  • Hi Vibhu.

    Thanks for the clarification.

    Regards,

    Shikhar