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Original question:

LMK1D1204: CMOS 3.3V Single ended input

LMK1D1204: Vdd 1.8V with 3.3V CMOS Single-Ended Oscillator Input

Ryan Fong
Prodigy 20 points
Part Number: LMK1D1204

Question 1: Can we operate LMK1D1204 with Vdd = 1.8V with LVDS input to IN1_P/N and 3.3V CMOS Single-Ended input to IN2_P?

Question 2: I'm trying to apply the guidance given in the last response to the referenced related question for our situation discussed in question 1 above:

"the requirement for the input swing is stated as VIN_S-E.

You'll need to check the actual input signal and take the VIH and VIL levels from that signal."

Am I correct in interpreting this as take our oscillator output specifications (Voh_min, Vol_max) for the signal going into IN2_P and use those to determine Vth for LMK1D1204 IN2_N? For example, Vth = (Voh_min + Vol_max) / 2?

  • 0
    TI__Genius 12160 points

    Hi Ryan, 

    Yes, you can operate the LMK1D1204 with a LVDS signal to IN0 and 3.3V CMOS at IN1 with VDD = 1.8V. I've provided an example schematic from the datasheet that is similar to your situation. For your second question, your interpretation is correct. Vth is set to be the midway point of Vh and Vl of the CMOS input to the LMK1D1204 so the peak differential voltage between IN1_P and IN1_N doesn't exceed maximum specifications. Let me know if you have any other questions.

    Regards,
    Connor