Other Parts Discussed in Thread: LMK5C33216, LMK5B12204
I would like to connect the output of the Analog Devices AD9545 oscillator to the input of the LMK1D2102. I am using 1.8V supplies. The AD9545 can be configured to output differential HCSL levels created from 15 mA current sources driving 50 ohm source termination resistors to ground. The resulting voltage across the 50 ohms resistors is 0 to 0.75V each. This gives a Input common mode voltage (VICM) of 0.375 V and Differential input voltage peak-to-peak (VIN,DIFF(p-p)) of 1.5 Vp-p. These values appear to meet the requirements of the DIFFERENTIAL CLOCK INPUT section of the data sheet but I would like confirmation. The LMK1D2102 data sheet states "Universal inputs accept LVDS, LVPECL, LVCMOS, HCSL and CML signal levels" but there is no example circuit showing HCSL as the input.
If the VICM of 0.375V is considered too low, what is the ideal value when operating the LMK1D2102 at 1.8V? Does the VAC_REF level scale with the VDD level or is it always fixed at 1.25V nominal?
