The LMK1D121x inputs can be interfaced with LVDS, LVPECL, LP-HCSL, HCSL, CML, or LVCMOS drivers.

LVDS drivers can be connected to LMK1D121x inputs with DC and AC coupling as shown Figure 9-3 and Figure 9-4, respectively.

Figure 9-3 LVDS Clock Driver Connected to LMK1D121x Input (DC-Coupled)

Figure 9-4 LVDS Clock Driver Connected to LMK1D121x Input (AC-Coupled)

Figure 9-5 shows how to connect LVPECL inputs to the LMK1D121x. The series resistors are required to reduce the LVPECL signal swing if the signal swing is >1.6 V_PP.

Figure 9-5 LVPECL Clock Driver Connected to LMK1D121x Input

Figure 9-6 shows how to couple a LVCMOS clock input to the LMK1D121x directly.

Figure 9-6 1.8-V, 2.5-V, or 3.3-V LVCMOS Clock Driver Connected to LMK1D121x Input

For unused input, TI recommends grounding both input pins (INP, INN) using 1-kΩ resistors.