6 Input Clock Selection

The LMK1D1212 can receive either a differential or single-ended clock as input. The default board configuration is for a differential signal at both device inputs. The inputs can be applied through the SMAs, J33, J34 (IN0_P, IN0_N) or J35, J36 (IN1_P, IN1_N). These inputs are AC-coupled to the device. The common-mode voltage is provided by the device on-chip bias generator (V_{AC_REF}) pins or TP2 and TP1.

LMK1D1216: Jumper, J39, can be used to select between the two input clocks. IN0 is selected when J39 connects IN_SEL to GND. IN1 is selected when J39 connects IN_SEL to VDD.

Figure 6-1 Input Clock Selection Layout .