The XTAL_IN input can accept a single-ended LVCMOS signal  through an AC coupling capacitor. A general interface diagram is  shown in Figure 2A. The XTAL_OUT pin can be left floating. The  maximum amplitude of the input signal should not exceed 2V and the  input edge rate can be as slow as 10ns. This configuration requires  that the output impedance of the driver (Ro) plus the series  resistance (Rs) equals the tran***ission line impedance. In addition,matched termination at the crystal input will attenuate the signal in  half. This can be done in one of two ways. First, R1 and R2 in parallel  should equal the tran***ission line impedance. For most 50Ω applications, R1 and R2 can be 100Ω. This can also be  accomplished by removing R1 and making R2 50Ω. By overdriving  the crystal oscillator, the device will be functional, but note, the device  performance is guaranteed by using a quartz crystal.