Si5345-EVB

Rev. 1.1

5

6. External Reference Input (XA/XB)

An external reference (XTAL) is used in combination with the internal oscillator to produce an ultra-low jitter

reference clock for the DSPLL and for providing a stable reference for the free-run and holdover modes. The

Si5345-EVB can also accommodate an external reference clock instead of a crystal. To evaluate the device with a

REFCLK, C111 and C113 must be populated and the XTAL removed (see Figure 4 below). The REFCLK can then

be supplied to J39 and J40.

Figure 4. External Reference Input Circuit