SI5347-EVB Datasheet, PDF (6/21 Pages) Silicon Laboratories – Powered from USB port or external

Si5347-EVB
6. External Reference Input (XA/XB)
An external timing reference (48 MHz 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 Si5347-EVB can also accommodate an external reference clock instead of a crystal. To evaluate the
device with an external REFCLK, C111 and C113 must be populated and XTAL Y1 removed (see Figure 4 below).
The REFCLK can then be applied to SMA connectors J39 and J40.
Figure 4. External Reference Input Circuit
6
Rev. 1.1