SI5315 Datasheet, PDF (41/54 Pages) Silicon Laboratories – Provides jitter attenuation and frequency translation between SONET/PDH and Ethemet

Si5315
8. Power Supply Filtering
This device incorporates an on-chip voltage regulator with excellent PSRR to power the device from a supply
voltage of 1.8, 2.5, or 3.3 V. The device requires minimal supply decoupling and no stringent layout or ground plane
islands. Internal core circuitry is driven from the output of this regulator while I/O circuitry uses the external supply
voltage directly. Table 3, “AC Characteristics” gives the sensitivity of the on-chip oscillator to changes in the supply
voltage. Refer to the Si5315 evaluation board for an example.
The center ground pad under the device must be electrically and thermally connected to the ground plane.
See Figure 26, “Ground Pad Recommended Layout,” on page 50.
System
Power
Supply
(1.8, 2.5, or
3.3 V)
Ferrite
Bead
0.1 uF
C₁ – C₃
1.0 uF
C₄
V_DD
GND &
GND Pad
Si5315
Figure 22. Typical Power Supply Bypass Network
Power Supply Noise to Output Transfer Function
-60
-65
-70
-75
-80
-85
-90
-95
-100
-105
1
10
100
Frequency of Power Supply Noise (kHz)
1000
Figure 23. Fout = 155 MHz with 112 Hz Loop Bandwidth, 100 mVp-p Supply Noise
Rev. 1.0
41