SI5364 Datasheet, PDF (22/40 Pages) Silicon Laboratories – SONET/SDH PRECISION PORT CARD CLOCK IC

Si5364
capacitor is selected with an appropriate equivalent
series resistance (ESR), the discrete series resistor can
be eliminated. The target RC time constant for this
combination is 15 to 50 µs. The capacitor used in the
Si5364 evaluation board is a 33 µF tantalum capacitor
with an ESR of 0.8 Ω. This gives an RC time constant of
26.4 µs and no discrete resistor is required. (See
Figure 7 on page 15.) The Venkel part number,
TA6R3TCR336KBR, is an example of a capacitor that
meets these specifications.
To get optimal performance from the Si5364 device, the
power supply noise spectrum must comply with the plot
in Figure 13. This plot shows the power supply noise
tolerance mask for the Si5364. The customer should
provide a 3.3 V supply that does not have noise density
in excess of the amount shown in the diagram.
However, the diagram cannot be used as spur criteria
for a power supply that contains single tone noise.
V_n (µV/√Hz)
230
4.5
10 kHz
500 kHz
f
100 Mhz
Figure 13. Power Supply Noise Tolerance Mask
22
Rev. 2.2