Si53xx-RM
Rev. 0.52
119
In some applications, a crystal with frequencies other than 114.285 MHz may be used. See “AN591: Crystal
Selection for the Si5315, Si5317, and other Si53xx Any-Frequency Jitter Attenuating Clocks” for details and a
current list of crystal vendors and approved part numbers.
External reference (and crystal) frequency values should be avoided that result in an output frequency that is an
integer or near integer multiple of the reference frequency. See Appendix B on page 121 for details.
Because the crystal is used as a jitter reference, rapid changes of the crystal temperature can temporarily disturb
the output phase and frequency. For example, it is recommended that the crystal not be placed close to a fan that
is being turned off and on. If a situation such as this is unavoidable, the crystal should be thermally isolated with an
insulating cover.
Fundamental Mode Crystals
For cost sensitive applications that do not have the most demanding jitter requirements, all of the narrow band
devices can use fundamental mode crystals that are in the lowest frequency band ranging from 37 to 41 MHz
(corresponding to RATE = LL). Unlike the other narrowband members of the family, the Si5327 is only capable of
using fundamental mode crystals that are in this range. For a more detailed discussion of the trade-offs associated
with this approach and a list of approved low frequency crystals, please see the application note AN591, which can
be downloaded from
www.silabs.com/timing
.
Reference Drift
During Digital Hold, long-term and temperature related drift of the reference input result in a one-to-one drift of the
output frequency. That is, the stability of the any-frequency output is identical to the drift of the reference frequency.
This means that for the most demanding applications where the drift of a crystal is not acceptable, an external
temperature compensated or ovenized oscillator will be required. Drift is not an issue unless the device is in Digital
Hold. Also, the initial accuracy of the reference oscillator (or crystal) is not relevant as long as it is within one of the
frequency bands described in Table 60.
Reference Jitter
Jitter on the reference input has a roughly one-to-one transfer function to the output jitter over the band from
100 Hz up to about 30 kHz. If the XA/XB pins implement a crystal oscillator, the reference will have suitably low
jitter if a suitable crystal is used. If the XA/XB pins are connected to an external reference oscillator, the jitter of the
external reference oscillator may also contribute significantly to the output jitter. A typical reference input-to-output
jitter transfer function is shown in Figure 59.
Содержание Si5316 Series
Страница 2: ...Si53xx RM 2 Rev 0 52 ...
Страница 109: ...Si53xx RM Rev 0 52 109 8 3 Typical Scope Shots for SFOUT Options Figure 46 sfout_2 CMOS Figure 47 sfout_3 lowSwingLVDS ...
Страница 110: ...Si53xx RM 110 Rev 0 52 Figure 48 sfout_5 LVPECL Figure 49 sfout_6 CML ...
Страница 111: ...Si53xx RM Rev 0 52 111 Figure 50 sfout_7 LVDS ...
Страница 127: ...Si53xx RM Rev 0 52 127 Figure 66 155 52 MHz In 622 08 MHz Out Loop BW 7 Hz Si5324 ...
Страница 128: ...Si53xx RM 128 Rev 0 52 Figure 67 19 44 MHz In 156 25 MHz Out Loop BW 80 Hz ...
Страница 129: ...Si53xx RM Rev 0 52 129 Figure 68 19 44 MHz In 156 25 MHz Out Loop BW 5 Hz Si5324 ...
Страница 130: ...Si53xx RM 130 Rev 0 52 Figure 69 27 MHz In 148 35 MHz Out Light Trace BW 6 Hz Dark Trace BW 110 Hz Si5324 ...
Страница 131: ...Si53xx RM Rev 0 52 131 Figure 70 61 44 MHz In 491 52 MHz Out Loop BW 7 Hz Si5324 ...
Страница 132: ...Si53xx RM 132 Rev 0 52 Figure 71 622 08 MHz In 672 16 MHz Out Loop BW 6 9 kHz ...
Страница 133: ...Si53xx RM Rev 0 52 133 Figure 72 622 08 MHz In 672 16 MHz Out Loop BW 100 Hz ...
Страница 134: ...Si53xx RM 134 Rev 0 52 Figure 73 156 25 MHz In 155 52 MHz Out ...
Страница 139: ...Si53xx RM Rev 0 52 139 Figure 78 86 685 MHz In 173 371 MHz Out ...
Страница 140: ...Si53xx RM 140 Rev 0 52 Figure 79 86 685 MHz In 693 493 MHz Out ...
Страница 142: ...Si53xx RM 142 Rev 0 52 Figure 81 10 MHz In 1 GHz Out ...
Страница 174: ...Si53xx RM 174 Rev 0 52 Figure 99 Si5374 Si5375 DSPLL A ...
Страница 175: ...Si53xx RM Rev 0 52 175 Figure 100 Si5374 Si5375 DSPLL B ...
Страница 176: ...Si53xx RM 176 Rev 0 52 Figure 101 Si5374 Si5375 DSPLL C ...