S i 5 3 x x - R M
92
Rev. 0.52
The
NC5_LS
divider uses CKOUT2 as its clock input to derive FS_OUT. The limits for the
NC5_LS
divider are
NC5_LS = [1, 2, 4, 6, …, 2
19
]
f
CKOUT2
< 710 MHz
Note that when in frame synchronization realignment mode, writes to
NC5_LS
are controlled by
FPW_VALID
. See
section “7.8.4. FS_OUT Polarity and Pulse Width Control (Si5368)”.
Common
NC5_LS
divider settings on FS_OUT are shown in Table 45.
7.8.1. FSYNC Realignment (Si5368)
The
FSYNC_ALIGN_PIN
bit determines if the realignment will be pin-controlled via the
FS_ALIGN
pin or register-
controlled via the
FSYNC_ALIGN_REG
register bit. The active CKIN3 or CKIN4 edge to be used is controlled via
the
FSYNC_POL
register bit.
In either FSYNC alignment control mode, the resolution of the phase realignment is 1 clock cycle of CKOUT2. If
the realignment control is not active, the NC5 divider will continuously divide down its f
CKOUT2
input. This
guarantees a fixed number of high-frequency clock (CKOUT2) cycles between each FS_OUT cycle.
At power-up, the device automatically performs a realignment of FS_OUT using the currently active sync input.
After this, as long as the PLL remains in lock and a realignment is not requested, FS_OUT will include a fixed
number of high-speed clock cycles, even if input clock switches are performed. If many clock switches are
performed in phase build-out mode, it is possible that the input sync to output sync phase relationship will shift due
to the accumulated residual phase transients of the phase build-out circuitry. The
ALIGN_ERR
[8:0] status register
reports the deviation of the input-to-output sync phase skew from the desired
FSYNC_SKEW
[16:0] value in units of
f
CKOUT2
periods. A programmable threshold to trigger the
ALIGN_INT
alarm can be set via the
ALIGN_THR
[2:0]
bits, whose settings are given in Table 46. If the sync alignment error exceeds the threshold in either the positive or
negative direction, the alarm becomes active. If it is then desired to reestablish the desired input-to-output sync
phase relationship, a realignment can be performed. A realignment request may cause FS_OUT to
instantaneously shift its output edge location in order to align with the active input sync phase.
Table 45. Common NC5 Divider Settings
CKOUT2 Frequency (MHz)
NC5 Divider Setting
2 kHz FS_OUT
8 kHz FS_OUT
19.44
9720
2430
77.76
38880
9720
155.52
77760
19440
622.08
311040
77760
Table 46. Alignment Alarm Trigger Threshold
ALIGN_THR [2:0]
Alarm Trigger Threshold (Units of T
CKOUT2
)
000
4
001
8
010
16
011
32
100
48
101
64
110
96
111
128
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 ...
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Страница 176: ...Si53xx RM 176 Rev 0 52 Figure 101 Si5374 Si5375 DSPLL C ...