Si53xx-RM
Rev. 0.52
99
7.11.6. C1B, C2B, C3B, ALRMOUT (Si5368 [CK_CONFIG_REG = 1])
The generation of alarms on the C1B, C2B, C3B, and ALRMOUT outputs is a function of the input clock
configuration, and the frequency offset alarm enable as shown in Table 53. The
LOSn_INT
and
FOSn_INT
signals
are the raw outputs of the alarm monitors. These appear directly in the device status registers. Sticky versions of
these bits (
LOSn_FLG
,
FOSn_FLG
) drive the output interrupt and can be individually masked. Since, CKIN3 and
CKIN4 are configured as frame sync inputs (
CK_CONFIG_REG
= 1), ALRMOUT functions as the alignment alarm
output (
ALIGN_INT
) as described in Section “7.8. Frame Synchronization Realignment (Si5368 and
CK_CONFIG_REG = 1)”. The equations below assume that the output alarm is active high; however, the active
polarity is selectable via the
CK_BAD_POL
bit.
Operation of the C1B, C2B, C3B, and ALRMOUT pins is enabled based on setting the
C1B_PIN
,
C2B_PIN
,
C3B_PIN
, and
ALRMOUT_PIN
register bits. Otherwise, the pin will tri-state. Also, if
INT_PIN
= 1, the interrupt
functionality will override the appearance of ALRMOUT at the output even if
ALRMOUT_PIN
= 1.
Once an LOS or FOS alarm is asserted for one of the input clocks, it is held high until the input clock is validated
over a designated time period. The validation time is programmable via the
VALTIME
[1:0] register bits as shown in
Table 8, “AC Characteristics—All Devices”. If another error condition on the same input clock is detected during the
validation time then the alarm remains asserted and the validation time starts over.
Note that hitless switching between input clocks applies only when the input clock validation time
VALTIME
[1:0] = 01 or higher.
7.11.7. LOS Algorithm for Reference Clock Input (Si5319, Si5324, Si5326, Si5327, Si5368, Si5369, Si5374,
Si5375)
The reference clock input on the XA/XB port is monitored for LOS. The LOS circuitry divides the signal at XA/XB by
128, producing a 78 kHz to 1.2 MHz signal, and monitors the signal for LOS using the same algorithm as described
in Section “7.11.1. Loss-of-Signal Alarms (Si5319, Si5324, Si5325, Si5326, Si5327, Si5367, Si5368, Si5369,
Si5374, Si5375)”. The
LOSX_INT
read only bit reflects the state of a loss-of-signal monitor on the XA/XB port. For
the Si5374 and Si5375, the XA/XB port refers to the OSC_P and OSC_N pins.
7.11.8. LOL (Si5319, Si5324, Si5326, Si5327, Si5368, Si5369, Si5374, Si5375)
The device has a PLL lock detection algorithm that indicates the lock status on the LOL output pin and the
LOL_INT
read-only register bit. The algorithm works by continuously monitoring the phase of the input clock in
relation to the phase of the feedback clock. A retriggerable one-shot is set each time a potential phase cycle slip
condition is detected. If no potential phase cycle slip occurs for the retrigger time, the LOL output is set low,
indicating the PLL is in lock. The LOL pin is held in the active state during an internal PLL calibration. The active
polarity of the LOL output pin is set using the
LOL_POL
register bit (default active high).
The lock detect retrigger time is user-selectable, independent of the loop bandwidth. The
LOCKT
[2:0] register bits
must be set by the user to the desired setting. Table 54 shows the lock detect retrigger time for both modes of
operation. LOCKT is the minimum amount of time that LOL will be active.
Table 53. Alarm Output Logic Equations [Si5368 and CKCONFIG_REG = 1]
FOS_EN
Alarm Output Equations
0
(Disables FOS)
C1B =
LOS1_INT
or (
LOS3_INT
and
FSYNC_SWTCH_REG
)
C2B =
LOS2_INT
or (
LOS4_INT
and
FSYNC_SWTCH_REG
)
C3B tri-state,
ALRMOUT = ALIGN_INT
1
C1B =
LOS1_INT
or (
LOS3_INT
and
FSYNC_SWTCH_REG
) or
FOS1_INT
C2B =
LOS2_INT
or (
LOS4_INT
and
FSYNC_SWTCH_REG
) or
FOS2_INT
C3B tri-state,
ALRMOUT = ALIGN_INT
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 ...