Si5345-44-42-D-RM
30
Rev. 1.0
4. Clear delay
a. CBPro sets this based upon the project plan
A block diagram of the LOL monitor is shown in Figure 13. The live LOL register always displays the current LOL
state and a sticky register always stays asserted until cleared. The LOL pin reflects the current state of the LOL
monitor.
Figure 13. LOL Status Indicators
The LOL frequency monitors have an adjustable sensitivity which is register configurable from 0.1 ppm to
10000 ppm. CBPro provides a wide range of set and clear thresholds for the LOL function. Having two separate
frequency monitors allows for hysteresis to help prevent chattering of LOL status.
An example configuration of the
LOL set and clear thresholds is shown in
Figure 14.
Figure 14. LOL Set and Clear Thresholds
Table 16. Loss of Lock Status Monitor and Control Registers
Register Name
Hex Address
[Bit Field]
Function
LOL
0x000E[1]
Status bit that indicates if the DSPLL is locked to an input clock
LOL_FLG
0x0013[1]
Sticky bits for LOL register. Writing 0 to a sticky bit will clear it.
LOL_SET_THR
0x009E[7:4] Configures the loss of lock set threshold in ppm.
LOL_CLR_THR
0x00A0[7:4] Configures the loss of lock clear threshold in ppm.
DSPLL
LPF
PD
÷M
Si5345/44/42
LOL
Clear
LOL
Set
Timer
LOL
LOS
LOL
Sticky
Live
LOL Monitor
f
IN
Feedback
Clock
Phase Detector Frequency Difference (ppm)
Hysteresis
LOL
LOCKED
Clear LOL
Threshold
Set LOL
Threshold
Lock Acquisition
0
Lost Lock
0.1
1
10,000