Datasheet

AD9558 Data Sheet
Rev. B | Page 8 of 104
REFERENCE MONITORS
Table 8.
Parameter Min Typ Max Unit Test Conditions/Comments
REFERENCE MONITORS
Reference Monitor
Loss of Reference Detection Time
1.1
DPLL PFD
period
Nominal phase detector period = R/f
REF
0F0F
1
Frequency Out-of-Range Limits
<2 10
5
Δf/f
REF
(ppm)
Programmable (lower bound is subject to quality
of the system clock (SYSCLK)); SYSCLK accuracy
must be better than the lower bound
Validation Timer 0.001 65.535 sec Programmable in 1 ms increments
1
f
REF
is the frequency of the active reference; R is the frequency division factor determined by the R-divider.
REFERENCE SWITCHOVER SPECIFICATIONS
Table 9.
Parameter Min Typ Max Unit Test Conditions/Comments
REFERENCE SWITCHOVER SPECIFICATIONS
Maximum Output Phase Perturbation
(Phase Build-Out Switchover)
Assumes a jitter-free reference; satisfies Telcordia
GR-1244-CORE requirements; select high PM base
loop filter bit (Register 0x070E, Bit 0) is set to 1 for
all active references
50 Hz DPLL Loop Bandwidth
Valid for automatic and manual reference switching
Peak
0 ±100 ps
Steady State
0
±100
ps
2 kHz DPLL Loop Bandwidth Valid for automatic and manual reference switching
Peak
0 ±250 ps
Steady State
0 ±100 ps
Time Required to Switch to
a New Reference
Phase Build-Out Switchover
1.1
DPLL PFD
period
Calculated using the nominal phase detector
period (NPDP = R/f
REF
); the total time required is
equal to the time plus the reference validation
time and the time required to lock to the new
reference