zl30462 Zarlink Semiconductor, zl30462 Datasheet - Page 13

• Manufacturer Part Number: zl30462
• Description: Vibratto-s Dvd Processor Product Brief
• Manufacturer: Zarlink Semiconductor

The new reference clock will most likely have a different phase but it may also have a different fractional frequency
offset. To lock to a new reference with a different frequency, the DPLL will step gradually towards the new
frequency. The frequency slope will be limited to less than 2.0 ppm/sec.
2.1.4
The Normal to Holdover to Normal sequence switching can be performed at any time. An example of this could be
during routine maintenance or an upgrade of equipment, where the active input references is going to be affected.
So, changing the input reference under controlled conditions should avoid any unnecessary chances of generating
a phase hit.
Reference Switching (RefSel): NORMAL --> HOLDOVER --> NORMAL
Figure 8 - Entry into Auto Holdover state and recovery into Normal mode by switching
______
RESET == 1
______
RESET == 1
Reset
Reset
unconditional return from
unconditional return from
MS2, MS1 == 10 forces
MS2, MS1 == 10 forces
any state to FreeRun
any state to FreeRun
MS2, MS1 != 10
MS2, MS1 != 10
FreeRun
FreeRun
10
10
Figure 9 - Manual Reference Switching
MS2, MS1 == 01 or
MS2, MS1 == 01 or
RSEL change
RSEL change
Zarlink Semiconductor Inc.
Holdover
Holdover
ZL30462
01
01
MS2, MS1 == 00
MS2, MS1 == 00
references
Ref: OK &
Ref: OK &
12
{Auto}
{Auto}
RSEL change
RSEL change
(Locked)
(Locked)
Normal
Normal
(automatic return enabled)
00
00
AHRD=0
MS2, MS1 == 00
MS2, MS1 == 00
Ref: OK --> Fail
Ref: OK --> Fail
{Auto}
{Auto}
&
&
Holdover
Holdover
Auto
Auto
Ref: Fail --> OK &
MS2, MS1 == 00
& AHRD=1 &
MHR 0 --> 1
{Manual}
Ref: Fail --> OK &
MS2, MS1 == 00
& AHRD=0 &
{Auto}
Ref: Fail --> OK &
MS2, MS1 == 00
& AHRD=1 &
MHR 0 --> 1
{Manual}
Ref: Fail --> OK &
MS2, MS1 == 00
& AHRD=0 &
{Auto}
Data Sheet