AD9547/PCBZ Analog Devices Inc, AD9547/PCBZ Datasheet - Page 28

• Manufacturer Part Number: AD9547/PCBZ
• Description: Clock Generator/Synchronizer Evaluation Board
• Manufacturer: Analog Devices Inc

Specifications of AD9547/PCBZ

• Silicon Manufacturer: Analog Devices
• Application Sub Type: Network Clock Generator/Synchronizer
• Kit Application Type: Clock & Timing
• Silicon Core Number: AD9547
• Main Purpose: Timing, Clock Generator
• Embedded: No
• Utilized Ic / Part: AD9547
• Primary Attributes: 2 Differential or 4 Single Ended Inputs
• Secondary Attributes: CMOS, LVPECL & LVDS Compatible
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD9547
Reference Validation Override Control
Register 0x0A0E to Register 0x0A10 provide the user with the
ability to override the reference validation logic, enabling a
certain level of troubleshooting capability. Each of the four
input references has a dedicated block of validation logic, as
shown in Figure 32. The state of the valid signal at the output
defines a particular reference as valid (1) or not valid (0), which
includes the validation period (if activated) as prescribed by the
validation timer. The override controls are the three control bits
on the left side of the diagram.
The main feature to note is that when faulted = 1, the output latch
is reset, which forces valid = 0 (indicating an invalid reference),
regardless of the state of any other signal. Under the default con-
dition (that is, all three control bits are set to 0), the reference
monitor is the primary source of the validation process. This is
because, under the default condition, the ref fault signal from the
reference monitor is identical to the faulted signal.
The function of the faulted signal is fourfold.
•
•
•
•
The reference monitor bypass control bit (Address 0x0A10) enables
bypassing of the reference fault signal generated by the reference
monitor. When the reference monitor bypass bit = 1, the state of the
faulted signal is dictated by the reference monitor override control
bit. This is useful when the user relies on an external reference
monitor rather than the internal monitor resident in the device.
When faulted = 1, valid = 0, regardless of the state of any
other control signal. Therefore, faulted = 1 indicates an
invalid reference.
When the faulted signal transitions from 0 to 1 (that is, from
not faulted to faulted), the validation timer is momentarily
reset, which means that, when it is enabled, it must exhaust its
full counting sequence before it expires.
When faulted = 0 (that is, the reference is not faulted), the
validation timer is allowed to perform its timing sequence.
When faulted = 1 (that is, the reference is faulted), the
validation timer is reset and halted.
The faulted signal passes through an inverter, which converts
it to a not faulted signal that appears at the input of the valid
latch. This allows the valid latch to capture the state of the
not faulted signal when the validation timer expires.
REGISTER CONTROL BITS
REFERENCE
FORCE VALIDATION
MONITOR
REF MONITOR
REF MONITOR
OVERRIDE
TIMEOUT
BYPASS
REF FAULT
(4 COPIES, 1 PER REFERENCE INPUT)
REFERENCE VALIDATION LOGIC
1
0
Figure 32. Reference Validation Override
FAULTED
Rev. B | Page 28 of 104
R
VALIDATION TIMER
The user programs the reference monitor override bit based on
the status of the external monitor. On the other hand, when the
reference monitor bypass bit = 0, the reference monitor override
control bit (Address 0x0A0F) allows the user to manually test
the operation of both the valid latch and the validation timer.
In this case, the user relies on the signal generated by the internal
reference monitor (reference fault) but uses the reference monitor
override bit to emulate a faulted reference. That is, when the
reference monitor override bit = 1, faulted = 1, but when the
reference monitor override bit = 0, faulted = reference fault.
In addition, the user can emulate a timeout of the validation timer
via the force validation timeout control register at Address 0x0A0E.
Writing a Logic 1 to this autoclearing bit triggers the valid latch,
which is identically equivalent to a timeout of the validation timer.
REFERENCE PROFILES
The AD9547 has eight independent profile registers. A profile
register contains 50 bytes that establish a particular set of device
parameters. Each of the four input references can be assigned to
any one of the eight profiles (that is, more than one reference can
be assigned to the same profile). The profiles allow the user to
prescribe the specific device functionality that should take effect
when one of the input references assigned to a profile becomes the
active reference. Each profile register has the same format and
stores the following device parameters:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
EN
Reference priority
Reference period value (in femtoseconds (fs))
Inner tolerance value (1/tolerance)
Outer tolerance value (1/tolerance)
Validation timer value (milliseconds (ms))
Redetect timer value (milliseconds (ms))
Digital loop filter coefficients
Reference prescaler setting (R divider)
Feedback divider settings (S, U, and V)
DPLL phase lock detector threshold level
DPLL phase lock detector fill rate
DPLL phase lock detector drain rate
DPLL frequency lock detector threshold level
DPLL frequency lock detector fill rate
DPLL frequency lock detector drain rate
TIMEOUT
D Q
R
VALID