Analog Devices AD9551 User Manual

Page of 12
 
Evaluation Board User Guide
UG-002
One
 
Technology
 
Way
 
 
P.O.
 
Box
 
9106
 
 
Norwood,
 
MA
 
02062-9106,
 
U.S.A.
 
 
Tel:
 
781.329.4700
 
 
Fax:
 
781.461.3113
 
 
www.analog.com 
 
Evaluating the AD9551 Multiservice Clock Generator 
 
 
See the last page for an important warning and disclaimers.
 
Rev. 0 | Page 1 of 12 
FEATURES 
Simple power connection using USB connection and  
on-board LDO voltage regulators 
LDOs are easily bypassed for power measurements 
AC-coupled differential LVPECL SMA connectors 
SMA connectors for  
2 reference inputs 
2 PLL lock detect outputs 
Microsoft Windows®–based evaluation software  
with simple graphical user interface 
On-board PLL loop filter 
Easy access to digital I/O and diagnostic signals  
via I/O header 
Status LEDs for diagnostic signals 
USB computer interface 
Dip switch configurable for manual operation 
Software calculator provides flexibility, allowing programming 
almost any rational input/output frequency ratio 
 
GENERAL DESCRIPTION 
This user guide describes the hardware and software of the 
AD9551 evaluation board and includes detailed schematics and 
PCB layout artwork. The AD9551 Revision D evaluation board 
is a compact, easy to use platform for evaluating all features of the 
AD9551 multiservice clock generator.  
The AD9551 accepts one or two reference input signals to 
synthesize one or two output signals. The AD9551 uses a 
fractional-N PLL that precisely translates the reference frequency 
to the desired output frequency. The input receivers and output 
drivers provide both single-ended and differential operation. 
Reference conditioning and switchover circuitry internally 
synchronizes the two references so that if one reference fails, 
there is virtually no phase perturbation at the output. 
The AD9551 uses an external crystal and an internal DCXO to 
provide for holdover operation. If both references fail, the device 
maintains a steady output signal. This may mislead you to believe 
that the PLL is locked and the board is configured properly. A 
simple test is to move the input REF A or REF B clock a few kilo-
hertz and verify that the changes in output frequency track the input. 
 
DIGITAL PICTURE OF THE EVALUATION BOARD 
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Figure 1. 
AD9551 Evaluation Board, Revision D