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12 LVPECL/24 CMOS Output
Clock Generator
Data Sheet
Rev. A
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FEATURES
Low phase noise, phase-locked loop (PLL)
Optional external 3.3 V/5 V VCO/VCXO to 2.4 GHz
1 differential or 2 single-ended reference inputs
Accepts CMOS, LVDS, or LVPECL references to 250 MHz
Accepts 16.62 MHz to 33.3 MHz crystal for reference input
Optional reference clock doubler
Reference monitoring capability
Automatic/ manual reference holdover and reference
switchover modes, with revertive switching
Glitch-free switchover between references
Automatic recovery from holdover
Digital or analog lock detect, selectable
Optional zero delay operation
Twelve 1.6 GHz LVPECL outputs divided into 4 groups
Each group of 3 outputs shares a 1-to-32 divider with
phase delay
Additive output jitter as low as 225 fs rms
Channel-to-channel skew grouped outputs < 16 ps
Each LVPECL output can be configured as 2 CMOS outputs
(for fOUT ≤ 250 MHz)
Automatic synchronization of all outputs on power-up
Manual output synchronization available
SPI- and IC-compatible serial control port
64-lead LFCSP
Nonvolatile EEPROM stores configuration settings
APPLICATIONS
Low jitter, low phase noise clock distribution
Clock generation and translation for SONET, 10Ge, 10GFC,
Synchronous Ethernet, OTU2/3/4
Forward error correction (G.710)
Clocking high speed ADCs, DACs, DDSs, DDCs, DUCs, MxFEs
High performance wireless transceivers
ATE and high performance instrumentation
Broadband infrastructures
GENERAL DESCRIPTION
function with subpicosecond jitter performance, along with
an on-chip PLL that can be used with an external VCO.
An in-package EEPROM, which can be programmed through the
serial interface, can store user-defined register settings for
power-up and chip reset.
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
The
AD9520 features 12 LVPECL outputs in four groups. Any
of the 1.6 GHz LVPECL outputs can be reconfigured as two
250 MHz CMOS outputs. If an application requires LVDS
drivers instead of LVPECL drivers, refer to th
e AD9522.Each group of three outputs has a divider that allows both the
divide ratio (from 1 to 32) and the phase offset or coarse time
delay to be set.
T
he AD9520 is available in a 64-lead LFCSP and can be operated
from a single 3.3 V supply. The external VCO can have an
operating voltage of up to 5.5 V. A separate output driver power
supply can be from 2.375 V to 3.465 V.
T
he AD9520 is specified for operation over the standard industrial
range of 40°C to +85°C.
AD9520 is used throughout this data sheet to refer to all the members of th
e AD9520 family. However, whe
n AD9520-5 is used, it refers to that specific member of the
REF1
REF2
CLK
SW
IT
C
H
O
VER
AND
M
O
NI
T
O
R
PL
L
DIVIDER
AND MUXES
ZERO
DELAY
CP
STATUS
MONITOR
SPI/I2C CONTROL
PORT AND
DIGITAL LOGIC
EEPROM
AD9520-5
OUT0
OUT1
OUT2
DIV/Φ
OUT3
OUT4
OUT5
DIV/Φ
OUT6
OUT7
OUT8
DIV/Φ
OUT9
OUT10
OUT11
DIV/Φ
LVPECL/
CMOS
REFIN
CLK
07239-
001