AD9547 Datasheet, PDF (1/104 Pages) Analog Devices – Dual/Quad Input Network Clock Generator/Synchronizer

Dual/Quad Input Network Clock
Generator/Synchronizer
AD9547
FEATURES
Supports Stratum 2 stability in holdover mode
Supports reference switchover with phase build-out
Supports hitless reference switchover
Automatic/manual holdover and reference switchover
2 pairs of reference input pins, with each pair configurable
as a single differential input or as 2 independent single-
ended inputs
Input reference frequencies from 1 kHz to 750 MHz
Reference validation and frequency monitoring (1 ppm)
Programmable input reference switchover priority
30-bit programmable input reference divider
2 pairs of clock output pins, with each pair configurable as
a single differential LVDS/LVPECL output or as 2 single-
ended CMOS outputs
Output frequencies up to 450 MHz
20-bit integer and 10-bit fractional programmable feedback
divider
Programmable digital loop filter covering loop bandwidths
from 0.001 Hz to 100 kHz
Optional low noise LC-VCO system clock multiplier
Optional crystal resonator for system clock input
On-chip EEPROM to store multiple power-up profiles
Software controlled power-down
64-lead LFCSP package
APPLICATIONS
Network synchronization
Cleanup of reference clock jitter
SONET/SDH clocks up to OC-192, including FEC
Stratum 2 holdover, jitter cleanup, and phase transient
control
Stratum 3E and Stratum 3 reference clocks
Wireless base stations, controllers
Cable infrastructure
Data communications
GENERAL DESCRIPTION
The AD9547 provides synchronization for many systems,
including synchronous optical networks (SONET/SDH). The
AD9547 generates an output clock that is synchronized to one
of two differential or four single-ended external input references.
The digital PLL allows for reduction of input time jitter or phase
noise associated with the external references. The AD9547 con-
tinuously generates a clean (low jitter), valid output clock, even
when all references fail, by means of digitally controlled loop and
holdover circuitry.
The AD9547 operates over an industrial temperature range of
−40°C to +85°C.
STABLE
SOURCE
FUNCTIONAL BLOCK DIAGRAM
ANALOG
FILTER
CLOCK
MULTIPLIER
AD9547
REFERENCE INPUTS
AND
MONITOR MUX
DIGITAL
PLL
DAC
SYNC
CLOCK DISTRIBUTION
CHANNEL 0
DIVIDER
CHANNEL 1
DIVIDER
SERIAL CONTROL INTERFACE
(SPI or I²C)
EEPROM
STATUS AND
CONTROL PINS
Figure 1.
Rev. 0
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