AD9548BCPZ

GENERAL DESCRIPTION

The AD9548 provides synchronization for many systems, including synchronous optical networks (SONET/SDH). The AD9548 generates an output clock synchronized to one of up to four differential or eight single-ended external input references. The digital PLL allows for reduction of input time jitter or phase noise associated with the external references. The AD9548 continuously generates a clean (low jitter), valid output clock even when all references have failed by means of a digitally controlled loop and holdover circuitry.
The AD9548 operates over an industrial temperature range of −40°C to +85°C.

FEATURES

Supports Stratum 2 stability in holdover mode
Supports reference switchover with phase build-out
Supports hitless reference switchover
Auto/manual holdover and reference switchover
4 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 Hz to 750 MHz
Reference validation and frequency monitoring (1 ppm)
Programmable input reference switchover priority
30-bit programmable input reference divider
4 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
30-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
88-lead LFCSP package

APPLICATIONS

Network synchronization
Cleanup of reference clock jitter
GPS 1 pulse per second synchronization
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 station controllers
Cable infrastructure
Data communications