ADI AD9547網(wǎng)絡(luò)時(shí)鐘發(fā)生與同步方案
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AD9547: Dual/Quad Input Network Clock Generator/Synchronizer
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 continuously 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℃ to +85℃.
AD9547主要特性:
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
AD9547應(yīng)用:
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
圖1.AD9547功能方框圖
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