Dual Input Network Clock Generator/Synchronizer

The AD9549 provides synchronization for many systems, including synchronous optical networks (SONET/SDH). The AD9549 generates an output clock, synchronized to one of two external input references. The external references may contain significant time jitter, also specified as phase noise. Using a digitally controlled loop and holdover circuitry, the AD9549 continues to generate a clean (low jitter), valid output clock during a loss of reference condition, even when both references have failed.

The AD9549 operates over an industrial temperature range of −40°C to +85°C.

Applications

* Network synchronization

* Reference clock jitter cleanup

* SONET/SDH clocks up to OC-192, including FEC

* Stratum 3/3E reference clocks

* Wireless base stations, controllers

* Cable infrastructure

* Data communications

* Flexible reference inputs

* Input frequencies: 8 kHz to 750 MHz

* Two reference inputs

* Loss of reference indicators

* Auto and manual holdover modes

* Auto and manual switchover modes

* Smooth A-to-B phase transition on outputs

* Excellent stability in holdover mode

* Programmable 16 + 1-bit input divider, R

* Differential HSTL clock output

* Output frequencies to 750 MHz

* Low jitter clock doubler for frequencies of >400 MHz