Semtech公司的ACS9510是多功能的器件,能在传统的TDM设备(TDM时序模式)中提供SETS功能. ACS9510还能为分组交换网络(PTP Grandmaster 和PTP Slave 模式)所采用的设备提供基于各种标准的时序. ACS9510有三种工作模式: PTP Grandmaster, PTP Slave和TDM Timing.本文介绍了ACS9510的主要性能,方框图, 系统方框图以及典型的应用方框图.
ACS9510: ToPSync™ Timing-over-packet synchronization technology
The ACS9510 is a multi-role device that can be used to provide SETS functionality in traditional TDM equipment (TDM Timing mode). Alternatively, it can provide standards-based timing for equipment used in packet switched networks (PTP Grandmaster and PTP Slave modes).
The ACS9510 has different operational modes:
PTP Grandmaster - packet clock master mode in which the device locks to a reference source and implements PTP Grandmaster functions (supporting frequency or time transportation across packet networks). Reference sources can be frequency-only or can include time (either a traceable Time-of-Day, such as GPS or UTC, or something with an arbitrary epoch). The device has a holdover mode which is invoked when the reference is lost.
PTP Slave - packet clock slave in which the device locks to PTP timing packets and implements IEEE 1588 slave functions. In this mode, the ACS9510 combines the PTP protocol with Semtechs patented packet delay filtering algorithms, so that it automatically adapts to changes in packet delay variation (packet jitter) and network reconfigurations. Hence, the device maintains the required timing performance for many telecom applications without the need to adapt switches or routers in the network. A holdover mode is available if the timing packet stream fails.
TDM Timing - TDM clock mode in which the device provides SETS functionality for standard SONET/SDH phase-locked loops, synchronizing to standard telecom reference/recovered clocks and generating a wide variety of dejittered telecom line interface clocks and frame pulses compliant with ITU-T G.81214/G.81315 and Telcordia GR-1244-CORE24/GR-25322. A holdover mode is available when all references are lost.
All ToPSync products come with a full support package including:
Datasheet
User Guide
Evaluation system
Application schematics and layouts
API driver code and messaging system with documentation
PTP Network management GUI tool
ToPSim network simulator and delay data analysis tool
ACS9510主要特性:
Fully integrated - IEEE1588 PTP Grandmaster, PTP Slave and SONET/SDH clock (TDM Timing) solution. Integrates hardware precision timestamping with on-the-fly insertion (no follow-up packets required). Powerful processor and clock recovery algorithm integrated. Backwards compatibility mode with Semtech ACS8520 SETS.
PTP Grandmaster selection - according to Best Master Clock (BMC) algorithm or an alternative.
Powerful network delay analysis delivers full time alignment in the slave over hostile networks (including Layer 2 & 3 routed).
Dynamic adaptation to network delay variations. Network loading change tolerant (ramps and steps).
Operational support - uni-cast only and multicast PTP.
Configurable DiffServ codepoint - for high priority packet routing.
Precision holdover - in all modes.
Interfaces for:
20 clock inputs and 19 clock outputs.
Media-independent interface (MII).
Time-of-day (ToD) - 1 PPS top-of-second signal plus current-time-since-epoch message: input to PTP Grandmaster mode, output from PTP Slave.
SPI compatible and JTAG boundary scan ports.
Outputs:
Time-aligned output pair: 1 PPS/125 MHz divided by n (n = 4 to 125000).
Frequency-aligned outputs: 1 Hz and programmable frequency 1 kHz to 62.5 MHz.
Low jitter frequency-aligned outputs: n x E1, n x DS1, frame sync + multi-frame sync clocks.
SONET and SDH OC-n rates: 3.84 MHz to 155.52 MHz.
Supports operation with a local oscillator of frequency accuracy to ±20 ppm or better.
Time alignment performance better than ±2 μs on a managed 5-switch GbE network under G.8261 test conditions.*
Frequency alignment performance better than ±10 ppb on a managed 5-switch GbE network under G.8261 test conditions.*
Standard compliance - IEEE 1588 v2, G.8261. 
图1. ACS9510方框图
图2. ACS9510 系统方框图
图3. ACS9510典型应用方框图
本文关键字：暂无联系方式电子技术，电工技术 - 电子技术
