SONET/SDH Synchronization (SETS)
Semtech's SETS devices each replace a dozen or more complex hardware ICs, plus DSP software, plus temperature calibration in a typical layout-sensitive, time consuming, large footprint custom design. The SETS solution is easily replicatible on each timing and line card, and the complete SETS solution consists of only two devices: a single SETS IC, plus a local crystal oscillator (XO). The SETS family comprises the full-featured, ACS8510 Master/Slave SETS, accompanied by the line-card optimized ACS8515 Protection Switch SETS.
The ideal synchronization solution consists of a Master and Slave pair of ACS8510 devices, on a central/main synchronization card; each generating a group of intermediate frequency SEC clocks (typically 19.44MHz), plus frame sync clocks (8kHz), distributed along the backplane. Each of the ACS8510 devices thus feed their clocks downstream to a supporting cast of ACS8515 ICs on each line card, optimized to follow the upstream ACS8510's PLLs. The ACS8515 devices on each line card in turn implement intelligent, hitless protection switching for each optical or copper line card.
In Semtech's SETS Interchangeable XO Architecture, Holdover performance is isolated to the external 12.8MHz XO. In this way, the quality of the XO used need only match the Holdover requirements – one design fits all. For example, a 0.37ppm TCXO is used to satisfy Stratum 3; a 0.011ppm OCXO for Stratum 3E; a 20ppm TCXO for SMC; and an 80ppm cheap XO can be used for Stratum 4/no Holdover. Semtech has been working closely with two highly regarded XO supplier partners – Vectron and C-MAC – to ensure a supply of all these 12.8MHz XOs that have been optimized for Semtech's SETS solution.
The ACS8510 and ACS8515 provide the same basic rich feature set, with every option imaginable. The features are all selectable/configurable via a combination of hardware (pins) and software (over 80 registers), and with ample register fields assigned for status monitoring and interrupt generation. Both are fully supported with Evaluation Boards and Reference Designs. Extensive characterization of these complex devices has resulted in a separate Test Report being available.
SETS Press Release
Semtech Sets a New Standard for SONET/SDH Network Synchronization
Single-Chip Integrated Solution Exceeds Domestic and International Telecommunications Standards (10 Oct 00)
SETS Family
Station Equipment Timing Synchronization (SETS) System Solution (119k, 30 Sep 00)
SETS FAQ
Implementation FAQ for the ACS8510 and ACS8515 (52k, 28 Sep 00)
SETS Intro
Station Equipment Timing Synchronization (SETS) Introduction (21k, 9 Oct 00)
SONET/SDH Products Backgrounder
Overview of Semtech SONET / SDH Transport Products (39k, 29 Oct 00)
ACS8510 SETS
SONET / SDH Network Synchronization Device with Master/Slave
The full-featured ACS8510 ICs are highly integrated, highly configurable 3-PLL devices with Master/Slave support. The ACS8510 devices sport a large clock I/O array (14 input + 11 output clocks) intended to support all manner of reference sources (BITS, GPS, line clocks) and backplane clock distribution. Frequencies supported for the 14 input clocks include 3 classes: BITS composite clocks (64/8kHz); T/E PDH class either at Nx 8kHz or Nx T1/E1; and SONET/SDH recovered line clocks, at all the OC sub-rates from 6.48MHz up to 155.52MHz. Likewise, frequencies supported for the 11 output clocks include 3 classes: 7 SEC clocks, at all the OC sub-rates from 6.48MHz to 155.52MHz, and Nx T1/E1 rates; 2 frame sync clocks (2kHz and 8kHz); and 2 BITS clocks (T1/E1 rate and composite 64/8kHz).
The ACS8510 devices are unique in the industry for these added features:
•Integrated support for Master/Slave phase interlocking
•BITS reference clock re-generation
•Adjustable and abundant input clock activity monitoring (one for each of the 14 inputs)
•Frequency monitor for the selected input clock
•Generation of phase-locked 8kHz frame sync and 2kHz multi-frame sync clocks
LQFP-100 package. (718k, 7 Nov 00)
ACS8515 SETS-LC (Line Card)
SONET/SDH Network Synchronization Protection Switch
The line-card optimized ACS8515 devices perform robust, hitless protection switching on the Master and Slave clock groups (replacing intelligent multiplexers) plus frequency translation with jitter attenuation (replacing a PLL). The ACS8515 has a clock I/O array reduced from the ACS8510 (6 input + 4 output clocks). Each ACS8515 accepts 3 groups of clock inputs (Master, Slave, Standby); and each independently generates two phase-locked SEC clocks at any Nx T1/E1 or OC frequencies up to 311MHz (for the line card SERDES interfaces), plus a pair of 2/8kHz frame sync clocks (for framer use).
The ACS8515 serves as a robust protection switch by implementing a wide choice of source switching mechanisms. There are two fast (immediate) manual methods: both hardware based (dedicated pin) and software based (register bits) source switching. And there are two automatic methods: fast (2 cycles) source switching; and the more meticulous standard, frequency/activity monitor based, source switching.
Semtech Corporation, 652 Mitchell Road, Newbury Park, CA 91320. Tel: 805-498-2111; Fax: 805-498-4803.