ACS8509T

Overview

The ACS8509T is a single-chip Synchronous Equipment Timing Source (SETS) for SONET and SDH network elements. It generates SEC, BITS/SSU, frame sync, and multi-frame sync clocks. The device supports free-run, locked, and holdover modes with four input reference ports and six output clock ports. It features programmable wander/jitter tracking from 0.1 Hz to 20 Hz, automatic hit-less switchover, and phase build-out. Operating on a single +3.3 V supply with +5 V I/O tolerance, it meets ITU-T, ETSI, and Telcordia standards. The T suffix indicates a lead-free, RoHS-compliant version in a 100-pin LQFP package.

Feature Summary

• Generates independent SEC, BITS/SSU, 8 kHz Frame Sync, and 2 kHz Multi-Frame Sync clocks
• Supports Master/Slave redundancy configurations for system protection
• Programmable jitter/wander tracking attenuation between 0.1 Hz and 20 Hz
• Includes Intel, Motorola, Serial, Multiplexed, and EPROM microprocessor interfaces

Applications

• SONET Minimum Clock (SMC) applications
• SONET/SDH Equipment Clock (SEC) generation
• Stratum 3E, Stratum 3, Stratum 4E, and Stratum 4 timing sources
• Synchronous equipment timing source systems

Procurement Notes

Verify the 'T' ordering suffix confirms the lead-free, RoHS, and WEEE compliant variant. Confirm the package type is the 100-pin LQFP. Ensure the operating temperature range of -40°C to +85°C matches the application requirements. Check that the specific revision (Rev 2.00) aligns with design documentation.

Selection Notes

Select based on required Stratum level performance and holdover stability. Choose between OCXO or TCXO local oscillators to define specific holdover characteristics. Verify compatibility with existing microprocessor interface protocols (Intel, Motorola, etc.). Ensure input reference clock types (TIN1, TIN2, TIN3) match the available network synchronization sources.

Part Context

The ACS8509T is part of Semtech's SETS family designed for telecom line cards. It serves as a highly integrated solution for generating precise timing signals in synchronous networks. The device replaces discrete timing components by integrating PLLs, frequency synthesizers, and control logic into a single chip.

Replacement Considerations

The ACS8509T is functionally compatible with the ACS8509. Pinouts are similar but not identical to the ACS8525; verify pin mapping before substitution. No other direct cross-model replacements are documented in the provided datasheet.

FAQ

What is the purpose of the SYNC2K pin?

The SYNC2K pin connects to the 2 kHz Multi-Frame Sync output of a partner ACS8509 in a redundancy system to synchronize phases between Master and Slave devices.

How does the device handle input reference loss?

The ACS8509 performs automatic hit-less source switchover using priority tables and maintains phase continuity through phase build-out during mode transitions.

What local oscillator options are supported?

The user can choose between an OCXO or TCXO to define the Stratum and/or Holdover performance required for the application.