ACS8520T

Overview

The ACS8520T is a Synchronous Equipment Timing Source (SETS) for SONET/SDH Network Elements, compliant with Stratum 3/4E/4 and SMC standards. It generates independent SEC, BITS/SSU, 8 kHz Frame Sync, and 2 kHz Multi-Frame Sync clocks. The device supports Free-run, Locked, and Holdover modes using OCXO or TCXO references. It accepts 14 input reference clocks and provides nine output clocks plus two sync pulses. Key features include programmable PLL bandwidth (0.1 Hz to 70 Hz), automatic hit-less source switchover, and microprocessor interface options. The T suffix indicates a lead-free, RoHS and WEEE compliant version in an LQFP 100 package.

Feature Summary

• Compliant with Telcordia GR-1244-CORE Stratum 3 and ITU-T G.813 Options I and II specifications.
• Supports 14 individual input reference clocks with robust quality monitoring and automatic hit-less switchover.
• Generates nine output clocks and two synchronization pulses with phase adjustment in 6 ps steps up to ±200 ns.
• Includes IEEE 1149.1 JTAG boundary scan and multiple microprocessor interface modes (Intel, Motorola, Serial, Multiplexed, EPROM).

Applications

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

Procurement Notes

Verify the 'T' ordering suffix confirms the lead-free, RoHS, and WEEE compliant variant of the ACS8520. Confirm the package type is LQFP 100. Ensure the specific revision matches system requirements, as datasheet revisions may update electrical characteristics or pin descriptions.

Selection Notes

Select the ACS8520T when Stratum 3/4E/4 compliance is required for SONET/SDH networks. Choose this part over standard versions if environmental regulations mandate lead-free construction. Verify that the available microprocessor interface modes match the host controller architecture.

Part Context

The ACS8520T belongs to the Semtech ACS8520 family of SETS devices. The 'T' suffix specifically denotes the lead-free manufacturing process, distinguishing it from non-compliant variants while maintaining identical functional performance and pinout compatibility within the LQFP 100 package.

Replacement Considerations

Direct replacements must be lead-free variants of the ACS8520. Non-'T' suffix parts are functionally identical but lack RoHS/WEEE compliance. Cross-family substitutes require verification of DPLL architecture and Stratum compliance.