ACS8522BT

Overview

The Semtech ACS8522BT is a single-chip Synchronous Equipment Timing Source (SETS) for SONET/SDH and Ethernet network elements. It generates SEC, frame synchronization, and Ethernet clocks using Digital Phase Locked Loop (DPLL) and Analog PLL (APLL) architectures. The device accepts four independent input reference sources and provides four output clock paths plus two sync pulses. It supports Stratum 3, 4E, 4, SMC, and Ethernet applications with absolute holdover accuracy better than 3 x 10^-10 (manual). Operating on a single 3.3 V supply, it features programmable PLL bandwidth from 0.1 Hz to 70 Hz and output phase adjustment in 6 ps steps.

Feature Summary

• Generates four independent output clocks and four Ethernet frequencies (25 MHz, 50 MHz, 62.5 MHz, 125 MHz)
• Supports automatic hit-less source switchover and manual holdover frequency control
• Includes SPI compatible serial interface and IEEE 1149.1 JTAG boundary scan support
• Provides output phase adjustment in 6 ps steps up to ±200 ns

Applications

• Stratum 3, 4E, and 4 timing systems
• SONET Minimum Clock (SMC) and Equipment Clock (SEC) generation
• Ethernet synchronization applications

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm package type and compliance status. Ensure the external oscillator selection (OCXO or TCXO) matches the required Stratum performance specifications for the target application environment.

Selection Notes

Select between OCXO or TCXO based on required Stratum and holdover performance levels. Consider the T0 path for complex node timing synchronization requiring advanced features like non-revertive mode, versus the simpler T4 path for independent equipment synchronization.

Part Context

The ACS8522BT is part of the eSETS family designed for synchronous equipment timing sources. It utilizes DPLL technology for stable performance over temperature variations and an APLL for low jitter output. This architecture ensures consistent behavior compared to traditional analog PLL solutions.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided datasheet.

FAQ

What is the maximum input frequency supported by the ACS8522BT?

The device supports input frequencies ranging from 2 kHz to 100 MHz.

How does the ACS8522BT handle source switching?

It supports automatic hit-less source switchover upon loss of input, controlled by an internal state machine or forced by register configuration.

What standards does the ACS8522BT comply with?

It meets Telcordia GR-1244-CORE Stratum 3, GR-253, ITU-T G.813 Options I and II, and ITU-T G.8262 (Draft) specifications.