ACS8947T

Overview

The ACS8947T is a general-purpose, Integer-N, jitter-attenuating differential phase-locked loop designed for generating low-jitter output clocks. It features two differential LVPECL reference inputs and one differential synchronization input, capable of locking across an input frequency range of 580 kHz to 180 MHz. The device includes four independently supplied differential outputs programmable as LVPECL or CML, supporting maximum frequencies up to 625 MHz. An integrated VCO operates between 2.35 GHz and 2.9 GHz. Configuration is achieved via a hardwired matrix without requiring an external microprocessor.

Feature Summary

• Fully configurable Integer-N PLL with integrated VCO (2.35 GHz–2.9 GHz) and hardwired configuration matrix
• Two differential LVPECL clock inputs (580 kHz–180 MHz) with automatic or manual source switching
• Four differential outputs (LVPECL or CML) with independent power supplies, supporting up to 625 MHz
• Data resynchronization path via SYNC input and output, compliant with OC3/OC12 RMS jitter requirements

Applications

• SONET/SDH clock cleaning and dejittering
• Ethernet interface synchronization
• PCI bus clock generation
• 3G wireless system timing
• Semtech line card parts integration (ACS8510, ACS8520, ACS8525, ACS8522, ACS8530, ACS9510)

Procurement Notes

Verify the specific package variant and temperature rating during acquisition. The datasheet specifies a QFN48 package (7 mm x 7 mm) and operation from -40°C to +85°C. Confirm that the ordering suffix matches the required configuration options, as settings are determined by hardwiring at power-up. Ensure evaluation tools are available for initial setup.

Selection Notes

Select this component when a microprocessor-free solution is required for jitter attenuation and frequency translation. The hardwired configuration method suits applications where system complexity must be minimized. Verify that the input frequency range (580 kHz–180 MHz) and output requirements (up to 625 MHz) align with the target design. Consider the need for external loop filter components to customize closed-loop bandwidth.

Part Context

The ACS8947T belongs to Semtech's Jitter Attenuating Multiplying Phase-Locked Loop (JAM PLL) family. It is positioned as a high-performance clock generator for telecommunications and data communication systems. The device complements other Semtech products like the ACS85xx series by providing robust clock conditioning and synchronization capabilities in a compact form factor.

Replacement Considerations

No direct public substitute part numbers are documented in the provided datasheet. When evaluating alternatives, ensure compatibility with LVPECL/CML interfaces, similar VCO frequency ranges, and comparable jitter performance metrics for SONET/SDH applications.