8T49N242NLGI

Overview

The Renesas 8T49N242NLGI is a FemtoClock NG Universal Frequency Translator featuring one fractional-feedback PLL and four integer output dividers. It generates up to four independent output frequencies ranging from 8kHz to 1.0GHz (differential) or 250MHz (LVCMOS). The device accepts two input clocks (8kHz–875MHz) and a crystal reference (10MHz–50MHz), supporting LVPECL, LVDS, HCSL, and LVCMOS levels. Key electrical parameters include a typical jitter of 0.35ps RMS (12kHz–20MHz), an initial holdover accuracy of ±50ppb, and programmable loop bandwidths from 0.2Hz to 6.4kHz. It operates on 2.5V or 3.3V supplies within a -40°C to 85°C temperature range.

Feature Summary

• Generates up to four independent output frequencies from 8kHz to 1.0GHz using integer dividers.
• Supports hitless switching between two input references with automatic or manual selection.
• Provides 0.35ps RMS typical jitter performance (12kHz to 20MHz) for high-speed applications.
• Configurable via I2C interface with support for external EEPROM booting.

Applications

• OTN or SONET/SDH equipment
• Gigabit and Terabit IP switches/routers including Synchronous Ethernet
• Video broadcast systems

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm package type and boot configuration. Confirm RoHS compliance status as specifications may evolve. Check for End-of-Life notifications or product change notices prior to finalizing procurement plans.

Selection Notes

Select this component when designing frequency translation circuits requiring independent output frequencies unrelated to input references. Ensure the application supports the required input voltage levels (2.5V or 3.3V) and output drive types (LVPECL, LVDS, HCSL, or LVCMOS). Verify that the required loop bandwidth settings align with the jitter attenuation needs of the target network standard.

Part Context

This part belongs to the FemtoClock NG family of universal frequency translators. It is designed to replace legacy clock generators in high-performance networking and telecommunications infrastructure. The device integrates a fractional-N PLL with integer output dividers to provide flexible frequency synthesis capabilities.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided source material. Consult official distributor databases for cross-reference information if direct replacement is required.

FAQ

What is the maximum differential output frequency?

The maximum differential output frequency is 1.0GHz.

How does the device handle input clock failure?

The device monitors inputs for Loss of Signal (LOS) and can automatically switch to a backup reference or enter holdover mode based on configuration.

Can the device operate without an external input clock?

Yes, it can operate as a frequency synthesizer using only the crystal input by setting the SYN_MODE register bit.