8T49N282C-999NLGI

Overview

The 8T49N282C-999NLGI is a FemtoClock NG Octal Universal Frequency Translator manufactured by Renesas Electronics. It features two independent fractional-feedback PLLs capable of jitter attenuation and frequency translation. The device generates up to eight output frequencies ranging from 8kHz to 1GHz using six integer and two fractional output dividers. It accepts up to four differential or single-ended input clocks and supports LVPECL, LVDS, or LVCMOS output levels. Key electrical parameters include an initial holdover accuracy of ±50ppb, programmable loop bandwidth from 0.5Hz to 512Hz, and RMS phase jitter below 0.3ps (including spurs) for differential outputs in the 12kHz to 20MHz range.

Feature Summary

• Dual independent fractional-feedback PLLs with hitless reference switching and holdover capabilities
• Generates up to eight output frequencies (8kHz to 1GHz) with <0.3ps RMS jitter for differential outputs
• Supports SDH/SONET and Synchronous Ethernet standards including ITU-T G.709 FEC rates
• Configurable via I2C/SPI interface with external EEPROM boot support

Applications

• OTN or SONET/SDH equipment line cards supporting FEC ratios
• Gigabit and Terabit IP switches/routers with Synchronous Ethernet support
• Wireless base station baseband units
• Data communications network infrastructure

Procurement Notes

Verify the specific ordering suffix '999' against the manufacturer's datasheet to confirm factory pre-programmed configuration settings. Confirm package type is 72QFN and operating temperature range is -40°C to 85°C. Ensure compatibility with required supply voltages (VCC/VCCA/VCCO).

Selection Notes

Select this component when dual independent clock domains are required for separate transmit and receive paths. Verify that the input frequency range (up to 875MHz) and output requirements (up to 1GHz) align with system specifications. Consider the need for gapped clock support and specific jitter attenuation limits for 100G Ethernet or STM-256 applications.

Part Context

The 8T49N282 belongs to the FemtoClock NG family of universal frequency translators. Originally developed by Integrated Device Technology (IDT), the product line was acquired by Renesas Electronics. This specific model provides octal output capabilities with advanced phase alignment and low-jitter performance suitable for high-speed serial communication standards.

Replacement Considerations

Consult official cross-reference documentation for pin-compatible alternatives within the 8T49N2xx series. Verify that any substitute maintains the same 72QFN package dimensions and electrical characteristics for direct replacement.

FAQ

What is the maximum RMS phase jitter for the differential outputs?

The differential outputs meet jitter limits of less than 0.3ps RMS (including spurs) in the 12kHz to 20MHz range.

How does the device handle input clock failure?

The device monitors all inputs for Loss of Signal (LOS) and supports automatic or manual hitless switching to redundant backup clocks. If no valid input remains, it enters holdover mode with an initial accuracy of ±50ppb.

Can the device operate as a standalone frequency synthesizer?

Yes, the device can act as a frequency synthesizer where the PLLs generate operating frequencies from the crystal input alone, without requiring external clock references.