78P2351-IGT/F

Overview

The 78P2351-IGT/F is a single-channel Line Interface Unit (LIU) designed for 155.52 Mbps OC-3/STM-1 and 140.064 Mbps E4 telecom interfaces. It integrates an adaptive equalizer, clock recovery unit, and CMI encoder/decoder to support both 75 Ω coaxial cable transmission with CMI coding and optical fiber links using NRZ signaling. The device operates from a single 3.3V supply and accepts reference clocks ranging from 19.44 MHz to 155.52 MHz depending on the selected mode. It provides flexible host interface options including serial LVPECL and 4-bit parallel CMOS modes.

Feature Summary

• Integrated adaptive equalizer and clock recovery unit in the receive path to handle significant cable loss.
• Supports dual media interfaces: 75 Ω coaxial via CMI coding and optical fiber via NRZ signaling.
• Flexible system interface supporting both serial LVPECL and 4-bit parallel CMOS data formats.
• Configurable through hardware control pins or a 4-wire serial interface for mode selection.

Applications

• Central Office Interconnects
• DSLAMs
• Add Drop Multiplexers (ADMs)
• PDH/SDH test equipment
• Multi Service Switches

Procurement Notes

Verify component authenticity by checking manufacturer markings against official datasheet specifications. Confirm package integrity and pin alignment prior to installation. Ensure compatibility with existing system voltage levels and signal standards. Review end-of-life status as this component may be discontinued. Source only from authorized distributors to avoid counterfeit parts.

Selection Notes

Select this component when a single-chip solution for OC-3/STM-1 or E4 line interfacing is required. Ensure the design supports either coaxial or optical media based on the SEN_CMI configuration. Verify that the system reference clock frequency matches the supported ranges of 19.44 MHz, 77.76 MHz, or higher. Confirm that the host framer supports the desired serial or parallel interface timing modes.

Part Context

This part belongs to the 78P235x series of Line Interface Units manufactured by Analog Devices / Maxim Integrated. It represents a second-generation LIU solution offering integrated clock and data recovery capabilities. The device is designed to replace discrete solutions by combining transmitter and receiver circuitry into a single 100-pin LQFP package.

Replacement Considerations

Check for direct substitutes within the 78P235x family such as the 78P2352. Verify pinout compatibility and register mapping if replacing with similar LIU devices. Ensure that any alternative component supports the same jitter performance standards and interface protocols.

FAQ

How does the 78P2351 handle cable loss in the receive path?

The device includes an integrated adaptive equalizer and clock recovery unit in the receive path, which can handle over 12.7dB of cable loss caused by inter-symbol interference.

What are the available host interface options?

The 78P2351 offers a serial LVPECL-compatible interface and a 4-bit parallel CMOS interface, both supporting master and slave clock modes for flexibility with various framers.

Can the device operate in both coaxial and fiber modes?

Yes, the device can interface to 75 Ω coaxial cable using CMI coding or directly to a fiber optics transceiver module using NRZ coding, selected via the SEN_CMI pin or register bit.