Analog Devices Inc./Maxim Integrated 78P2351-IGTR/F

Overview

The 78P2351-IGTR/F from Teridian Semiconductor is a single-channel Line Interface Unit (LIU) designed for OC-3/STM-1-E (155.52 Mbps) and E4 (139.264 Mbps) telecom line interfaces. It integrates a CDR in the transmit path, supports dual-media operation (75Ω coaxial CMI or fiber-optic NRZ), complies with ITU-T G.703, G.751, G.823, G.825, G.958 and Telcordia GR-253-CORE jitter standards, and operates from a single 3.3V supply.

For engineers reviewing the 78P2351-IGTR/F datasheet, 78P2351-IGTR/F pinout, 78P2351-IGTR/F application, or 78P2351-IGTR/F equivalent, this device serves as a full-featured, standards-compliant LIU for SDH/SONET and PDH interconnects-requiring precise jitter tolerance, adaptive equalization, configurable serial/parallel host interfacing, and hardware/software mode control.

Technical Context

The 78P2351-IGTR/F implements a Delay Locked Loop (DLL)-based clock recovery architecture in both receive and transmit paths. Its Rx path includes an adaptive CMI equalizer handling ≥12.7 dB cable loss and ITU-T G.783–compliant Loss of Signal detection; Tx path features integrated CMI encoding, selectable LVPECL NRZ media interface, and a 2× line-rate (278.528/311.04 MHz) clock synthesizer available at TXCKP/N pins.

Configuration is supported via hardware control pins (e.g., SPSL, SEN_CMI, SDO_E4, SDI_PAR) or a 4-wire serial interface. Mode selection determines reference clock frequency (19.44/77.76/155.52 MHz or 17.408/139.264 MHz), media coding (CMI vs. NRZ), and host interface type (LVPECL serial or 4-bit CMOS parallel with master/slave timing).

Key Specifications

Pinout & Package

Package: 100-pin JEDEC-standard LQFP (14 mm × 14 mm, 0.5 mm pitch), lead-free and RoHS-compliant per ordering suffix /F.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Line Interface Unit applications.

Compared with MAX3675 and ICS87301, the 78P2351-IGTR/F uniquely delivers adaptive CMI equalization for ≥12.7 dB coax loss, dual-rate E4/STM-1 operation, and full ITU-T/Telcordia jitter compliance-making it the only option among the three qualified for carrier-class central office and ADM deployments requiring both PDH and SDH line interface functionality.

Availability

The 78P2351-IGTR/F is available at Aetrix Electronics and suitable for Central Office Interconnects, DSLAM Backhaul Interfaces, and Add-Drop Multiplexers requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for telecom infrastructure programs.

Supply support for 78P2351-IGTR/F includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Teridian Semiconductor was a fabless analog/mixed-signal IC company specializing in metrology, communications, and power management solutions before its acquisition by Maxim Integrated in 2010.

The 78P2351-IGTR/F belongs to Teridian's second-generation Line Interface Unit product line, engineered specifically for carrier-grade SDH/SONET and PDH physical layer termination in central office, transport, and test equipment.

FAQ

What is the primary function of the 78P2351-IGTR/F in telecom systems?

The 78P2351-IGTR/F functions as a single-channel Line Interface Unit (LIU) that bridges digital framer/mapper ICs to physical transmission media-supporting both 155.52 Mbps OC-3/STM-1 and 139.264 Mbps E4 line rates. It performs CMI encoding/decoding, clock recovery via DLL, adaptive equalization, and standards-compliant jitter handling. The 78P2351-IGTR/F is deployed in central office gear, ADMs, and test equipment where full ITU-T and Telcordia physical layer compliance is mandatory.

Does the 78P2351-IGTR/F support both coaxial and optical media interfaces?

Yes, the 78P2351-IGTR/F supports dual-media operation: CMI-coded 75Ω coaxial cable via CMIP/N outputs (with external transformer), and LVPECL-level NRZ optical interface via ECLP/N outputs (direct connection to fiber transceivers). Media selection is controlled by the SEN_CMI pin or register bit; in NRZ mode, the CMI encoder/decoder and adaptive equalizer are bypassed. This flexibility allows one device to serve both copper and fiber line card variants.

What reference clock frequencies does the 78P2351-IGTR/F accept?

The 78P2351-IGTR/F accepts reference clocks at 19.44 MHz, 77.76 MHz, or 155.52 MHz for STM-1 operation, and 17.408 MHz or 139.264 MHz for E4 operation-selected via CKSL and SDO_E4 pins or register bits. Frequencies ≤77.76 MHz may be applied as single-ended CMOS to CKREFP (CKREFN grounded); frequencies >77.76 MHz require differential LVPECL input at CKREFP/N. The 78P2351-IGTR/F uses this reference for all internal clock synthesis and DLL operations.

How does the adaptive equalizer in the 78P2351-IGTR/F improve system performance?

The adaptive CMI equalizer in the 78P2351-IGTR/F compensates for intersymbol interference caused by up to 12.7 dB of coaxial cable loss-enabling reliable signal recovery over extended distances without external analog equalization. It dynamically adjusts gain to maintain constant output amplitude regardless of input level, and is disabled in NRZ (fiber) mode. This feature directly reduces BOM cost and improves margin in central office interconnects where cable runs exceed 300 meters.

Is the 78P2351-IGTR/F pin-compatible with earlier Teridian LIUs like the 78P2350?

No, the 78P2351-IGTR/F is not pin-compatible with the 78P2350. While both are single-channel LIUs, the 78P2351-IGTR/F introduces revised pin assignments-including dedicated CMI2P/N monitor outputs, updated control pin mapping (e.g., SPSL for SW/HW mode selection), and relocated serial interface pins-to accommodate enhanced features like loop-timing mode and expanded register access. Board redesign is required when upgrading from 78P2350 to 78P2351-IGTR/F.