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

Overview

The 78P2351-IGT/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-IGT/F datasheet, 78P2351-IGT/F pinout, 78P2351-IGT/F application, or 78P2351-IGT/F equivalent, key selection considerations include its dual-rate support (139.264/155.52 Mbps), configurable serial (LVPECL) or 4-bit parallel CMOS host interface, adaptive CMI equalizer handling >12.7 dB cable loss, integrated Rx LOS detection per ITU-T G.783, and 100-pin JEDEC LQFP package with hardware/software configuration flexibility.

Technical Context

The 78P2351-IGT/F implements a Delay Locked Loop (DLL)-based clock recovery architecture in both receive and transmit paths, using a reference clock applied to CKREFP/N pins at 19.44 MHz, 77.76 MHz, 139.264 MHz, or 155.52 MHz depending on rate and CKSL/SDO_E4 settings. Its receiver includes an AGC-controlled variable-gain amplifier and adaptive equalizer for CMI-mode coaxial inputs, while bypassing both in NRZ fiber mode.

In transmit, it supports synchronous re-timing (with FIFO), plesiochronous (CDR-enabled, FIFO-bypassed), and loop-timing modes; the CMI encoder generates a 278.528/311.04 MHz 2× line-rate clock available at TXCKP/N pins. Configuration is possible via dedicated HW control pins (e.g., SPSL, SEN_CMI, SDO_E4) or a 4-wire serial interface supporting register-level control of mode, signal, and advanced Tx functions.

Key Specifications

Pinout & Package

Package: 100-pin JEDEC LQFP (14 mm × 14 mm, 0.5 mm pitch), lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with the 78P2351-IGT/F, MAX3675 offers simpler power architecture but omits E4 rate support and adaptive coax equalization, while DS38EP100 provides higher bandwidth and advanced equalization yet lacks CMI coding, LOS detection, and telecom standard compliance - making the 78P2351-IGT/F uniquely suited for dual-rate, standards-compliant telecom line interface designs.

Availability

The 78P2351-IGT/F is available at Aetrix Electronics and suitable for Central Office Interconnects, DSLAMs, and Add Drop Multiplexers requiring stable component supply across extended product lifecycles and legacy telecom infrastructure refresh cycles.

Supply support for 78P2351-IGT/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 IC design company specializing in mixed-signal telecom and energy metering solutions before its acquisition by Maxim Integrated in 2008.

The 78P2351-IGT/F belongs to Teridian's second-generation Line Interface Unit product line, engineered specifically for carrier-grade OC-3/STM-1-E and E4 physical layer interfacing with full jitter compliance and dual-media (coax/fiber) support.

FAQ

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

The 78P2351-IGT/F serves as a Line Interface Unit (LIU) that bridges digital framer/mapper ASICs to physical transmission media-supporting both 75Ω coaxial (CMI-coded) and fiber-optic (NRZ) interfaces at 139.264 Mbps (E4) or 155.52 Mbps (OC-3/STM-1). It performs clock recovery, line coding, jitter filtering, and Loss of Signal detection per ITU-T and Telcordia standards. The 78P2351-IGT/F integrates all necessary analog and digital circuitry for compliant, single-chip line interface implementation.

Does the 78P2351-IGT/F support both E4 and OC-3/STM-1 data rates?

Yes, the 78P2351-IGT/F natively supports both 139.264 Mbps (E4) and 155.52 Mbps (OC-3/STM-1) rates. Rate selection is controlled by the SDO_E4 pin or corresponding E4 register bit, and automatically adjusts reference clock frequency requirements (e.g., 17.408 MHz for E4, 19.44 MHz for STM-1 in low-CKSL mode). This dual-rate capability enables reuse across PDH and SDH infrastructure without hardware redesign.

How does the 78P2351-IGT/F handle jitter compliance for carrier-grade applications?

The 78P2351-IGT/F meets jitter tolerance, generation, and transfer requirements per ANSI T1.105.03-1994, ITU-T G.751, G.813, G.823, G.825, G.958, and Telcordia GR-253-CORE. Its DLL-based CDR architecture, adaptive equalizer, and precision CMI encoder ensure end-to-end jitter performance within specification limits across temperature and voltage variations. The 78P2351-IGT/F is validated for use in Central Office and ADM deployments where jitter compliance is mandatory.

Can the 78P2351-IGT/F operate with a single 3.3V supply?

Yes, the 78P2351-IGT/F operates from a single 3.3 V ± 5% supply rail for all internal logic, analog front-end, and I/O circuits. No auxiliary voltages (e.g., 2.5 V or 1.8 V) are required. This simplifies power delivery design and reduces BOM count compared to multi-rail LIUs. The 78P2351-IGT/F maintains full functionality-including CDR lock, equalization, and LOS detection-across the specified supply range and operating temperature.

What configuration interfaces does the 78P2351-IGT/F support?

The 78P2351-IGT/F supports two independent configuration methods: hardware pin control (SPSL pin low) using dedicated mode-select pins (SEN_CMI, SDO_E4, SDI_PAR, CKMODE), and software control (SPSL pin high) via a 4-wire serial interface accessing 16 global and port-specific registers. Both methods configure rate, media mode, host interface type, loopback, and advanced timing parameters. The 78P2351-IGT/F allows seamless transition between modes without reset.