Analog Devices Inc./Maxim Integrated 78P2352-IGTR

Overview

78P2352-IGTR from Teridian Semiconductor is a dual-channel Line Interface Unit (LIU) for OC-3/STM-1-E (155.52 Mbps) and E4 (139.264 Mbps) telecom line interfaces, integrating CDR-based NRZ-to-CMI conversion, adaptive receive equalization, and LVPECL/CMOS host interfacing in a single 128-pin LQFP package. It supports coaxial (75Ω CMI) and optical (NRZ) media paths with full ITU-T G.703, G.751, G.823, and Telcordia GR-253-CORE compliance.

For engineers reviewing the 78P2352-IGTR datasheet, 78P2352-IGTR pinout, 78P2352-IGTR application, or 78P2352-IGTR equivalent, key selection criteria include dual-channel jitter performance (±100 ppm Rx loss-of-lock threshold), configurable serial/parallel interface timing modes, integrated CDR-enabled re-timing, and hardware/software mode control via SPSL, SDO_E4, and SEN_CMI pins.

Technical Context

The 78P2352-IGTR implements two independent channel paths, each with a Delay Locked Loop (DLL)-based CDR for clock recovery and synthesis, supporting both synchronous (FIFO-re-timed) and plesiochronous (CDR-only, FIFO-bypassed) transmit operation. Its receiver includes an adaptive CMI equalizer handling ≥12.7 dB cable loss and AGC-controlled differential amplification.

Transmit path features include selectable LVPECL NRZ output for optical modules, transformer-coupled CMI driver compliant with ITU-T G.703 templates, and programmable loopback modes (local analog, remote analog, full digital). Reference clock inputs support 19.44 MHz to 155.52 MHz across CMOS and LVPECL formats depending on CKSL/SDO_E4 configuration.

Key Specifications

Pinout & Package

78P2352-IGTR is housed in a standard 128-pin JEDEC-compliant LQFP package with exposed thermal pad. Pin functions are fully documented across transmitter (CMIxP/N, ECLxP/N), receiver (RXxP/N), reference clock (CKREFP/N), system interface (SIxDP/N, POx[3:0]D), and control (SPSL, SDO_E4, SEN_CMI) groups.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 78P2352-IGTR, the 78P2351-IGTR offers channel isolation for unsynchronized E4 timing but sacrifices density, while the ICS87201AGI-01LFT provides OC-3 CDR functionality in smaller footprint but omits E4 support, adaptive equalization, and parallel interface-making neither a functional substitute without system-level redesign.

Availability

78P2352-IGTR is available at Aetrix Electronics and suitable for Central Office Interconnects, DSLAM Line Cards, and Add-Drop Multiplexers requiring stable component supply, long-lifecycle support, and traceable sourcing for telecom infrastructure programs.

Supply support for 78P2352-IGTR 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 designer specializing in highly integrated analog/mixed-signal solutions for telecommunications and energy metering before its acquisition by Maxim Integrated in 2010.

The 78P2352-IGTR belongs to Teridian's second-generation LIU product line, engineered specifically for carrier-grade SDH/SONET and PDH line interface consolidation in space-constrained, thermally demanding telecom line cards.

FAQ

What is the primary function of the 78P2352-IGTR in telecom systems?

The 78P2352-IGTR serves as a dual-channel Line Interface Unit (LIU) that bridges digital framer ASICs to physical telecom line media-supporting both 155.52 Mbps OC-3/STM-1 and 139.264 Mbps E4 rates. It performs CMI encoding/decoding, clock recovery, adaptive equalization, and media interface translation between coaxial and optical paths. Its integration reduces external component count while meeting stringent ITU-T and Telcordia jitter specifications required for carrier-class deployment.

Does the 78P2352-IGTR support both coaxial and fiber-optic media simultaneously?

Yes-the 78P2352-IGTR supports per-channel media selection: one channel can operate in CMI mode (75Ω coaxial) while the other operates in NRZ mode (fiber-optic), controlled independently via the SEN_CMI register bit. Hardware pin SEN_CMI applies globally, but register-level control enables mixed-media configurations without PCB modification. In NRZ mode, the CMI encoder/decoder is disabled and ECLxP/N pins drive LVPECL signals directly to optical transceivers.

How does the 78P2352-IGTR handle clock domain mismatches between framer and line interface?

The 78P2352-IGTR resolves clock domain mismatches using a 4×8 transmit FIFO and DLL-based CDR. In synchronous modes, the FIFO decouples framer clock (SIxCKP/N or PIxCK) from the synthesized 2× line-rate clock, tolerating up to ±25.6 ns phase drift. In plesiochronous mode, the Tx CDR recovers clock directly from incoming NRZ data, bypassing the FIFO. Both mechanisms prevent bit errors caused by long-term clock wander between framer and line-rate domains.

What are the power supply requirements for the 78P2352-IGTR?

The 78P2352-IGTR operates from a single 3.3 V supply across all functional blocks-including analog front-end, CDRs, digital logic, and I/O drivers. This eliminates need for auxiliary voltage rails and simplifies power delivery design. The device specifies recommended operating conditions at VCC = 3.3 V ± 0.3 V, with absolute maximum rating of 3.9 V. Thermal performance is enhanced in the IGTR variant via exposed thermal pad, supporting continuous operation in telecom line-card environments up to 70°C ambient.

Can the 78P2352-IGTR be configured without software initialization?

Yes-the 78P2352-IGTR supports hardware pin-control mode when SPSL is held low, enabling full configuration via dedicated pins (SDO_E4, SEN_CMI, SDI_PAR, CKMODE, etc.) without serial port access. This allows immediate operation after power-up in fixed-function applications. However, advanced features like per-channel media selection, full-digital loopback (FLBK), and fine-grained interrupt control require software mode (SPSL high) and register writes via the 4-wire serial interface.