Analog Devices Inc./Maxim Integrated 78P2352-IELR/F

Overview

78P2352-IELR/F from Teridian Semiconductor is a dual-channel Line Interface Unit (LIU) for OC-3/STM-1-E/E4 telecom systems, supporting 155.52 Mbps CMI coax and 139.264 Mbps NRZ optical interfaces. It integrates adaptive CMI equalization, receive clock recovery via DLL, and transmit CDR with 278.528/311.04 MHz synthesized clock generation. Used in central office interconnects requiring ITU-T G.703 compliance and jitter performance per GR-253-CORE.

For engineers reviewing the 78P2352-IELR/F datasheet, 78P2352-IELR/F pinout, 78P2352-IELR/F application, or 78P2352-IELR/F equivalent, key selection criteria include dual-channel CMI/NRZ media interface flexibility, hardware/software configuration via SPSL/serial port, 3.3V single-supply operation, and support for both synchronous and plesiochronous transmit timing modes.

Technical Context

The 78P2352-IELR/F implements two independent LIU channels, each with a Delay Locked Loop (DLL)-based clock recovery system for both Rx and Tx paths. It supports selectable reference clock inputs (19.44/77.76/155.52 MHz CMOS or LVPECL) and provides dual-mode media interface: transformer-coupled 75Ω CMI for coax or AC-coupled 100Ω NRZ for fiber.

Each channel features configurable serial (LVPECL) or 4-bit parallel (CMOS) host interface, with FIFO-based clock decoupling enabling ±25.6 ns phase drift tolerance. Transmit path includes integrated CMI encoder, tri-state CMI driver, and optional fixed LVPECL backplane equalizer activated by TXOUT1/TXEQ.

Key Specifications

Pinout & Package

78P2352-IELR/F is housed in a standard 128-pin JEDEC LQFP package with exposed thermal pad. Pin functions are fully defined per channel (Rx/Tx), including differential analog I/O (RXxP/N, CMIxP/N, ECLxP/N), LVPECL system interface (SIxDP/N, SOxDP/N), CMOS parallel interface (PIx[3:0]D, POx[3:0]D), and dedicated control/status pins (SPSL, SEN_CMI, SDO_E4).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 78P2352-IELR/F, the 78P2351-IELR/F reduces channel count but retains full feature parity per channel-ideal for E4-constrained deployments-while the ICS87333AG-01LFT offers OC-3-only capability in smaller package but lacks dual-channel integration and E4 support.

Availability

78P2352-IELR/F is available at Aetrix Electronics and suitable for central office interconnects, DSLAMs, and add-drop multiplexers requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for carrier-grade telecom hardware.

Supply support for 78P2352-IELR/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 measurement solutions before its acquisition by Maxim Integrated in 2010.

The 78P2352 belongs to Teridian's second-generation LIU product line, engineered specifically for carrier-class SDH/SONET and PDH line interface applications with emphasis on jitter performance, media flexibility, and system-level configurability.

FAQ

What is the primary function of the 78P2352-IELR/F in telecom systems?

The 78P2352-IELR/F serves as a dual-channel Line Interface Unit (LIU) that bridges digital framer/mapper ICs to physical transmission media-supporting both 155.52 Mbps OC-3/STM-1 CMI coax and 139.264 Mbps E4 NRZ optical interfaces. It performs clock recovery, line coding, jitter filtering, and LOS detection, making it essential for central office, DSLAM, and ADM equipment compliant with ITU-T and Telcordia standards.

Does the 78P2352-IELR/F support both hardware and software configuration modes?

Yes, the 78P2352-IELR/F supports dual configuration modes. When SPSL pin is low, it operates in hardware mode using dedicated control pins (SEN_CMI, SDO_E4, SDI_PAR). When SPSL is high, it enters software mode and is configured via a 4-wire serial port interface, allowing dynamic register-level control of media type, rate, interface mode, and loopback functions-all without changing PCB layout.

How does the 78P2352-IELR/F handle clock domain mismatches between host and line interfaces?

The 78P2352-IELR/F uses a 4×8 deep FIFO with DLL-synthesized clocks to decouple host and line timing domains. It tolerates up to ±25.6 ns of bounded phase drift between the reference clock (CKREFP/N) and host transmit clock. Exceeding this causes FIFO overflow/underflow, flagged by FERRx-enabling real-time error detection and corrective action such as FRSTx reset in the 78P2352-IELR/F.

What are the key differences between CMI and NRZ modes in the 78P2352-IELR/F?

In CMI mode (SEN_CMI = high), the 78P2352-IELR/F encodes/decodes CMI line code, applies adaptive equalization to RXxP/N, and drives CMIxP/N for 75Ω coax. In NRZ mode (SEN_CMI = low), it bypasses CMI encoder/decoder and equalizer, routing raw NRZ through ECLxP/N to optical transceivers. Both modes share the same reference clock architecture and LOS detection logic, but only CMI mode supports full G.703 compliance.

Is the 78P2352-IELR/F compatible with legacy E4 and modern STM-1 infrastructure?

Yes, the 78P2352-IELR/F natively supports both E4 (139.264 Mbps) and STM-1 (155.52 Mbps) rates via SDO_E4 pin or E4 register bit. Its dual-rate capability, combined with independent channel configuration and G.703/G.783 compliance, enables seamless integration into hybrid PDH/SDH networks-allowing service providers to migrate incrementally while reusing existing 78P2352-IELR/F-based line cards.