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

Overview

78P2352-IEL/F 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 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 fiber (NRZ) media paths with full ITU-T G.703, G.751, G.823, and Telcordia GR-253-CORE compliance.

For engineers reviewing the 78P2352-IEL/F datasheet, 78P2352-IEL/F pinout, 78P2352-IEL/F application, or 78P2352-IEL/F equivalent, key selection considerations include dual-channel jitter performance (±100 ppm Rx loss-of-lock threshold), configurable serial/parallel interface timing modes (synchronous, plesiochronous, loop-timing), and hardware/software mode selection via SPSL, SDO_E4, and SEN_CMI pins.

Technical Context

The 78P2352-IEL/F implements two independent channel paths, each with a Delay Locked Loop (DLL)-based CDR for both transmit and receive clock recovery. The Rx path includes an adaptive equalizer handling ≥12.7 dB cable loss and ITU-T G.783-compliant Loss of Signal detection with 110 UI assertion/clear thresholds.

In transmit, the device supports three serial timing modes (synchronous re-timing, plesiochronous, loop-timing) and two parallel modes (master/slave), all using a 4×8 FIFO for clock decoupling. The Tx CDR synthesizes a 278.528 MHz (E4) or 311.04 MHz (OC-3) clock, available at TXxCKP/N for system synchronization.

Key Specifications

Pinout & Package

78P2352-IEL/F is housed in a standard and thermally enhanced 128-pin JEDEC LQFP package (20 mm × 20 mm, 0.5 mm pitch). Pin functions are validated per datasheet Pages 16–21 and include dual-channel differential I/O (RXxP/N, CMIxP/N, ECLxP/N), reference clock inputs (CKREFP/N), serial control (SDI, SDO, SCLK, CS), and power/ground distribution across multiple VCC/GND pairs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 78P2352-IEL/F, the 78P2351-IEL/F offers identical per-channel performance at lower cost and power but eliminates dual-port capability, while the ICS87302AG-01LF provides CDR functionality only - requiring additional components to achieve full LIU functionality and increasing PCB area and validation effort.

Availability

78P2352-IEL/F is available at Aetrix Electronics and suitable for Central Office Interconnects, DSLAMs, and Add Drop Multiplexers requiring stable component supply, long-lifecycle support, and telecom-grade reliability.

Supply support for 78P2352-IEL/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 precision metrology and telecom interface solutions before its acquisition by Maxim Integrated in 2010.

The 78P2352-IEL/F belongs to Teridian's second-generation LIU product line, designed specifically for carrier-grade OC-3/STM-1 and E4 line interface applications in central office and access network equipment.

FAQ

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

The 78P2352-IEL/F serves as a dual-channel Line Interface Unit (LIU) that bridges digital framer ASICs to physical telecom media - supporting both 155.52 Mbps OC-3/STM-1 and 139.264 Mbps E4 rates. It performs clock and data recovery, CMI encoding/decoding, adaptive equalization, and jitter-compliant transmission. Its role is to ensure robust, standards-compliant signal integrity across coaxial and optical line interfaces in carrier infrastructure.

Does the 78P2352-IEL/F support independent configuration of each channel?

Yes, the 78P2352-IEL/F supports independent per-channel configuration for media type (CMI vs. NRZ), interface mode (serial LVPECL vs. 4-bit parallel), and timing mode (synchronous, plesiochronous, loop-timing) via dedicated register bits (CMI, PAR, SMOD[1:0]). Hardware pins like SDO_E4 and SEN_CMI set global defaults, but register-level control enables asymmetric operation - e.g., one channel on coax (CMI), the other on fiber (NRZ).

What reference clock frequencies does the 78P2352-IEL/F require for OC-3 and E4 operation?

For OC-3/STM-1 (155.52 Mbps), the 78P2352-IEL/F requires a 155.52 MHz differential LVPECL reference clock on CKREFP/N. For E4 (139.264 Mbps), it requires 139.264 MHz on the same pins. Lower-frequency options (77.76 MHz, 19.44 MHz, 17.408 MHz) are supported depending on CKSL and SDO_E4 settings, but full-rate operation mandates the corresponding line-rate clock.

How does the 78P2352-IEL/F handle Loss of Signal (LOS) detection?

The 78P2352-IEL/F implements ITU-T G.783-compliant LOS detection: in CMI mode, LOS asserts when peak signal drops ~19 dB below nominal for 110 unit intervals (UI), and clears at ~18 dB below nominal for 110 UI. In NRZ (fiber) mode, LOS triggers after >2.3 µs without transitions and clears after >4 transitions within 32 UI. LOS detection is disabled during local/remote loopback and monitor modes.

Can the 78P2352-IEL/F operate with a single-ended reference clock?

Yes - for reference frequencies ≤77.76 MHz, the 78P2352-IEL/F accepts a single-ended CMOS clock applied to CKREFP with CKREFN grounded. However, at full line rates (139.264/155.52 MHz), a differential LVPECL clock on CKREFP/N is mandatory to meet jitter and timing margin requirements specified in the datasheet.