Analog Devices Inc./Maxim Integrated 78P2344JAT-IGTR/F

Overview

The 78P2344JAT from TDK is a 4-port, single-chip Line Interface Unit (LIU) supporting E3 (34.368 Mbps), DS3 (44.736 Mbps), and STS-1 (51.840 Mbps) line rates with integrated jitter attenuator, adaptive digital clock recovery, and B3ZS/HDB3 ENDEC - designed for coaxial cable interfaces up to 1350 ft in DSLAMs, SONET add/drop multiplexers, and ATM WAN access routers.

For engineers reviewing the 78P2344JAT datasheet, 78P2344JAT pinout, 78P2344JAT application, or 78P2344JAT equivalent, key selection considerations include per-channel jitter attenuator path configuration (transmit/receive), LBO-controlled pulse shaping for 75-Ω coax, register-based local/remote loopback, DSX3 monitor signal reception, and 3.3V-only operation with no external loop filter or current-setting resistors.

Technical Context

The 78P2344JAT implements four independent transceiver channels, each with adaptive equalization, AGC (±6 dB flat loss compensation), and standards-compliant LOS detection per ITU-T G.775. Its digital PLL-based clock recovery uses an external line-rate CKREF input (34.368/44.736/51.840 MHz) and maintains nominal output frequency during loss-of-signal conditions.

Jitter attenuation is implemented via a configurable low-bandwidth digital PLL (≤283 Hz bandwidth) driving a FIFO-based elastic store (16–64 UI depth); it operates independently per channel in either transmit or receive path, meeting Telcordia GR-499-CORE (DS3), GR-253-CORE (STS-1), and ETSI TBR-24 (E3) requirements without external VCXO.

Key Specifications

Pinout & Package

Package: 100-pin Exposed Pad JEDEC LQFP (14 mm × 14 mm, 0.5 mm pitch) with thermal pad for enhanced thermal management in dense line card deployments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ICS87304AG-01 and MAX3675, the 78P2344JAT uniquely delivers quad-channel E3/DS3/STS-1 support with fully integrated, configurable jitter attenuation - eliminating external VCXOs and enabling compact, standards-compliant line cards for multi-protocol transport equipment.

Availability

The 78P2344JAT is available at Aetrix Electronics and suitable for DSLAM line cards, SONET add/drop multiplexers, ATM WAN access routers, PDH digital multiplexers, and fiber-to-coax conversion gateways requiring stable component supply and long-lifecycle support.

Supply support for 78P2344JAT 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

TDK Corporation is a Japanese multinational electronics company specializing in passive components, magnetic technology, and high-performance semiconductor solutions for communications infrastructure.

The 78P2344JAT belongs to TDK's high-integration Line Interface Unit product line, engineered specifically for carrier-class E3/DS3/STS-1 transport equipment requiring jitter compliance, redundancy, and multi-protocol flexibility in space-constrained line cards.

FAQ

What line rates does the 78P2344JAT support, and how is rate selection configured?

The 78P2344JAT supports E3 (34.368 Mbps), DS3 (44.736 Mbps), and STS-1 (51.840 Mbps) line rates. Rate selection is configured either via hardware pins (MSL0) at power-up or through the Master Control Register (MSCR) bits DS3/E3. The CKREF pin must be driven with the corresponding line-rate clock, and the MSCR register defaults reflect the MSL0 state after reset.

Does the 78P2344JAT require an external VCXO for jitter attenuation?

No, the 78P2344JAT does not require an external VCXO. Its fully integrated jitter attenuator uses an on-chip low-bandwidth digital PLL and FIFO-based elastic store. The JAT can be independently enabled and configured for transmit or receive path per channel via the Jitter Attenuator Control Register (JACR), meeting GR-499, GR-253, and ETSI TBR-24 requirements without external components.

How does the 78P2344JAT handle loss-of-signal (LOS) detection and maintain timing integrity?

The 78P2344JAT implements standards-based LOS detection per ITU-T G.775, asserting the LOS bit after a programmable delay to avoid false triggers. Critically, RCLKx continues to output a stable line-rate clock even during LOS - ensuring downstream framer ICs retain timing reference. The SGLO bit provides additional low-signal-level indication for diagnostic granularity.

Can the 78P2344JAT receive and process DSX3 monitor signals?

Yes, the 78P2344JAT supports DSX3 monitor signal reception via its Monitor Mode (MON bit in MDCR). When enabled, the receiver applies 20 dB of flat gain before the adaptive equalizer - allowing reliable decoding of split-off signals attenuated by 16–20 dB, commonly found at DS3 cross-connect test points.

What is the role of the LLBKA and LLBKB pins in redundant system design?

The LLBKA and LLBKB pins (or their register equivalents in MDCR) configure a 4-input MUX per receiver channel, enabling flexible redundancy schemes. For example, Port 1's receiver can be set to monitor Port 2's transmitter output (LLBKA/B = '10'), allowing real-time failover validation without external switch ICs - a key capability for carrier-grade 1+1 protection architectures.