Analog Devices Inc./Maxim Integrated DS2155LNB+

Overview

DS2155LNB+ from Maxim Integrated is a software-selectable T1/E1/J1 single-chip transceiver (SCT) integrating line interface unit (LIU), framer, dual HDLC controllers, and TDM backplane interface. It supports long-haul and short-haul operation, delivers programmable 75Ω/100Ω/120Ω termination, and synthesizes 16.384MHz/8.192MHz/4.096MHz/2.048MHz clocks locked to recovered network timing - deployed in carrier-grade T1/E1 line cards and add-drop multiplexers.

For engineers reviewing the DS2155LNB+ datasheet, DS2155LNB+ pinout, DS2155LNB+ application, or DS2155LNB+ equivalent, key selection criteria include software-selectable T1/E1/J1 mode support, crystal-less jitter attenuation, dual elastic-store slip buffers for asynchronous backplanes up to 16.384MHz, CMI coding capability for optical interfaces, and JTAG boundary-scan test compliance.

Technical Context

The DS2155LNB+ implements a fully independent transmit/receive architecture with separate LIU paths: its transmit interface generates G.703-compliant waveshapes for 75Ω coax and 120Ω twisted-pair E1 links, plus DSX-1 and CSU line buildouts (-7.5dB, -15dB, -22.5dB) for T1. The receive side performs clock/data recovery with jitter tolerance per ITU-T G.823/G.824 and includes a crystal-less jitter attenuator meeting GR-499-CORE requirements.

Control is handled via an 8-bit parallel port configurable for Intel- or Motorola-style bus timing, while dual HDLC controllers support independent framing and signaling on T1 (D4/ESF) and E1 (PCM-30/PCM-31) channels. The TDM backplane interface operates at up to 16.384MHz with two-frame elastic-store buffering and interleaved PCM bus (IBO) support.

Key Specifications

Pinout & Package

DS2155LNB+ is housed in a 100-pin LQFP (14mm × 14mm, 0.5mm pitch) package with exposed thermal pad. Pin functions are grouped into transmit/receive LIU, parallel control port (Intel/Motorola modes), extended system information bus (ESIB), JTAG test access, user output ports, and supply rails.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar T1/E1 transceiver applications.

Compared with DS2155LN+ and DS2156+, the DS2155LNB+ provides identical feature set and register compatibility at commercial temperature grade, making it optimal for cost-constrained indoor telecom infrastructure where extended temp range or next-gen diagnostics are not required.

Availability

DS2155LNB+ is available at Aetrix Electronics and suitable for T1/E1 line cards, carrier-grade routers, and add-drop multiplexers requiring stable component supply, RoHS-compliant packaging, and long-term industrial availability.

Supply support for DS2155LNB+ 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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and digital ICs for communications, computing, and industrial markets.

The DS2155LNB+ belongs to Maxim's telecom transceiver product line, designed specifically for carrier-class TDM infrastructure requiring multi-standard flexibility, jitter resilience, and system-level integration in compact form factors.

FAQ

What is the operating temperature range for DS2155LNB+?

The DS2155LNB+ is specified for operation from 0°C to +70°C. This commercial temperature grade suits indoor telecom equipment such as central office line cards, enterprise routers, and ISDN gateways where ambient conditions remain within this range. For extended-temperature applications down to -40°C, the DS2155LN+ variant is recommended. The DS2155LNB+ uses a lead-free 100-pin LQFP package compliant with RoHS Directive 2011/65/EU.

Does DS2155LNB+ support both T1 and E1 standards simultaneously?

Yes, the DS2155LNB+ supports T1, E1, and J1 standards via software-selectable configuration - but only one standard operates at a time per device instance. Its dual HDLC controllers and independent framer logic allow full protocol stack implementation for either T1 (D4/ESF) or E1 (PCM-30/PCM-31) in active mode, with seamless reconfiguration through register writes. Simultaneous dual-standard operation requires two DS2155LNB+ devices or use of the DS2156+ in multi-device ESIB configurations.

What clock synthesis capabilities does DS2155LNB+ provide?

The DS2155LNB+ integrates a programmable backplane clock synthesizer that generates 16.384MHz, 8.192MHz, 4.096MHz, or 2.048MHz outputs, all phase-locked to the recovered network clock. This eliminates need for external clock generators and ensures deterministic jitter transfer from line to backplane. The synthesizer supports fractional-N division for precise frequency alignment and maintains lock during network clock interruptions using holdover timing based on internal jitter attenuator stability.

Is DS2155LNB+ pin-compatible with other devices in the DS2155 family?

Yes, the DS2155LNB+ shares identical pinout and footprint with all LQFP-packaged DS2155 variants including DS2155L, DS2155LN, and DS2155LN+. Differences are limited to temperature grade and RoHS compliance (the "+" suffix denotes lead-free). This allows direct substitution in existing designs without PCB revision - provided thermal and reliability requirements align with the 0°C to +70°C rating of DS2155LNB+.

How does DS2155LNB+ handle jitter in long-haul T1/E1 links?

The DS2155LNB+ incorporates a crystal-less jitter attenuator meeting GR-499-CORE requirements, providing ≥20dB attenuation across 10Hz–10kHz. It recovers clean clock from jittered input signals and suppresses wander accumulation in long-haul links. Jitter tolerance complies with ITU-T G.823 (T1) and G.824 (E1), supporting input jitter up to 20UI peak-to-peak. The attenuator operates without external crystal, relying on internal PLL bandwidth tuning via register configuration.