Analog Devices Inc./Maxim Integrated DS2155L+

Overview

DS2155L+ 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 0°C to +70°C operation in 100-pin LQFP, delivers crystal-less jitter attenuation, programmable 75Ω/100Ω/120Ω termination, and 16.384MHz backplane clock synthesis locked to recovered network clock - deployed in carrier-grade T1/E1 line cards and edge routers.

For engineers reviewing the DS2155L+ datasheet, DS2155L+ pinout, DS2155L+ application, or DS2155L+ equivalent, key selection considerations include software-selectable T1/E1/J1 mode configuration, independent transmit/receive functionality, dual elastic-store slip buffers for asynchronous backplanes, CMI coding support for optical interfaces, and integrated BERT generator/detector for loop testing.

Technical Context

The DS2155L+ implements a fully integrated T1/E1/J1 physical layer transceiver with separate transmit and receive signal paths. Its LIU provides G.703-compliant waveshaping for 75Ω coax and 120Ω twisted-pair E1 lines, plus DSX-1 and CSU line buildouts (-7.5dB, -15dB, -22.5dB) for T1, while the framer handles T1 D4/ESF and E1 PCM-30/PCM-31 framing with CRC-4 multiframe processing.

Control is executed via an 8-bit parallel port supporting both Intel- and Motorola-bus timing, and the device features dual HDLC controllers with FIFO-based packet handling, programmable backplane clock synthesis (16.384/8.192/4.096/2.048MHz), and JTAG boundary-scan test access - all operating without external crystal reference due to its crystal-less jitter attenuator.

Key Specifications

Pinout & Package

DS2155L+ is housed in a 100-pin LQFP (14mm × 14mm, 0.5mm pitch) with exposed thermal pad. Pin functions are grouped into transmit interface, receive interface, parallel control port (8-bit Intel/Motorola bus), extended system information bus (ESIB), user output ports, JTAG test access, line interface, and supply pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2155L+, DS2156L+ offers drop-in upgrade path with identical pinout and register map but adds E1-specific alarm granularity and jitter performance margin; MC2021AIP serves narrower E1-framing use cases at lower integration level, requiring three additional ICs to match DS2155L+ functionality.

Availability

DS2155L+ is available at Aetrix Electronics and suitable for carrier-grade line cards, edge routers, add-drop multiplexers, and ISDN-PRI gateways requiring stable component supply across multi-year telecom equipment lifecycles.

Supply support for DS2155L+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and RF solutions for communications, industrial, and computing markets.

The DS2155L+ belongs to Maxim's Telecom Interface product line, engineered specifically for carrier-class T1/E1/J1 physical layer convergence in modular line interface units and multiservice access platforms.

FAQ

What is the operating temperature range for the DS2155L+?

The DS2155L+ is rated for commercial temperature operation from 0°C to +70°C. This range is validated per Maxim's production test flow and supports deployment in controlled-environment telecom infrastructure such as central office shelves and enterprise edge routers. The DS2155L+ does not support extended industrial or automotive temperature grades - those require the DS2155LN+ variant.

Does the DS2155L+ require an external crystal oscillator?

No, the DS2155L+ incorporates a crystal-less jitter attenuator that recovers and cleans clock signals directly from the incoming T1/E1 line. It eliminates the need for external TCXOs or VCXOs, reducing bill-of-materials cost and board space. External crystal connections are optional and only used if a local reference is required for specific test modes or backup timing.

How many HDLC controllers does the DS2155L+ integrate?

The DS2155L+ integrates two independent HDLC controllers - one for D-channel signaling (e.g., ISDN-PRI) and one for embedded operations channel (EOC) or control-plane messaging. Each controller features configurable FIFO depth, automatic flag detection, CRC-16 generation/checking, and interrupt-driven status reporting - enabling concurrent protocol handling without host CPU overhead.

Can the DS2155L+ support both T1 and E1 on the same hardware platform?

Yes, the DS2155L+ supports software-selectable T1, E1, and J1 modes via internal register configuration. A single PCB layout can be used across regional deployments by loading appropriate firmware - no hardware changes or jumper settings are needed. Mode selection is non-volatile and persists across power cycles when stored in external EEPROM or configured at boot.

What termination impedances does the DS2155L+ support on its line interface?

The DS2155L+ supports programmable termination impedances of 75Ω, 100Ω, and 120Ω on both transmit and receive sides - selectable independently per channel via register writes. This enables one hardware design to interface with T1 metallic (100Ω), E1 coaxial (75Ω), and E1 twisted-pair (120Ω) media without external resistor networks or layout variants.