Analog Devices Inc./Maxim Integrated DS21554LB

Overview

DS21554LB from Maxim Integrated is a 5V E1 single-chip transceiver (SCT) designed for CEPT PCM-30/ISDN-PRI line interface applications. It performs clock/data recovery from AMI/HDB3 E1 waveforms, provides 32-bit or 128-bit crystal-less jitter attenuation, supports G.703-compliant waveshaping for 75Ω coax and 120Ω twisted-pair, and integrates HDLC controller with 64-byte buffers for Sa-bit or DS0 operation. It operates over 0°C to +70°C in 100-pin LQFP.

For engineers reviewing the DS21554LB datasheet, DS21554LB pinout, DS21554LB application, or DS21554LB equivalent, key selection criteria include E1 framer compliance (G.703/G.704/G.706), dual elastic store support for asynchronous backplane interfacing up to 8.192MHz, IEEE 1149.1 JTAG boundary scan capability, programmable output clocks for fractional E1/H0/H12, and hardware-based CAS signaling extraction/insertion.

Technical Context

The DS21554LB implements a fully independent transmit and receive path architecture, each with dedicated elastic stores synchronized to separate backplane clocks (RSYSCLK/TSYSCLK). Its framer locates FAS, CAS, CCS, and CRC4 multiframe boundaries while monitoring for RLOS, AIS, RAIS, and remote alarm conditions.

It features a selectable jitter attenuator (32-bit or 128-bit depth) placed in either transmit or receive data path, an on-chip 8.192MHz clock synthesizer, and line interface circuitry supporting transformer-coupled analog input (RRING/RTIP) with receive sensitivity of 0 to –43dB, enabling operation over 2km of 22AWG twisted-pair cable.

Key Specifications

Pinout & Package

DS21554LB is housed in a 100-pin LQFP package (14mm × 14mm, 0.5mm pitch), thermally optimized for telecom line card applications with exposed thermal pad. Pin functions are organized into transmit-side, receive-side, parallel control port, JTAG test access, interleave bus, line interface, and supply groups.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS21554LN and DS2154L, the DS21554LB delivers optimal balance of industrial-grade feature set and commercial-temperature cost efficiency-supporting modern E1 system requirements like Sa-bit HDLC, JTAG testability, and 8.192MHz backplane interfacing without over-specifying for harsh environments.

Availability

DS21554LB is available at Aetrix Electronics and suitable for PCM-30 multiplexers, E1 line cards, ISDN PRI gateways, and network monitoring taps requiring stable component supply and long-term manufacturability.

Supply support for DS21554LB 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, computing, and industrial markets.

The DS21554LB belongs to Maxim's E1/T1 transceiver product line, engineered specifically for CEPT-compliant telecom infrastructure where integration, jitter performance, and regulatory compliance are critical.

FAQ

What is the operating voltage requirement for the DS21554LB?

The DS21554LB requires a nominal 5V ±5% supply voltage. This 5V operation aligns with legacy telecom system power rails and eliminates the need for level-shifting circuitry when interfacing with standard 5V logic and analog components. The DS21554LB does not support 3.3V operation-unlike the pin-compatible DS21354L variant-and its internal regulators and line drivers are optimized exclusively for 5V performance per G.703 specifications.

Does the DS21554LB support both coaxial and twisted-pair E1 interfaces?

Yes, the DS21554LB supports both 75Ω coaxial and 120Ω twisted-pair E1 interfaces through programmable line build-out (LBO) settings in the Line Interface Control Register (LICR). Its transmit waveshaping circuitry meets G.703 templates for both media types, and its receive sensitivity of 0 to –43dB ensures reliable operation over up to 2km of 22AWG twisted-pair cable without external amplification.

How does the DS21554LB handle E1 framing and alarm detection?

The DS21554LB's integrated framer locates FAS (Frame Alignment Signal), CAS (Channel-Associated Signaling), CCS (Common-Channel Signaling), and CRC4 multiframe boundaries in real time. It detects and generates RLOS (Receive Loss of Signal), AIS (Alarm Indication Signal), RAIS (Remote AIS), and remote alarm conditions, with interrupt capability on state change per ETS 300 011 and ETS 300 233 standards-ensuring rapid fault response in carrier-grade systems.

Can the DS21554LB be used in systems with asynchronous backplane clocks?

Yes, the DS21554LB includes dual independent elastic stores-one for receive and one for transmit-that accept asynchronous backplane clocks (RSYSCLK and TSYSCLK) up to 8.192MHz. This allows seamless bridging between the recovered 2.048MHz E1 clock domain and non-synchronous system clocks, supporting byte- or frame-interleaved PCM bus architectures without data loss or slip events.

Is the DS21554LB pin-compatible with earlier Maxim E1 transceivers?

Yes, the DS21554LB is pin-compatible with the DS2154/DS2152/DS21352/DS21552 single-chip transceivers. This enables drop-in replacement in existing designs while adding new capabilities-including HDLC-controlled Sa-bit/DS0 operation, JTAG boundary scan, 8.192MHz clock synthesis, and interleaved PCM bus support-without PCB layout changes or signal routing modifications.