Analog Devices Inc./Maxim Integrated DS21455N+

Overview

DS21455N+ from Maxim Integrated is a quad T1/E1/J1 transceiver IC featuring four independent, software-configurable transceivers with integrated line interface unit (LIU), framer, dual HDLC controllers, and TDM backplane interface. It operates across -40°C to +85°C, supports 75Ω/100Ω/120Ω termination, delivers 16.384MHz clock output synchronized to recovered network clock, and uses 3.3V supply with 5V-tolerant I/O for telecom channel banks and CSUs.

For engineers reviewing the DS21455N+ datasheet, DS21455N+ pinout, DS21455N+ application, or DS21455N+ equivalent, key selection considerations include quad-channel T1/E1/J1 interoperability, crystal-less jitter attenuation, software-selectable termination, IEEE 1149.1 JTAG boundary scan, and compatibility with legacy DS21Q55-based designs in industrial telecom infrastructure.

Technical Context

The DS22455N+ implements per-channel framer logic supporting both T1 (1.544Mbps) and E1 (2.048Mbps) framing standards, with full G.704/G.706 CRC-4 interworking and SS7 signaling support. Each transceiver includes independent transmit/receive paths, dual elastic-store slip buffers, and CMI encoding/decoding for short- and long-haul line interfaces.

Its 8-bit parallel control port supports Intel/Motorola bus timing and enables configuration of HDLC controllers, BERT generator/detector, and programmable output clocks for fractional T1/E1, H0, and H12 applications - all synchronized to a recovered network clock without external crystal.

Key Specifications

Pinout & Package

DS21455N+ is housed in a 256-ball BGA package (27mm × 27mm, 1.0mm pitch), RoHS-compliant and lead-free. Pin functions are defined per Maxim's official pin diagram (Figure 5-1, DS21455 Pin Diagram, 27mm BGA).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS21455 and DS21458N+, the DS21455N+ uniquely combines industrial temperature range (-40°C to +85°C), 27mm BGA mechanical compatibility with legacy DS21Q55 layouts, and full software equivalence - making it the preferred drop-in upgrade for deployed CSU/DSU systems requiring extended environmental resilience.

Availability

DS21455N+ is available at Aetrix Electronics and suitable for channel service units (CSUs), data service units (DSUs), and telecom routers requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for DS21455N+ 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 RF solutions for communications, computing, and industrial markets.

The DS21455N+ belongs to Maxim's telecom transceiver product line, designed specifically for carrier- and enterprise-grade T1/E1/J1 infrastructure where interoperability, jitter performance, and software configurability are critical.

FAQ

What is the operating temperature range of the DS21455N+?

The DS21455N+ is rated for industrial operation from -40°C to +85°C. This extended range enables reliable deployment in outdoor telecom cabinets, industrial control panels, and unconditioned central office environments where ambient temperatures exceed commercial-grade limits. The DS21455N+ maintains full electrical specifications across this entire range, including jitter tolerance, clock synthesis accuracy, and HDLC controller timing.

Is the DS21455N+ pin-compatible with the DS21Q55?

Yes, the DS21455N+ is a direct replacement for the DS21Q55 quad MCM device, maintaining identical 256-ball BGA footprint (27mm × 27mm) and pinout. However, the DS21455N+ integrates all functions monolithically and features a single JTAG controller for all four transceivers - unlike the per-transceiver JTAG architecture of the DS21Q55 - requiring minor firmware adaptation for boundary-scan test patterns.

Does the DS21455N+ support both T1 and E1 framing standards?

Yes, the DS21455N+ supports full T1 (DS1), E1 (CEPT), and J1 framing standards within each of its four independent transceivers. Configuration is performed via internal registers: T1 mode enables G.704 D4/Superframe and ESF framing; E1 mode supports G.704 PCM-30, CRC-4 multiframe, and SS7 signaling. Both modes share the same physical interface and clock synthesis architecture.

What termination resistances does the DS21455N+ support, and how are they selected?

The DS21455N+ supports software-selectable 75Ω, 100Ω, and 120Ω line termination for both T1 and E1 interfaces. Selection is made per channel using dedicated bits in the LIU control registers (e.g., TERMO[1:0]). This allows mixed-termination configurations across channels - for example, Channel 0 set to 75Ω for coaxial T1, Channel 2 set to 120Ω for twisted-pair E1 - without external resistor changes.

How does the DS21455N+ handle clock synchronization without an external crystal?

The DS21455N+ uses an on-chip crystal-less jitter attenuator that locks to the recovered network clock, synthesizing precise output clocks (16.384MHz, 8.192MHz, etc.) directly from the incoming data stream. This eliminates the need for external crystal oscillators or VCXOs while meeting GR-499-CORE jitter transfer and jitter tolerance requirements for T1/E1 applications.