Analog Devices Inc./Maxim Integrated DS21Q43AT

Overview

DS21Q43AT from Maxim Integrated (now part of Analog Devices) is a quad E1 framing transceiver IC designed for telecom line cards and access multiplexers. It integrates four independent E1 framers supporting FAS, CAS, CCS, and CRC4 formats; operates at 2.048 MHz primary clock; features dual two-frame elastic stores per framer up to 8.192 MHz; and delivers industrial-grade operation from −40°C to +85°C in a 128-pin TQFP package.

For engineers reviewing the DS21Q43AT datasheet, DS21Q43AT pinout, DS21Q43AT application, or DS21Q43AT equivalent, key selection considerations include per-framer elastic store independence, programmable output clocks for Fractional E1/H0/H12, CAS signaling extraction/insertion, AIS/remote alarm detection/generation, and pin compatibility with DS21Q41B Quad T1 Framer.

Technical Context

The DS21Q43AT implements four fully autonomous E1 framers-each with separate transmit/receive paths, independent elastic stores, and dedicated control registers-enabling concurrent asynchronous backplane interfacing up to 8.192 MHz. Each framer supports ITU-T G.704/G.706/G.962/I.431 and ETSI 300 011/300 233 compliance.

It provides parallel 8-bit non-multiplexed or multiplexed bus interface with Intel/Motorola timing support, framer-select logic (FS0/FS1), and hardware 3-state control (TEST). The device enables per-channel loopback, Sa/Si bit access, and automatic AIS/remote alarm generation upon loss of frame sync.

Key Specifications

Pinout & Package

DS21Q43AT is housed in a 128-pin Thin Quad Flat Package (TQFP) with exposed thermal pad, optimized for signal integrity and thermal dissipation in high-density telecom modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS21Q43AT, DS21Q41B targets T1-only systems and cannot process E1 framing or CAS signaling, while DS2155 offers identical functionality per channel but increases PCB area, power, and routing complexity-making DS21Q43AT optimal for space-constrained, multi-E1 telecom hardware.

Availability

DS21Q43AT is available at Aetrix Electronics and suitable for access multiplexers, E1 line cards, ISDN-PRI gateways, and fractional E1 routers requiring stable component supply across extended product lifecycles.

Supply support for DS21Q43AT 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 (acquired by Analog Devices in 2021) is a semiconductor leader specializing in high-performance analog, mixed-signal, and power management solutions for communications, industrial, and computing markets.

The DS21Q43AT belongs to Maxim's telecom framer product line, engineered specifically for carrier-grade E1 infrastructure-emphasizing multi-framer independence, ITU-T compliance, and industrial temperature resilience.

FAQ

What is the primary function of the DS21Q43AT in an E1 system?

The DS21Q43AT functions as a quad E1 framing transceiver, performing frame alignment (FAS), cyclic redundancy check (CRC4), channel-associated signaling (CAS), and multiframe synchronization for four independent 2.048 Mbps E1 lines. It handles both transmit and receive paths separately per framer, enabling full-duplex operation with hardware-accelerated alarm generation and elastic store buffering.

Does the DS21Q43AT support both CAS and CCS signaling modes?

Yes, the DS21Q43AT supports both Channel Associated Signaling (CAS) and Common Channel Signaling (CCS) modes. This is controlled by the RSM bit (CCR1.3): setting it to 0 selects CAS mode (e.g., for ETSI 300 011), and setting it to 1 selects CCS mode (e.g., for ISDN-PRI). The device provides dedicated Sa/Si bit access and RLINK/TLINK interfaces for seamless integration with signaling processors.

How does the elastic store feature operate in the DS21Q43AT?

The DS21Q43AT includes dual two-frame elastic stores per framer-configurable independently via RCR2.1 (receive) and TCR2.1 (transmit). When enabled, they buffer data to absorb clock domain mismatches between line-rate (2.048 MHz) and backplane clocks (up to 8.192 MHz), allowing asynchronous interfacing. RSYSCLK/TSYSCLK must be supplied at 1.544 MHz or 2.048 MHz, and associated sync pins (RFSYNC/RMSYNC/TFSYNC) become active.

Is the DS21Q43AT pin-compatible with other Maxim quad framers?

Yes, the DS21Q43AT is explicitly stated as pin-compatible with the DS21Q41B Quad T1 Framer. However, this compatibility applies only to physical footprint and parallel bus interface signals-not electrical behavior or framing logic. T1-specific functions (e.g., SF/B8ZS) and E1-specific features (e.g., CRC4, CAS) are not interchangeable; system-level redesign is required for cross-standard migration.

What industrial temperature range does the DS21Q43AT support?

The DS21Q43AT is specified for industrial operation from −40°C to +85°C, as confirmed by the DS21Q43ATN ordering variant referenced in the datasheet. This rating ensures reliable performance in uncontrolled environments such as outdoor cabinets, base station radios, and central office line cards where ambient temperatures exceed commercial limits.