Analog Devices Inc./Maxim Integrated DS21FT42N

Overview

DS21FT42N from Maxim Integrated is a 12-channel T1 framer multichip module (MCM) implementing four DS21Q42 quad-framer die in a single 300-pin BGA package. It supports full T1 line framing (1.544 Mbps per channel), IEEE 1149.1 JTAG boundary scan, and operates across –40°C to +85°C for industrial telecom line cards. Each of its 12 framers handles independent receive/transmit data paths with elastic store buffering and HDLC signaling support.

For engineers reviewing the DS21FT42N datasheet, DS21FT42N pinout, DS21FT42N application, or DS21FT42N equivalent, this device serves as a high-density, temperature-hardened solution for DSLAMs, TDM multiplexers, and carrier-grade switching systems requiring precise T1 timing, channelized signaling, and JTAG-testable framer integration.

Technical Context

The DS21FT42N implements a 4×3 MCM architecture-three DS21Q42 quad-framer die-delivering 12 independent T1 framers with full DS0-level monitoring, FDL/FS extraction/insertion, and programmable in-band code generation. Its clock architecture uses a shared 8.192 MHz system clock derived from CLKSI, with individual RCLK/TCLK inputs per framer and synchronized TSYSCLK/RSYSCLK domains.

It supports both processor-based and hardware-based signaling modes, includes an HDLC controller for DS0 channels, and enables concatenated backplane streaming at 8.192 MHz. The fourth framer quadrant is unpopulated (NC), eliminating associated signals like RLOS, RLINK, TLCLK, and TCHCLK per Table 1-1 and Figure 1-1.

Key Specifications

Pinout & Package

DS21FT42N is housed in a 300-pin, 27 mm × 27 mm, 1.27 mm pitch ball grid array (BGA) package. Pin functions are defined per Table 2-1 in the official datasheet, with dedicated signal groups per framer quadrant (1–3 active; quadrant 4 NC). Power and ground pins are distributed across all quadrants for low-noise operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar T1 framer applications.

Compared with DS21FT42N, DS21FT42 lacks extended temperature support but offers identical functionality at lower cost for controlled environments, while DS21FF42N provides 4 additional framers in the same footprint-enabling scalable line-card designs without layout changes.

Availability

DS21FT42N is available at Aetrix Electronics and suitable for DSLAMs, TDM multiplexers, and carrier-class switching systems requiring stable component supply, long lifecycle assurance, and industrial temperature resilience.

Supply support for DS21FT42N 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) designs precision analog, mixed-signal, and high-reliability communication ICs for telecom, industrial, and automotive markets.

The DS21FT42N belongs to Maxim's T1/E1 framer family, engineered specifically for high-density, carrier-grade access equipment requiring robust framing, signaling, and testability in harsh thermal environments.

FAQ

What is the operating temperature range of the DS21FT42N?

The DS21FT42N is rated for –40°C to +85°C operation, making it suitable for uncontrolled environments such as street cabinets, remote DSLAMs, and industrial telecom enclosures. This extended range distinguishes it from the commercial-grade DS21FT42 (0°C to +70°C) and ensures reliable framer performance under thermal stress.

How many T1 framers does the DS21FT42N integrate, and how are they organized?

The DS21FT42N integrates 12 independent T1 framers arranged as three DS21Q42 quad-framer die in a 4×3 multichip module. Quadrant 4 is unpopulated-signals like RLOS, RLINK, TLCLK, and TCHCLK are No Connects-and all 12 framers share JTAG, control bus, and 8.192 MHz backplane resources.

Is the DS21FT42N pin-compatible with other devices in the same family?

Yes, the DS21FT42N is pin-compatible with DS21FT44 (T1/E1 dual-mode version) and shares the same 300-pin BGA footprint as DS21FF42N. This allows a single PCB layout to support 12-channel T1, 16-channel T1, or mixed T1/E1 configurations through firmware and BOM changes only.

Does the DS21FT42N support JTAG boundary scan, and what is its implementation scope?

Yes, the DS21FT42N fully implements IEEE 1149.1 JTAG boundary scan across all 12 framers and the MCM interconnect. It supports instruction register loading, data register access, and scan chain visibility for all digital I/O pins-including RCLK, TCLK, RPOS/TPOS, and control signals-enabling comprehensive board-level test coverage.

What signaling protocols and features does the DS21FT42N support per T1 channel?

The DS21FT42N supports D4, ESF, and SLC-96 framing; HDLC-based CAS/CCS signaling; FDL/FS extraction and insertion; and programmable in-band code generation/detection. Each of its 12 channels independently handles robbed-bit scanning, AIS/RAI generation, and DS0-level monitoring per GR-499-CORE and Telcordia requirements.