Analog Devices Inc./Maxim Integrated DS21FT44

Overview

DS21FT44 from Maxim Integrated is a 12-channel E1 quad framer multichip module (MCM) integrating three DS21Q44 die in a single 300-pin BGA package. It performs frame synchronization, CRC-4 checking, signaling extraction/insertion, and HDLC processing for E1 lines at 2.048 Mbps per channel. Designed for high-density line cards in DSLAMs and multiplexers, it supports IEEE 1149.1 JTAG boundary scan and operates from 0°C to +70°C.

For engineers reviewing the DS21FT44 datasheet, DS21FT44 pinout, DS21FT44 application, or DS21FT44 equivalent, this device delivers consolidated E1 framing functionality with reduced PCB footprint versus discrete solutions, integrated clock synthesis from 8.192 MHz, and parallel bus interface compatibility with Intel/Motorola timing modes.

Technical Context

The DS21FT44 implements four independent quad-framer blocks-three fully populated (Framers 1–12) and one unpopulated (Framers 13–16), resulting in 12 active E1 channels. Each framer supports full E1 G.704/G.706 compliance, including multiframe alignment, Sa/Si bit handling, and DS0 monitoring.

It features a shared 8.192 MHz clock derived from CLKSI, concatenated backplane output capability, and JTAG test access via dedicated TAP controller. Signal routing omits RFSYNC/RLINK/RCHCLK/TLCLK/TCHCLK and related status pins-confirmed absent per Table 1-1 and Figure 1-1.

Key Specifications

Pinout & Package

DS21FT44 uses a 300-pin BGA package (27mm × 27mm, 1.27mm pitch) with power/ground distribution across multiple DVDD/DVSS balls per framer block and dedicated signal groups per framer quadrant. Pin functions are validated per Table 2-1 and Figure 4-1 (DS21FT44-specific land pattern).

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS21FF44 and DS21FT42, the DS21FT44 provides optimal cost-per-E1-channel for dedicated E1 line cards, avoids T1-mode overhead, and delivers full G.706-compliant multiframe processing unavailable in dual-mode variants.

Availability

DS21FT44 is available at Aetrix Electronics and suitable for DSLAMs, multiplexers/demultiplexers, switches, and high-density line cards requiring stable component supply and long-term industrial temperature support.

Supply support for DS21FT44 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 semiconductor solutions for communications, industrial, and computing markets.

The DS21FT44 belongs to Maxim's E1/T1 framer product line, engineered specifically for carrier-grade access equipment requiring high channel density, low power, and full ITU-T standard compliance in compact MCM packaging.

FAQ

What is the exact channel count and framer architecture of the DS21FT44?

The DS21FT44 integrates three DS21Q44 quad-framer die in a multichip module, delivering exactly 12 active E1 channels (Framers 1–12). Framer block 4 is unpopulated-pins RCLK13–RCLK16, TCLK13–TCLK16, and associated signals are marked NC in the DS21FT44 datasheet and land pattern.

Does the DS21FT44 support JTAG boundary scan, and which pins are used?

Yes, the DS21FT44 implements IEEE 1149.1 JTAG boundary scan using JTCLK, JTMS, JTDI, JTRST*, and JTDOT. JTDOT is the dedicated output pin for the 4×3 configuration; JTDOF is NC. All five signals are electrically validated and routed per Table 2-1 and Figure 4-1.

How does the DS21FT44 handle clocking for its 12 E1 channels?

The DS21FT44 requires individual 2.048 MHz receive and transmit clocks per channel (RCLK1–RCLK12, TCLK1–TCLK12), plus a single CLKSI reference input to generate the internal 8.192 MHz system clock (8MCLK). TSYSCLK/RSYSCLK are internally tied together per design revision notes.

Is the DS21FT44 pin-compatible with other devices in the DS21Fxx family?

Yes, the DS21FT44 is pin-compatible with DS21FT42, sharing identical pinout, package, and footprint. This allows reuse of PCB layouts between E1-only (DS21FT44) and T1/E1 dual-mode (DS21FT42) designs, though register mapping and signaling capabilities differ.

What are the key power supply requirements for the DS21FT44?

The DS21FT44 requires a single 3.3V digital supply (DVDD) distributed across multiple balls per framer block (DVDD1–DVDD3), with dedicated DVSS ground balls for each. All I/O pins are 5V-tolerant, enabling direct interfacing with legacy 5V logic without level shifters.