Analog Devices Inc./Maxim Integrated DS21448LN+

Overview

DS21448LN+ from Maxim Integrated is a quad-port E1/T1/J1 line interface unit (LIU) designed for short-haul and long-haul telecom trunking. It integrates four independent transceivers, supports 75Ω/120Ω line impedances, delivers programmable line build-outs (0dB to –22.5dB), implements AMI/HDB3/B8ZS encoding/decoding, and operates from a single 3.3V supply. It serves in T1/E1 cross-connects and wireless base station backhaul interfaces.

For engineers reviewing the DS21448LN+ datasheet, DS21448LN+ pinout, DS21448LN+ application, or DS21448LN+ equivalent, key selection criteria include quad-channel E1/T1 compliance, crystal-less jitter attenuation with 2.048MHz/1.544MHz master clock support, software-selectable receive termination (75Ω/100Ω/120Ω), 128-pin LQFP package with industrial temperature range (–40°C to +85°C), and IEEE 1149.1 JTAG boundary scan test capability.

Technical Context

The DS21448LN+ implements four fully independent E1/T1/J1 LIUs with integrated transmit drivers and receive amplifiers. Each channel features G.703-compliant waveshaping, programmable line build-out (LBO) for E1 (75Ω/120Ω) and T1 (DSX-1/CSU), and dual-mode clock/data recovery supporting both bipolar and NRZ data formats.

Its jitter attenuator uses a 32-bit or 128-bit PLL architecture synchronized to a 2.048MHz (E1) or optional 1.544MHz (T1) master clock, synthesizing backplane clocks at 16.384MHz, 8.192MHz, 4.096MHz, or 2.048MHz. The device supports hardware, serial, and multiplexed/nonmultiplexed parallel interfaces with Intel/Motorola bus timing options.

Key Specifications

Pinout & Package

DS21448LN+ is housed in a 128-pin LQFP package (56-G4011-001), measuring 20mm × 20mm × 1.4mm, with exposed thermal pad for enhanced heat dissipation in high-density telecom line cards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS21Q348, DS21448LN+ adds JTAG testability and updated compliance coverage; compared with MAX3440, it delivers 4× channel density, crystal-less jitter attenuation, and industrial temperature support - making DS21448LN+ optimal for carrier-grade multiservice platforms requiring scalability and test readiness.

Availability

DS21448LN+ is available at Aetrix Electronics and suitable for integrated multiservice access platforms, T1/E1 cross-connects, and wireless base station backhaul requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for DS21448LN+ 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 precision analog, mixed-signal, and high-reliability interface solutions for communications, industrial, and automotive markets.

The DS21448LN+ belongs to Maxim's telecom line interface product line, engineered specifically for carrier-class T1/E1/J1 physical layer termination in central office, access network, and wireless infrastructure equipment.

FAQ

What is the operating temperature range for DS21448LN+?

The DS21448LN+ is rated for industrial operation from –40°C to +85°C. This specification is confirmed in the Ordering Information table and applies specifically to the "LN" and "LN+" variants. The extended range ensures reliable performance in outdoor cabinets, base station enclosures, and uncontrolled central office environments where thermal management is constrained. DS21448LN+ maintains full electrical compliance across this entire range without derating.

Does DS21448LN+ support both E1 and T1 standards simultaneously?

Yes, DS21448LN+ supports E1 and T1 standards per channel via the ETS (E1/T1 Select) bit (CCR1.7). Each of the four ports can be independently configured for E1 (2.048Mbps, G.703) or T1 (1.544Mbps, DSX-1) operation. Line build-out, encoding (HDB3 for E1, B8ZS for T1), and clock synthesis adapt automatically. This per-channel flexibility allows mixed E1/T1 line cards without hardware changes.

What package type is used for DS21448LN+?

DS21448LN+ uses a 128-pin LQFP package (56-G4011-001), 20mm × 20mm, with exposed thermal pad. This is explicitly stated in the Ordering Information table and Package Information section. The "L" in "LN+" denotes LQFP, distinguishing it from the 144-pin PBGA variants (e.g., DS21448N+). Pin assignments and thermal characteristics are documented separately for this LQFP variant.

How does DS21448LN+ handle jitter attenuation without an external crystal?

DS21448LN+ implements a crystal-less 32-bit or 128-bit PLL-based jitter attenuator synchronized to the 2.048MHz (E1) or 1.544MHz (T1) master clock applied to the MCLK pin. It recovers line timing, filters jitter per ITU-T G.823, and synthesizes clean backplane clocks (2.048/4.096/8.192/16.384MHz). No external crystal or VCXO is required - eliminating a common failure point and reducing bill-of-materials cost.

Is JTAG boundary scan supported on DS21448LN+?

Yes, DS21448LN+ includes full IEEE 1149.1 JTAG boundary scan test capability, with dedicated JTMS, JTCK, JTDI, JTDO, and JTRST pins. This is explicitly listed in the Features section and detailed in Section 8 of the datasheet. JTAG support enables automated PCB test, in-system programming verification, and structural diagnostics - critical for high-reliability telecom manufacturing and field maintenance of DS21448LN+ based line cards.