Analog Devices Inc./Maxim Integrated DS26504L

Overview

DS26504L from Maxim Integrated is a building-integrated timing-supply (BITS) clock-recovery element and T1/E1/J1/64KCC transceiver. It recovers clocks from T1 (1.544MHz), E1 (2.048MHz), 64kHz composite clock (64KCC), and 6312kHz interfaces; supports SSM recovery/transmission in T1/E1 modes; operates from 3.3V supply with 5V-tolerant I/O; and is used in telecom central office timing distribution systems.

For engineers reviewing the DS26504L datasheet, DS26504L pinout, DS26504L application, or DS26504L equivalent, key selection criteria include G.703 compliance across multiple sync interfaces (64KCC, 6312kHz, E1, T1), independent transmit/receive rate conversion capability, hardware/software control flexibility (parallel/SPI/JTAG), and crystal-less jitter attenuation for T1/E1 line interfaces.

Technical Context

The DS26504L implements dual-path architecture with fully independent transmit and receive PLLs, enabling simultaneous rate translation between any supported input (e.g., 64KCC) and output (e.g., E1) synchronization rates. It integrates a G.703-compliant line interface unit (LIU) with software-selectable termination (75Ω/100Ω/110Ω/120Ω/133Ω) and supports both short- and long-haul operation via configurable line build-out.

Control is implemented through three parallel modes: 8-bit multiplexed/nonmultiplexed Intel/Motorola bus, SPI serial port (CPOL/CPHA configurable), and hardware mode using dedicated pins. JTAG boundary scan (IEEE 1149.1) provides test access, while status indications (LOS, AIS, LOF) are delivered on dedicated output pins.

Key Specifications

Pinout & Package

DS26504L is housed in a 64-pin LQFP package (10mm × 10mm, 0.5mm pitch) with exposed thermal pad. Pin functions are defined per Maxim's DS26504 datasheet Rev 072308, Table 5-1 (LQFP Pinout).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar T1/E1/J1/64KCC timing and transceiver applications.

Compared with DS26503L and DS26502L, the DS26504L delivers full global telecom sync interface coverage (including 6312kHz and J-64KCC), complete SSM handling for both T1 and E1, and expanded termination flexibility - making it the only variant qualified for stratum-3 BITS applications across North America, Europe, and Japan.

Availability

DS26504L is available at Aetrix Electronics and suitable for central office timing distribution, T1/E1 line card design, and telecom infrastructure upgrades requiring stable component supply, long-term lifecycle assurance, and full G.703/G.781 compliance.

Supply support for DS26504L 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 ICs for communications, industrial, and automotive markets.

The DS26504L belongs to Maxim's telecom timing and interface product line, designed specifically for building-integrated timing supply (BITS) systems and T1/E1/J1 physical layer synchronization in carrier-grade network equipment.

FAQ

What is the operating temperature range for the DS26504L?

The DS26504L is specified for operation from 0°C to +70°C. This commercial temperature grade makes it suitable for controlled-environment telecom infrastructure such as central office line cards and indoor network elements. The DS26504LN variant extends this to –40°C to +85°C for extended-temperature applications. DS26504L maintains full G.703 compliance and jitter performance across its rated range.

Does the DS26504L support both T1 and E1 Synchronization Status Message (SSM) handling?

Yes, the DS26504L fully supports SSM in both T1 and E1 modes: it receives and validates T1 BOC SSM and E1 Sa(n) bit SSM, and transmits regenerated SSM with change-of-state indication. This meets ITU-T G.781 requirements for SSM propagation in hierarchical timing networks. DS26504L is the only device in the DS2650x family to provide bidirectional SSM for E1.

Can the DS26504L operate without an external crystal oscillator?

Yes, the DS26504L includes a crystal-less jitter attenuator for T1 and E1 operation, eliminating the need for an external crystal. It uses internal PLLs locked to the incoming line signal or master clock to achieve G.823/G.824-compliant jitter performance. The device also supports bypass mode for direct clock pass-through when ultra-low latency is required.

What control interfaces does the DS26504L support?

The DS26504L supports three independent control interfaces: an 8-bit parallel port (configurable for Intel or Motorola timing, multiplexed or nonmultiplexed), a 4-wire SPI serial port (with configurable CPOL/CPHA), and a hardware control mode using dedicated pins. All interfaces provide full register-level access to configuration, status, and diagnostic functions without requiring external protocol translation logic.

Is the DS26504L pin-compatible with other devices in the DS2650x family?

Yes, the DS26504L is pin- and software-compatible with the DS26502L and DS26503L. This allows direct replacement in existing designs to upgrade functionality - for example, adding 6312kHz support or full E1 SSM transmission - without PCB layout changes. Firmware and driver code remain fully reusable across the family.