Analog Devices Inc./Maxim Integrated DS33M31N+

Overview

DS33M31N+ from Maxim Integrated is a dual-port Ethernet-over-SONET/SDH mapper IC supporting EoS at VC-4 and 3×VC-3, plus EoPoS over three concatenated DS3 tributaries. It integrates two 155.52Mbps SerDes ports, a configurable 10/100/1000Mbps Ethernet MAC (GMII/MII/RMII), GFP-F/HDLC/cHDLC/X.86 encapsulation, and QoS traffic policing via CIR/CBS - deployed in multiservice provisioning platforms for carrier-grade LAN extension.

For engineers reviewing the DS33M31N+ datasheet, DS33M31N+ pinout, DS33M31N+ application, or DS33M31N+ equivalent, this device serves as a high-order mapping solution requiring precise SONET/SDH timing alignment, VC-3 concatenation support, and dual-protected STS-3c transport interfaces - with critical attention to DDR SDRAM buffering, CLAD clock rate adaptation, and SPI/parallel µP control interface selection.

Technical Context

The DS33M31N+ implements dual independent STS-3/STM-1 SerDes interfaces operating at 155.52Mbps with LVDS/LVPECL signaling, each paired with dedicated framer, pointer processor, and VC-4/VC-3 path termination logic. It supports virtual concatenation (VCAT) across up to three VC-3s and performs EoPoS mapping of Ethernet frames into DS3-level tributaries without external line framing.

Its Ethernet MAC layer supports VLAN (IEEE 802.1Q) and Q-in-Q tagging, classification via PCP/DSCP, and traffic shaping using committed information rate (CIR) and committed burst size (CBS) parameters. The integrated 125MHz DDR SDRAM controller manages up to 512Mb buffer space across a 16-bit data bus for jitter-tolerant frame storage between asynchronous Ethernet and SONET domains.

Key Specifications

Pinout & Package

DS33M31N+ is housed in a 17mm × 17mm, 256-ball CSBGA package with 0.8mm ball pitch and Pb-free/RoHS-compliant finish. Pin assignment follows Maxim's standard ball map for the DS33M31 family, optimized for high-speed SerDes routing and DDR SDRAM signal integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Ethernet-over-SONET/SDH mapping applications.

Compared with DS33M31N+, DS33M33N+ adds physical DS3/E3 line interfaces and add/drop muxing, making it suitable for edge nodes requiring tributary-level access; DS33X162 lacks Ethernet and SONET functions entirely and serves only as a PDH companion chip - neither is pin-compatible nor functionally interchangeable with DS33M31N+.

Availability

DS33M31N+ is available at Aetrix Electronics and suitable for multiservice provisioning platforms, Ethernet-over-SONET service gateways, and carrier LAN extension systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for DS33M31N+ 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 digital ICs for communications, computing, and industrial applications - with emphasis on high-reliability, low-power, and time-critical systems.

The DS33M31N+ belongs to Maxim's Ethernet-over-SONET/SDH mapper product line, engineered specifically for carrier-class transport of Gigabit Ethernet across legacy optical networks using standardized GFP, HDLC, and SONET/SDH protocols.

FAQ

What is the primary function of the DS33M31N+ in a carrier network?

The DS33M31N+ functions as an Ethernet-over-SONET/SDH mapper IC that transports Gigabit Ethernet traffic over OC-3/STM-1 optical networks. It performs GFP-F/HDLC encapsulation, maps Ethernet frames into VC-4 or three concatenated VC-3 containers, and interfaces directly to optical transceivers via dual 155.52Mbps SerDes ports - enabling service providers to deliver Ethernet services over legacy SONET infrastructure without protocol conversion.

Does the DS33M31N+ support both SONET and SDH standards?

Yes, the DS33M31N+ supports both SONET and SDH standards through its dual-mode STS-3/STM-1 SerDes and framer architecture. It complies with GR-253 for SONET and ITU-T G.707/G.783 for SDH, handling STS-3c/VC-4, STS-1/VC-3, AU-3, TU-3, and AU-4 structures with full pointer processing, overhead insertion/extraction, and defect monitoring per respective standards.

Can the DS33M31N+ operate without external DDR SDRAM?

No, the DS33M31N+ requires external DDR SDRAM for frame buffering between the asynchronous Ethernet and synchronous SONET/SDH domains. Its integrated 125MHz DDR controller supports up to 512Mb capacity across a 16-bit data bus - omitting DDR SDRAM will prevent proper operation, as the device lacks on-chip packet memory sufficient for jitter tolerance and traffic shaping.

What clock sources does the DS33M31N+ require?

The DS33M31N+ requires a single reference clock input (19.44MHz or 77.76MHz) fed to the CLKIN pin. Its internal Clock Rate Adapter (CLAD) synthesizes all necessary frequencies: 155.52MHz for SerDes, 44.736MHz for DS3, 34.368MHz for E3, and 125MHz for DDR SDRAM - eliminating the need for multiple crystal oscillators and simplifying clock tree design.

Is the DS33M31N+ pin-compatible with the DS33M30N+ or DS33M33N+?

No, the DS33M31N+ is not pin-compatible with DS33M30N+ or DS33M33N+. While all three share the same 256-ball CSBGA footprint, their pin assignments differ significantly due to expanded functionality: DS33M31N+ includes dual SerDes, parallel µP interface, and enhanced VCAT logic - requiring unique PCB layout and signal routing distinct from the 144-ball DS33M30N+ and the DS33M33N+'s added DS3/E3 line interface pins.