Analog Devices Inc./Maxim Integrated MAX3681EAG-TG068

Overview

MAX3681EAG-TG068 from Maxim Integrated is a 1:4 deserializer IC for SDH/SONET and ATM systems, converting 622Mbps PECL serial data to 4-bit 155Mbps LVDS parallel outputs. It operates from a single +3.3V supply, features LVDS synchronization inputs for realignment, and supports -40°C to +85°C operation in telecom transmission nodes.

For engineers reviewing the MAX3681EAG-TG068 datasheet, MAX3681EAG-TG068 pinout, MAX3681EAG-TG068 application, or MAX3681EAG-TG068 equivalent, key selection criteria include 622Mbps serial input compatibility, LVDS output drive capability, SYNC-controlled reframing latency, and SSOP-24 thermal/power behavior under extended temperature conditions.

Technical Context

The MAX3681EAG-TG068 implements a 4-bit shift register clocked by differential PECL SCLK, a 2-bit counter dividing SCLK by four to generate PCLK, and an LVDS-output parallel register synchronized to PCLK edges. Its internal architecture enables deterministic bit alignment control via differential SYNC+/- pulses.

It accepts PECL inputs (SD+/-, SCLK+/-) terminated to VCC − 2V with 50Ω, while LVDS interfaces (PCLK+/-, PD0–3+/-, SYNC+/-) use 100Ω differential termination - SYNC inputs are internally terminated, eliminating external resistors. Output offset voltage is specified at 1.125V to 1.275V with 250mV–400mV differential swing.

Key Specifications

Pinout & Package

MAX3681EAG-TG068 is housed in a 24-pin SSOP (Shrink Small Outline Package) with 0.635mm pitch, JEDEC MO-150 compliant, body size 7.65mm × 5.38mm × 1.99mm. Pin 1 is marked by bevelled corner; leads are coplanar within 0.10mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3680EAG+, MAX3681EAG-TG068 adds critical SYNC-controlled reframing for dynamic SONET network reconfiguration; compared with DS90CR288AMTDX, it integrates PECL input buffers and SONET-timed 4:1 deserialization, eliminating external clock recovery and level translation.

Availability

MAX3681EAG-TG068 is available at Aetrix Electronics and suitable for 622Mbps SDH/SONET transmission systems, telecom add/drop multiplexers, and digital cross-connect equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX3681EAG-TG068 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-speed interface ICs for industrial, communications, and computing applications.

The MAX3681EAG-TG068 belongs to Maxim's high-speed telecom interface product line, engineered specifically for OC-12/STM-4 serial-to-parallel conversion in carrier-grade SDH/SONET infrastructure.

FAQ

What is the maximum serial clock frequency supported by the MAX3681EAG-TG068?

The MAX3681EAG-TG068 supports a maximum serial clock frequency of 622MHz, corresponding to 622Mbps data rate. This is validated across the full -40°C to +85°C operating range with VCC = +3.0V to +3.6V. The device maintains timing compliance without derating, making MAX3681EAG-TG068 suitable for OC-12 line-rate applications without oversampling.

Does the MAX3681EAG-TG068 require external termination resistors on its LVDS outputs?

Yes, the MAX3681EAG-TG068 requires 100Ω differential DC termination between each LVDS output pair (PCLK+/-, PD0+/- through PD3+/-). This termination must be placed at the receiver end of the transmission line. The SYNC+/- inputs are internally terminated and do not require external resistors. Failure to terminate LVDS outputs correctly results in signal integrity degradation and timing violations in MAX3681EAG-TG068 operation.

How does the SYNC input function in the MAX3681EAG-TG068?

The SYNC+/- inputs in MAX3681EAG-TG068 accept a differential LVDS pulse that, when held high for at least two SCLK cycles, causes the parallel output register to drop one bit and shift alignment by one bit position. Realignment completes within two PCLK cycles of the SYNC pulse's rising edge. This feature enables dynamic frame synchronization in MAX3681EAG-TG068-based ADMs without resetting the entire deserializer.

What is the power consumption of the MAX3681EAG-TG068 under typical operating conditions?

The MAX3681EAG-TG068 draws 80mA typical supply current at VCC = +3.3V and TA = +25°C, resulting in approximately 265mW power dissipation. At maximum temperature (+85°C), ICC increases to 120mA, raising power to ~396mW. Thermal design must account for this in densely populated line cards, as MAX3681EAG-TG068 uses a 24-pin SSOP package with limited heat-spreading capability.

Can the MAX3681EAG-TG068 interface directly with PECL sources without level-shifting components?

Yes, the MAX3681EAG-TG068 accepts differential PECL inputs (SD+/-, SCLK+/-) directly, but requires proper termination: 50Ω to VCC − 2V (i.e., +1.3V) for each input pair. The device's PECL input buffers are designed for this bias point. If VCC − 2V is unavailable, Thevenin-equivalent termination (e.g., 130Ω/82Ω divider) or ECL AC-coupling networks must be used - MAX3681EAG-TG068 does not include internal PECL termination.