Analog Devices Inc./Maxim Integrated MAX3735EGG-T

Overview

The MAX3735EGG-T from Maxim Integrated is a +3.3V, 2.7Gbps laser driver IC for SFP/SFF optical transceiver modules, providing programmable bias current (1–100mA) and modulation current (10–60mA DC-coupled, up to 85mA AC-coupled), with integrated automatic power control (APC), TX_DISABLE/TX_FAULT safety logic, and 24-pin QFN-EP package. It drives FP/DFB lasers in Gigabit Ethernet and Fibre Channel applications.

For engineers reviewing the MAX3735EGG-T datasheet, MAX3735EGG-T pinout, MAX3735EGG-T application, or MAX3735EGG-T equivalent, key selection criteria include SFF-8472 compliance, APC loop stability over −40°C to +85°C, deterministic jitter <38ps at 2.67Gbps, edge transition times <51ps, and compatibility with DS1858 controller ICs via optimized resistor-set current programming.

Technical Context

The MAX3735EGG-T implements a high-speed differential modulation driver with 15Ω load optimization and programmable current sources, paired with a closed-loop APC system that uses photodiode feedback (via MD pin) and external CAPC filtering between APCFILT1/APCFILT2 to maintain constant average optical power across temperature and laser lifetime. Its safety circuitry includes latched TX_FAULT assertion triggered by BC_MON or PC_MON voltage thresholds (1.22–1.39V) and fault recovery timing governed by t_init (60–200ms).

It features on-chip 100Ω differential input termination, internal TX_DISABLE pullup (4.7–10kΩ), and dual monitoring outputs (BC_MON, PC_MON) with gain stability of ±8% (MAX3735) or ±6% (MAX3735A); the MAX3735EGG-T variant corresponds to the base MAX3735 family and excludes the improved multirate operation of the MAX3735A.

Key Specifications

Pinout & Package

MAX3735EGG-T is housed in a 24-pin, 4mm × 4mm QFN-EP (exposed pad) package rated for −40°C to +85°C operation. The exposed pad must be soldered to PCB ground for thermal management and signal integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3735AETG+, the MAX3735EGG-T offers proven stability for established SFP designs but with wider APC drift tolerance; versus SY88315BLEY, it provides simpler, lower-power laser driving without CDR-ideal for cost-sensitive, non-retiming SFP modules where external SERDES handles timing recovery.

Availability

MAX3735EGG-T is available at Aetrix Electronics and suitable for Gigabit Ethernet SFP transceivers, Fibre Channel modules, multirate OCx optical links, and SFP reference designs requiring stable component supply, long-lifecycle support, and SFF-8472 diagnostic compliance.

Supply support for MAX3735EGG-T 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 high-performance analog, mixed-signal, and power management ICs for communications, computing, and industrial applications.

The MAX3735EGG-T belongs to Maxim's SFP laser driver product line, designed specifically for compact, low-power, MSA-compliant optical transceiver modules operating from −40°C to +85°C.

FAQ

What is the operating temperature range for the MAX3735EGG-T?

The MAX3735EGG-T operates over the extended industrial temperature range of −40°C to +85°C. This rating applies to the packaged device (QFN-EP), and all electrical specifications-including bias current accuracy, modulation current stability, and APC loop performance-are guaranteed across this full range per the datasheet's test conditions.

Does the MAX3735EGG-T require external termination resistors on its IN+/IN− inputs?

No, the MAX3735EGG-T includes on-chip 100Ω differential input termination, fully compliant with SFP MSA requirements. Its internal biasing network allows direct AC-coupling without external resistors, simplifying layout and reducing component count in SFP module designs.

How does the APC loop in the MAX3735EGG-T maintain stable optical output power?

The MAX3735EGG-T's APC loop compares photodiode current (fed into the MD pin) against a reference set by RAPCSET, then adjusts the BIAS output current to hold average optical power constant. Stability relies on external CAPC (between APCFILT1/APCFILT2) to set loop dynamics; typical values range from 0.01µF to 2.7nF depending on laser characteristics and data rate.

Can the MAX3735EGG-T drive both FP and DFB laser diodes?

Yes, the MAX3735EGG-T supports both FP and DFB lasers via its wide bias current range (1–100mA) and modulation current capability (10–60mA DC-coupled). Its APC loop compensates for DFB threshold drift, while its low-jitter, high-speed output meets FP laser rise/fall time requirements for 2.7Gbps operation.

What is the function of the SHUTDOWN pin on the MAX3735EGG-T?

The SHUTDOWN pin (Pin 9) is a voltage-output control signal used to drive an external transistor for enhanced laser safety. When asserted high during a fault condition, it cuts off laser current independently of TX_DISABLE-providing redundant shutdown in case of laser cathode grounding or other failure modes per IEC 60825 eye-safety standards.