Analog Devices Inc./Maxim Integrated MAX3667ECJ-T

Overview

MAX3667ECJ-T from Maxim Integrated is a +3.3V, 622Mbps SDH/SONET laser driver IC with integrated automatic power control (APC), differential PECL input interface, single-ended bias (IBIAS) and modulation (IMOD) current outputs, and operation across –40°C to +85°C. It delivers 5–90mA bias current and 5–60mA_P-P modulation current for fiber-optic transmitter applications in access nodes and repeaters.

For engineers reviewing the MAX3667ECJ-T datasheet, MAX3667ECJ-T pinout, MAX3667ECJ-T application, or MAX3667ECJ-T equivalent, key selection criteria include APC loop stability (CCOMP/CAPC configuration), PECL input compatibility, TTL-compatible disable timing (25ns response), bias/modulation current monitor gain accuracy (1/38 and 1/33), and TQFP-32 thermal performance under 622Mbps eye-diagram compliance.

Technical Context

The MAX3667ECJ-T implements a closed-loop APC architecture using an operational transconductance amplifier (OTA) that compares monitor photodiode current (MD) against a reference set by APCSET, driving COMP and APC pins to regulate IBIAS via BIASSET. Its modulation path accepts 620mV_P-P minimum differential PECL inputs and delivers IMOD through an AC-coupled, 31Ω pullup-biased output stage optimized for 10Ω loads.

It features dual current monitors (BIASMON at 1/38×IBIAS, MODMON at 1/33×IQMOD), temperature-compensated 1.0V internal reference, and slow-start turn-on (>50ns). The device supports both open-loop (RBIASSET/MODSET programming) and closed-loop (APCSET + MD feedback) bias control, with output current limiting (170mA IBIAS, 140mA IQMOD at 3.3V).

Key Specifications

Pinout & Package

The MAX3667ECJ-T is housed in a 32-pin Thin Quad Flat Package (TQFP) with exposed thermal pad, 0.8mm pitch, and JEDEC MO-220 standard footprint. Pin 1 is located at top-left corner with dot marking; package dimensions are 7.0mm × 7.0mm × 1.0mm (max height).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3667ECJ-T, MAX3668ECJ-T offers higher speed and tighter jitter but demands more stringent layout and filtering; LMH6522MA/NOPB provides flexibility at the cost of added complexity and missing integrated APC-making MAX3667ECJ-T optimal for cost-sensitive, standards-compliant 622Mbps SDH/SONET deployments.

Availability

MAX3667ECJ-T is available at Aetrix Electronics and suitable for 622Mbps SDH/SONET access nodes, fiber-optic repeaters, and pluggable optical transceivers requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature operation.

Supply support for MAX3667ECJ-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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for communications, industrial, and computing markets.

The MAX3667ECJ-T belongs to Maxim's optical communications product line, designed specifically for reliable, low-jitter laser driving in telecom infrastructure equipment compliant with SDH/SONET OC-12/STM-4 standards.

FAQ

What is the maximum modulation current supported by the MAX3667ECJ-T at +3.3V operation?

The MAX3667ECJ-T supports a modulation current range of 5mAP-P to 60mAP-P at +3.3V operation. This is achieved through AC-coupled IMOD outputs with external RFILT (22Ω) and RDAMP (4.7Ω) components. Exceeding 60mAP-P requires +5.0V operation and DC-coupled configuration, which is not supported by the MAX3667ECJ-T's default AC-coupling architecture. The 60mAP-P upper limit is validated across –40°C to +85°C and guarantees <±10% output aberrations per datasheet AC specifications.

How does the APC loop in the MAX3667ECJ-T maintain constant laser output power?

The MAX3667ECJ-T's APC loop maintains constant laser output power by comparing the current from an external monitor photodiode (connected to MD pin) against a reference current set by the APCSET resistor. The internal OTA drives the COMP and APC pins to adjust the bias current at IBIAS until the two currents balance. With CCOMP = 1µF and CAPC = 1nF, the loop achieves stable regulation across temperature and aging, delivering <1100ppm/°C bias current stability and <1000ppm/°C modulation stability as confirmed in typical operating characteristics.

Can the MAX3667ECJ-T operate with +5.0V supply, and what changes are required?

Yes, the MAX3667ECJ-T supports +5.0V operation per its Absolute Maximum Ratings and DC Electrical Characteristics tables. At +5.0V, supply current increases to 134–160mA, modulation current range extends up to 60mAP-P (same max), and output aberrations improve slightly. No schematic changes are required, but RFILT/RDAMP values may need retuning for optimal eye quality. The PECL input common-mode range expands to 1.5V–4.25V, and disable timing remains at ~25ns. All temperature specs and APC functionality remain fully valid.

What is the function of the BIASMON and MODMON pins on the MAX3667ECJ-T?

BIASMON (Pin 29) and MODMON (Pin 30) are open-collector PNP current monitor outputs on the MAX3667ECJ-T. BIASMON delivers IBIAS/38 (e.g., 2.37mA for 90mA IBIAS), while MODMON delivers IQMOD/33 (e.g., 1.82mA for 60mA IQMOD). These signals enable real-time analog monitoring of laser bias and modulation currents without introducing parasitic loading. Both require external pull-down resistors to ground if used; leaving them unconnected disables monitoring without affecting MAX3667ECJ-T operation.

Is the MAX3667ECJ-T pin-compatible with other devices in the MAX366x family?

No, the MAX3667ECJ-T is not pin-compatible with other MAX366x devices such as MAX3668ECJ-T or MAX3691. Although all share the 32-pin TQFP package, pin functions differ significantly - for example, MAX3668ECJ-T repurposes several N.C. pins for additional monitoring or control, and its APC loop uses different compensation node assignments. The MAX3667ECJ-T pinout is unique to its APC architecture and must be laid out per its specific pin configuration diagram (page 11 of datasheet). Substitution requires full PCB redesign.