Analog Devices Inc./Maxim Integrated MAX9691EUA

Overview

The MAX9691EUA from Maxim Integrated is a single-channel, ultra-fast ECL-output comparator with 1.2ns typical propagation delay, ±11.5mV input offset voltage, and dual ±5.2V/+5V supply operation. It features differential ECL-compatible inputs, complementary open-emitter outputs requiring external 50Ω–200Ω pull-down resistors to -2.0V, and is designed for high-speed line receivers and threshold detection in >600MHz signal processing systems.

For engineers reviewing the MAX9691EUA datasheet, MAX9691EUA pinout, MAX9691EUA application, or MAX9691EUA equivalent, this device requires attention to ECL-level termination, ground-plane PCB layout, input slew-rate compliance (>1V/µs), and proper biasing of GND1 (input stage) and GND2 (output stage) - all critical for stable sub-2ns timing performance.

Technical Context

The MAX9691EUA implements a BiCMOS-based high-gain, wide-bandwidth comparator core optimized for minimal propagation delay dispersion (150ps) and skew (100ps). Its input stage operates over a -2.5V to +3.0V common-mode range with 60dB CMRR, while the ECL output stage delivers fast rise/fall times (<500ps) into 50Ω loads terminated to VT = -2V.

No latch-enable function is integrated - unlike MAX9692/MAX9693 variants - so LE pin is absent. The device uses two independent ground pins (GND1 for input biasing, GND2 for output biasing), mandating low-inductance connection to a solid ground plane to maintain DC matching and AC stability at multi-GHz edge rates.

Key Specifications

Pinout & Package

MAX9691EUA is housed in an 8-pin µMAX package (U8+1 outline, 3mm × 3mm, 0.5mm pitch), with exposed pad for thermal enhancement. Pin 1 is VCC; pins 7 and 8 are GND1 and GND2 respectively - not interchangeable due to separate internal bias domains.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-fast ECL-output comparator applications.

Compared with MAX9692EUB, MAX9691EUA eliminates latch-enable circuitry to reduce supply current (34mA vs. 50mA), simplify layout, and lower cost - ideal for always-on high-speed receivers. Against ADCMP572BCPZ-R7, MAX9691EUA provides native ECL drive and negative supply support essential for legacy telecom and military signal chains.

Availability

MAX9691EUA is available at Aetrix Electronics and suitable for high-speed line receivers, threshold detectors, peak detectors, and high-speed triggers requiring stable component supply across industrial temperature ranges (-40°C to +85°C) and long-lifecycle programs.

Supply support for MAX9691EUA 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 RF ICs for industrial, communications, and computing markets.

The MAX9691/MAX9692/MAX9693 family was designed specifically for ultra-high-speed signal conditioning in ECL-based systems - prioritizing propagation delay, skew, and dispersion control over power efficiency or integration density.

FAQ

What power supplies does the MAX9691EUA require?

The MAX9691EUA requires dual supplies: +5V on VCC (Pin 1) and -5.2V on VEE (Pin 4). Both rails must be bypassed with 0.1µF ceramic capacitors placed close to their respective pins. The device draws 34mA typical supply current and is not compatible with single-supply or 3.3V-only operation. These supply requirements are fixed for proper ECL-level output swing and input common-mode range compliance in the MAX9691EUA.

Does the MAX9691EUA have a latch-enable function?

No, the MAX9691EUA does not include a latch-enable (LE) function. That feature is exclusive to the MAX9692 and MAX9693 variants. The MAX9691EUA has only eight pins - VCC, IN+, IN-, VEE, Q OUT, Q OUT, GND1, and GND2 - with no LE pin allocated. If latch functionality is needed, MAX9692EUB (10-pin µMAX) or MAX9693EEE (16-pin QSOP) must be selected instead of the MAX9691EUA.

How should the outputs of the MAX9691EUA be terminated?

The MAX9691EUA outputs (Q OUT and Q OUT) are open-emitter and must be terminated with external pull-down resistors to -2.0V. Recommended values are 50Ω–200Ω for -2.0V termination or 240Ω–2000Ω for -5.2V termination. Improper termination causes logic level violations and increased propagation delay variation. This termination scheme is mandatory for correct ECL logic levels and is specified in the MAX9691EUA functional diagrams and Absolute Maximum Ratings table.

What is the role of GND1 and GND2 in the MAX9691EUA?

GND1 (Pin 7) biases the input differential pair and gain stages, while GND2 (Pin 8) biases the ECL output transistors. They are electrically separate internal nodes and must both connect to a low-inductance solid ground plane - not tied together locally. Separating these grounds prevents output switching noise from modulating input offset voltage, preserving the MAX9691EUA's 100ps skew and ±11.5mV offset specs across temperature.

Can the MAX9691EUA operate with input signals outside its common-mode range?

Yes - the MAX9691EUA will not false trip if one input remains within the valid common-mode range (-2.5V to +3.0V) while the other goes outside it. This robustness is explicitly guaranteed in the datasheet and enables reliable operation in noisy environments or with mismatched source terminations. However, full performance (e.g., propagation delay, skew) is only assured when both inputs stay within the specified common-mode range for the MAX9691EUA.