Analog Devices Inc./Maxim Integrated MAX9691EUA+T

Overview

The MAX9691EUA+T 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 chains.

For engineers reviewing the MAX9691EUA+T datasheet, MAX9691EUA+T pinout, MAX9691EUA+T application, or MAX9691EUA+T equivalent, this device requires attention to ECL-level termination, ground-plane PCB layout, latch-enable handling (not present on MAX9691), and temperature-stable biasing of GND1/GND2 reference nodes.

Technical Context

The MAX9691EUA+T employs BiCMOS process technology to achieve sub-2ns propagation delay while maintaining DC matching-100ps skew between Q/Q̅ outputs and 150ps dispersion across 10mV–100mV overdrive. Its input stage operates over –2.5V to +3.0V common-mode range with 60kΩ differential input resistance and 3pF input capacitance.

Output stage uses open-emitter ECL topology compatible with –2.0V or –5.2V termination voltages; logic high output is –0.76V (typ) at –2V VT, logic low is –1.55V (typ); supply current is 46mA (typ) at +25°C. No latch-enable function is integrated-LE pin is absent per MAX9691 selector guide and pin configuration.

Key Specifications

Pinout & Package

MAX9691EUA+T is housed in an 8-pin µMAX® package (U8+1 outline, 3mm × 3mm body, 0.65mm pitch), RoHS-compliant with lead-free terminations. Pin 1 = VCC, Pin 2 = IN+, Pin 3 = IN–, Pin 4 = VEE, Pin 5 = Q̅ OUT, Pin 6 = Q OUT, Pin 7 = GND2, Pin 8 = GND1. GND1 biases input stage; GND2 biases output stage-both must connect to solid copper ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX9691EUA+T, MAX9692EUB+T adds latch functionality at the cost of extra pin count and layout complexity, while ADCMP572BCPZ-R7 trades ECL compatibility for single-supply convenience and lower power-neither is pin-compatible, and both require PCB redesign.

Availability

MAX9691EUA+T is available at Aetrix Electronics and suitable for high-speed line receivers, peak detectors, threshold detectors, and high-speed triggers requiring stable component supply across industrial temperature ranges.

Supply support for MAX9691EUA+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) designs precision analog and mixed-signal ICs for industrial, communications, and computing applications.

The MAX9691EUA+T belongs to Maxim's ultra-high-speed comparator product line, engineered specifically for sub-2ns decision latency in ECL/PECL signal conditioning and timing-critical measurement systems.

FAQ

What is the correct termination scheme for MAX9691EUA+T outputs?

The MAX9691EUA+T features open-emitter Q and Q̅ outputs that require external pull-down resistors. For –2.0V termination voltage, use 50Ω–200Ω resistors; for –5.2V, use 240Ω–2000Ω. These resistors must connect to the respective VT rail-not ground-and be placed close to the output pins to minimize stub inductance. Incorrect termination causes overshoot, ringing, or degraded skew performance in the MAX9691EUA+T.

Does MAX9691EUA+T include a latch-enable function?

No, the MAX9691EUA+T does not include a latch-enable (LE) function. Per the Selector Guide and Pin Description, only MAX9692 and MAX9693 variants integrate LE inputs. The MAX9691EUA+T has no LE pin-its 8-pin µMAX package contains only VCC, IN+, IN–, VEE, Q̅, Q, GND2, and GND1. If latching is required, MAX9692EUB+T or MAX9693EEE+T must be selected instead of the MAX9691EUA+T.

How should GND1 and GND2 be connected in a MAX9691EUA+T layout?

GND1 (Pin 8) and GND2 (Pin 7) serve distinct internal functions: GND1 biases the input differential pair, GND2 biases the ECL output stage. Both must connect to a low-inductance solid copper ground plane-but avoid daisy-chaining them. Use separate short traces from each pin to the plane, and do not route high-current digital return paths through either node. Improper grounding degrades MAX9691EUA+T input offset stability and output skew.

What is the minimum input slew rate required for clean switching in MAX9691EUA+T?

With proper microstrip layout and 50Ω source/load termination, the MAX9691EUA+T requires ≥1V/µs input slew rate to avoid oscillation during linear-region crossing. This value increases with higher source impedance or poor grounding. Adding regenerative feedback (e.g., 1kΩ/10pF) reduces the requirement by up to 4×. Below the minimum slew rate, the MAX9691EUA+T exhibits output steps or multiple transitions instead of monotonic edges.

Can MAX9691EUA+T operate with a single +3.3V supply?

No, the MAX9691EUA+T requires dual supplies: +5V on VCC and –5.2V on VEE. Its ECL-compatible outputs and input stage are designed for this rail configuration. Attempting single-supply operation violates absolute maximum ratings-applying +3.3V to VEE risks permanent damage. For single-supply alternatives, consider the ADCMP572BCPZ-R7, but note it lacks ECL compatibility and is not a functional replacement for the MAX9691EUA+T.