Analog Devices Inc./Maxim Integrated MAX9691EPA+

Overview

The MAX9691EPA+ from Maxim Integrated is a single-channel, ultra-fast ECL-output comparator with no latch-enable function, housed in an 8-pin PDIP package and rated for -40°C to +85°C operation. It delivers 1.2ns typical propagation delay, 100ps skew, and 150ps dispersion while operating from +5V and -5.2V supplies, enabling high-speed line reception and threshold detection in >600MHz signal chains.

For engineers reviewing the MAX9691EPA+ datasheet, MAX9691EPA+ pinout, MAX9691EPA+ application, or MAX9691EPA+ equivalent, key selection criteria include ECL-compatible differential inputs, open-emitter outputs requiring external 50Ω–200Ω pull-downs to -2V, propagation delay stability across temperature, input offset voltage ≤±11.5mV, and compatibility with microstrip PCB layouts using ground planes and local 0.01µF decoupling.

Technical Context

The MAX9691EPA+ implements a BiCMOS-based high-gain, wide-bandwidth comparator core optimized for minimal propagation delay and tight matching between complementary outputs (Q and Q̅). Its differential input stage supports common-mode voltages from -2.5V to +3.0V and exhibits 60–80dB CMRR, while the ECL output stage drives 50Ω-terminated transmission lines with VOH = -0.76V to -1.06V and VOL = -1.55V to -1.89V at TA = +25°C.

No latch-enable logic is integrated - the LE pin is absent in the MAX9691 variant, distinguishing it from the MAX9692/MAX9693 family members. Input bias current remains ≤30µA over temperature, and the device requires separate GND1 (input-stage reference) and GND2 (output-stage reference) connections tied to a solid copper ground plane per layout guidelines.

Key Specifications

Pinout & Package

MAX9691EPA+ uses an 8-pin plastic dual in-line package (PDIP) with standard through-hole mounting. Pin 1 is VCC, Pin 2 is IN+, Pin 3 is IN-, Pin 4 is VEE, Pin 5 is Q̅, Pin 6 is Q, Pin 7 is GND2, and Pin 8 is GND1. GND1 and GND2 must be connected together to a low-impedance ground plane per layout requirements.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed ECL comparator applications.

Compared with MAX9691EPA+, the MAX9691EUA+ offers identical performance in a miniature package ideal for dense layouts, while the MAX9692EPE+ introduces latch-enable capability at the cost of larger footprint and additional control logic - neither is pin-compatible, and both require schematic and layout revision.

Availability

MAX9691EPA+ 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 and long-lifecycle programs.

Supply support for MAX9691EPA+ 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 demanding industrial, communications, and computing applications.

The MAX9691EPA+ belongs to Maxim's ultra-high-speed comparator product line, engineered specifically for ECL-level signal conditioning in >600MHz data acquisition, test equipment, and RF subsystems where nanosecond timing fidelity is critical.

FAQ

What is the supply voltage requirement for MAX9691EPA+?

The MAX9691EPA+ requires two independent supplies: +5V on VCC (Pin 1) and -5.2V on VEE (Pin 4). These rails power the internal BiCMOS circuitry and establish ECL-compatible output voltage levels. Operation outside the absolute maximum ratings - VCC from -0.3V to +6V and VEE from -6V to +0.3V - risks permanent damage. The MAX9691EPA+ does not support single-supply or rail-to-rail operation.

Does MAX9691EPA+ include a latch-enable function?

No, the MAX9691EPA+ does not include a latch-enable (LE) function. It is the single-comparator variant without LE logic, unlike the MAX9692EPE+ or MAX9693EEE+. The MAX9691EPA+ pinout contains no LE pin; its functional block diagram shows only IN+, IN-, Q, Q̅, VCC, VEE, GND1, and GND2. Using MAX9691EPA+ in sample-hold mode requires external latching circuitry.

How should the open-emitter outputs of MAX9691EPA+ be terminated?

The Q and Q̅ outputs of MAX9691EPA+ are open-emitter and require external pull-down resistors to generate valid ECL logic levels. For -2V termination, use 50Ω–200Ω resistors; for -5.2V termination, use 240Ω–2000Ω resistors. These resistors must connect to the appropriate negative rail (not ground), and layout must follow microstrip guidelines with a solid ground plane to maintain signal integrity and minimize reflections.

What is the maximum operating frequency supported by MAX9691EPA+?

The MAX9691EPA+ supports signal processing at frequencies exceeding 600MHz, as confirmed by its 1.2ns propagation delay, 100ps skew, and verified 100MHz waveform response in the datasheet. While not a clock oscillator, its propagation characteristics enable reliable decision-making in RF sampling, high-speed data recovery, and pulse timing applications up to and beyond 600MHz bandwidth.

Why does MAX9691EPA+ have two separate ground pins (GND1 and GND2)?

MAX9691EPA+ separates GND1 (Pin 8) and GND2 (Pin 7) to isolate the input-stage reference from the high-current ECL output stage, minimizing supply-induced crosstalk and improving noise immunity. GND1 biases the differential input pair, while GND2 serves the output transistors. Per the datasheet, both must be connected to a low-impedance solid copper ground plane - splitting them improves AC performance but requires careful PCB grounding strategy.