Analog Devices Inc. AD842KQ

Overview

AD842KQ from Analog Devices is a wideband, high-output-current operational amplifier optimized for precision high-speed signal conditioning. It delivers 80 MHz gain bandwidth, 375 V/µs slew rate, and 100 ns settling to 0.01% for 10 V step - enabling use in 12-bit data acquisition systems, video line drivers, and DAC/ADC buffer stages.

For engineers reviewing the AD842KQ datasheet, AD842KQ pinout, AD842KQ application, or AD842KQ equivalent, key selection criteria include guaranteed 100 mA output drive into 499 Ω, ±15 V operation with 14 mA max quiescent current, laser-trimmed 1.5 mV max input offset voltage, and CERDIP (Q-14) package suitability for industrial temperature range (0°C to 70°C).

Technical Context

The AD842KQ employs Analog Devices' junction-isolated complementary bipolar (CB) process, enabling simultaneous dc precision and wideband ac performance unattainable in earlier monolithic op amps. Its fully differential input stage ensures stable operation at gains ≥2, while internal compensation eliminates external phase compensation in standard configurations.

Designed for demanding transient fidelity, the AD842KQ achieves sub-100 ns linear settling via minimized transistor isolation capacitance discharge and thermally stable layout. Its 300–375 V/µs slew rate and 6 MHz full-power bandwidth support ±10 V p-p signals at video frequencies without distortion.

Key Specifications

Pinout & Package

CERDIP (Q-14) ceramic dual-in-line package with 0.300-inch body width, 0.100-inch lead pitch, and hermetic sealing suitable for industrial environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed operational amplifier applications.

Compared with AD842JQ and AD842JRZ-16, the AD842KQ provides tighter input offset voltage (1.5 mV max), identical CERDIP reliability, and guaranteed 100 mA output drive - making it optimal for industrial-grade precision line drivers where long-term drift and thermal stability are critical.

Availability

AD842KQ is available at Aetrix Electronics and suitable for video line drivers, DAC/ADC buffers, and pulse amplifiers requiring stable component supply across extended industrial temperature ranges (0°C to 70°C) and long-lifecycle programs.

Supply support for AD842KQ 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

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD842KQ belongs to Analog Devices' precision high-speed op amp product line, engineered specifically for applications demanding simultaneous wide bandwidth, low distortion, and dc accuracy - such as test & measurement, medical imaging, and military communications.

FAQ

What is the operating temperature range for the AD842KQ?

The AD842KQ is rated for operation from 0°C to 70°C, as specified in the Analog Devices ordering guide. This range applies specifically to the CERDIP (Q-14) package variant and is validated per MIL-STD-883B test conditions. The AD842KQ does not support extended or military temperature grades - those are reserved for the AD842SQ variant (−55°C to +125°C). Always verify ambient and junction temperature limits using θJA = 110°C/W under actual load conditions.

Does the AD842KQ require external offset nulling?

The AD842KQ features laser-wafer trimming that guarantees input offset voltage ≤1.5 mV at 25°C, eliminating external nulling in most applications. Pins 1 and 7 are provided for optional fine adjustment using a 10 kΩ potentiometer, but this is only necessary in systems requiring <0.5 mV offset or operating across full temperature range where drift (14 µV/°C) accumulates. For industrial video or data acquisition use cases, the AD842KQ typically operates without nulling circuitry.

Can the AD842KQ drive a 50 Ω coaxial cable directly?

Yes - the AD842KQ delivers ≥100 mA output current, enabling ±5 V into a 50 Ω load (10 V p-p). For optimal signal integrity, use the terminated line driver configuration shown in Figure 32: place a back-termination resistor (RBT = 50 Ω) between AD842KQ output and cable, and match the far-end termination (RT = 50 Ω). This prevents reflections and maintains 375 V/µs slew rate performance. Avoid direct capacitive loading >20 pF without series isolation.

What is the maximum capacitive load the AD842KQ can drive stably?

The AD842KQ is characterized for stable operation with capacitive loads ≤20 pF. Loads between 20 pF and 100 pF degrade bandwidth and increase settling time but do not cause oscillation. Loads >100 pF risk instability due to added phase lag. To drive larger capacitive loads (e.g., long PCB traces or cables), insert a small series resistor (10–50 Ω) between AD842KQ output and load - this isolates the amplifier from the capacitance while preserving dc gain via feedback path.

How does the AD842KQ compare to the AD842JR-16 in terms of thermal performance?

The AD842KQ (CERDIP Q-14) has θJA = 110°C/W, while the AD842JR-16 (SOIC_W RW-16) has θJA = 100°C/W - indicating slightly better board-level heat dissipation for the SOIC version. However, the AD842KQ's hermetic ceramic package offers superior long-term reliability and moisture resistance in humid industrial environments. Junction temperature rise for AD842KQ at 14 mA quiescent current and 100 mA load is ~1.5°C/W × (110°C/W × 14 mA + 100 mA² × 5 Ω), requiring attention in sealed enclosures above 50°C ambient.