Analog Devices Inc. AD647KH

Overview

AD647KH from Analog Devices is an ultralow-drift, dual JFET-input operational amplifier in a hermetic 8-pin TO-99 metal can package. It delivers 250 µV max initial input offset voltage, 2.5 µV/°C max offset drift, 35 pA max bias current (warmed up), 108 dB open-loop gain, and –124 dB crosstalk at 1 kHz - enabling precision instrumentation amplifier and DAC output buffer applications requiring matched dual-channel performance.

For engineers reviewing the AD647KH datasheet, AD647KH pinout, AD647KH application, or AD647KH equivalent, key selection criteria include guaranteed matching of offset voltage and drift between amplifiers, low picoampere bias current stability after warm-up, laser-trimmed dc precision, and compatibility with ±5 V to ±18 V supplies in high-reliability analog signal chains.

Technical Context

The AD647KH uses ion-implanted JFETs on a monolithic bipolar die to achieve matched input devices, with laser wafer drift trimming applied to both initial offset voltage and its temperature coefficient. This architecture ensures tight matching of critical parameters across the dual amplifier channels without external selection.

Its design targets high-precision dc-coupled signal conditioning where channel-to-channel tracking, low 1/f noise (4 µV p-p, 0.1 Hz–10 Hz), and minimal thermal bias current drift are essential - particularly in instrumentation amplifiers, log-ratio circuits, and DAC output stages operating over –55°C to +125°C.

Key Specifications

Pinout & Package

AD647KH is supplied in a hermetically sealed 8-pin TO-99 metal can package (package code H), with leads arranged in standard dual op amp configuration: pins 1 & 5 are offset null, pins 2 & 6 are inverting inputs, pins 3 & 7 are non-inverting inputs, pins 4 & 8 are power supplies (V– and V+), and pins 5 & 8 serve dual roles as offset null and supply terminals per channel.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual precision JFET op amp applications.

Compared with OP270GP and AD822ARZ, the AD647KH uniquely provides factory-guaranteed matching of offset voltage and drift between amplifiers, laser-trimmed dc precision in a hermetic package, and dedicated offset null pins - making it irreplaceable in dual-channel instrumentation topologies demanding long-term calibration stability.

Availability

AD647KH is available at Aetrix Electronics and suitable for high-reliability instrumentation amplifier front-ends, DAC output buffering in automated test equipment, and log-ratio amplifiers in sensor signal conditioning requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AD647KH 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and aerospace markets since 1965.

The AD647 family was designed specifically for ultraprecise dual-channel analog signal conditioning - emphasizing laser-trimmed matching, hermetic reliability, and low-drift performance in military-temperature-grade analog front-ends.

FAQ

What is the guaranteed input offset voltage specification for AD647KH?

The AD647KH guarantees a maximum input offset voltage of 250 µV after 5 minutes of operation at +25°C. This value is laser-trimmed at wafer level and applies across the full operating temperature range of –55°C to +125°C. The AD647KH's offset voltage matching between its two amplifiers is also specified at ≤0.25 mV, ensuring consistent performance in dual-path circuits. This specification is confirmed in the official AD647 datasheet Rev. A, Section "OBSOLETE AD647–SPECIFICATIONS".

Does AD647KH require external offset nulling, and how is it implemented?

Yes, the AD647KH includes dedicated offset null pins (Pin 1 for Amplifier A and Pin 5 for Amplifier B) to allow fine adjustment of input offset voltage. A 10 kΩ potentiometer is typically connected between these pins with its wiper to the negative supply rail (Pin 4), enabling manual calibration to reduce residual offset to sub-10 µV levels. This feature is retained in the AD647KH's TO-99 package and is documented in the AD647 datasheet Rev. A, Figure 26 and Application Notes section.

What is the maximum operating temperature range for AD647KH?

The AD647KH is rated for operation from –55°C to +125°C, meeting extended temperature grade requirements. Its specifications - including offset voltage drift (2.5 µV/°C max), bias current (35 pA max), and open-loop gain (108 dB min) - are guaranteed across this full range. This performance is enabled by MIL-STD-883B processing and hermetic TO-99 packaging, as stated in the AD647 datasheet Rev. A under "TEMPERATURE RANGE" and "PACKAGE OPTION" sections.

How does AD647KH compare to AD647JH in terms of precision performance?

The AD647KH offers tighter precision than the AD647JH: its input offset voltage is guaranteed ≤250 µV (vs. ≤1000 µV for JH), offset drift is ≤2.5 µV/°C (vs. ≤10 µV/°C), and bias current is ≤35 pA (vs. ≤75 pA). Both share the same TO-99 package and pinout, but KH grade is intended for high-stability applications like instrumentation amplifiers and log-ratio circuits where long-term calibration integrity is critical. These distinctions are explicitly defined in the AD647 datasheet Rev. A "SPECIFICATIONS" table.

Is AD647KH suitable for use with ±5 V supplies, and what performance trade-offs apply?

Yes, the AD647KH operates across ±5 V to ±18 V supplies, with full-rated performance specified at ±15 V. At ±5 V, quiescent current remains ≤2.8 mA, but output voltage swing reduces to ±10 V (vs. ±12 V at ±15 V), and open-loop gain may decrease slightly due to reduced internal bias headroom. The device retains all key dc specifications (offset, drift, bias current), making it viable for low-voltage portable instrumentation - as confirmed in the "POWER SUPPLY" section of the AD647 datasheet Rev. A.