Texas Instruments INA166UA

Overview

INA166UA from Texas Instruments is a low-noise, low-distortion, current-feedback instrumentation amplifier with fixed G = 2000 gain, 1.3nV/√Hz input voltage noise at 1kHz, 450kHz bandwidth, and ±4.5V to ±18V supply range. It serves as a precision front-end amplifier for microphones, hydrophones, and bridge transducers in industrial and medical signal acquisition systems.

For engineers reviewing the INA166UA datasheet, INA166UA pinout, INA166UA application, or INA166UA equivalent, this page delivers verified specifications, SO-14 package mapping, real-world use scenarios, and two validated alternative parts for differential low-level signal conditioning where high CMR (>100dB), low THD+N (0.09% at 1kHz), and stable gain accuracy (±0.3% typ) are critical.

Technical Context

The INA166UA employs a three-op-amp current-feedback architecture with laser-trimmed internal resistors (6kΩ, 60kΩ, 3kΩ) to achieve 200× first-stage gain and 10× second-stage gain. Its distortion cancellation circuitry reduces harmonic content while maintaining wide dynamic response across its 450kHz small-signal bandwidth.

Input stage bias currents (2.5–12µA) and current noise (0.8pA/√Hz at 1kHz) are optimized for low-source-impedance applications (<10Ω recommended to avoid oscillation). Output Sense (pin 8) and Reference (pin 10) terminals enable remote sensing for improved load regulation and gain accuracy under varying output current conditions.

Key Specifications

Pinout & Package

INA166UA is housed in a 14-pin SOIC (SO-14) surface-mount package with θ_JA = 100°C/W, rated for –40°C to +85°C operation and RoHS-compliant NIPDAU lead finish (MSL Level-3).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with AD8429ARZ and INA128UA, the INA166UA uniquely combines factory-set G=2000, integrated Sense/Ref terminals for load-regulated gain, and current-feedback architecture delivering 450kHz bandwidth with minimal phase shift-making it ideal for fixed-gain, low-noise, high-CMR sensor signal chains where layout control and remote sensing are design priorities.

Availability

INA166UA is available at Aetrix Electronics and suitable for microphone preamplifiers, bridge transducer interfaces, differential receivers, and moving-coil transducer amplifiers requiring stable component supply across industrial, medical, and test equipment production cycles.

Supply support for INA166UA 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

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in precision amplifiers, data converters, and power management ICs.

The INA166 series was designed specifically for high-fidelity, low-noise signal conditioning in sensor-based measurement systems-emphasizing current-feedback architecture, laser-trimmed gain accuracy, and robust common-mode rejection for demanding industrial and medical applications.

FAQ

What is the gain configuration of the INA166UA?

The INA166UA has a fixed internal gain of G = 2000, achieved via laser-trimmed resistor ratios (6kΩ, 60kΩ, 3kΩ). This configuration eliminates external gain-setting components and ensures ±0.3% typical gain error. While pins 3 and 12 (GS1/GS2) allow optional gain increase using an external resistor, the INA166UA is specified and tested exclusively at G = 2000 per its datasheet SBOS178.

Can the INA166UA operate with a single supply?

No, the INA166UA is a dual-supply instrumentation amplifier requiring symmetric or asymmetric bipolar supplies between ±4.5V and ±18V. Its input common-mode range extends to (V+) – 4V and (V–) + 4V, and output swings to within 1.8V of each rail-making single-supply operation incompatible with its internal architecture and pinout. For single-supply designs, consider TI's INA333 or similar rail-to-rail output instrumentation amplifiers.

Why does the INA166UA require input stabilization for low-impedance sources?

The INA166UA's current-feedback topology and high-speed input stage can oscillate with very low source impedances (<10Ω), especially with long cables or poor PCB layout. Figure 2 in the SBOS178 datasheet specifies a 47Ω resistor + 1.2µH inductor network at each input to dampen peaking. This network is mandatory for stable operation with microphone capsules, piezoelectric sensors, or direct PCB traces under 10Ω impedance.

What is the function of the Sense and Ref pins on the INA166UA?

Pin 8 (Sense) and pin 10 (Ref) enable remote output sensing to correct for voltage drop across PCB traces or connectors. Connecting Sense directly to the load's input and Ref to the load's reference point closes the feedback loop around the entire path, maintaining gain accuracy independent of output current. Resistance exceeding 5Ω in either path degrades CMR, so low-impedance routing is essential for both pins.

Is the INA166UA still in active production?

The base part INA166UA is marked "Obsolete" by Texas Instruments, but the tape-and-reel variant INA166UA/2K5 remains Active with 2500-piece reels, RoHS-compliant NIPDAU finish, and MSL Level-3 rating. Aetrix Electronics stocks and distributes the active /2K5 variant, ensuring supply continuity for legacy designs requiring this specific fixed-gain, low-noise instrumentation amplifier.