Texas Instruments INA122UA

Overview

INA122UA from Texas Instruments is a precision single-supply instrumentation amplifier optimized for low-power, high-accuracy differential signal acquisition in portable and battery-powered systems. It delivers 60μA quiescent current, rail-to-rail output swing, 250μV max offset voltage, 3μV/°C max offset drift, and 60nV/√Hz voltage noise - enabling high-fidelity sensor interfacing in ECGs, pressure transmitters, and infusion pumps.

For engineers reviewing the INA122UA datasheet, INA122UA pinout, INA122UA application, or INA122UA equivalent, key selection criteria include micropower operation (60μA), wide 2.2V–36V supply range, gain programmability via single external resistor (5–10,000 V/V), laser-trimmed DC accuracy, and SOIC-8 packaging suitable for space-constrained medical and industrial sensing designs.

Technical Context

The INA122UA implements a two-op-amp architecture with internal level-shifting buffers to extend input common-mode range down to ground on single supplies - unlike conventional op-amp-based instrumentation amplifiers. Its gain is set by a single external resistor (RG) connected between pins 1 and 8, with G = 5 + 200kΩ/RG.

This topology enables stable operation across −40°C to +85°C while maintaining 96dB typical CMRR, 30μV/V PSRR, and 100kHz bandwidth at G = 5. Input bias current remains ≤25nA, and the REF pin supports precise output-level shifting with low-impedance drive requirements.

Key Specifications

Pinout & Package

INA122UA is supplied in an 8-pin SOIC package (4.9mm × 6mm), rated for −40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD8221ARMZ and INA333AIDR, the INA122UA uniquely balances micropower operation (60μA), wide 2.2V–36V supply compatibility, and laser-trimmed DC precision - making it the only option among the three viable for both battery-powered medical devices and 24V industrial transmitters without design compromise.

Availability

INA122UA is available at Aetrix Electronics and suitable for portable electronics, field transmitters and sensors, and electrocardiograms (ECGs) requiring stable component supply across extended product lifecycles.

Supply support for INA122UA 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 leader specializing in analog and embedded processing technologies, with decades of heritage in precision signal chain solutions.

The INA122UA belongs to TI's precision instrumentation amplifier product line, engineered specifically for low-power, high-accuracy sensor signal conditioning in medical, industrial, and portable instrumentation systems.

FAQ

What is the minimum supply voltage required for reliable operation of the INA122UA?

The INA122UA operates reliably down to 2.2V on a single supply, as specified in its Recommended Operating Conditions. At this voltage, it maintains full functionality including rail-to-rail output swing and 60μA quiescent current. Performance parameters such as CMRR and gain accuracy remain within datasheet limits across the full −40°C to +85°C temperature range, making the INA122UA suitable for coin-cell or single-LiFePO₄ powered applications where headroom is constrained.

How does the INA122UA achieve rail-to-rail output with single-supply operation?

The INA122UA achieves rail-to-rail output through internal output-stage design that allows the output to swing within ~100mV of both supply rails under typical loads. Unlike basic op-amps, its two-op-amp architecture incorporates level-shifting circuitry on the inputs, enabling valid linear operation even when common-mode voltage equals ground - a capability confirmed by the device's specified VCM range extending to 0V on single supply. This eliminates the need for negative supply rails in portable ECG or pressure sensor front-ends.

Can the INA122UA be used with a grounded reference (REF = 0V)?

Yes, the INA122UA is routinely used with REF tied to ground, which sets the output DC level to match the reference potential. However, the REF pin must be driven by a low-impedance source (<10Ω) to maintain specified CMRR performance; a series resistance >10Ω degrades CMRR to ~80dB. For most applications, connecting REF directly to system ground or using a low-impedance buffer (e.g., OPA391) satisfies this requirement and preserves the INA122UA's 96dB typical common-mode rejection.

What is the recommended external gain-setting resistor (RG) for a gain of 100 V/V with the INA122UA?

For a gain of 100 V/V, the INA122UA requires an RG value of 2.105 kΩ, calculated using G = 5 + 200kΩ/RG. The nearest standard 1% resistor value is 2.1 kΩ, which yields a nominal gain of 100.2 V/V - well within the ±0.5% gain error specification at G = 100. TI's datasheet Table 6-1 explicitly lists 2.1 kΩ as the recommended 1% value for G = 100, confirming its suitability for production use with the INA122UA without recalibration.

Does the INA122UA support operation from dual supplies, and how does performance differ?

Yes, the INA122UA supports dual-supply operation from ±1.1V to ±18V (total 2.2V–36V), identical to its single-supply range. Electrical characteristics - including offset voltage, noise, CMRR, and bandwidth - are fully specified and tested under dual-supply conditions. No performance degradation occurs; in fact, certain parameters like output swing symmetry improve slightly due to balanced rail margins. The device's absolute maximum ratings and recommended operating conditions apply equally to both configurations, allowing seamless migration between single- and dual-supply designs using the same INA122UA part.