Texas Instruments INA126U/2K5G4

Overview

INA126U/2K5G4 from Texas Instruments is a single-channel, micropower instrumentation amplifier optimized for precision low-level differential signal acquisition in battery-powered and space-constrained industrial systems. It delivers 250 µV max offset voltage, 3 µV/°C max drift, 35 nV/√Hz input voltage noise, ±1.35V to ±18V dual-supply operation, and gain programmable from 5 to 10,000 V/V via a single external resistor - enabling high-accuracy sensor interfacing in ECG monitors and flow transmitters.

For engineers reviewing the INA126U/2K5G4 datasheet, INA126U/2K5G4 pinout, INA126U/2K5G4 application, or INA126U/2K5G4 equivalent, key selection criteria include its 175 µA/channel quiescent current, 8-pin SOIC (D) package compatibility, guaranteed –40°C to +85°C operation, and two-op-amp architecture enabling low-power, high-CMRR signal conditioning without external trimming.

Technical Context

The INA126U/2K5G4 implements a two-op-amp instrumentation amplifier topology that eliminates the third op-amp of conventional designs, reducing quiescent current to 175 µA/channel while preserving high input impedance (>1 GΩ) and balanced input structure. Its internal 40kΩ/10kΩ resistor network sets minimum gain at 5 V/V, with external RG (pin 1–8) scaling gain up to 10,000 V/V using G = 5 + 80 kΩ/RG.

Input stage common-mode range is constrained by internal node A2's output swing, limiting usable VCM to ±11.25 V at ±15 V supplies; output is referenced to the Ref pin (pin 5), requiring low-impedance drive (<8 Ω) to maintain >80 dB CMRR. The device supports both dual-supply (±1.35V to ±18V) and single-supply (2.7V to 36V) operation with appropriate Ref biasing.

Key Specifications

Pinout & Package

INA126U/2K5G4 is housed in an 8-pin SOIC (D) package with 1.27 mm pitch, 4.9 mm × 3.91 mm body, and standard JEDEC MS-012AC footprint - compatible with automated SMT assembly and IPC-7351B land patterns.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD620ARZ and INA333AIDR, the INA126U/2K5G4 uniquely balances ultra-low power, extended gain range (up to 10,000 V/V), and wide supply flexibility (±1.35V to ±18V), making it the optimal choice for retrofitting legacy industrial transmitters and extending battery life in portable diagnostics without sacrificing signal fidelity.

Availability

INA126U/2K5G4 is available at Aetrix Electronics and suitable for ECG monitoring, flow transmitter design, and multiparameter patient monitor development requiring stable component supply across automotive, industrial, and medical OEM programs.

Supply support for INA126U/2K5G4 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 expertise in precision signal chain solutions for industrial, medical, and automotive markets.

The INA126 series belongs to TI's precision instrumentation amplifier product line, designed specifically for low-power, high-accuracy differential signal acquisition in portable and harsh-environment measurement systems.

FAQ

What is the maximum gain achievable with INA126U/2K5G4, and how is it set?

The INA126U/2K5G4 supports gains from 5 V/V to 10,000 V/V using the formula G = 5 + 80 kΩ/RG. To achieve 10,000 V/V, a 7.87 Ω resistor is placed between pins 1 and 8. The internal laser-trimmed 40kΩ/10kΩ network ensures gain accuracy remains within ±0.1% at G = 5 and ±1% at G = 100 for the INA126U/2K5G4, eliminating need for external calibration in most applications.

Does INA126U/2K5G4 require external trimming for offset voltage?

No, the INA126U/2K5G4 does not require external offset trimming in typical applications. Its maximum input offset voltage is 250 µV with drift of only 3 µV/°C across –40°C to +85°C, meeting requirements for most bridge sensor and biomedical front-ends. An optional offset trim circuit using the Ref pin (pin 5) is documented in the datasheet but rarely needed unless sub-50 µV residual offset is mandated.

Can INA126U/2K5G4 operate from a single 3.3V supply?

Yes, the INA126U/2K5G4 supports single-supply operation from 2.7V to 36V. For 3.3V use, the Ref pin (pin 5) must be biased to ~1.65V (mid-supply) using a low-impedance source (<8 Ω) to prevent output saturation. Input common-mode range shrinks accordingly - at 3.3V, VCM is limited to approximately 0.3V to 2.9V - verified in Figure 5-7 of the INA126U/2K5G4 datasheet.

What is the purpose of the Sense pins on INA126U/2K5G4?

The INA126U/2K5G4 does not have Sense pins - those are exclusive to the dual-channel INA2126. The INA126U/2K5G4 uses a simplified two-op-amp architecture with no dedicated Sense terminals. Its output (pin 6) connects directly to the load; feedback is internal. Confusion may arise from the INA2126's SenseA/SenseB pins (pins 7 and 10), which are absent on the single-channel INA126U/2K5G4.

How does the 8-pin SOIC package of INA126U/2K5G4 impact thermal performance?

The INA126U/2K5G4 in 8-pin SOIC (D) package has a junction-to-ambient thermal resistance (RθJA) of 116.4°C/W. At its maximum 175 µA quiescent current and typical 15 V supply, power dissipation remains below 3 mW, resulting in negligible self-heating (<0.35°C rise). This makes thermal derating unnecessary in standard PCB layouts with minimal copper, unlike higher-power amplifiers requiring heatsinking or thermal vias.