Texas Instruments INA126E/2K5G4

Overview

INA126E/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 175 μA/channel quiescent current, ±1.35V to ±18V dual-supply operation, 250 μV max input offset voltage, 3 μV/°C max offset drift, and 35 nV/√Hz input voltage noise - enabling high-accuracy sensor interfacing in ECG monitors and flow transmitters.

For engineers reviewing the INA126E/2K5G4 datasheet, INA126E/2K5G4 pinout, INA126E/2K5G4 application, or INA126E/2K5G4 equivalent, this page provides verified technical context, validated pin functions, confirmed gain-setting behavior (G = 5 + 80 kΩ/R_G), real-world application constraints for V_REF and common-mode range, and two rigorously cross-checked alternative parts with documented functional and packaging differences.

Technical Context

The INA126E/2K5G4 implements a two-op-amp topology that reduces power consumption versus traditional three-op-amp instrumentation amplifiers while maintaining high input impedance and balanced input structure. Its internal laser-trimmed 40 kΩ/10 kΩ resistor network enables precise gain setting from 5 V/V to 10,000 V/V using a single external resistor (R_G) between pins 1 and 8.

It operates across –40°C to +85°C with guaranteed performance at ±1.35V minimum supply, supports single-supply operation via the REF pin (pin 5), and requires low-impedance REF connection to preserve >80 dB CMRR. Input protection diodes clamp signals to within ~0.7 V of supply rails, and internal A2 output swing limits the negative common-mode input range.

Key Specifications

Pinout & Package

INA126E/2K5G4 is packaged in an 8-pin VSSOP (DGK) with 0.65 mm pitch, 3.0 mm × 3.0 mm body, and exposed thermal pad - optimized for compact PCB layouts and improved thermal dissipation in dense sensor modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD620ARZ and INA333AIDR, the INA126E/2K5G4 uniquely balances micropower operation (175 μA), wide dual-supply range (±1.35V), and robust 80–94 dB CMRR across 5–1000 gain - making it optimal for industrial field transmitters requiring long-life batteries and harsh-environment reliability without sacrificing accuracy.

Availability

INA126E/2K5G4 is available at Aetrix Electronics and suitable for level transmitter calibration, flow meter signal conditioning, and multiparameter patient monitor front-ends requiring stable component supply across extended production lifecycles.

Supply support for INA126E/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.

The INA126 product line was designed specifically for low-power, high-accuracy industrial and medical sensor signal conditioning - emphasizing micropower operation, wide supply flexibility, and robust common-mode rejection in compact packages.

FAQ

What is the minimum supply voltage required for reliable operation of the INA126E/2K5G4?

The INA126E/2K5G4 supports dual-supply operation down to ±1.35 V (2.7 V total) and single-supply operation from 2.7 V to 36 V. At ±1.35 V, guaranteed specifications include 175 μA quiescent current, 250 μV max offset, and functional gain setting - though common-mode input range shrinks, requiring careful REF pin biasing. The INA126E/2K5G4 datasheet Section 5.3 confirms these limits under Recommended Operating Conditions.

How does the REF pin (pin 5) affect output accuracy and common-mode rejection in the INA126E/2K5G4?

The REF pin sets the output DC level relative to which VO is referenced. A high-impedance connection degrades CMRR to ~80 dB; a low-impedance drive (<8 Ω) maintains >80 dB CMRR. In single-supply use, REF is typically tied to mid-supply (e.g., 1.35 V for 2.7 V system) to maximize output swing. The INA126E/2K5G4 application note SBOS062D Section 7.1 specifies that improper REF routing directly causes measurable CMR loss and output offset shift.

Can the INA126E/2K5G4 be used in a dual-supply configuration with asymmetric rails, such as +5 V and –3 V?

Yes - the INA126E/2K5G4 supports asymmetric dual supplies as long as the total differential supply (V+ – V–) remains within 2.7 V to 36 V and each rail stays within absolute maximum ratings (±18 V). For +5 V/–3 V operation, V+ = +5 V and V– = –3 V yields 8 V total supply, enabling full functionality. However, input common-mode range becomes asymmetric: (V–) – 0.5 V to (V+) + 0.5 V, i.e., –3.5 V to +5.5 V, per Section 5.6 of the INA126E/2K5G4 datasheet.

What is the impact of external R_G resistor tolerance and temperature coefficient on gain accuracy in the INA126E/2K5G4?

R_G directly determines gain via G = 5 + 80 kΩ/R_G. A 1% tolerance R_G contributes ~1% gain error; a 100 ppm/°C TC adds ~0.1% drift over 10°C. For G = 100 (R_G = 842 Ω), a 0.1% R_G drift causes ~0.1% gain drift. TI's SBOS062D Section 7.2.2.1 states that wiring/solder resistance becomes significant above G = 100, so 0.1% metal-film R_G with Kelvin connections is recommended for precision applications using the INA126E/2K5G4.

Does the INA126E/2K5G4 require external decoupling capacitors, and if so, what values are recommended?

Yes - TI recommends 0.1 μF ceramic capacitors placed as close as possible to pins 4 (V–) and 7 (V+), with short traces to ground. For noisy supplies or high-precision applications, add a 10 μF tantalum or aluminum electrolytic in parallel. Figure 7-1 in the INA126E/2K5G4 datasheet SBOS062D shows this configuration, and Section 7.2 explicitly states that omitting decoupling degrades PSRR and introduces supply-induced ripple into VO, especially at high gains.