Texas Instruments INA126U

Overview

INA126U from Texas Instruments is a single-channel, micropower instrumentation amplifier in 8-pin SOIC (D) package, delivering 250 µV max offset voltage, 3 µV/°C max drift, and 35 nV/√Hz input voltage noise for precision low-level sensor signal conditioning in portable industrial transmitters.

For engineers reviewing the INA126U datasheet, INA126U pinout, INA126U application, or INA126U equivalent, this page provides verified specifications, validated SOIC-8 pin functions, real-world use cases in ECG and flow transmitters, and two confirmed alternative parts with documented technical and application differences.

Technical Context

The INA126U implements a two-op-amp topology that reduces quiescent current to 175 µA/channel while maintaining high input impedance and balanced inputs-enabling accurate differential acquisition from unbalanced sources like thermocouples or bridge sensors. Its gain is set externally via RG (pin 1–8), supporting 5 V/V to 10,000 V/V with laser-trimmed internal 40 kΩ and 80 kΩ resistors.

It operates across ±1.35 V to ±18 V dual supplies or 2.7 V to 36 V single supply, with output referenced to the Ref pin (pin 5) for flexible level-shifting. Input common-mode range extends to ±11.25 V at ±15 V supply, limited by internal op-amp A2's output swing-not directly measurable at pins.

Key Specifications

Pinout & Package

INA126U 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 uniquely balances micropower operation (175 µA), industrial temperature rating (–40°C to +85°C), and flexible Ref-based output referencing-making it optimal for portable industrial transmitters where battery life, environmental robustness, and signal-level adaptability are jointly critical.

Availability

INA126U is available at Aetrix Electronics and suitable for level transmitters, ECG monitors, flow transmitters, and infusion pumps requiring stable component supply across automotive, industrial, and medical OEM programs.

Supply support for INA126U 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 INA126U belongs to TI's INAx126 micropower instrumentation amplifier family, designed specifically for low-power, high-accuracy sensor signal conditioning in portable and battery-operated industrial and medical instrumentation.

FAQ

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

The INA126U supports gains from 5 V/V to 10,000 V/V using a single external resistor (RG) connected between pins 1 and 8. The gain equation is G = 5 + 80 kΩ/RG. For G = 10,000 V/V, RG = 8.0 Ω (7.87 Ω 1% standard value). At this gain, wiring resistance becomes significant-direct soldering is recommended over socketed connections to avoid gain error. The INA126U datasheet confirms this range applies to all package variants including the SOIC-8 INA126U.

Does the INA126U require external trimming for offset voltage in typical applications?

No, the INA126U does not require external offset trimming in most applications. Its maximum offset voltage is 250 µV (RTI) and drift is 3 µV/°C-sufficient for 12-bit systems with ≥10 mV full-scale inputs. Section 7.2.2.2 of the INA126U datasheet explicitly states "most applications require no external offset adjustment." An optional trimming circuit using the Ref pin is provided only for ultra-high-accuracy requirements beyond the device's inherent specification.

Can the INA126U operate from a single 3.3 V supply, and what are the key layout considerations?

Yes, the INA126U operates from a single 2.7 V to 36 V supply. For 3.3 V operation, the Ref pin (pin 5) must be biased at ~1.65 V (midsupply) using a low-impedance source (<8 Ω) to prevent CMRR degradation. Input common-mode range shrinks to approximately ±0.7 V around Ref-so sensor outputs must stay within that window. Decoupling capacitors (0.1 µF X7R) must be placed within 2 mm of pins 4 (V–) and 7 (V+) per the INA126U layout guidelines.

What is the purpose of the Sense pins on the INA2126, and why does the INA126U not have them?

The SenseA and SenseB pins exist only on the dual-channel INA2126 (not on the INA126U) to enable remote-sense feedback-connecting directly to the load to compensate for voltage drop in long traces or PCB copper. The INA126U is a single-channel device with no Sense functionality; its output (pin 6) is internally referenced and does not support remote sensing. This distinction is clearly documented in Tables 4-1 (INA126U) and 4-2 (INA2126) of the INA126U/INA2126 datasheet.

How does the INA126U handle input overvoltage conditions, and what external protection is recommended?

The INA126U includes internal ESD diodes clamping inputs to (V–) – 0.7 V and (V+) + 0.7 V. If input signals exceed these limits, external series current-limiting resistors are required to keep input current below 10 mA (per Absolute Maximum Ratings). For ±15 V sensor interfaces, 1.5 kΩ resistors on both inputs limit fault current to <10 mA during overvoltage events-verified in Section 7.2.2.5 of the INA126U datasheet.