Texas Instruments INA126E/250

Overview

INA126E/250 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 INA126E/250 datasheet, INA126E/250 pinout, INA126E/250 application, or INA126E/250 equivalent, this page provides verified package mapping (8-pin VSSOP, DGK), confirmed pin functions (RG, V+IN, V–IN, Ref, VO), real-world performance boundaries (±175 μA quiescent current, 200 kHz BW at G=5), and two validated alternative parts with documented functional and layout implications.

Technical Context

The INA126E/250 implements a two-op-amp topology that reduces quiescent current versus traditional three-op-amp IAs while maintaining high common-mode rejection (80–94 dB) and balanced input impedance (>1 GΩ). Its internal laser-trimmed 40 kΩ and 10 kΩ thin-film resistors set the base gain of 5 and define the gain equation G = 5 + 80 kΩ/R_G, where RG tolerance and TCR directly impact system-level gain accuracy and drift.

Operation requires a low-impedance reference connection at Pin 5 (Ref) to preserve CMRR; a series resistance >8 Ω degrades typical CMR to ~80 dB. The device supports true single-supply operation (2.7–36 V) by level-shifting output via the Ref pin, but dual-supply use (±1.35V min) simplifies biasing and extends input common-mode range to ±11.25 V at ±15 V supplies.

Key Specifications

Pinout & Package

INA126E/250 is housed in an 8-pin Very Small Outline Package (VSSOP, DGK), 3.0 mm × 3.0 mm body, 0.5 mm pitch, exposed thermal pad (optional soldering), 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 INA126E/250 offers the broadest gain range (5–10,000×) with external resistor control and unique single-supply Ref pin flexibility, making it optimal for cost-sensitive, field-configurable industrial sensors where moderate noise and proven reliability outweigh ultra-high precision.

Availability

INA126E/250 is available at Aetrix Electronics and suitable for ECG monitoring systems, industrial flow transmitters, multiparameter patient monitors, and AC charging station current sensing requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for INA126E/250 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 INAx126 product line was designed specifically for low-power, high-accuracy instrumentation in portable and distributed sensing systems - emphasizing micropower operation, wide supply flexibility, and robust performance across extended temperature ranges.

FAQ

What is the maximum gain achievable with INA126E/250, and how is it set?

The INA126E/250 supports gains from 5 to 10,000 V/V, set by a single external resistor RG connected between Pins 1 and 8 using the equation G = 5 + 80 kΩ/R_G. For G = 10,000, RG = 8.0 Ω (7.87 Ω 1% standard value). Layout care is essential at high gains due to trace resistance contributing measurable error - the INA126E/250 datasheet specifies RG values for common gains and warns against socket use above G = 100.

Does INA126E/250 support true single-supply operation, and how is the reference handled?

Yes, the INA126E/250 supports true single-supply operation from 2.7 V to 36 V. Its Ref pin (Pin 5) enables output level-shifting: connecting Ref to mid-supply (e.g., 1.65 V for 3.3 V system) centers the output swing. This avoids saturation and preserves linearity. Critically, the Ref connection must be low-impedance (<8 Ω); higher impedance degrades CMRR to ~80 dB, as confirmed in the INA126E/250 electrical characteristics table.

What is the input common-mode voltage range for INA126E/250 at ±15V supplies?

At ±15 V supplies, the INA126E/250 input common-mode voltage range is –11.25 V to +11.25 V (±75% of V_S), as specified in Section 5.6 of the datasheet. This range is limited by internal op-amp A2's output swing and shrinks at lower supplies. Figure 5-6 shows the exact V_CM vs. V_O boundary; exceeding it saturates A2 and invalidates the output, even if A1 remains linear - a key constraint when interfacing with high-common-mode bridge sensors.

How does the INA126E/250 handle input overvoltage protection?

The INA126E/250 integrates internal ESD diodes from each input (V+IN, V–IN) to V+ and V– rails, clamping input voltages to approximately V+ + 0.7 V and V– – 0.7 V. To prevent damage, input current must be limited to <10 mA - typically achieved with series resistors. This protection allows safe interfacing with sensors prone to transient overvoltage (e.g., thermocouples in industrial furnaces), provided external current limiting is implemented per the INA126E/250 Absolute Maximum Ratings table.

Is the INA126E/250 pin-compatible with other members of the INAx126 family?

No - the INA126E/250 (single-channel, 8-pin VSSOP) is not pin-compatible with the dual-channel INA2126E/250 (16-pin SSOP) or with SOIC/PDIP variants of the INA126. While all share identical pin *functions* (e.g., Pin 5 = Ref), the physical pin count, spacing, and layout differ. The INA126E/250 uses the DGK package (0.5 mm pitch, 3 mm × 3 mm), whereas SOIC (D) and PDIP (P) variants have different footprints and thermal characteristics - PCB redesign is required for package substitution.