Texas Instruments INA331AIDGKR

Overview

INA331AIDGKR from Texas Instruments is a rail-to-rail output, low-power CMOS instrumentation amplifier optimized for single-supply operation (2.7V to 5.5V), delivering 2.0MHz bandwidth, 5V/µs slew rate, and ±250µV input offset voltage. It features internal gain of 5V/V (0.02% accuracy), shutdown mode drawing only 0.01µA, and operates across –55°C to +125°C - ideal for battery-powered sensor signal conditioning in industrial and medical systems.

For engineers reviewing the INA331AIDGKR datasheet, INA331AIDGKR pinout, INA331AIDGKR application, or INA331AIDGKR equivalent, this page provides verified technical context, package-specific pin functions, real-world use cases, and validated alternative options for precision differential amplification in space-constrained, low-quiescent-current designs.

Technical Context

The INA331AIDGKR implements a modified two-op-amp instrumentation architecture with an integrated third gain stage, enabling accurate fixed-gain (G = 5) operation and external programmability up to G = 1000 via resistors R1/R2 per G = 5 + 5(R2/R1). Its CMOS input stage delivers 0.5pA bias current and 10¹³Ω input impedance, supporting high-impedance bridge and RTD sensors without loading error.

It achieves 94dB DC CMRR and maintains >70dB CMRR at 45kHz, rejecting line noise harmonics effectively. The rail-to-rail output swings to within 25mV of V+ (at G ≥ 10, RL ≥ 10kΩ), and settles to 0.1% in 1.7µs - making it suitable for direct interface with SAR ADCs like ADS7818 without external buffering.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: ultra-thin, 2.0mm × 1.5mm body, 0.5mm pitch, moisture-sensitive level 2, compatible with standard SMT reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA331AIDGKR, INA333AIDGKR trades gain accuracy and CMRR for lower power, while AD8421ARMZ offers superior precision and voltage range at the cost of higher consumption and no power management - guiding selection based on whether power, accuracy, or supply flexibility dominates the design priority.

Availability

INA331AIDGKR is available at Aetrix Electronics and suitable for industrial sensor amplifiers, portable medical devices, and field utility meters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for INA331AIDGKR 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 INA331 family was designed specifically for low-cost, low-power instrumentation in space-constrained, single-supply systems - targeting industrial process control, portable diagnostics, and energy metering applications demanding rail-to-rail output and microamp shutdown.

FAQ

What is the maximum gain achievable with INA331AIDGKR?

The INA331AIDGKR supports externally programmable gain from 5V/V to 1000V/V using the equation G = 5 + 5(R2/R1). With standard 1% metal-film resistors, gains up to 100V/V maintain <0.1% total error; beyond that, resistor tolerance and temperature coefficient dominate accuracy. The internal 5V/V path remains active even when external resistors are used.

Does INA331AIDGKR require external capacitors for stability?

Yes - the INA331AIDGKR requires 0.1µF ceramic bypass capacitors placed as close as possible to pins 4 (V–) and 6 (V+) to ensure stability under noisy supply conditions. For high-impedance feedback networks (R1/R2 > 100kΩ), a feedback capacitor (CF) may also be needed across R2 to compensate for RG-pin input capacitance (~3pF) and layout parasitics, per the equation RIN·CIN = RF·CF.

Can INA331AIDGKR operate from a 3.3V supply?

Yes - the INA331AIDGKR is fully specified from +2.7V to +5.5V. At 3.3V, it maintains rail-to-rail output swing (to within 25mV of rails at G ≥ 10), 2.0MHz bandwidth, and 415µA quiescent current. Common-mode input range shrinks to 0.35V–1.5V, so REF must be set accordingly (e.g., 1.0V) to preserve linear operation.

How does the shutdown function work on INA331AIDGKR?

The shutdown pin (pin 5) is active-low: pulling it below 0.8V (on a 5V supply) places INA331AIDGKR into sleep mode, reducing quiescent current to 0.01µA. Wake-up occurs in <1µs upon return to V+; during shutdown, the output enters high-impedance state, enabling multiplexed sensor architectures. No external pull-up is required - internal bias holds it high when unused.

Is INA331AIDGKR pin-compatible with other members of the INA331 family?

Yes - all VSSOP-8 variants (e.g., INA331IDGKR, INA331AIDGKT) share identical pinout, footprint, and electrical specifications except for initial offset and gain error grading. The 'A' suffix denotes improved initial accuracy (±250µV offset vs ±500µV for non-A grade), but no layout changes are needed when upgrading or substituting within the DGK package family.