Texas Instruments INA331IDGKR

Overview

INA331IDGKR from Texas Instruments is a rail-to-rail output, low-power CMOS instrumentation amplifier optimized for single-supply sensor signal conditioning. It features fixed internal gain of 5 V/V (0.02% accuracy), 415 µA quiescent current, ±250 µV input offset voltage, and operates from –55°C to +125°C - enabling use in battery-powered industrial sensors and medical ECG front-ends.

For engineers reviewing the INA331IDGKR datasheet, INA331IDGKR pinout, INA331IDGKR application, or INA331IDGKR equivalent, this page delivers verified specifications, MSOP-8 package mapping, real-world application context for bridge/RTD/ECG systems, and two validated alternative parts with documented technical and application differences.

Technical Context

The INA331IDGKR implements a modified three-op-amp architecture with an integrated gain stage, delivering high common-mode rejection (94 dB DC) and low bias current (0.5 pA) for precision differential measurement. Its rail-to-rail output swing (within 25 mV of rails at G ≥ 10) and 2.0 MHz bandwidth support direct interfacing with SAR ADCs like ADS7818.

Gain is internally set to 5 V/V but scalable to 1000 V/V via external resistors using G = 5 + (5R₂/R₁). Shutdown mode reduces quiescent current to 0.01 µA, enabling microsecond wake-up in multi-channel or portable systems.

Key Specifications

Pinout & Package

VSSOP-8 (DGK) package: 3.0 mm × 3.0 mm, 0.65 mm pitch, thermally enhanced exposed pad (not electrically connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA333IDGKR and AD8421ARMZ, the INA331IDGKR offers the best balance of low cost, moderate speed, and proven reliability in industrial sensor nodes - especially where shutdown capability and wide temperature range are mandatory.

Availability

INA331IDGKR is available at Aetrix Electronics and suitable for industrial sensor amplifiers, medical ECG front-ends, and single-supply data acquisition systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for INA331IDGKR 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 over 50 years of innovation in precision signal chain components.

The INA331IDGKR belongs to TI's precision instrumentation amplifier product line, designed specifically for low-power, single-supply industrial and medical sensor signal conditioning where rail-to-rail output, low offset, and robust CMRR are critical.

FAQ

What is the maximum gain achievable with the INA331IDGKR?

The INA331IDGKR supports externally programmable gain from 5 V/V to 1000 V/V using the equation G = 5 + (5R₂/R₁). At G = 1000, bandwidth drops to ~10 kHz, and stability requires careful PCB layout with feedback capacitor compensation per Figure 8 in SBOS215C. The internal 5 V/V gain remains fixed and laser-trimmed for 0.02% accuracy.

Does the INA331IDGKR require external resistors for basic operation?

No - the INA331IDGKR operates at its default gain of 5 V/V with RG pin (Pin 1) shorted to VOUT (Pin 7), requiring no external resistors. External resistors R₁ and R₂ are only needed when configuring gain >5 V/V per the formula G = 5 + (5R₂/R₁). This simplifies design for standard bridge-sensor applications.

Can the INA331IDGKR drive an ADC input directly?

Yes - the INA331IDGKR's rail-to-rail output, 2.0 MHz bandwidth, and 2.5 µs 0.01% settling time make it suitable for direct connection to SAR ADCs such as the ADS7818. For capacitive-input ADCs, ensure load capacitance ≤100 pF or add series resistance per Figure 4 in SBOS215C to maintain stability.

What is the purpose of the REF pin on the INA331IDGKR?

On the INA331IDGKR, the REF pin (Pin 8) sets the output's zero-reference voltage level. It must be driven by a low-impedance source (<160 Ω) to preserve CMRR >80 dB. REF also influences common-mode input range: lowering REF expands the lower input limit but restricts upper limit per VOA₂ < V+ – 1.2 V.

How does shutdown mode affect output behavior in the INA331IDGKR?

When the INA331IDGKR enters shutdown (Shutdown pin <0.8 V), output impedance rises sharply and VOUT enters high-impedance state - ideal for multiplexing multiple sensors onto one ADC channel. Recovery to full operation occurs in microseconds, with output settling to final value within 2 µs after shutdown release.