Texas Instruments INA331IDGKT

Overview

INA331IDGKT 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), 2.0 MHz bandwidth, 5 V/µs slew rate, and ultra-low quiescent current of 415 µA - enabling battery-powered industrial and medical applications such as bridge-based load cells and ECG front-ends.

For engineers reviewing the INA331IDGKT datasheet, INA331IDGKT pinout, INA331IDGKT application, or INA331IDGKT equivalent, this page delivers verified technical context, package-specific pin functions, real-world use cases, and validated alternative options - all grounded in TI's SBOS215C production data sheet and official ordering information.

Technical Context

The INA331IDGKT implements a modified two-op-amp architecture with an integrated third gain stage, enabling precise differential-to-single-ended conversion while maintaining high common-mode rejection (94 dB DC) and low input bias current (0.5 pA). Its internal 5× gain is laser-trimmed, and external resistors allow programmable gains up to 1000 V/V via G = 5 + 5(R₂/R₁).

It operates from +2.7 V to +5.5 V single supply, supports rail-to-rail output swing (within 25 mV of rails at G ≥ 10), and includes a dedicated shutdown pin that reduces quiescent current to 0.01 µA - critical for multi-channel or portable systems requiring microsecond wake-up latency.

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), RoHS-compliant, MSL Level-2-260°C-1 year.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA333IDGKT and AD8421ARMZ, the INA331IDGKT uniquely balances ultra-low power (415 µA), rail-to-rail output, and integrated shutdown in a miniature VSSOP-8 - making it optimal for space-constrained, battery-operated sensor nodes where moderate precision suffices.

Availability

INA331IDGKT is available at Aetrix Electronics and suitable for industrial sensor amplifiers, portable physiological monitors, and low-power data acquisition systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for INA331IDGKT 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 amplifiers and signal-chain solutions.

The INA331 family was designed specifically for low-cost, low-power instrumentation in single-supply industrial and medical sensor interfaces - emphasizing ease of use, small footprint, and robust performance across –55°C to +125°C.

FAQ

What is the maximum gain achievable with INA331IDGKT?

The INA331IDGKT supports externally programmable gains from 5 V/V to 1000 V/V using the equation G = 5 + 5(R₂/R₁). With appropriate resistor selection and layout, gains up to 1000× are achievable while maintaining stability and specified accuracy. The internal 5× gain stage remains active regardless of external resistor configuration, and gain error remains below ±0.1% at G = 5. The INA331IDGKT datasheet confirms this range under Electrical Characteristics and Applications Information sections.

Does INA331IDGKT require external resistors for basic operation?

No - the INA331IDGKT operates at its default gain of 5 V/V without any external resistors. Pin 1 (RG) is internally connected to VOUT to set G = 5. External resistors are optional and only needed when higher gain is required. This simplifies BOM and layout for standard gain applications. The INA331IDGKT pinout and functional diagram in SBOS215C confirm the internal RG-to-VOUT short for nominal operation.

Can INA331IDGKT operate from a 3.3 V supply?

Yes - the INA331IDGKT is fully specified for single-supply operation from +2.7 V to +5.5 V, including 3.3 V. At 3.3 V, it maintains rail-to-rail output swing (within 25 mV of rails at G ≥ 10), 2.0 MHz bandwidth, and 415 µA quiescent current. Key parameters such as CMRR and offset voltage are tested across the full temperature range (–55°C to +125°C) at all supply voltages. The INA331IDGKT Electrical Characteristics table explicitly lists performance at VS = +2.7 V and +5.5 V.

What is the purpose of the REF pin on INA331IDGKT?

The REF pin sets the output's zero-reference voltage level - for example, connecting REF to 1.65 V on a 3.3 V supply centers the output swing around mid-supply. It must be driven by a low-impedance source (<160 Ω series resistance) to preserve CMRR. The REF pin also influences the input common-mode range and can be used for offset trimming. All INA331IDGKT applications, including ECG and bridge amplifiers, rely on proper REF biasing as detailed in the Applications Information section of SBOS215C.

Is INA331IDGKT pin-compatible with INA333IDGKT?

No - although both are VSSOP-8 packaged instrumentation amplifiers from Texas Instruments, the INA331IDGKT and INA333IDGKT have different internal architectures and pin functions. The INA333IDGKT uses a different gain-setting method (RG pin tied to ground or VREF for gain selection) and lacks a dedicated shutdown pin. Their pinouts are not interchangeable; PCB redesign is required for substitution. This incompatibility is confirmed by comparing the PIN CONFIGURATION diagrams and Functional Block Diagrams in their respective datasheets (SBOS215C vs SBOS592).