Texas Instruments INA131AP

Overview

INA131AP from Texas Instruments (formerly Burr-Brown) is a precision instrumentation amplifier with fixed G = 100 gain, designed for high-accuracy signal conditioning of low-level differential signals in noisy environments. It features 50 µV max input offset voltage, 110 dB min CMR, ±40 V input overvoltage protection, and operates from ±2.25 V to ±18 V supplies - ideal for bridge, thermocouple, and RTD sensor interfaces in industrial data acquisition systems.

For engineers reviewing the INA131AP datasheet, INA131AP pinout, INA131AP application, or INA131AP equivalent, this page delivers verified specifications, real-world use context, package-validated pin functions, and two confirmed alternative parts for design flexibility in precision analog front-ends.

Technical Context

The INA131AP uses a 3-op-amp architecture with on-chip laser-trimmed resistors to fix gain at 100, achieving <0.024% gain error and ±0.25 µV/°C offset drift. Its input stage includes internal ±40 V fault protection diodes and high-impedance (10¹⁰ Ω || 6 pF) inputs, enabling direct connection to transducers without external clamping.

Common-mode rejection remains ≥110 dB up to 10 kHz, and the output reference (Ref) pin enables precise level-shifting - critical for single-supply ADC interfacing. The device maintains stable operation with load capacitance up to 1000 pF and delivers 0.7 V/µs slew rate with 70 kHz bandwidth at G = 100.

Key Specifications

Pinout & Package

INA131AP is housed in an 8-pin plastic DIP (PDIP-P) package with 0.3-inch width, compatible with standard through-hole prototyping and industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA131AP, INA126PA offers wider gain adjustability but sacrifices input ruggedness and CMR, while AD620ARZ provides identical offset performance in a compact SOIC package but lacks integrated overvoltage protection and requires external gain configuration - making INA131AP optimal for fixed-gain, high-reliability industrial sensor nodes.

Availability

INA131AP is available at Aetrix Electronics and suitable for bridge amplifier circuits, thermocouple interfaces, RTD sensor modules, medical biopotential acquisition, and industrial data loggers requiring stable component supply across extended temperature ranges.

Supply support for INA131AP 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 delivering analog and embedded processing solutions, with deep heritage in precision signal chain components dating to Burr-Brown's acquisition in 2000.

The INA131AP belongs to TI's legacy instrumentation amplifier portfolio, engineered specifically for high-accuracy, low-drift sensor signal conditioning in industrial, test & measurement, and medical equipment where reliability and long-term stability are critical.

FAQ

What is the maximum input common-mode voltage range for INA131AP?

The INA131AP supports an input common-mode voltage range of ±13.5 V at ±15 V supplies, extending to ±11 V at ±11.4 V supplies. This range is limited by the output swing of its internal op-amps and improves over earlier instrumentation amplifiers like the INA114 due to its 5× output-stage gain architecture. The actual usable range depends on output voltage and supply rails - see Figure "Input Common-Mode Range vs Output Voltage" in the INA131AP datasheet for exact boundaries under specific conditions.

Does INA131AP require external resistors to achieve G = 100?

No, the INA131AP does not require external resistors to achieve G = 100. Its gain is set by on-chip laser-trimmed resistors, delivering ±0.024% typical gain error and excellent temperature stability. Pins 1 and 8 (RG) are left unconnected for fixed gain operation. An external resistor between these pins can increase gain, but it is optional and not needed for the specified G = 100 function of the INA131AP.

Can INA131AP operate from a single supply?

The INA131AP is specified for dual-supply operation (±2.25 V to ±18 V) and is not characterized for true single-supply use. While it may function with asymmetric rails (e.g., +5 V and ground), the input common-mode and output swing ranges become severely constrained, and key specs like CMR and offset drift are not guaranteed. For single-supply designs, TI recommends alternatives such as the INA333 or INA826, which are explicitly rated for rail-to-rail input/output and 2.7–36 V operation.

What is the purpose of the Ref pin on INA131AP?

The Ref pin on the INA131AP sets the DC level of the output voltage - VO = 100 × (VIN+ − VIN−) + VREF. It must be driven by a low-impedance source (≤5 Ω) to maintain specified CMR; even 5 Ω series resistance degrades CMR from 110 dB to ~106 dB. Grounding Ref yields output centered at 0 V, while connecting to a precision voltage (e.g., 2.5 V) shifts the entire output range accordingly - essential for interfacing with unipolar ADCs.

Is INA131AP RoHS compliant?

Yes, the INA131AP is RoHS compliant. According to Texas Instruments' packaging addendum, the orderable part number INA131AP carries a "Yes" RoHS status, confirming compliance with Directive 2011/65/EU and its amendments. The device uses lead-free lead finish and meets JEDEC J-STD-020 moisture sensitivity requirements, though MSL rating is marked "N/A for Pkg Type" due to its PDIP through-hole construction.