Texas Instruments INA131BP

Overview

INA131BP from Texas Instruments (formerly Burr-Brown) is a precision instrumentation amplifier with fixed G = 100 gain, designed for low-noise, high-CMR signal conditioning of bridge, thermocouple, and RTD sensors. 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 in industrial temperature range (–40°C to +85°C).

For engineers reviewing the INA131BP datasheet, INA131BP pinout, INA131BP application, or INA131BP equivalent, this page delivers verified specifications, validated DIP-8 pin functions, real-world sensor interface use cases, and two technically documented alternative parts with explicit functional and application-level differences.

Technical Context

The INA131BP implements a 3-op-amp architecture with on-chip laser-trimmed thin-film resistors that fix gain at exactly 100, eliminating external gain-setting components while ensuring ±0.024% max gain error and ±5 ppm/°C gain drift. Its input stage includes integrated ±40 V fault-tolerant protection diodes and achieves 10¹⁰ Ω || 6 pF input impedance.

Common-mode rejection is maintained above 110 dB up to 1 kHz due to matched internal resistor ratios and precision trimming; output swing reaches ±13.5 V into 2 kΩ at ±15 V supplies, with 70 kHz –3 dB bandwidth and 0.7 V/µs typical slew rate - optimized for DC-coupled sensor front-ends requiring stability and accuracy over temperature.

Key Specifications

Pinout & Package

INA131BP is housed in an 8-pin plastic dual in-line package (PDIP-8, package drawing 006), through-hole mountable with 0.3-inch row spacing and standard DIP footprint compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA131BP, INA128P offers programmable gain and lower bias current but lacks integrated ±40 V protection; AD620ANZ provides broader gain range and faster response but requires external resistor placement and sacrifices ruggedness for speed - making INA131BP optimal for cost-sensitive, fixed-gain, high-reliability sensor interfaces.

Availability

INA131BP is available at Aetrix Electronics and suitable for bridge amplifier, thermocouple amplifier, and RTD sensor amplifier applications requiring stable component supply, long-term BOM continuity, and industrial temperature-grade performance.

Supply support for INA131BP 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 (TI) is a global semiconductor leader delivering analog and embedded processing solutions, with heritage in precision linear ICs dating to Burr-Brown's acquisition in 2000.

The INA131BP belongs to TI's precision instrumentation amplifier product line, engineered specifically for high-accuracy, low-drift DC-coupled sensor signal conditioning in industrial, medical, and test equipment.

FAQ

What is the maximum input common-mode voltage range for INA131BP?

The INA131BP supports an input common-mode voltage range of ±13.5 V at ±15 V supplies, limited by internal op-amp headroom. At lower supply voltages (e.g., ±2.25 V), the usable range contracts to ±1 V. This range is defined relative to the supply rails and remains stable across the full –40°C to +85°C operating temperature range. The INA131BP maintains linear operation within this window only when output swing constraints are respected - exceeding it causes saturation of input amplifiers without damage due to built-in ±40 V protection.

Does INA131BP require external components to achieve G = 100 gain?

No, the INA131BP does not require external components to achieve its nominal G = 100 gain. On-chip laser-trimmed resistors set the gain ratio precisely, delivering ±0.024% max gain error at +25°C. External resistors are optional and only needed if gain adjustment beyond 100 is required via the RG pins (1 and 8). For standard G = 100 operation, Pins 1 and 8 are left unconnected, simplifying layout and reducing thermal drift contributors in the signal path.

Can INA131BP operate from a single supply?

The INA131BP is specified exclusively for dual-supply operation (±2.25 V to ±18 V) and does not support true single-supply use. Its internal architecture relies on symmetrical rails to bias the 3-op-amp core and maintain input common-mode range centered near ground. Attempting single-supply operation (e.g., 0 V and +15 V) violates absolute maximum ratings for input voltage and will result in undefined behavior or saturation. For single-supply applications, TI recommends alternatives such as the INA333 or AD8221 with rail-to-rail output and input common-mode range extending to V–.

What is the purpose of the Ref pin (Pin 5) on INA131BP?

The Ref pin (Pin 5) on INA131BP sets the output common-mode voltage reference level - typically grounded for bipolar output swing. It must be driven by a low-impedance source (≤5 Ω recommended) to preserve common-mode rejection; adding series resistance degrades CMR by ~4 dB per 5 Ω. The pin accepts external DC offsets (e.g., for level-shifting) or buffered trim voltages, but floating or high-Z connections cause input amplifier saturation and invalid output. In all cases, the INA131BP output VO equals 100 × (VIN+ − VIN–) + V_REF.

How does INA131BP handle input overvoltage conditions?

The INA131BP incorporates internal diode-based protection on both inputs, allowing safe operation with differential or common-mode voltages up to ±40 V - even when power supplies are absent. During overload, input current is clamped to ~1.5 mA, preventing latch-up or permanent damage. Post-overload recovery is fast (<20 µs), and device performance remains within datasheet limits after transient clearance. This protection is intrinsic and requires no external components, distinguishing INA131BP from unprotected instrumentation amplifiers like the AD620 or INA128 that mandate external series resistors or TVS diodes.