Texas Instruments INA131AP-1

Overview

INA131AP-1 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, ±2.25 V to ±18 V supply range, and operates from –40°C to +85°C in an 8-pin plastic DIP package.

For engineers reviewing the INA131AP-1 datasheet, INA131AP-1 pinout, INA131AP-1 application, or INA131AP-1 equivalent, this page delivers verified specifications, validated pin functions, real-world use cases in sensor front-ends, and technically accurate alternative options for industrial and medical measurement systems.

Technical Context

The INA131AP-1 implements a 3-op-amp architecture with on-chip laser-trimmed resistors to fix gain at exactly 100, eliminating external gain-setting components. Its input stage provides ±40 V absolute maximum input tolerance and internal bias current return paths compatible with high-impedance sources.

CMR exceeds 110 dB at DC and maintains >100 dB up to 10 kHz; input-referred noise is 0.4 µV_p-p (0.1–10 Hz) and 12 nV/√Hz at 1 kHz. The output stage delivers ±13.5 V swing into 2 kΩ at ±15 V supplies, with 70 kHz –3 dB bandwidth and 0.7 V/µs typical slew rate.

Key Specifications

Pinout & Package

INA131AP-1 is housed in an 8-pin plastic DIP (PDIP-P) package with 0.3-inch body width and through-hole mounting. Pin spacing follows standard 0.1-inch grid; thermal resistance θ_JA is 100°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA131AP-1, INA128P offers superior CMR and lower offset but demands external gain configuration, while AD620ANZ provides higher bandwidth at the expense of CMR and input protection-neither is pin-compatible, and both require PCB layout changes for replacement.

Availability

INA131AP-1 is available at Aetrix Electronics and suitable for bridge amplifier circuits, thermocouple signal conditioning, and RTD-based temperature sensing requiring stable component supply across industrial automation, test equipment, and medical device manufacturing.

Supply support for INA131AP-1 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 analog from its acquisition of Burr-Brown in 2000.

The INA131 product line was developed specifically for cost-sensitive, high-accuracy industrial and medical sensor signal conditioning-emphasizing fixed-gain simplicity, robust input protection, and guaranteed DC precision without user calibration.

FAQ

What is the maximum input voltage the INA131AP-1 can withstand without damage?

The INA131AP-1 features integrated input protection rated for ±40 V absolute maximum input voltage on either input terminal-even with no power applied. This allows direct connection to unconditioned transducers and eliminates need for external clamping diodes in most industrial sensor interfaces. The protection circuit limits input current to ~1.5 mA during overload, preventing latch-up or permanent damage to the INA131AP-1.

Does the INA131AP-1 require external resistors to achieve G = 100 gain?

No, the INA131AP-1 does not require external resistors to achieve G = 100. Its gain is set by on-chip laser-trimmed resistors, delivering ±0.024% gain error and ±10 ppm/°C drift without any external components. Pins 1 and 8 (RG) are left unconnected for fixed-gain operation; adding an external resistor between them increases gain per the formula G = 100 + 250 kΩ/R_G, but is unnecessary for standard INA131AP-1 use.

What is the operating temperature range specified for the INA131AP-1?

INA131AP-1 is specified over the industrial temperature range of –40°C to +85°C. Its electrical parameters-including offset voltage (±50 µV max), CMR (110 dB min), and gain error-are guaranteed across this full range. The device also supports extended operation up to +125°C, though only the –40°C to +85°C range is production-tested and warranted for the INA131AP-1.

Can the INA131AP-1 be used with single-supply operation?

The INA131AP-1 is designed for dual-supply operation (±2.25 V to ±18 V) and does not support true single-supply operation. Its input common-mode range extends to within 1.25 V of each rail, and output swing is centered around the Ref pin potential. To operate from a single supply, the Ref pin must be biased to mid-rail (e.g., V_CC/2) using a low-impedance source, and input signals must remain within the valid common-mode window-this configuration is not characterized or guaranteed for the INA131AP-1 and may degrade CMR or offset performance.

How does the INA131AP-1 handle input bias current return paths?

The INA131AP-1 requires explicit bias current return paths for both inputs due to its 10¹⁰ Ω input impedance. Input bias current is typically <±1 nA but must flow to a defined reference-usually ground or the Ref pin. For low-source-impedance bridges, a single resistor from one input to ground suffices; for high-impedance thermocouples or RTDs, balanced resistors (e.g., 10 kΩ each) to Ref improve CMR and minimize offset errors. Without this path, inputs float and saturate, causing invalid output from the INA131AP-1.