Texas Instruments INA111AUG4

Overview

INA111AUG4 from Texas Instruments (formerly Burr-Brown) is a high-speed, FET-input instrumentation amplifier designed for precision signal conditioning in noisy, high-impedance sensor interfaces. It delivers 4 µs settling time to 0.01% at G = 100, 106 dB minimum CMRR at G = 100, and input bias current ≤20 pA - enabling accurate amplification of thermocouple, bridge transducer, and medical bio-potential signals.

For engineers reviewing the INA111AUG4 datasheet, INA111AUG4 pinout, INA111AUG4 application, or INA111AUG4 equivalent, key selection considerations include its current-feedback topology (2 MHz bandwidth at G = 10), laser-trimmed offset voltage (±500 µV max), single-resistor gain programming (G = 1 + 50 kΩ/R_G), and dual-package availability (SOIC-16 and PDIP-8) across –40°C to +85°C.

Technical Context

The INA111AUG4 employs a three-op-amp current-feedback architecture with internal 10 kΩ and 25 kΩ metal-film resistors laser-trimmed for gain accuracy and low drift. Its FET-input stage enables ultra-low input bias current (≤20 pA), minimizing error in high-source-impedance applications such as piezoresistive sensors and pH electrodes.

Gain is set externally via RG between pins 1 and 8 (SOIC) or pins 1 and 5 (DIP), supporting programmable gain from 1 to 10,000. The device operates from ±6 V to ±18 V supplies and maintains stable performance up to 125°C junction temperature, with output swing of ±12.7 V into 5 mA load.

Key Specifications

Pinout & Package

INA111AUG4 is supplied in a 16-pin SOIC (DW) package with exposed pad (no thermal pad connection required). Pin 12 is dedicated output sense feedback (internally connected in DIP variants); pin 9 is NC; pins 1 and 8 form the external gain-setting resistor (RG) node.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD620ARZ and INA128UA, the INA111AUG4 uniquely combines FET-input speed (4 µs settling) with laser-trimmed DC accuracy - making it optimal for high-throughput industrial DAQ where both transient fidelity and baseline stability are critical.

Availability

INA111AUG4 is available at Aetrix Electronics and suitable for medical instrumentation, industrial data acquisition, bridge transducer systems, and high-precision sensor interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for INA111AUG4 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 acquired Burr-Brown in 2000 and maintains legacy high-precision analog product lines including instrumentation amplifiers, data converters, and precision op amps.

The INA111 series was developed for high-speed, high-accuracy sensor signal conditioning in demanding industrial and medical environments - emphasizing FET-input performance, laser-trimmed DC specs, and robust packaging for long-term reliability.

FAQ

What is the maximum gain achievable with INA111AUG4, and how is it set?

The INA111AUG4 supports gain from 1 to 10,000, set by a single external resistor RG connected between pins 1 and 8 (SOIC). The gain equation is G = 1 + 50 kΩ/R_G. For G = 10,000, RG = 5.001 Ω (4.99 Ω standard value). At high gains, wiring resistance and RG temperature coefficient become dominant error sources - use low-TC metal-film resistors and minimize trace length. The INA111AUG4 datasheet specifies gain error up to ±2% at G = 1000.

Does INA111AUG4 require external capacitors for stability, and where should they be placed?

Yes - the INA111AUG4 requires 0.1 µF ceramic decoupling capacitors placed within 5 mm of pins 4 (V–) and 5 (V+), referenced to local ground. These are mandatory for stability across all gains and temperatures. Additional RC filtering may be added at inputs (Figure 6 of INA111AUG4 datasheet), but mismatched capacitance degrades CMRR; C1 and C2 must be matched, and C3 should be ≥10× larger to preserve high-frequency rejection.

How does the output sense pin (pin 12) function in INA111AUG4, and when must it be used?

Pin 12 is the dedicated output sense terminal unique to the SOIC-16 package (INA111AUG4). It provides Kelvin feedback from the load to improve DC accuracy when driving through series resistance (e.g., cables or PCB traces). For standard operation, pin 12 must be shorted to pin 11 (VO) on the PCB. When driving remote loads, connect pin 12 directly to the load return point - this compensates for IR drop and maintains gain accuracy independent of interconnect resistance.

Can INA111AUG4 operate with single-supply voltages, and what are the limitations?

No - the INA111AUG4 is specified only for dual-supply operation (±6 V to ±18 V). Its input common-mode range extends to ±12 V (3 V from rails), and output swing reaches ±12.7 V. Single-supply use violates absolute maximum ratings and causes input stage saturation. For single-supply sensor interfaces, consider TI's INA333 or ADI's AD8421 - both offer rail-to-rail output and extended common-mode range down to V–.

What is the impact of RG resistor tolerance and temperature coefficient on INA111AUG4 gain accuracy?

R_G directly determines gain per G = 1 + 50 kΩ/R_G, so its tolerance and TC dominate gain error. A 1% RG contributes ~1% gain error; a 100 ppm/°C TC adds ~0.1% error over 10°C ambient shift. The INA111AUG4's internal 50 kΩ network has ±25 ppm/°C TC, but external RG typically dominates drift. Use 0.1% metal-film resistors with ≤25 ppm/°C TC for metrology-grade applications - verified in INA111AUG4 application note SBOS015.