Texas Instruments INA116UA

Overview

INA116UA from Texas Instruments (originally Burr-Brown) is an ultra-low-input-bias-current FET-input instrumentation amplifier with 3 fA typical bias current at 25°C, ±2 mV max offset voltage, and gain range of 1–1000 set by a single external resistor. It features buffered guard drive pins, ±40 V input over-voltage protection, and is designed for high-impedance sensor signal conditioning in precision measurement systems.

For engineers reviewing the INA116UA datasheet, INA116UA pinout, INA116UA application, or INA116UA equivalent, this page delivers verified technical context, real-world design meaning for key specs, validated pin functions, application-specific implementation guidance, and two confirmed alternative parts with documented functional and packaging differences.

Technical Context

The INA116UA uses a 3-op-amp topology with laser-trimmed 50 kΩ internal feedback resistors to achieve precise gain accuracy and low drift. Its Difet® input stage enables femtoampere-level bias current, supported by dedicated guard drive outputs adjacent to both inputs to minimize PCB leakage paths.

It integrates input over-voltage protection clamps (±40 V), operates from ±4.5 V to ±18 V supplies, and delivers 84 dB CMRR at G = 10 across –40°C to +85°C. The guard outputs provide ±2 mA/–50 µA drive capability with <650 Ω output impedance for active cable shielding.

Key Specifications

Pinout & Package

SOL-16 surface-mount package (SOIC-DW, 16-pin), 10.3 mm × 7.5 mm body, 1.27 mm pitch, moisture sensitivity level 3 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-bias-current instrumentation amplifier applications.

Compared with AD8428ARZ and LTC6915IGN#PBF, the INA116UA uniquely combines femtoampere bias current, integrated guard drivers, and flexible gain setting-making it irreplaceable in applications demanding sub-picoampere input integrity and active leakage suppression.

Availability

INA116UA is available at Aetrix Electronics and suitable for laboratory instrumentation, pH measurement systems, and ion-selective probe interfaces requiring stable component supply and long-term calibration consistency.

Supply support for INA116UA 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 product support, quality assurance, and documentation for precision analog components like the INA116UA.

The INA116UA belongs to TI's legacy instrumentation amplifier portfolio, originally engineered for ultra-high-impedance DC signal conditioning in scientific measurement equipment where femtoampere-level input integrity is non-negotiable.

FAQ

What is the guaranteed maximum input bias current for INA116UA over its full operating temperature range?

The INA116UA guarantees ≤25 fA input bias current at +85°C, with typical performance of 3 fA at +25°C. This specification is validated per the datasheet's "Bias Current" row under "INA116PA, UA" column, and reflects worst-case behavior across –40°C to +85°C. The INA116UA achieves this via Difet® input transistors and on-die guarding architecture-no external compensation is needed to meet this limit.

Can INA116UA operate with a single supply, or does it require dual-rail ±V operation?

The INA116UA requires dual-rail supplies (e.g., ±5 V to ±18 V) and cannot operate from a single-ended supply. Its internal architecture relies on symmetrical positive and negative rails to bias the Difet® inputs and enable full differential swing. Attempting single-supply use will result in input saturation, loss of common-mode range, and undefined output behavior-confirmed by the Absolute Maximum Ratings table specifying "Supply Voltage: ±18 V" and "Input Common-Mode Voltage Range: (V+)–4 V to (V–)+4 V."

How does the guard drive functionality of INA116UA reduce measurement error in high-impedance circuits?

The INA116UA's Guard+ and Guard– pins actively drive PCB traces and cable shields to the same potential as their adjacent VIN+ and VIN– nodes, eliminating voltage gradients that cause surface leakage currents. This reduces effective input bias current by up to 1000× compared to unguarded layouts-verified by typical curves showing <10 fA leakage with proper guarding versus >1 pA without. The guard outputs deliver ±2 mA/–50 µA, enabling direct coaxial shield driving without external buffers in DC–1 kHz applications.

What is the minimum external gain-setting resistor (RG) value supported for stable operation of INA116UA at G = 1000?

For G = 1000, the INA116UA requires RG = 50.05 Ω (per datasheet Table on page 7), with nearest 1% value of 49.9 Ω. Layout must minimize trace resistance (<0.1 Ω) and avoid sockets-since wiring resistance contributes directly to gain error. At this value, the amplifier remains stable with ≥100 pF load capacitance and delivers 7 kHz bandwidth, as confirmed in the "Frequency Response" specifications table and typical curve on page 4.

Is INA116UA RoHS-compliant and qualified for industrial temperature operation?

Yes, the INA116UA is RoHS-compliant (NIPDAUAG lead finish) and rated for industrial operation from –40°C to +85°C, as stated in the Package Option Addendum and Absolute Maximum Ratings. Its SOIC-DW package carries MSL Level-3 rating (260°C peak reflow), and TI documents full qualification per JESD22-A108 thermal cycling and JESD22-A110 high-temperature storage. No derating is required within this range for bias current, CMRR, or gain accuracy.