Texas Instruments INA118UB/2K5G4

Overview

INA118UB/2K5G4 from Texas Instruments is a precision, low-power instrumentation amplifier designed for high-accuracy signal conditioning in sensor front-ends. It delivers 50 µV max input offset voltage, 0.5 µV/°C max drift, 110 dB min CMR at G = 1000, ±2.25 V to ±18 V dual supply operation, and 350 µA quiescent current - enabling high-fidelity measurement in battery-powered pressure transmitters and ECG systems.

For engineers reviewing the INA118UB/2K5G4 datasheet, INA118UB/2K5G4 pinout, INA118UB/2K5G4 application, or INA118UB/2K5G4 equivalent, this page provides verified technical context, gain-setting resistor design guidance, input protection behavior under ±40 V overvoltage, output swing limits across supply voltages, and validated alternative options for precision analog signal chains.

Technical Context

The INA118UB/2K5G4 uses a three-op-amp architecture with JFET-input stages and internal 25 kΩ/40 kΩ feedback networks laser-trimmed for accuracy. Its current-feedback topology sustains 70 kHz bandwidth at G = 100 while maintaining low noise (10 nV/√Hz at 1 kHz) and stable operation up to 1000 pF load capacitance.

Gain is set externally via a single resistor (RG) between pins 1 and 8 per G = 1 + 50 kΩ/RG. Input common-mode range extends from (V–) + 2 V to (V+) – 2 V at TA = 25°C, and linear output swing reaches (V+) – 0.8 V / (V–) + 0.35 V into 10 kΩ, supporting both dual-supply and single-supply (4.5 V to 0 V) configurations.

Key Specifications

Pinout & Package

INA118UB/2K5G4 is packaged in an 8-pin SOIC (SO-8) with 3.91 mm × 4.90 mm body size, optimized for automated assembly and thermal performance (RθJA = 115°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA118UB/2K5G4, INA818IDR improves DC precision and noise floor for static measurements, while INA828IDR enhances AC response for time-domain signal fidelity - both retain pin compatibility and gain-setting methodology, enabling drop-in evaluation without layout changes.

Availability

INA118UB/2K5G4 is available at Aetrix Electronics and suitable for pressure transmitter design, ECG front-end development, weigh scale production, and industrial analog input module manufacturing requiring stable component supply and long-term lifecycle support.

Supply support for INA118UB/2K5G4 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 specializing in analog and embedded processing technologies, with decades of heritage in precision amplifier design and manufacturing.

The INA118UB/2K5G4 belongs to TI's precision instrumentation amplifier product line, engineered specifically for high-accuracy, low-power sensor signal conditioning in industrial process control, medical instrumentation, and test equipment.

FAQ

What is the maximum safe input voltage for INA118UB/2K5G4?

The INA118UB/2K5G4 inputs are protected to ±40 V - meaning either input can withstand –40 V to +40 V relative to ground, even with power supplies disconnected. This rating applies independently to each input (e.g., –40 V on Pin 2 and +40 V on Pin 3 causes no damage). The device limits input current to ~6 mA during overload, eliminating need for external protection in most 24 V industrial environments. Always verify that external circuitry (e.g., series resistors, filters) does not degrade this protection in the INA118UB/2K5G4 application.

How do I calculate the gain-setting resistor RG for a target gain with INA118UB/2K5G4?

Use the formula G = 1 + 50 kΩ / RG, rearranged as RG = 50 kΩ / (G – 1). For example, G = 100 requires RG = 50 kΩ / 99 ≈ 505 Ω; standard 1% value is 511 Ω. The INA118UB/2K5G4 datasheet Table 9-1 lists common RG values (e.g., 49.9 Ω for G = 1001). Note that RG connects between Pins 1 and 8, and must be a stable, low-tempco resistor - carbon film types introduce gain drift exceeding the INA118UB/2K5G4's specified 10 ppm/°C limit.

Can INA118UB/2K5G4 operate from a single 5-V supply?

Yes - the INA118UB/2K5G4 supports single-supply operation with V+ = 5 V and V– = 0 V. In this mode, the input common-mode range is limited to 0.2 V to 4.8 V (per Figure 7-5), and output swing reaches 60 mV to 2 V (typical) into 10 kΩ. To maintain CMR, the Ref pin must be driven by a low-impedance source (e.g., op-amp buffer or voltage divider with ≤12 Ω Thebénin resistance). The INA118UB/2K5G4 achieves usable performance in 5 V systems such as portable data loggers, but dual-supply operation yields wider dynamic range.

What is the typical noise performance of INA118UB/2K5G4 at G = 100?

At G = 100, the INA118UB/2K5G4 exhibits 10 nV/√Hz input-referred voltage noise at 1 kHz and 0.28 µVPP integrated noise from 0.1 Hz to 10 Hz. This enables resolution of ~1 µV signals in 100 Hz bandwidth applications. Noise is dominated by the input stage; source impedance >1 kΩ increases total noise due to current noise contribution (2 pA/√Hz at 10 Hz). For low-noise optimization, keep source impedances <1 kΩ and use the INA118UB/2K5G4's low 5 nA bias current to minimize Johnson noise in high-value gain-setting resistors.

Does INA118UB/2K5G4 require external decoupling capacitors?

Yes - the INA118UB/2K5G4 requires 0.1 µF ceramic capacitors placed as close as possible (≤5 mm) between Pins 4 (V–) and 7 (V+) and their respective ground/power planes. These capacitors suppress high-frequency supply noise that could modulate the input stage or degrade PSRR (120 dB at DC, falling to 60 dB at 100 kHz). Omitting them risks oscillation or increased THD+N, especially in noisy industrial environments. The INA118UB/2K5G4 datasheet Figure 9-1 shows recommended placement; tantalum or electrolytic bulk capacitors may supplement but cannot replace the local 0.1 µF ceramics.