Texas Instruments INA118UG4

Overview

INA118UG4 from Texas Instruments is a precision, low-power instrumentation amplifier designed for high-accuracy signal conditioning of low-level differential sensor outputs in the presence of large common-mode voltages. It delivers 50 µV max input offset voltage, 110 dB min CMR at G = 1000, ±40 V input overvoltage protection, and operates from ±2.25 V to ±18 V supplies with only 350 µA quiescent current - making it suitable for battery-powered industrial transmitters and medical ECG front-ends.

For engineers reviewing the INA118UG4 datasheet, INA118UG4 pinout, INA118UG4 application, or INA118UG4 equivalent, this page provides verified technical context, gain-setting resistor design guidance, input protection behavior under overload, CMR vs frequency trade-offs, and validated alternatives for precision analog signal chains requiring stable DC accuracy and wide supply flexibility.

Technical Context

The INA118UG4 uses a three-op-amp architecture with JFET-input stages enabling 5 nA max input bias current and ±40 V input protection via current-limited FET clamps. Its gain is set by a single external resistor (RG) between pins 1 and 8 per G = 1 + 50 kΩ/RG, supporting gains from 1 to 10,000 with laser-trimmed internal 25 kΩ/40 kΩ resistor networks.

It features current-feedback topology delivering 70 kHz bandwidth at G = 100 and 800 kHz at G = 1, with output swing from (V–) + 0.35 V to (V+) – 0.8 V (RL = 10 kΩ), and maintains 110 dB CMR up to 100 Hz at G = 1000. Input common-mode range is specified as V– + 2 V to V+ – 2 V at VO = 0 V.

Key Specifications

Pinout & Package

INA118UG4 is supplied in an 8-pin SOIC (SO-8) package with 3.91 mm × 4.90 mm body size, RoHS-compliant lead finish, and –40°C to +125°C operating temperature range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA118UG4, INA828 offers superior noise and CMR in identical packaging for drop-in upgrades, while INA333 trades supply flexibility and bandwidth for ultra-low offset drift and power - making them complementary rather than interchangeable across voltage domains.

Availability

INA118UG4 is available at Aetrix Electronics and suitable for pressure transmitters, temperature transmitters, and weigh scale systems requiring stable component supply, long-term calibration integrity, and industrial-grade overvoltage resilience.

Supply support for INA118UG4 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 company headquartered in Dallas, Texas, specializing in analog and embedded processing technologies with over 50 years of precision amplifier innovation.

The INA118UG4 belongs to TI's precision instrumentation amplifier product line, engineered for high-accuracy sensor signal conditioning in industrial process control, test equipment, and medical instrumentation where DC stability and robust input protection are mandatory.

FAQ

What is the maximum gain achievable with INA118UG4, and how is it set?

The INA118UG4 supports gains from 1 to 10,000, set by a single external resistor RG connected between Pins 1 and 8 per the equation G = 1 + 50 kΩ/RG. For G = 10,000, RG = 5 Ω is required; however, PCB trace resistance becomes significant above G = 100, so 1% metal-film resistors and Kelvin connections are recommended. The INA118UG4 datasheet provides standard RG values for common gains in Table 9-1.

Does INA118UG4 require external components for basic operation?

Yes - the INA118UG4 requires at minimum an external gain-setting resistor (RG) between Pins 1 and 8, plus 0.1 µF decoupling capacitors on V+ (Pin 7) and V– (Pin 4) rails placed within 1 cm of the device. The Ref pin (Pin 5) must be connected to a low-impedance node (e.g., ground or DAC reference); a series resistance >12 Ω degrades CMR below 80 dB at G = 1.

Can INA118UG4 operate from a single 5-V supply?

Yes - the INA118UG4 functions with V+ = 5 V and V– = 0 V, delivering output swing from 60 mV to 2 V (typical) into 10 kΩ. However, input common-mode range is reduced to 0.2 V to 4.8 V, and CMR drops to ~90 dB at G = 1000. For optimal performance, TI recommends using split supplies (e.g., ±5 V) or biasing Ref to mid-supply when operating single-ended.

How does INA118UG4 handle input overvoltage conditions?

The INA118UG4 incorporates JFET-based input protection that withstands continuous ±40 V on either input, even with supplies disconnected. During overload, internal circuitry limits input current to ~6 mA, preventing damage to the amplifier core. This eliminates the need for external series resistors or TVS diodes in 24 V loop-powered sensor interfaces - a key reliability advantage over non-protected amplifiers.

What is the typical settling time of INA118UG4 at G = 1000?

The INA118UG4 exhibits a 210 µs settling time to 0.01% for a full-scale step input at G = 1000, as measured with RL = 10 kΩ and CL = 100 pF. This value increases with capacitive loading; for fast step response in DAQ systems, keep output capacitance <100 pF or add a small series resistor (10–50 Ω) to isolate capacitive loads. Settling time is independent of supply voltage across ±2.25 V to ±18 V.