Texas Instruments INA128UAG4

Overview

INA128UAG4 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 offset voltage, 0.5 μV/°C max drift, 1.3 MHz bandwidth at G = 1, 120 dB min CMRR, and ±40 V input overvoltage protection - enabling robust use in industrial pressure transmitters and medical ECG front-ends.

For engineers reviewing the INA128UAG4 datasheet, INA128UAG4 pinout, INA128UAG4 application, or INA128UAG4 equivalent, this page provides verified technical context, gain-setting resistor guidance, thermal performance data, real-world application constraints (e.g., REF pin impedance impact on CMR), and validated alternative options for precision analog signal chains.

Technical Context

The INA128UAG4 implements a three-op-amp topology with current-feedback input stages, enabling stable 200 kHz bandwidth even at G = 100. Its laser-trimmed thin-film resistors set the industry-standard gain equation G = 1 + 50 kΩ/R_G, where R_G connects pins 1 and 8 to configure gain from 1 to 10,000.

Input overvoltage protection circuitry clamps ±40 V faults without damage, while internal input buffers eliminate the need for external impedance matching. The device operates from ±2.25 V to ±18 V dual supplies or 4.5 V to 36 V single supply, drawing only ±700 μA quiescent current across –40°C to +85°C.

Key Specifications

Pinout & Package

INA128UAG4 is supplied in an 8-pin SOIC (D package), 4.9 mm × 6 mm body size, with gull-wing leads and standard JEDEC MS-012AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA128UAG4, INA128UA offers identical performance in a RoHS-compliant reel format ideal for SMT lines, while INA828IDR trades minor gain-equation variation for significantly lower input bias current - making it preferable for electrochemical sensors but unnecessary for standard bridge or thermocouple applications.

Availability

INA128UAG4 is available at Aetrix Electronics and suitable for industrial pressure transmitters, medical ECG monitors, weigh scale electronics, and analog input modules requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for INA128UAG4 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 signal chain components.

The INA12x family was engineered specifically for high-accuracy, low-power industrial and medical sensor signal conditioning - prioritizing low drift, robust input protection, and flexible gain configuration over raw speed or digital integration.

FAQ

What is the maximum gain achievable with INA128UAG4, and how is it set?

The INA128UAG4 supports gains from 1 to 10,000, set by a single external resistor R_G connected between pins 1 and 8 using the equation G = 1 + 50 kΩ/R_G. For G = 10,000, R_G = 5.001 Ω (1% tolerance); for G = 1, pins 1 and 8 are left unconnected. The INA128UAG4 datasheet specifies gain error ≤1% up to G = 1000 and ≤2% at G = 10,000 under recommended operating conditions.

Does INA128UAG4 require external input protection when used with industrial sensors?

No - the INA128UAG4 integrates robust input overvoltage protection that withstands ±40 V applied to VIN+ or VIN– without damage or parametric shift. This eliminates the need for external series resistors or TVS diodes in typical pressure, temperature, or strain gauge applications, simplifying layout and improving reliability in field-deployed equipment.

How does REF pin impedance affect common-mode rejection in INA128UAG4?

REF pin impedance directly degrades CMRR: a series resistance of just 8 Ω reduces typical CMRR from >120 dB to ~80 dB at G = 1. To maintain specified performance, the INA128UAG4 REF pin must be driven by a low-impedance source - typically a dedicated op-amp buffer or direct connection to clean system ground with short, wide traces and local 0.1 μF decoupling.

What is the bandwidth limitation of INA128UAG4 at G = 100, and how does it impact sensor signal fidelity?

At G = 100, the INA128UAG4 has a –3 dB bandwidth of 200 kHz (CSO: SHE) or 33 kHz (CSO: FRE). This supports faithful amplification of sensor signals up to ~50 kHz (for 20 dB gain flatness), making it suitable for dynamic pressure sensing or ultrasonic transducer readout. Bandwidth rolls off predictably per gain, enabling straightforward anti-alias filter design before ADC sampling.

Can INA128UAG4 operate from a single 5 V supply, and what are the output swing limitations?

Yes - the INA128UAG4 operates from single supplies as low as 4.5 V (e.g., 5 V). With V+ = 5 V and V– = 0 V, the output swing is limited to approximately 0.15 V to 4.85 V (CSO: FRE) or 1.4 V to 3.6 V (CSO: SHE), depending on chip site origin. For rail-to-rail output, use the CSO: FRE variant (INA128UAG4) and ensure REF is tied to mid-supply or buffered ground.