Texas Instruments OPA228UAG4

Overview

OPA228UAG4 from Texas Instruments is a dual-channel, high-precision, low-noise operational amplifier optimized for closed-loop gains ≥5, delivering 33 MHz unity-gain bandwidth, 10 V/µs slew rate, and 75 µV max input offset voltage. It operates from ±2.5 V to ±18 V supplies and targets precision analog signal conditioning in professional audio, spectrum analysis, and industrial data acquisition systems.

For engineers reviewing the OPA228UAG4 datasheet, OPA228UAG4 pinout, OPA228UAG4 application, or OPA228UAG4 equivalent, this page provides verified specifications, package mapping, functional alternatives, thermal performance data, and design-critical electrical behavior - all confirmed against TI's SBOS110C (March 2023) production datasheet.

Technical Context

The OPA228UAG4 implements a compensated bipolar input stage with internal offset trim capability, enabling stable operation at minimum closed-loop gain of 5 V/V. Its architecture prioritizes wide-bandwidth ac fidelity while maintaining dc precision: open-loop gain exceeds 132 dB over –40°C to +85°C, and CMRR remains ≥120 dB across frequency up to 10 kHz.

Unlike the unity-gain-stable OPA227, the OPA228UAG4 uses higher transconductance and reduced compensation capacitance to achieve 33 MHz GBW and 1.5 µs settling time (to 0.1%) - but requires ≥5× noise gain for stability. Input voltage noise is flat at 3 nV/√Hz above 100 Hz, and current noise is 0.4 pA/√Hz at 1 kHz.

Key Specifications

Pinout & Package

OPA228UAG4 is supplied in an 8-pin SOIC (SO-8) package with exposed pad (G4 suffix per TI ordering guide). Pin 1 is offset trim; pins 2 and 3 are inverting/noninverting inputs for Channel A; pins 4 and 8 are V– and V+ power rails; pin 5 is +In B; pin 6 is –In B; pin 7 is Output B; pin 8 is V+. Pin 1 and pin 8 are dedicated trim terminals - floating if unused.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-precision, low-noise op-amp applications.

Compared with OPA228UAG4, OPA227UA trades bandwidth for unconditional stability at low gains, while AD8675ARZ sacrifices noise performance and speed for single-supply flexibility and lower power - making each suitable only in distinct gain, supply, and noise-constrained contexts.

Availability

OPA228UAG4 is available at Aetrix Electronics and suitable for professional audio equipment, spectrum analyzer signal chains, and industrial data acquisition systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for OPA228UAG4 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 op-amp design and manufacturing.

The OPAx228 product line was engineered specifically for high-fidelity, wide-bandwidth analog signal conditioning in test & measurement, professional audio, and industrial instrumentation - balancing low noise, high speed, and dc precision in a single platform.

FAQ

Is OPA228UAG4 unity-gain stable?

No, OPA228UAG4 is not unity-gain stable. It is optimized for closed-loop gains of 5 V/V or greater. Attempting G = 1 operation risks oscillation due to reduced phase margin. For unity-gain applications, use the pin-compatible OPA227UA instead - both share the same SO-8 (U) package and ±75 µV offset specification.

What is the maximum capacitive load OPA228UAG4 can drive reliably?

OPA228UAG4 maintains stability with ≤100 pF capacitive load when configured for G ≥ 5. Driving larger loads (e.g., ADC input capacitance + PCB trace) requires a series isolation resistor (10–50 Ω) between output and load to restore phase margin. TI's SBOS110C Figure 6-26 confirms overshoot remains <5% under these conditions.

Does OPA228UAG4 support single-supply operation?

Yes, OPA228UAG4 supports single-supply operation from 4.5 V to 36 V (per Section 6.3). Input common-mode range extends to (V–) + 2 V and (V+) – 2 V; output swings to (V–) + 2 V and (V+) – 2 V with 10 kΩ load. For true rail-to-rail I/O, consider alternative families like OPA377 or TLV9062.

How does the offset trim function work on OPA228UAG4?

OPA228UAG4 provides two dedicated offset trim pins (Pin 1 and Pin 8). Connect a 10-kΩ potentiometer across them, with wiper to V– (Pin 4). Adjusting the potentiometer nulls input offset voltage - typically reducing residual error to <5 µV. Leaving both pins floating defaults to factory-trimmed ±75 µV max performance.

What thermal metrics apply to OPA228UAG4 in SO-8 package?

For OPA228UAG4 (SO-8, "U" suffix), junction-to-ambient thermal resistance (RθJA) is 110.1°C/W, junction-to-board (RθJB) is 52.3°C/W, and junction-to-case (top) is 52.2°C/W (Section 6.4). These values assume JEDEC-standard PCB mounting with 2 oz copper and 1 in² copper pour - derate power dissipation accordingly at elevated ambient temperatures.