Texas Instruments OPA2228PG4

Overview

OPA2228PG4 from Texas Instruments is a dual, high-precision, low-noise operational amplifier optimized for closed-loop gains ≥5, delivering 33 MHz gain bandwidth, 11 V/µs slew rate, and 3 nV/√Hz input voltage noise at 1 kHz. It operates from ±2.5 V to ±18 V supplies and is used in professional audio preamplifiers, spectral analysis front-ends, and precision data acquisition systems requiring simultaneous AC fidelity and DC accuracy.

For engineers reviewing the OPA2228PG4 datasheet, OPA2228PG4 pinout, OPA2228PG4 application, or OPA2228PG4 equivalent, key selection criteria include its minimum stable gain of 5 V/V, 138 dB CMRR at DC, 160 dB open-loop gain, ±75 µV max input offset voltage, and SOIC-8 package compatibility with legacy OP-37 designs.

Technical Context

The OPA2228PG4 employs a compensated bipolar input stage enabling high-speed operation while maintaining low 1/f noise and excellent DC precision. Its internal architecture supports stable closed-loop configurations at gains ≥5 but is not unity-gain stable-requiring external compensation for G = 1 applications.

It features rail-to-rail output swing capability (±3.5 V into 600 Ω), differential input impedance of 10⁷ Ω || 12 pF, and common-mode input range extending to within 2 V of either supply rail. Input bias current remains ≤10 nA across –40°C to +85°C.

Key Specifications

Pinout & Package

OPA2228PG4 is housed in an 8-pin SOIC (SO-8) package measuring 4.90 mm × 3.91 mm, with standard dual op amp pinout compatible with industry footprint requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA2228DR, OPA2228PG4 offers identical performance in a tube-packaged variant for manual handling; versus AD827ARZ, it trades unity-gain stability for superior noise, speed, and CMRR-making it optimal for fixed-gain, high-fidelity signal chains.

Availability

OPA2228PG4 is available at Aetrix Electronics and suitable for professional audio equipment, spectral analysis instruments, and precision data acquisition systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for OPA2228PG4 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 expertise in precision op amp design.

The OPAx22x product line was engineered specifically for applications demanding concurrent high AC bandwidth and sub-100 µV DC precision-targeting test & measurement, audio, and scientific instrumentation markets.

FAQ

What is the minimum closed-loop gain required for stable operation of the OPA2228PG4?

The OPA2228PG4 requires a minimum closed-loop gain of 5 V/V for stable operation. Unlike unity-gain stable amplifiers, it is internally compensated for higher gains only; using it at G = 1 risks oscillation unless external compensation is applied per TI's Application Report SBAA227. This constraint directly impacts filter design and buffer stage selection in systems using OPA2228PG4.

Does the OPA2228PG4 support rail-to-rail input or output operation?

The OPA2228PG4 does not provide rail-to-rail input or output operation. Its common-mode input range extends from (V–)+2 V to (V+)-2 V, and its output swings to within 3.5 V of either rail under 600 Ω load. For example, with ±15 V supplies, output is limited to ±11.5 V. This behavior is confirmed in Section 6.7 of the SBOS110B datasheet and must be accounted for in headroom-sensitive signal chains using OPA2228PG4.

Can the OPA2228PG4 replace the OP-37 in existing designs?

Yes, the OPA2228PG4 is a pin-for-pin replacement for the OP-37 in SOIC-8 packages, offering improved specifications: 33 MHz GBW vs. 63 MHz (but optimized for G ≥ 5), 11 V/µs slew rate vs. 17 V/µs, and 3 nV/√Hz noise vs. 3.5 nV/√Hz. Layout changes are unnecessary, but gain configuration must remain ≥5 V/V. This makes OPA2228PG4 a drop-in upgrade for OP-37-based precision amplifiers where stability at high gain is prioritized over unity-gain speed.

What is the maximum capacitive load the OPA2228PG4 can drive without instability?

The OPA2228PG4 is characterized for stable operation with ≥100 pF capacitive loads when configured per recommended layout guidelines (local 0.1 µF supply decoupling, short traces). Driving larger loads-such as ADC input capacitances exceeding 1 nF-requires series isolation resistance (typically 10–50 Ω) between the OPA2228PG4 output and the load to maintain phase margin. This requirement is documented in Figure 26 and Section 8.2 of the SBOS110B datasheet.

How does temperature affect the input offset voltage of the OPA2228PG4?

The OPA2228PG4 exhibits a maximum input offset voltage drift of ±0.6 µV/°C over –40°C to +85°C, with typical performance at ±0.1 µV/°C. This low drift ensures minimal calibration drift in precision weighing scales or laboratory instrumentation using OPA2228PG4. The distribution is Gaussian, with >95% of units falling within ±0.3 µV/°C, as shown in Figure 11 of the SBOS110B datasheet.