Texas Instruments OPA2228P

Overview

OPA2228P from Texas Instruments is a dual, high-precision, low-noise operational amplifier optimized for closed-loop gains ≥5, delivering 33 MHz gain-bandwidth product, 11 V/µs slew rate, and 3 nV/√Hz input voltage noise at 1 kHz - used in professional audio preamplifiers, spectral analysis front-ends, and geophysical sensor signal conditioning.

For engineers reviewing the OPA2228P datasheet, OPA2228P pinout, OPA2228P application, or OPA2228P equivalent, key selection criteria include its minimum stable gain of 5 V/V, ±2.5 V to ±18 V supply flexibility, 75 µV max input offset voltage, and PDIP-8 package thermal resistance of 48.9°C/W - critical for low-drift, wide-dynamic-range analog signal chains.

Technical Context

The OPA2228P implements a compensated bipolar input stage with precision laser-trimmed resistors for ultra-low offset and drift, enabling DC-coupled operation in high-gain instrumentation paths. Its internal compensation ensures stability only at closed-loop gains ≥5, distinguishing it from unity-gain-stable variants like the OPA2227P.

It features rail-to-rail output swing capability (±2 V from rails at 10 kΩ load), 138 dB common-mode rejection, and 160 dB open-loop gain - supporting high-accuracy differential measurements in noisy industrial environments without external nulling circuitry.

Key Specifications

Pinout & Package

OPA2228P is supplied in an 8-pin PDIP (Plastic Dual In-line Package) with body size 9.81 mm × 6.35 mm, rated for through-hole mounting and manual prototyping. Thermal resistance θ_JA = 48.9°C/W enables operation at full spec under natural convection at ambient ≤70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA2227P and AD8620ARZ, the OPA2228P uniquely balances high speed (33 MHz), ultra-low noise (3 nV/√Hz), and precision DC specs (75 µV offset) in a cost-effective bipolar process - making it optimal for G ≥ 5, wide-dynamic-range analog signal chains where both AC fidelity and DC accuracy are non-negotiable.

Availability

OPA2228P is available at Aetrix Electronics and suitable for professional audio equipment, geophysical data loggers, and vibration monitoring systems requiring stable component supply across extended production lifecycles.

Supply support for OPA2228P 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 over 50 years of innovation in precision amplifiers and data conversion.

The OPAx22x series was designed specifically for high-fidelity analog signal chains demanding simultaneous excellence in AC performance (bandwidth, slew rate, noise) and DC precision (offset, drift, CMRR) - targeting test & measurement, audio, and scientific instrumentation.

FAQ

What is the minimum closed-loop gain required for stable operation of the OPA2228P?

The OPA2228P requires a minimum closed-loop gain of 5 V/V for stable operation. This is due to its internal compensation optimized for higher-speed performance; using it at gains below 5 may cause peaking or oscillation. Always verify stability with phase margin simulation or lab testing when operating near this threshold. The OPA2228P datasheet explicitly specifies "Minimum Closed-Loop Gain = 5 V/V" in Section 6.7.

Can the OPA2228P operate from a single 5 V supply?

Yes, the OPA2228P supports single-supply operation down to 5 V total supply (e.g., V+ = 5 V, V– = 0 V), though input common-mode and output swing ranges are reduced. With 5 V supply, the guaranteed input range is 2 V to 3 V, and output swings to within 2 V of each rail. For rail-to-rail input/output, consider alternative amplifiers - the OPA2228P is not rail-to-rail. Its design intent is dual-supply precision systems.

Does the OPA2228P have offset trim pins?

No, the OPA2228P does not include offset trim pins. Unlike the single-channel OPA228P (which has pins 1 and 8 for offset adjustment), the dual OPA2228P uses a different pinout (Out A, –In A, +In A, V–, +In B, –In B, Out B, V+) with no dedicated trim terminals. Offset correction must be implemented externally via servo loops or digital calibration. This is confirmed in the "Pin Functions" table for OPA2227/OPA2228 in Section 5 of the SBOS110B datasheet.

How does the OPA2228P compare to the OPA228P in terms of package and pin compatibility?

The OPA2228P (dual) and OPA228P (single) are not pin-compatible. The OPA228P uses an 8-pin PDIP/SOIC pinout with offset trim pins (1 and 8), while the OPA2228P uses a fully independent dual-channel pinout (1=Out A, 2=–In A, 3=+In A, 4=V–, 5=+In B, 6=–In B, 7=Out B, 8=V+). PCB layout must be redesigned when substituting between them. Both share the same PDIP-8 package footprint but differ electrically and physically in pin assignment.

What is the maximum capacitive load the OPA2228P can drive without instability?

The OPA2228P can safely drive up to 100 pF directly, as verified in typical characteristics (Figure 26). For loads >100 pF, an isolation resistor (e.g., 10–50 Ω) must be placed in series with the output to maintain phase margin. Driving 1500 pF directly causes >30% overshoot and ringing. This limitation stems from its high GBW and internal compensation - always simulate or test with actual load capacitance and PCB trace parasitics before final design.