Texas Instruments OPA251UA

Overview

OPA251UA from Texas Instruments is a single-channel, micro-power operational amplifier optimized for ±15V dual-supply operation, delivering 25μA quiescent current, ±250μV max input offset voltage, rail-to-rail output swing within 50mV of rails, and 128dB open-loop gain - used in precision signal conditioning stages of portable medical instruments and battery-powered test equipment.

For engineers reviewing the OPA251UA datasheet, OPA251UA pinout, OPA251UA application, or OPA251UA equivalent, key selection criteria include its ±15V-optimized offset trim, 30kHz gain-bandwidth product at high supply, low 65nV/√Hz input voltage noise density, and SOIC-8 package compatibility with space-constrained analog front-ends requiring stable DC accuracy and low power.

Technical Context

The OPA251UA employs a precision bipolar input stage with laser-trimmed offset voltage specifically calibrated at ±15V, enabling low drift (±0.5μV/°C) and high common-mode rejection (124dB) over –40°C to +85°C. Its unity-gain-stable architecture supports direct connection to capacitive loads up to 2700pF when operated at ±15V with gain ≥10.

Input common-mode range extends to (V–) – 0.2V, supporting single-supply configurations down to 2.7V, while rail-to-rail output delivers full dynamic range into high-impedance loads. External offset trim pins (1 and 5) are provided exclusively on the single-channel variants for system-level nulling without degrading baseline performance.

Key Specifications

Pinout & Package

OPA251UA is housed in an 8-pin SOIC (D package), 1.27mm pitch, with exposed pad not present. Thermal resistance R_θJA = 150°C/W enables operation up to +85°C ambient without forced airflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA251UA, OPA241UA offers lower offset at low voltage but reduced high-voltage stability margin, while TLV2461CDR sacrifices micropower operation for bandwidth - making OPA251UA the optimal choice for ±15V, ultra-low-power, high-accuracy analog front-ends.

Availability

OPA251UA is available at Aetrix Electronics and suitable for battery-operated instruments, portable medical devices, and industrial test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for OPA251UA 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 OPAx251 family was engineered specifically for high-accuracy, low-power signal conditioning in dual-supply portable instrumentation - emphasizing offset stability, rail-to-rail output, and robustness across wide temperature and supply ranges.

FAQ

What supply voltage range does the OPA251UA support?

The OPA251UA operates from single supplies of 2.7V to 36V or dual supplies of ±1.35V to ±18V. It is laser-trimmed for optimal performance at ±15V, where it achieves ±50μV typical input offset voltage and 124dB common-mode rejection ratio. Performance remains functional across the full range, though offset and drift specifications are guaranteed only at ±15V per the datasheet's recommended operating conditions.

Does the OPA251UA require external offset trimming in most applications?

No - the OPA251UA features laser-trimmed offset voltage with ±250μV maximum at ±15V, making user adjustment unnecessary in the majority of precision applications. External trim pins (1 and 5) are provided only for specialized cases requiring sub-50μV residual offset; however, applying trim may degrade temperature drift performance and is not recommended unless strictly required by system-level calibration targets.

Can the OPA251UA drive capacitive loads, and what is the maximum stable value?

Yes - the OPA251UA is unity-gain stable and can drive capacitive loads up to 2700pF when configured with gain ≥10 and powered from ±15V. At unity gain and ±15V, stability is maintained up to ~500pF; for larger loads, a series resistor (e.g., 5kΩ) inserted in the feedback path improves phase margin without compromising DC accuracy. The device's internal compensation eliminates need for external components in standard gain configurations.

What is the input common-mode voltage range of the OPA251UA?

The OPA251UA accepts input signals from (V–) – 0.2V up to (V+) – 0.8V - extending 200mV below the negative rail. This allows true single-supply operation with ground-referenced sensors and simplifies biasing in low-voltage systems. For example, with V– = 0V and V+ = 5V, the valid input range is –0.2V to +4.2V, accommodating signals that swing slightly below ground or near the positive rail.

How does the OPA251UA compare to the OPA241UA in terms of key performance trade-offs?

The OPA251UA is optimized for ±15V operation (±50μV typical offset, 30kHz GBW), while the OPA241UA is trimmed for 5V (±50μV typical at 5V, 35kHz GBW). Both share identical SOIC-8 packaging, rail-to-rail output, and 25μA quiescent current. The OPA251UA delivers superior CMRR (124dB vs. 106dB) and open-loop gain (128dB vs. 120dB) at high supply, making it preferred for industrial and test equipment; the OPA241UA excels in low-voltage portable designs.