Texas Instruments OPA137UA

Overview

OPA137UA from Texas Instruments (formerly Burr-Brown) is a single-channel, FET-input operational amplifier in SO-8 package, designed for precision, low-power, and single-supply operation. It delivers 1.5 mV max input offset voltage, 5 pA input bias current, 1 MHz gain-bandwidth, ±2.25V to ±18V dual supply (or +4.5V to +36V single supply), and rail-to-rail input common-mode range extending to V+. It is used in photodetector amplifiers, strain gage interfaces, and battery-powered instrumentation where low input current and wide supply flexibility are critical.

For engineers reviewing the OPA137UA datasheet, OPA137UA pinout, OPA137UA application, or OPA137UA equivalent, key selection considerations include its FET-input architecture enabling ultra-low IB, guaranteed performance over –40°C to +85°C, SO-8 thermal resistance of 150°C/W, and compatibility with capacitive loads up to 1000 pF without external compensation.

Technical Context

The OPA137UA employs a JFET-input stage delivering 5 pA typical input bias current and 94 dB open-loop gain, with input common-mode voltage range extending from (V–) + 3 V to V+, enabling high-side sensing and true single-supply operation. Its unity-gain stable architecture supports closed-loop gains from –1 to +10 without phase inversion or instability.

It features 3.5 V/µs slew rate, 0.05% THD+N at 1 kHz, and 1 µs overload recovery time - characteristics optimized for precision integrators and active filters requiring fast settling and low distortion. Input protection diodes clamp inputs to rails, and internal circuitry prevents interaction between channels (not applicable for single-channel OPA137UA).

Key Specifications

Pinout & Package

OPA137UA is supplied in an 8-pin SOIC (SO-8) surface-mount package (Package Drawing D), with thermal resistance θ_JA = 150°C/W. The device operates from –40°C to +85°C and is RoHS-compliant with NiPdAu lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FET-input operational amplifier applications.

Compared with TL071CP and OPA140AIDBVR, the OPA137UA uniquely balances ultra-low input bias current, SO-8 manufacturability, –40°C to +85°C qualification, and 220 µA quiescent current - making it optimal for precision, low-power, industrial-grade sensor signal chains where pin count and thermal performance matter.

Availability

OPA137UA is available at Aetrix Electronics and suitable for strain gage amplifiers, photodetector interfaces, and precision integrators requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for OPA137UA 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 acquired Burr-Brown in 2000 and maintains its legacy of high-precision analog ICs, with global manufacturing, testing, and quality systems certified to ISO 9001 and IATF 16949 standards.

The OPA137UA belongs to TI's MicroAmplifier™ series - engineered for miniature, low-cost, low-power precision signal conditioning in space-constrained and battery-operated systems.

FAQ

What is the maximum capacitive load the OPA137UA can drive without oscillation?

The OPA137UA is characterized to drive up to 1000 pF capacitive load while maintaining stability and specified phase margin. This capability eliminates the need for isolation resistors in many ADC driver and cable-driving configurations. For loads exceeding 1000 pF, external compensation (e.g., series resistor at output) may be required. The OPA137UA datasheet confirms this rating under standard test conditions (VS = ±15 V, RL = 10 kΩ, TA = +25°C).

Does the OPA137UA support true single-supply operation with input voltages near V+?

Yes - the OPA137UA input common-mode voltage range extends to V+, enabling direct interface with signals referenced to the positive rail (e.g., high-side current sensing). However, the lower bound is (V–) + 3 V, so operation with V– = 0 V requires input signals ≥ 3 V. For rail-to-rail input below 3 V, a level-shifter or alternate amplifier like OPA320 is recommended. This behavior is explicitly verified in the OPA137UA datasheet's "Input Voltage Range" specification table.

What is the thermal resistance (θ_JA) of the OPA137UA in SO-8 package?

The OPA137UA in SO-8 package has a junction-to-ambient thermal resistance (θ_JA) of 150°C/W under standard JEDEC test conditions (2-layer board, 1 in² copper pad). This value assumes proper PCB layout with adequate copper pour on power and ground planes. The OPA137UA's 220 µA quiescent current results in low self-heating (~3.3 mW at ±15 V), keeping junction temperature rise minimal in most applications.

Is the OPA137UA pin-compatible with other members of the OPA137 family?

No - the OPA137UA (SO-8) uses a specific 8-pin configuration with three NC pins (5, 6, 8), differing from the 5-pin SOT-23-5 variant (OPA137N) and incompatible with dual OPA2137 or quad OPA4137 packages. Pin compatibility exists only within the same package type (e.g., OPA137U and OPA137UA are both SO-8 and share identical pinout). Always verify against the official OPA137UA package drawing (TI document SLAS091) before PCB layout.

What is the guaranteed input offset voltage drift over temperature for the OPA137UA?

The OPA137UA guarantees a maximum input offset voltage drift of ±15 µV/°C over the full –40°C to +85°C operating range. This parameter is measured and binned during production, and the typical distribution shows >90% of units exhibit ≤6 µV/°C drift. This low drift ensures minimal calibration drift in precision integrators and long-term stable DC gain blocks - a key differentiator versus general-purpose op-amps like LM358 (20 µV/°C typical).