Texas Instruments OPA347UA/2K5

Overview

OPA347UA/2K5 from Texas Instruments is a single-channel, rail-to-rail input/output microPower operational amplifier in SOIC-8 package, delivering 350kHz bandwidth, 20µA quiescent current, and operation from 2.3V to 5.5V supply - ideal for battery-powered smoke detectors and 2-wire transmitters.

For engineers reviewing the OPA347UA/2K5 datasheet, OPA347UA/2K5 pinout, OPA347UA/2K5 application, or OPA347UA/2K5 equivalent, key selection criteria include ultra-low IQ, rail-to-rail swing within 5mV of rails at light loads, input range extending 200mV beyond supplies, and guaranteed operation from –55°C to +125°C.

Technical Context

The OPA347UA/2K5 employs a complementary differential input stage (N- and P-channel pairs) enabling rail-to-rail common-mode input range from (V–) – 0.2V to (V+) + 0.2V. Its class AB output stage supports rail-to-rail output swing down to 5mV from rails with 100kΩ load.

It is unity-gain stable and optimized for driving medium-speed ADCs like the ADS7822, featuring low input bias current (±0.5pA typ), 60nV/√Hz input voltage noise density at 1kHz, and 115dB open-loop gain at 25°C with 100kΩ load.

Key Specifications

Pinout & Package

OPA347UA/2K5 is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package with standard JEDEC MS-012AC footprint, 1.27mm pitch, and surface-mount compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA347UA/2K5, OPA344UA/2K5 trades ultra-low power for higher speed and lacks rail-to-rail input, while MCP6001T-E/OT achieves lower IQ but sacrifices military-grade temperature qualification - making OPA347UA/2K5 the sole option balancing sub-25µA IQ, full rail-to-rail I/O, and –55°C to +125°C operation in SOIC-8.

Availability

OPA347UA/2K5 is available at Aetrix Electronics and suitable for smoke detectors, 2-wire transmitters, and portable gas sensors requiring stable component supply across long-lifecycle safety-critical programs.

Supply support for OPA347UA/2K5 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 amps and industrial-grade signal conditioning.

The OPA347 series belongs to TI's microPower precision op amp product line, engineered specifically for battery-constrained safety and sensing applications demanding rail-to-rail operation, wide temperature range, and long-term reliability.

FAQ

What is the maximum capacitive load the OPA347UA/2K5 can drive in unity-gain configuration?

The OPA347UA/2K5 can directly drive up to 250pF of pure capacitive load in unity-gain configuration while maintaining stability. For larger loads, TI recommends adding a 10Ω–20Ω series resistor at the output or using gain ≥2 to improve phase margin. This capability is confirmed in the SBOS167D datasheet Figure "Small-Signal Overshoot vs Load Capacitance" and Application Information section on capacitive load drive. The OPA347UA/2K5's internal compensation is optimized for this performance envelope.

Does the OPA347UA/2K5 support true rail-to-rail input - including beyond the supply rails?

Yes, the OPA347UA/2K5 supports true rail-to-rail input with a common-mode range from (V–) – 0.2V to (V+) + 0.2V, verified per Electrical Characteristics table in SBOS167D. This 200mV rail extension enables direct interfacing with sensors whose outputs exceed supply rails - e.g., thermocouples or unregulated transducer outputs - provided input current is limited to ≤10mA. The OPA347UA/2K5 does not invert phase under such overvoltage conditions, unlike many legacy op amps.

What is the typical input bias current of the OPA347UA/2K5, and how does it vary with temperature?

The OPA347UA/2K5 has a typical input bias current of ±0.5pA at 25°C, with a maximum of ±10pA over temperature (–55°C to +125°C), as specified in the Electrical Characteristics table. The Typical Characteristics section shows Ib remains below 1pA up to 85°C and rises gradually to ~5pA at 125°C. This ultra-low bias current makes the OPA347UA/2K5 suitable for high-impedance sensor interfaces where leakage would otherwise dominate error - a key advantage over general-purpose op amps.

Can the OPA347UA/2K5 operate from a 2.3V supply, and is this voltage validated across temperature?

Yes, the OPA347UA/2K5 is fully specified and tested down to 2.3V supply voltage, with all key parameters (including GBW, VOS, and output swing) guaranteed across the full –55°C to +125°C range at this minimum voltage. The datasheet explicitly lists "Minimum Operating Voltage: 2.3V" and confirms functionality in Applications Information. This enables direct use with single LiFePO₄ cells or aging alkaline batteries, distinguishing the OPA347UA/2K5 from op amps rated only down to 2.5V or higher.

How does the OPA347UA/2K5 handle input signals that cross the rail-to-rail transition region?

The OPA347UA/2K5 uses complementary N- and P-channel input stages, creating a ~400mV transition region near (V+) – 1.3V where both pairs are active. Within this region, PSRR, CMRR, and offset drift may degrade - as documented in the Applications Information section. To avoid discontinuities, TI recommends biasing noninverting amplifiers so inputs stay below the transition voltage, or setting inverting amplifier common-mode voltage (VB) outside the region. This behavior is intrinsic to the OPA347UA/2K5's architecture and must be considered in precision DC-coupled designs.