Texas Instruments OPA891DGNR

Overview

OPA891DGNR from Texas Instruments is a single-channel, ultra-low-noise, high-speed voltage-feedback operational amplifier in an 8-pin HVSSOP package. It delivers 180MHz unity-gain bandwidth, 0.95nV/√Hz input voltage noise, –100dBc THD at 1MHz (RL = 1kΩ), ±13.6V output swing (±15V supply), and 200mA output drive - enabling precision signal conditioning in professional audio front-ends and ultrasound time-gain control circuits.

For engineers reviewing the OPA891DGNR datasheet, OPA891DGNR pinout, OPA891DGNR application, or OPA891DGNR equivalent, key selection criteria include its offset-nulling capability, thermal-pad-enabled HVSSOP package for high-power analog stages, low distortion at high frequencies, and compatibility with ±4.5V to ±18V dual supplies or 9V–36V single supplies.

Technical Context

The OPA891DGNR employs a complementary bipolar 36V process with GHz f_T transistors, enabling voltage-feedback architecture with unity-gain stability and minimal phase margin degradation across load conditions. Its internal offset-nulling circuitry connects to pins 1 and 8, allowing precise DC calibration without external components.

It achieves 105V/μs slew rate and 70ns 0.1% settling time (±15V, gain = –1) while maintaining –137dBc THD+N at 1kHz (BW = 80kHz, RL = 2kΩ), making it suitable for driving ADC inputs and high-fidelity active filters where noise and distortion dominate system SNR.

Key Specifications

Pinout & Package

The OPA891DGNR is housed in an 8-pin HVSSOP (DGN) package measuring 3mm × 4.9mm with an exposed thermal pad on the bottom for enhanced heat dissipation. The thermal pad must be connected to a large copper plane for optimal junction-to-board thermal resistance (33°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed, low-noise operational amplifier applications.

Compared with OPA847IDR and LMH6629MA/NOPB, the OPA891DGNR uniquely balances ultra-low noise (0.95nV/√Hz), offset trim capability, ±18V operation, and thermal-pad-enhanced HVSSOP packaging - making it the preferred choice for high-fidelity, wide-dynamic-range analog signal chains in medical imaging and pro-audio infrastructure.

Availability

OPA891DGNR is available at Aetrix Electronics and suitable for professional audio mixer design, ultrasound TGC modules, high-speed data acquisition front-ends, and active video filter development requiring stable component supply and long-term manufacturability.

Supply support for OPA891DGNR 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 90 years of innovation in high-performance signal chain solutions.

The OPAx891 product line targets ultra-low-noise, high-speed analog signal conditioning for professional audio, medical ultrasound, and precision test equipment - emphasizing distortion-free wideband amplification with robust DC accuracy.

FAQ

What is the maximum operating temperature range for the OPA891DGNR?

The OPA891DGNR is rated for continuous operation from –40°C to +85°C ambient temperature. Junction temperature must remain below 125°C for long-term reliability, and thermal design using the exposed pad is critical to maintain this limit under 200mA output load conditions. Derating applies above 70°C ambient per TI's thermal metrics documentation.

Does the OPA891DGNR require external compensation for stability?

No, the OPA891DGNR is unity-gain stable and does not require external compensation components. It maintains phase margin >45° across all gains ≥1V/V with capacitive loads ≤100pF. For loads >100pF, a small series resistor (10–50Ω) at the output is recommended to isolate capacitance and preserve stability.

How is the thermal pad of the OPA891DGNR package intended to be connected on the PCB?

The thermal pad on the OPA891DGNR must be soldered to a solid copper plane on the PCB, ideally connected to the VCC– net or system ground. TI specifies R_θJB = 33°C/W when the pad is thermally coupled to ≥1cm² internal layer copper. Avoid floating or isolated pads, as this degrades thermal performance by >2× and risks junction overheating.

Can the OPA891DGNR operate from a single 12V supply?

Yes, the OPA891DGNR supports single-supply operation from 9V to 36V. At 12V, it delivers ±3.4V output swing into 1kΩ (typical), with common-mode input range extending to 0.2V above VCC– and 1.2V below VCC+. Input bias current remains stable, and THD+N stays below –124dBc at 1kHz with proper decoupling.

What is the purpose of the NULL pins (1 and 8) on the OPA891DGNR?

The NULL pins (1 and 8) provide access to the amplifier's internal offset voltage trimming network. Connecting a 10kΩ potentiometer between these pins-with the wiper tied to VCC–-allows manual adjustment of input offset voltage to <0.1mV, critical for DC-coupled integrators, precision summing amplifiers, and zero-drift sensor interfaces where residual offset impacts long-term accuracy.