Texas Instruments OPA650U

Overview

OPA650U from Texas Instruments (formerly Burr-Brown) is a unity-gain stable, low-power voltage-feedback operational amplifier in SO-8 package, delivering 560MHz closed-loop bandwidth at G = +1, 240V/µs slew rate, and 20ns 0.01% settling time. It features ±2.0V output swing into 100Ω, 75mA sourcing/sinking capability, and –77dBc harmonic distortion at 5MHz - making it suitable for high-resolution video amplification and CCD imaging front-ends.

For engineers reviewing the OPA650U datasheet, OPA650U pinout, OPA650U application, or OPA650U equivalent, this page provides verified technical context, SO-8 package mapping, real-world settling performance, differential gain/phase accuracy (0.01%/0.03°), and validated alternatives for baseband, ultrasound, and ADC driver use cases.

Technical Context

The OPA650U implements a classical voltage-feedback op amp architecture with fully symmetrical differential input stage and internal unity-gain compensation. Its 560MHz bandwidth and 180MHz gain-bandwidth product are achieved without external compensation, while its 2pF nominal parasitic load tolerance enables stable operation in low-inductance layouts.

It delivers true 12-bit settling (20ns to 0.01%) with 240V/µs slew rate and maintains <1ns rise/fall times under 0.2V step conditions. The device operates from ±5V supplies, supports ±2.8V common-mode input range, and achieves 84µVrms integrated input noise (10Hz–100MHz).

Key Specifications

Pinout & Package

OPA650U is housed in an 8-pin SOIC (SO-8) surface-mount package with θ_JA = 125°C/W. Pin 1 is located at the top-left corner adjacent to the index mark; pins are numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar wideband voltage-feedback amplifier applications.

Compared with OPA650U, OPA656U trades output drive and settling speed for femtoampere input bias - ideal for photodiode preamps - while LMH6629MA delivers extreme bandwidth at the cost of stability and power efficiency, requiring careful layout and compensation.

Availability

OPA650U is available at Aetrix Electronics and suitable for high-resolution video, ultrasound signal processing, and ADC/DAC gain amplification requiring stable component supply across industrial, medical, and broadcast design cycles.

Supply support for OPA650U 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 (TI) acquired Burr-Brown in 2000 and maintains legacy high-performance analog product lines including precision op amps, data converters, and interface ICs.

The OPA650U belongs to TI's OPA65x family of wideband voltage-feedback op amps, designed specifically for demanding signal-chain applications where speed, accuracy, and low power must coexist - such as portable medical imaging, broadcast video, and high-speed test equipment.

FAQ

What is the maximum capacitive load the OPA650U can drive without oscillation?

The OPA650U is nominally compensated for 2pF parasitic load. Capacitive loads exceeding 10pF require series isolation resistance (15–30Ω) between output and load to maintain phase margin. Driving >100pF loads - such as flash ADC inputs - is feasible only with RISO and careful layout per Figure 4 in the OPA650U datasheet. Without RISO, instability occurs above ~15pF in typical SO-8 layouts.

Does the OPA650U support single-supply operation?

Yes, the OPA650U supports single-supply operation provided the common-mode input and output voltage constraints are respected. With ±5V supplies, its input common-mode range is ±2.8V; for a +10V single supply, biasing the non-inverting input at +2.5V allows full-swing output from ~0.5V to ~9.5V. Figure 1 in the OPA650U datasheet shows a practical implementation using resistive divider and bypass capacitors.

What is the thermal resistance (θJA) of the OPA650U in SO-8 package?

The OPA650U in SO-8 package has a junction-to-ambient thermal resistance (θJA) of 125°C/W, as specified in the Absolute Maximum Ratings table. This value assumes standard JEDEC 2-layer board conditions. For continuous operation at maximum ambient temperature (+85°C), power dissipation must be limited to ensure junction temperature stays below +175°C - yielding a max PD of ~720mW under ideal heatsinking, but typically <160mW in standard layouts.

Can the OPA650U replace the OPA650P in existing DIP-based designs?

No - the OPA650U (SO-8) and OPA650P (8-pin DIP) are not pin-compatible. While both share identical electrical specifications, their pinouts differ: OPA650P uses standard DIP pin numbering (1=–In, 2=+In, 3=Vs–, 4=Output, 5=Vs+, 6=NC, 7=NC, 8=NC), whereas OPA650U has NC on Pins 1, 7, and 8 with +VS on Pin 6 and –VS on Pin 4. Direct replacement requires PCB redesign.

What is the small-signal output impedance of the OPA650U at 10MHz?

At 10MHz and G = +1, the OPA650U exhibits a closed-loop output impedance of approximately 0.02Ω, as shown in Figure 3 of the datasheet. This ultra-low impedance remains stable up to ~100MHz due to high loop gain retention, enabling robust driving of reactive loads like coaxial cables or ADC input capacitances without signal degradation.