Texas Instruments OPA3684IDR

Overview

OPA3684IDR from Texas Instruments is a triple-channel, low-power current-feedback operational amplifier with disable control, delivering 170MHz bandwidth at G = +2, < –82dBc harmonic distortion at 5MHz, and 120mA output current per channel. It operates from ±2.5V to ±6V dual supplies or +2.8V to +12V single supply and is used in RGB line drivers and ADC input stages requiring high fidelity and low power.

For engineers reviewing the OPA3684IDR datasheet, OPA3684IDR pinout, OPA3684IDR application, or OPA3684IDR equivalent, key selection considerations include its CFBPLUS architecture for gain-independent bandwidth, 1.7mA/ch quiescent current, 40ns enable time, and SO-14 package compatibility with video and broadcast signal chain designs.

Technical Context

The OPA3684IDR implements a CFBPLUS architecture featuring an internally closed-loop input buffer stage that linearizes inverting-input impedance, enabling stable bandwidth up to G = +10 (>120MHz) and minimizing distortion across gain settings. Its transimpedance gain is 355kΩ (min), with RI = 4.0Ω (typ) at the inverting input.

Each of the three independent channels includes a dedicated disable pin (DIS A/B/C), allowing individual channel shutdown with <100µA/ch supply current and 70dB off-isolation at 5MHz. The amplifier supports DC-coupled and AC-coupled configurations, with input common-mode range extending to ±3.6V on ±5V supplies and output swing to ±3.8V into 1kΩ.

Key Specifications

Pinout & Package

OPA3684IDR is housed in a 14-pin SOIC (SO-14) package with exposed pad not present; thermal resistance θ_JA = 100°C/W. Pin functions are validated per TI SBOS241C datasheet Figure 1 (top view).

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA2684IDR, OPA3684IDR adds a third channel and per-channel disable for RGB or trilevel video systems; compared with OPA3691IDR, it trades output drive and bandwidth for lower power and integrated shutdown-making it optimal for portable or thermally constrained multi-channel video front-ends.

Availability

OPA3684IDR is available at Aetrix Electronics and suitable for RGB line drivers, ADC input stages, professional camera signal chains, and equalizing filter designs requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for OPA3684IDR 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 company specializing in analog and embedded processing technologies, with leadership in high-performance op amps, data converters, and interface ICs.

The OPA3684IDR belongs to TI's CFBPLUS current-feedback op amp product line, designed specifically for low-power, high-fidelity video and instrumentation signal conditioning where gain stability, distortion performance, and multi-channel integration are essential.

FAQ

What is the maximum operating supply voltage for OPA3684IDR?

The OPA3684IDR supports a maximum dual-supply voltage of ±6V and a maximum single-supply voltage of +12V, as specified in the Absolute Maximum Ratings table. Operation beyond these limits risks permanent damage. At ±6V, the device maintains full AC performance including 170MHz bandwidth at G = +2 and < –82dBc distortion at 5MHz, consistent with its characterization at ±5V.

Does OPA3684IDR support true single-supply operation below +5V?

Yes, OPA3684IDR operates down to +2.8V single supply, with tested performance including 110MHz small-signal bandwidth (G = +2, RF = 1.0kΩ) and 380V/µs slew rate. Input common-mode range extends from 1.25V to 3.75V, and output swing reaches 0.9V to 4.1V into 1kΩ, enabling functional operation in low-voltage portable video systems.

How does the CFBPLUS architecture of OPA3684IDR improve bandwidth stability over conventional CFB op amps?

The CFBPLUS architecture uses an internally closed-loop input buffer to linearize the inverting-input impedance to ~4.0Ω, decoupling bandwidth from gain-setting resistor variations. This enables >120MHz bandwidth even at G = +10-unlike earlier low-power CFB amplifiers whose bandwidth dropped sharply above G = +2. The result is predictable, flat frequency response across gain configurations without re-optimizing feedback networks.

Can OPA3684IDR drive a 50Ω load with full ±4Vp-p swing?

No-OPA3684IDR delivers >±3Vp-p into 50Ω (per Electrical Characteristics), not full ±4Vp-p. The ±4Vp-p specification applies to 1kΩ loads. Driving 50Ω requires careful attention to output current limits: sourcing/sinking ≥120mA is guaranteed, but thermal derating and PCB layout (e.g., ground plane, trace width) must ensure junction temperature remains ≤+175°C under sustained load.

What is the purpose of the separate DIS A, DIS B, and DIS C pins on OPA3684IDR?

The DIS A, DIS B, and DIS C pins provide independent active-low shutdown control for each of the three amplifier channels. Pulling any DIS pin LOW reduces that channel's supply current to <100µA/ch while placing its I/O pins in high-impedance state-enabling dynamic power management in multi-channel systems like RGB video paths, where one or two channels may be idle during certain frame intervals or modes.