Texas Instruments OPA2381AIDRBR

Overview

OPA2381AIDRBR from Texas Instruments is a dual-channel, precision transimpedance amplifier optimized for photodiode current-to-voltage conversion. It delivers 18MHz gain-bandwidth, 25µV max offset voltage, 3pA bias current, and >250kHz transimpedance bandwidth in typical configurations-enabling high-fidelity optical signal acquisition in medical imaging front-ends and industrial light-sensing systems.

For engineers reviewing the OPA2381AIDRBR datasheet, OPA2381AIDRBR pinout, OPA2381AIDRBR application, or OPA2381AIDRBR equivalent, key selection criteria include its dual-channel DFN-8 package, −40°C to +125°C operation, low 10nV/√Hz voltage noise, 5-decade dynamic range (10nA–1mA), and fast 200ns overload recovery-critical for real-time optical power monitoring and CAT-scan detector circuits.

Technical Context

The OPA2381AIDRBR integrates an auto-zero core with a high-speed 18MHz amplifier to achieve ultra-low drift (0.1µV/°C max) and exceptional long-term stability without 1/f noise degradation. Its input stage supports common-mode voltages from V− to (V+) − 1.8V and features ESD-protected inputs rated to ±10mA.

Designed explicitly for inverting transimpedance topologies, it uses the noninverting input as a fixed bias node and includes internal circuitry to accelerate overload recovery-returning to linear operation within 200ns after positive-rail saturation. Output swing extends to 0V when paired with an external pulldown resistor to −5V.

Key Specifications

Pinout & Package

OPA2381AIDRBR is housed in a 3mm × 3mm DFN-8 package with exposed thermal pad (DRB designation), optimized for low-inductance photodiode connections and thermal dissipation in compact optical modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA2381AIDRBR, OPA2380AIDRBR offers higher bandwidth at the cost of increased noise and reduced dynamic range fidelity, while OPA2188AIDR provides superior long-term stability but lacks the speed needed for real-time optical control loops.

Availability

OPA2381AIDRBR is available at Aetrix Electronics and suitable for precision photodiode monitoring, CAT-scan detector front-ends, and optical amplifier signal conditioning requiring stable component supply across industrial, medical, and test equipment programs.

Supply support for OPA2381AIDRBR 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 amp design and manufacturing.

The OPA2381AIDRBR belongs to TI's precision transimpedance amplifier product line, engineered specifically for high-dynamic-range, low-noise optical current sensing in medical imaging, analytical instrumentation, and industrial light detection systems.

FAQ

What is the maximum transimpedance bandwidth achievable with OPA2381AIDRBR?

The OPA2381AIDRBR achieves >250kHz transimpedance bandwidth in typical configurations using standard photodiode capacitances (e.g., 10–50pF) and feedback resistors up to 10MΩ. This is enabled by its 18MHz gain-bandwidth product and low input capacitance (1pF differential). Bandwidth scales inversely with √(RF × CTOT), so actual performance depends on photodiode and PCB parasitics. The OPA2381AIDRBR datasheet confirms this limit under Figure 6 and Table 1 conditions.

Does OPA2381AIDRBR support true 0V output swing in single-supply operation?

Yes-OPA2381AIDRBR can deliver 0V output with a single +5V supply when an external pulldown resistor (e.g., 10kΩ) is connected between VOUT and −5V. This technique leverages the OPA2381AIDRBR's output stage design, which allows sinking current to the negative rail. Without the pulldown, minimum output is ~50mV above V−; with it, output reaches 0V with excellent linearity across −40°C to +125°C, as verified in Figure 3 and Section 9 of the OPA2381AIDRBR datasheet.

How does the auto-zero architecture of OPA2381AIDRBR impact system-level noise?

The OPA2381AIDRBR's auto-zero topology corrects input offset every 100µs with proprietary filtering that suppresses fundamental correction energy at 10kHz-shifting residual artifacts above 20MHz where they are easily filtered or ignored. Measured voltage noise is 10nV/√Hz above 1MHz and 3µVPP (0.1–10Hz), confirming negligible 1/f contribution. This makes OPA2381AIDRBR suitable for wideband applications where traditional chopper amps introduce switching interference.

Can OPA2381AIDRBR drive a 16-bit ADC such as the ADS8325 directly?

Yes-the OPA2381AIDRBR is explicitly characterized and recommended for driving 16-bit ADCs like the ADS8325. Its low output impedance, fast settling (7µs to 0.003%), and ability to source/sink 10mA allow it to buffer ADC input capacitance and absorb charge injection. Figure 13 in the OPA2381AIDRBR datasheet shows a validated interface with RC filter optimization. No external buffer is needed, preserving SNR and reducing board area.

What is the thermal resistance (θJA) of the OPA2381AIDRBR in its DFN-8 package?

The OPA2381AIDRBR in the DFN-8 (DRB) package has a junction-to-ambient thermal resistance (θJA) of 65°C/W, as specified in the Electrical Characteristics table on page 3 of the OPA2381AIDRBR datasheet. This value assumes standard JEDEC 2-layer board conditions with the exposed thermal pad soldered to a solid copper plane. Proper thermal pad connection is essential to maintain operation within the −40°C to +125°C junction temperature limit under 1.6mA total quiescent current.