Texas Instruments OPA3S328RGRR

Overview

OPA3S328RGRR from Texas Instruments is a dual-channel, 40-MHz precision CMOS operational amplifier with integrated analog switches, optimized for transimpedance applications in optical sensing and high-accuracy current-to-voltage conversion. It delivers 60 µV max offset voltage, 0.2 pA input bias current, rail-to-rail I/O, and 30 V/µs slew rate - enabling stable, low-noise signal conditioning of sub-nA photocurrents in space-constrained optical modules.

For engineers reviewing the OPA3S328RGRR datasheet, OPA3S328RGRR pinout, OPA3S328RGRR application, or OPA3S328RGRR equivalent, key selection criteria include its integrated switch matrix (SELA0/SELA1/SELB0/SELB1), 100 GΩ shutdown output impedance, zero-crossover input stage, and VQFN-20 (3.5 mm × 3.5 mm) package compatibility with high-density PCB layouts.

Technical Context

The OPA3S328RGRR integrates two independent precision op amps (A and B) each with dedicated 3×1 analog switch matrices (A1/A2/A3 and B1/B2/B3), controlled via four digital select pins. Its zero-crossover input architecture ensures consistent offset behavior across the full supply range (–0.1 V to V+ + 0.1 V), eliminating crossover distortion during rail-to-rail operation.

Switch control supports three operating modes: per-amplifier enable/disable, independent channel selection (e.g., OUTSA1/OUTSA2 routing), and special mode (SELA0 = SELA1 = HIGH) for coordinated power-down sequencing. Switch on-resistance is 84 Ω typical at 5 V, with <2 Ω matching and 40 Ω flatness over 0–5 V input swing.

Key Specifications

Pinout & Package

RGR package is a 20-pin, 3.5-mm × 3.5-mm VQFN with exposed thermal pad connected to V–. Pin count and layout are optimized for compact optical module integration and thermal dissipation under 4.5 mA/channel quiescent load.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC6268IMS8E#PBF, OPA3S328RGRR trades 460 MHz bandwidth for integrated switching, 3.8-mA/channel quiescent current, and VQFN-20 footprint - delivering a complete, space-optimized TIA subsystem rather than a standalone amplifier requiring external components.

Availability

OPA3S328RGRR is available at Aetrix Electronics and suitable for optical transport interconnect, optical network terminal units (ONT), and digital multimeter (DMM) applications requiring stable component supply, long-term manufacturability, and guaranteed traceability.

Supply support for OPA3S328RGRR 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 amplifiers and signal chain solutions.

The OPA3S328RGRR belongs to TI's OPA precision op amp portfolio, designed specifically for high-fidelity optical sensing, low-current measurement, and space-constrained transimpedance applications where integration, noise, and offset performance are critical.

FAQ

What is the maximum operating temperature range for the OPA3S328RGRR?

The OPA3S328RGRR is specified for operation from –40°C to +125°C ambient temperature. Electrical characteristics including offset voltage (±175 µV max), input bias current (±100 pA max), and open-loop gain (≥90 dB) are guaranteed across this full industrial temperature range, making it suitable for outdoor ONT deployments and base station environments.

Does the OPA3S328RGRR support true rail-to-rail input with zero-crossover distortion?

Yes, the OPA3S328RGRR features a proprietary zero-crossover input stage that maintains linear operation and stable offset behavior across the entire input common-mode range from (V–) – 0.1 V to (V+) + 0.1 V. This eliminates the traditional "dead zone" near the rails seen in conventional RRIO amplifiers, ensuring distortion-free performance even when input signals approach supply limits - confirmed in Figure 5-6 and Section 7.1.

How does the switch matrix in the OPA3S328RGRR function during power-down mode?

When both amplifiers are disabled via SELA0/SELA1/SELB0/SELB1 in special mode (all HIGH), all six switches (A1–A3, B1–B3) open simultaneously, presenting >100 GΩ output impedance at each OUTSAx/OUTSBx node. This prevents loading between parallel TIA channels and avoids signal corruption during idle periods - a key requirement in burst-mode optical receivers using the OPA3S328RGRR.

Can the OPA3S328RGRR be used with a single 2.2-V supply?

Yes, the OPA3S328RGRR operates down to 2.2 V single supply, delivering rail-to-rail output swing within 5 mV of both rails under 10-kΩ load. Its 0.2 pA input bias current and 60 µV offset remain fully specified at 2.2 V, enabling high-accuracy current measurement in battery-powered DMMs and portable optical test equipment powered by single-cell Li-ion batteries.

What is the purpose of the thermal pad on the OPA3S328RGRR VQFN package?

The exposed thermal pad on the OPA3S328RGRR RGR package must be soldered to a PCB copper plane connected to V–. It reduces junction-to-board thermal resistance to 19.5°C/W, preventing thermal runaway during continuous 4.5-mA/channel operation at elevated ambient temperatures. Proper thermal pad connection is mandatory to meet the device's 125°C maximum junction temperature rating.