OPA604AU - 20MHz 25V/us FET-Input Audio Op Amp | TI
MPN: OPA604AU ✓ ActiveOPA604AU Overview
An operational amplifier, commonly called an op amp, is a high-gain differential amplifier used to amplify small signals. The OPA604 belongs to the FET-input operational-amplifier family and combines low input current, low distortion, wide bandwidth, and high slew rate. In the broader semiconductor hierarchy, it is an analog amplifier IC within the integrated-circuit and signal-conditioning categories.
The OPA604AU combines a 20 MHz gain-bandwidth product with a 25 V/us slew rate, allowing it to process audio-bandwidth signals with low crossover distortion. Its FET input stage is suitable for high-impedance sources because it avoids the higher input bias currents commonly associated with bipolar transistor input stages. The wide ±24 V supply limit provides additional headroom for high-output-signal applications.
The internal design emphasizes low distortion and wide dynamic range. Laser trimming of input offset voltage improves channel consistency and reduces circuit complexity in precision signal paths. The device is specified over a -40°C to +85°C temperature range and is available in the surface-mount SOIC-8 format designated by TI as package code D.
Typical uses include high-fidelity audio preamplifiers, active crossover networks, line-level stages, instrumentation amplifiers, low-distortion filters, and analog signal-conditioning circuits. It is especially relevant where the source impedance is high enough to make input bias current important or where large slew rate is needed to preserve low distortion at audio signal levels.
Circuit design must preserve adequate output-voltage swing and common-mode headroom within the selected supply rails. Decoupling capacitors should be placed close to the power pins, and the feedback network should use suitable resistor values to maintain stability with the load capacitance and source impedance present on the board.
This product page combines the manufacturer specifications with practical pin-assignment guidance, drop-in replacement analysis, application examples, and design notes for evaluating the OPA604AU in precision analog and audio signal chains. It is intended to help engineers confirm electrical fit, package compatibility, thermal constraints, and application suitability before incorporating the amplifier into a production design.
Drop-in alternatives for OPA604AU — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
OPA604AUE4
✅ Drop-In📋 Reference alternative (not in catalog)
OPA604AU Maximum Ratings & Electrical Characteristics
| Amplifier Type | Single-circuit operational amplifier |
| Input Stage | FET input |
| Gain-Bandwidth Product | 20 MHz |
| Slew Rate | 25 V/us |
| Minimum Supply Voltage | ±4.5 V |
| Maximum Supply Voltage | ±24 V |
| Operating Temperature Range | -40°C to +85°C |
| Package | 8-pin SOIC, package code D |
| Pin Count | 8 pins |
| Mounting Type | Surface mount |
| Offset Voltage Trimming | Laser trimmed |
| RoHS Status | Unknown; RoHS status not stated |
| REACH Status | Unknown; REACH status not stated |
| AEC-Q100 Qualification | Not applicable; not identified as an automotive-qualified variant |
OPA604AU Pin Configuration
| Pin 1 | NC — Not connected (per datasheet) |
| Pin 2 | -IN — Inverting input |
| Pin 3 | +IN — Non-inverting input |
| Pin 4 | V- — Negative supply connection |
| Pin 5 | NC — Not connected (per datasheet) |
| Pin 6 | OUT — Output |
| Pin 7 | V+ — Positive supply connection |
| Pin 8 | NC — Not connected (per datasheet) |
Typical Applications
OPA604AU is suitable for 6 applications: High-Fidelity Audio Preamplifier, Active Crossover Network, Instrumentation Signal Conditioning, ADC and DAC Analog Interface, Precision Audio Filter, Professional Audio Line Driver.
High-Fidelity Audio Preamplifier
The OPA604AU fits a low-distortion audio preamplifier because its FET input stage supports high-impedance sources while the 20 MHz gain-bandwidth product and 25 V/us slew rate preserve signal fidelity across the audio band. Place the device in a non-inverting gain stage with local supply bypassing and short feedback tracks. Compared with a bipolar-input stage, the FET architecture is advantageous when source impedance is high, while the 25 V/us slew rate helps prevent slew-induced distortion at larger signal amplitudes.
Recommended
Active Crossover Network
OPA604AU is appropriate for active low-pass, high-pass, and band-pass crossover sections that require low distortion and predictable large-signal behavior. Its 20 MHz gain-bandwidth product gives ample closed-loop bandwidth for audio crossover filters, and its 25 V/us slew rate reduces the risk of full-power bandwidth limitations. Use stable feedback ratios, check the actual load capacitance, and keep the filter node routing compact to prevent added phase shift or oscillation.
Recommended
Instrumentation Signal Conditioning
The OPA604AU can serve as a low-noise gain stage in instrumentation systems where the source may have relatively high output impedance. Its FET input avoids the comparatively high bias current of bipolar transistor input stages, helping preserve the accuracy of the sensed signal. The 20 MHz gain-bandwidth product supports precise gain-bandwidth allocation, while the ±4.5 V to ±24 V supply range permits operation from low dual-supply rails to higher-voltage analog systems.
Recommended
ADC and DAC Analog Interface
OPA604AU is useful in the analog interface around audio and mixed-signal converters when the design requires low distortion, flexible supply voltage, and high input impedance. Its 20 MHz bandwidth and 25 V/us slew rate provide more bandwidth than typical audio conversion rates, while the FET input minimizes loading of the preceding converter or driver. The designer should still verify converter settling requirements, output common-mode range, and filter isolation in the complete signal chain.
Recommended
Precision Audio Filter
OPA604AU can implement precision active filters in audio and measurement equipment where low distortion and stable gain are more important than minimum cost. The 20 MHz gain-bandwidth product supports higher-order filter designs with reasonable closed-loop bandwidth margin, and the 25 V/us slew rate reduces large-signal distortion. Select resistor and capacitor tolerances according to the required filter accuracy, and verify stability with the source impedance, load, and parasitic capacitance present in the final assembly.
Recommended
Professional Audio Line Driver
OPA604AU is well matched to line-level audio and professional signal stages that require low distortion over a broad amplitude range. The 25 V/us slew rate supports fast signal transitions, while the ±24 V maximum supply provides additional output headroom compared with low-voltage audio amplifiers. The application requires careful grounding, balanced or unbalanced input arrangement as appropriate, and output protection for external cables and downstream equipment. Verify the output-current and load-capacitance limits in the datasheet before connecting external hardware.
Recommended
Recommended Products Summary
Engineering reference data for OPA604AU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | OPA604AUE4 |
|---|---|---|
| Package | 8-pin SOIC | 8-pin SOIC - same footprint |
| Brand | Texas Instruments | Texas Instruments |
| Amplifier Type | Single FET-input operational amplifier | Single FET-input operational amplifier |
| Gain-Bandwidth Product | 20 MHz | 20 MHz |
| Slew Rate | 25 V/us | 25 V/us |
| Supply Voltage Range | ±4.5 V to ±24 V | ±4.5 V to ±24 V |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C |
| Input Stage | FET input | FET input |
Key Differentiators
- Verified same-family drop-in configuration (vs OPA604AUE4)
- High-impedance audio signal handling (vs OPA604AUE4)
- Wide supply-voltage operating range (vs OPA604AUE4)
Design Notes
Place the supply-bypass capacitors as close as practical to pins 4 and 7, and connect their ground returns directly to the device ground region. Keep the inverting-input and feedback components close to pins 2 and 6 to minimize parasitic feedback. Because the OPA604AU combines low noise with a 20 MHz gain-bandwidth product, long exposed input and feedback traces can increase coupling and reduce the benefit expected from the low-noise input stage.
Do not assume that any audio amplifier with a similar bandwidth can replace the OPA604AU. The FET input stage, 25 V/us slew rate, ±24 V maximum supply, offset behavior, and 8-pin SOIC pin arrangement must all be checked. Before fitting OPA604AUE4 to an OPA604AU design, confirm the ordering suffix, temperature grade, package markings, and production packing. Also verify the input common-mode range and output swing against the actual supply rails.
Estimated thermal analysis should use the maximum intended supply voltage, output voltage, load current, ambient temperature, and the SOIC junction-to-ambient thermal resistance. The dissipated power equals the total supply voltage multiplied by the average supply current, subject to the actual output waveform and quiescent current. Estimated: if total supply voltage is 36 V and average supply current is 10 mA, dissipation is 0.36 W; use the package thermal data and PCB copper area to determine the resulting junction-temperature rise.
Compliance Information
The OPA604AU is not identified as an AEC-Q100-qualified automotive variant. RoHS, REACH, lead-free, halogen-free, and conflict-minerals status were not stated and must be confirmed using current manufacturer documentation before a regulated design is released.
