Texas Instruments OPA1655DR

Overview

OPA1655 from Texas Instruments is a single-channel, FET-input audio operational amplifier engineered for ultra-low-noise, low-distortion signal amplification in high-fidelity analog audio paths. It delivers 2.9 nV/√Hz voltage noise at 10 kHz, –129 dB THD+N at 20 kHz, and 100 mA output drive into 2-kΩ loads while operating from ±2.25 V to ±18 V supplies - making it suitable for professional microphone preamplifiers and tone-control circuits.

For engineers reviewing the OPA1655 datasheet, OPA1655 pinout, OPA1655 application, or OPA1655 equivalent, this page provides verified technical context, package-specific pin functions, real-world audio use cases, and validated alternative options - all grounded in TI's SBOS901C production data sheet (Rev. C, September 2022).

Technical Context

The OPA1655 employs a three-stage architecture with low-noise input and feedforward path coupled to a high-current output stage, enabling superior distortion performance across varying load conditions. Its FET-input design achieves 10 pA input bias current and 6 fA/√Hz current noise density, supporting high-impedance sensor and passive-filter interfaces without signal degradation.

It features rail-to-rail output swing within 250 mV of supply rails under 2-kΩ load, phase-reversal protection to prevent output inversion during common-mode overdrive, and stable operation with capacitive loads up to 100 pF - critical for active filter and DAC-output buffering applications.

Key Specifications

Pinout & Package

OPA1655 is available in two industry-standard packages: 8-pin SOIC (D) and 5-pin SOT-23 (DBV). The SOIC variant includes NC pins for layout flexibility; the SOT-23 version optimizes board space for compact audio modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA1655, OPA1612AID offers superior noise performance in dual-channel systems but increases board area and power draw, while LM4562MA trades measurable distortion and robustness for cost - making OPA1655 the balanced choice for professional-grade single-channel audio with demanding transient and overload requirements.

Availability

OPA1655 is available at Aetrix Electronics and suitable for professional microphone preamplifiers, active tone-control modules, and A/V receiver line-output stages requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for OPA1655 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 heritage in high-performance audio IC design.

The OPA165x family was developed specifically for professional and high-end consumer audio applications where signal fidelity, low noise, and robust overload behavior are non-negotiable - targeting microphone preamps, mixing consoles, and premium playback systems.

FAQ

What is the maximum capacitive load the OPA1655 can drive stably?

The OPA1655 maintains stability with capacitive loads up to 100 pF in unity-gain configuration, as confirmed by phase margin measurements in TI's SBOS901C datasheet (Figure 6-35). For loads exceeding 100 pF - such as long cables or DAC output filters - a series isolation resistor (R_ISO = 25 Ω to 50 Ω) is recommended to preserve phase margin and prevent overshoot. This behavior is validated across both SOIC and SOT-23 packages of the OPA1655.

Does the OPA1655 support single-supply operation?

Yes, the OPA1655 supports true single-supply operation from 4.5 V to 36 V, as specified in Section 6.3 (Recommended Operating Conditions) of the SBOS901C datasheet. Its rail-to-rail output and wide input common-mode range (V− to V+ − 2.25 V) allow direct interfacing with single-ended ADCs or microcontroller inputs without level-shifting circuitry - a key advantage over legacy audio op-amps limited to dual-supply use.

How does the OPA1655's phase-reversal protection work in practice?

The OPA1655 incorporates internal circuitry that clamps the output to the nearest supply rail instead of inverting polarity when either input exceeds the linear common-mode range - a failure mode common in noninverting configurations with large-signal transients. This is demonstrated in Figure 7-1 of the SBOS901C datasheet, where overdriven input produces clean rail-limited output without oscillation or latch-up. This feature directly benefits Baxandall tone-control and guitar effects-loop designs where input overdrive is routine.

What is the typical input offset voltage drift of the OPA1655 over temperature?

The OPA1655 exhibits a typical input offset voltage drift of 0.3 µV/°C across –40°C to +125°C, with a maximum specification of 2 µV/°C (Section 6.6, Electrical Characteristics). This low drift - combined with its ±1 mV max V_OS - ensures minimal DC error accumulation in precision summing amplifiers or DC-coupled headphone drivers operating across extended ambient ranges, such as automotive infotainment or outdoor broadcast equipment.

Can the OPA1655 replace the OPA2134 in an existing design?

The OPA1655 is not a direct drop-in replacement for the OPA2134 due to differences in pinout (OPA2134 SO-8 has different pin assignments), noise profile (OPA1655: 2.9 nV/√Hz vs OPA2134: 8 nV/√Hz), and output drive (OPA1655: ±100 mA vs OPA2134: ±25 mA). While both are FET-input audio op-amps, substituting OPA1655 requires verifying PCB layout compatibility, recalculating feedback networks for gain accuracy, and validating thermal performance under higher output current demand - especially in dual-channel implementations.