Texas Instruments OPA1688ID

Overview

OPA1688ID from Texas Instruments is a dual-channel, 36-V, rail-to-rail output audio operational amplifier optimized for high-fidelity signal conditioning in professional audio systems. It delivers –109 dB THD+N at 1 kHz into 32 Ω, 10 MHz gain bandwidth, and ±0.25 mV input offset voltage, enabling low-distortion headphone and line-level amplification in A/V receivers and mixer front-ends.

For engineers reviewing the OPA1688ID datasheet, OPA1688ID pinout, OPA1688ID application, or OPA1688ID equivalent, this page provides verified package mapping (SOIC-8), confirmed dual-channel rail-to-rail output behavior, EMI-filtered inputs, and real-world performance data across supply voltages (±2.25 V to ±18 V) and temperature (–40°C to +85°C).

Technical Context

The OPA1688ID implements a three-stage amplifier topology with active feedforward gain stage, supporting stable operation from 4.5 V to 36 V single-supply or ±2.25 V to ±18 V dual-supply configurations. Its input operates 100 mV below V– and within 2 V of V+, while output swings to within 100 mV of both rails under 1 mA load.

It features integrated EMI/RFI filtering on both inputs and phase-reversal protection-critical for robustness in noisy environments like DJ equipment and wireless microphone receivers. Common-mode rejection reaches 120 dB at ±18 V, and channel separation is –120 dB at 1 kHz.

Key Specifications

Pinout & Package

OPA1688ID is packaged in industry-standard SOIC-8 (4.90 mm × 3.91 mm) with exposed pad not present. Pin functions are electrically identical across all OPA1688 variants and validated per TI SBOS724A Rev. June 2022.

Key Features

Applications

Equivalent & Alternatives

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

Compared with OPA1656ID and OPA1662ID, the OPA1688ID uniquely combines 36-V operation, integrated EMI filtering, and –109 dB THD+N at 32 Ω - making it the only option qualified for high-headroom, noise-immune, dual-supply professional audio front-ends.

Availability

OPA1688ID is available at Aetrix Electronics and suitable for professional audio mixer design, guitar amplifier signal chains, and A/V receiver headphone output stages requiring stable component supply across extended temperature and voltage ranges.

Supply support for OPA1688ID 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 high-performance audio signal conditioning.

The OPA1688ID belongs to TI's SoundPlus™ audio op amp family, engineered specifically for low-noise, low-distortion, high-voltage audio signal paths in professional and high-end consumer equipment.

FAQ

What is the maximum supply voltage rating for the OPA1688ID?

The OPA1688ID supports absolute maximum supply voltage of ±20 V (40 V single-supply), but its recommended operating range is ±2.25 V to ±18 V (4.5 V to 36 V). Operation beyond ±18 V risks exceeding thermal limits and degrading long-term reliability, even if within absolute ratings. The OPA1688ID is characterized and guaranteed across the full ±2.25 V to ±18 V range for parameters including THD+N, CMRR, and offset drift.

Does the OPA1688ID support true rail-to-rail input operation?

The OPA1688ID supports rail-to-rail output swing but has limited rail-to-rail input capability: the common-mode input range extends from V– – 0.1 V to V+ – 2 V under normal operation. Full rail-to-rail input (to V+) is possible but with reduced performance - specifically, increased offset voltage and degraded CMRR within 2 V of V+. This behavior is documented in TI SBOS724A Section 3 and confirmed in Figure 7-4 and Figure 7-5.

Can the OPA1688ID be used in single-supply 5-V audio applications?

Yes, the OPA1688ID is fully specified down to 4.5 V single-supply operation and is commonly used in 5-V headphone amplifiers and USB audio interfaces. At 5 V, it delivers –109 dB THD+N into 32 Ω with rail-to-rail output swing (V– + 0.1 V to V+ – 0.1 V), and maintains 10 MHz GBP and 8 V/µs slew rate. Input common-mode range is 0 V to 3 V, requiring proper DC biasing for AC-coupled sources.

What is the thermal resistance (RθJA) of the OPA1688ID in SOIC-8 package?

The OPA1688ID in SOIC-8 (D) package has a junction-to-ambient thermal resistance (RθJA) of 116.1°C/W, as measured per JEDEC JESD51-2 standard on a 2-layer board with 1-in² copper area. This value assumes no internal thermal vias or heatsinking. For continuous 1.6 mA per amplifier operation at ambient 70°C, junction temperature remains below 125°C - within safe operating limits. Derating is required above 70°C ambient or with higher output loading.

How does the EMI rejection performance of the OPA1688ID compare to standard op amps?

The OPA1688ID integrates on-chip R-C filters on both inputs, achieving EMIRR IN+ of 69.2 dB at 2.4 GHz and 114 dB at 5 GHz - significantly exceeding unfiltered op amps (typically <30 dB). This is validated per TI's EMIRR test methodology (SBAA212) and enables reliable operation near Wi-Fi 2.4/5 GHz, Bluetooth, and cellular bands without external ferrite beads or LC filters. Real-world benefit includes elimination of audible buzz in wireless microphone receivers and DJ controllers.