The HT8691 is a highly integrated Class-D audio power amplifier designed by Holtek Semiconductor. This amplifier is engineered to deliver high-quality audio output with exceptional efficiency, making it an ideal solution for portable audio devices and other battery-powered applications. Its Class-D architecture significantly reduces power dissipation compared to traditional Class-AB amplifiers, resulting in longer battery life and reduced heat generation. The HT8691 also includes various protection features to ensure reliable operation and prevent damage to the amplifier and connected speakers.

Applications:

• Portable Speakers: Amplifying audio signals in portable speakers for enhanced sound quality and volume.
• Bluetooth Speakers: Providing efficient audio amplification in Bluetooth speakers for wireless audio playback.
• Mobile Phones: Integrated into mobile phones to drive the built-in speaker and/or headphone output.
• Tablet Computers: Amplifying audio signals in tablets for multimedia playback and audio output.
• MP3/MP4 Players: Delivering high-quality audio output in portable media players.
• USB Speakers: Enhancing the audio performance of USB-powered speakers.

Features:

• Class-D Amplifier: Highly efficient Class-D architecture for reduced power dissipation and extended battery life.
• Low THD+N: Low total harmonic distortion plus noise for clear and accurate audio reproduction.
• High PSRR: High power supply rejection ratio for minimizing the impact of power supply noise on audio quality.
• Short-Circuit Protection: Built-in short-circuit protection to prevent damage to the amplifier and connected speakers.
• Over-Temperature Protection: Over-temperature protection to prevent thermal damage to the amplifier.
• Under-Voltage Lockout: Under-voltage lockout to prevent malfunction during low-voltage conditions.
• Adjustable Gain: Adjustable gain settings to accommodate different input signal levels.
• Filter-Free Operation: Operates without the need for external filters, simplifying the design and reducing component count.

Benefits:

• Extended Battery Life: High efficiency extends battery life in portable devices.
• Improved Audio Quality: Low THD+N ensures clear and accurate audio reproduction.
• Enhanced Reliability: Protection features prevent damage to the amplifier and connected speakers.
• Simplified Design: Filter-free operation simplifies the design and reduces component count.
• Compact Size: Small package allows for integration into space-constrained designs.

Additional Details:

The HT8691 typically operates from a low voltage supply (e.g., 2.5V to 5.5V). The output power depends on the supply voltage and speaker impedance, but it can often deliver several watts into a 4-ohm or 8-ohm speaker. The amplifier typically includes a shutdown mode to further reduce power consumption when not in use. The package is typically a small surface-mount package, such as a QFN or TSSOP. The amplifier often includes a volume control input for adjusting the output level.