ALC655

AC'97 Rev 2.3 Audio CODEC

General Description

The ALC655 is a 16-bit, full-duplex AC'97 Rev. 2.3 compatible six-channel audio CODEC designed for PC multimedia systems, including host/soft audio and AMR/CNR-based designs.

The ALC655 incorporates proprietary converter technology to meet performance requirements for PC99/2001 systems. The ALC655 CODEC provides three pairs of stereo outputs with 5-bit volume control, a mono output, and multiple stereo and mono inputs, along with flexible mixing, gain, and mute functions to provide a complete integrated audio solution for PCs.

The digital interface circuitry of the ALC655 CODEC operates from a 3.3V power supply for use in notebook and PC applications. An integrated 50mW/20ohm headset audio amplifier for Front-Out and Surround-Out, a 14.318MHz -> 24.576MHz PLL, and a PCBEEP generator cut BOM costs. The ALC655 also supports S/PDIF input and output for easy connection of PCs to consumer electronic products, such as AC3 decoders/speakers and mini-disk devices. 

The ALC655 CODEC supports host/soft audio from Intel ICHx chipsets as well as audio controller-based VIA/SIS/ALI/AMD/nVIDIA/ATI chipsets. Bundled Windows series drivers (98/ME/NT/2000/XP), EAX/Direct Sound 3D/ I3DL2/A3D compatible sound effect utilities (supporting Karaoke, 26 types of environment sound emulation, 10-band equalizer), HRTF 3D positional audio and Sensaura™ 3DPA (optional) provide an excellent entertainment package and game experience for PC users. In addition, the ALC655 is embedded with an impedance sensing capability to detect when a device has been connected to input or output jacks.

Features

  • Meets performance requirements for audio on PC99/2001 systems
  • Meets Microsoft WHQL/WLP 2.0 audio requirements
  • 16-bit Stereo full-duplex CODEC with 48KHz sampling rate
  • Compatible with AC'97 Rev 2.3 specifications
    • Front-Out, Surround-Out, MIC-In and LINE-In Jack Sensing
    • 14.318MHz -> 24.576MHz PLL to eliminate crystal
    • 12.288MHz BITCLK input
    • Integrated PCBEEP generator to save buzzer
    • Interrupt capability
  • Three analog line-level stereo inputs with 5-bit volume control, LINE_IN, CD, AUX
  • High-quality differential CD input
  • Two analog line-level mono inputs: PCBEEP, PHONE-IN
  • Two software selectable MIC inputs
  • Dedicated Front-MIC input for front panel applications (software selectable)
  • Boost preamplifier for MIC input
  • LINE input shared with surround output; MIC input shared with Center and LFE output
  • Built-in 50mW/20ohm amplifier for both Front-out and Surround-Out
  • External Amplifier Power Down (EAPD) capability
  • Power management and enhanced power saving features
  • Supports Power-Off CD function
  • Adjustable VREFOUT control
  • Supports 48KHz S/PDIF output, compatible with AC'97 Rev 2.3 specifications
  • Supports 32K/44.1K/48KHz S/PDIF input
  • Power support: Digital: 3.3V; Analog: 3.3V/5V
  • Standard 48-pin LQFP package
  • EAX™ 1.0 & 2.0 compatible
  • Direct Sound 3D™ compatible
  • A3D™ compatible
  • I3DL2 compatible
  • HRTF 3D positional audio
  • Sensaura™ 3DPA enhancement (optional)
  • 10-band software equalizer
  • Voice cancellation and key shifting in Karaoke mode
  • AVRack® Media Player
  • Configuration Panel for improved user convenience

Applications

  • Multimedia PCs
  • 3D PC games
  • Information appliances (IA)
  • Voice recognition
  • Audio conferencing