High Fidelity Multifunctional Sound Processors for Car Audio Systems


ROHM Co., Ltd. has announced the development of eighteen different sound processors optimized for today's increasingly sophisticated car- and home-audio systems. The greater number of inputs and outputs required to accommodate multiple audio sources and speakers for higher fidelity playback, coupled with the need for fine-tuning of the characteristics to match the acoustic effects of the particular environment, have created a demand for high performance, multifunctional sound processors.

In order to meet these various needs, ROHM offers a complete lineup of eighteen different types of sound processor ICs in a variety of input source channels, speaker outputs, and acoustic correction functions. Features include low distortion and low noise – factors essential to high fidelity audio – along with advanced switching functionality that reduces unpleasant switching shock sounds by smoothing discontinuous waveforms generated during volume switching. In addition, models are available that integrate acoustic correction functions, including parametric equalizers, loudness circuits, and subwoofer LPF/HPFs that allow optimized audio playback based on vehicle cabin characteristics. A common register map is also included in all models, allowing simple control from most existing microcontroller software, and upgrading performance is as easy as changing the sound processor.

Pricing : 1000yen/unit (For sample shipments)
Availability : February 2010 (OEM Quantities)

Car Audio Sound Processor ICs BD375□□ Series (PDF:563KB)

Key Features

  • Complete product lineup
  • Industry's best volume/tone switching shock noise reduction characteristics
  • Virtually all external components required built in – only input/output coupling capacitors needed
  • Low 0.001% distortion ensures faithful reproduction of original audio
  • Optimized circuit structure minimizes noise (3.8µVrms)




  • Sound Processor
    A sound control IC with an input source selector, input gain adjustment, main volume, and equalizer circuit for sound quality adjustment integrated into a single chip. After the selector switches based on the input signal (i.e. MD, CD, TUNER, TAPE, AUX) and the volume is adjusted to a constant level, the main volume and equalizer further modifies the volume and audio characteristics, after which the signal is output.
  • LPF/HPF(Low Pass Filter/High Pass Filter)
    In higher performance car audio systems, specialized speakers (subwoofers) are used to strengthen the low-frequency (bass) range. An LPF is normally used to extract only low frequency signals, since subwoofers are specialized for bass reproduction.
    Often, when a subwoofer is used, an HPF is included to eliminate unnecessary bass from speakers other than the subwoofer, preventing unpleasant resonance from doors, dashboards, and other components.
  • Loudness
    This function corrects audio using a sound processor IC to optimize the audio characteristics to the human ear, which does not hear low and high sounds well at low volumes. In proprietary brand-name car audio systems the audio characteristics are fine-tuned to the size and shape of the vehicle interior.
  • Differential Input
    An input terminal with a ground noise canceling function. For example, in situations where a CD changer is mounted in the trunk some distance away from the main audio system a differential signal is used to cancel noise picked up from the car generator through the wiring.

Products Sound Processor Series for Car Audio
New Products Sound Processor ICs for Car Audio

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