New Fixed Equalizer IC from Mitsubishi Electric Optimizes Sound Quality in Car Audio Systems

Business Wire, March 3, 2003

Business Editors/Automotive Writers/High-Tech Writers

SUNNYVALE, Calif.--(BUSINESS WIRE)--March 3, 2003

The Electronic Device Group of Mitsubishi Electric & Electronics USA, Inc., today introduced two highly integrated audio signal processors that use switched capacitor filter (SCF) technology to improve sound quality in car audio systems. The M61528FP Fixed Equalizer IC enables developers to optimize the audio system's sound to match a car passenger compartment's unique acoustical characteristics, and the M61523FP Electronic Volume and Tone Control IC gives designers the ability to manipulate bass and treble tones in six-speaker car audio systems. In addition to improved sound quality, the number of external components needed is dramatically reduced, thereby reducing system cost.

"For a variety of reasons, every different car interior poses a unique acoustic challenge for the car audio system designer," said George Riehm, senior marketing manager for consumer products at Mitsubishi Electric & Electronics USA, Inc. "To simplify the challenge, saving time and money, our Fixed Equalizer IC enables manufacturers to adjust the equalizer one time to the optimal acoustical setting, then go directly to production. Because SCF technology allows the user to vary the 'Q' and the center frequency of the audio signal in our Electronic Volume and Tone Control IC, different environmental effects can be created without using a more expensive digital signal processor."

M61528FP Fixed Equalizer IC

A car passenger compartment's size and shape, as well as the materials used to construct it, create unique sonic characteristics that affect how a car audio system's sound energy is distributed throughout the compartment. Irregular shapes inside the compartment and the materials used to construct the dashboard, car seats, windows, carpets, and other components can cause standing waves that eclipse certain sound frequencies and cause certain audio frequencies to be reflected and absorbed. The M61528FP Fixed Equalizer IC enables developers to eliminate the standing waves, boost underemphasized and subdue overemphasized frequencies, and move the sound envelope so the audio system's entire frequency range is evenly distributed throughout the compartment.

The M61528FP is a three-band device that features a wide dynamic range throughout bass, midrange, and treble frequency ranges. It also features independent volume controls in each of four channels (left front, left rear, right front, and right rear), a fader volume control with a built-in noise suppression circuit, and a microcontroller interface. SCF technology enables the device to eliminate the need for external resistor-capacitor (RC) networks in the equalizer circuit, since this function is handled internally, which decreases system cost.

M61523FP Electronic Volume and Tone Control IC

The M61523FP Electronic Volume and Tone Control IC provides a wide dynamic range of volume control in six-speaker car audio systems. Like the M61528FP, it uses SCF technology to save system cost by eliminating RC network components in the tone control circuit. It features a built-in, soft-switching noise-suppression circuit to reduce the noise in the master and fader volume controls. A dual input selector function enables designers to use three single inputs and one differential input for design flexibility. The device also contains a microcontroller interface that connects the system microcontroller to the volume controller's main and sub input selector, independent gain control, soft mute, base/treble tone controls, and loudness, volume, and fader controls.

Packaging, Availability, and Pricing

The M61528FP and M61523FP are each available in a 24-pin SSOP package that occupies a 7.8-mm x 10.1-mm footprint.

Samples of both devices are available now. The M61523FP is in volume production now, with M61528FP volume production scheduled for June 2003. Sample-quantity pricing is $5.50 each for the M61528FP and $4.00 each for the M61523FP.

   M61528FP Specifications:

   --  Fader Volume: 0dB to -50dB / 2dB steps

   --  Low

       -- 0dB to -8dB / 0.5dB steps

       -- f0 = 120Hz, 150Hz, 200Hz, 300Hz

       -- Front Q = 1.5 to 3.0 / 0.5 steps

       -- Rear Q = 2.0 to 4.0 / 0.5 steps

   --  Midrange

       -- +4dB to -8dB / 0.5 dB steps

       -- f0 = 800Hz, 1.2kHz, 1.5kHz, 2kHz, 3kHz

       -- Q = 0.8 to 2.0 / 0.2 steps

   --  High

       -- +8dB to -8dB / 0.5 dB steps

       -- f0 = 8kHz, 10kHz, 18kHz

       -- Q = 0.4 to 1.0 / 0.2 steps

   M61523FP Specifications:

   --  Input Gain Control: 0dB to +14dB / 1dB steps; +14dB to +20dB /
       2dB steps

   --  Master Volume: +6dB to -80dB / 1dB steps

   --  Front-Rear Fader Volume: 0dB to -50dB / 2dB steps (4-channel
       independent control)

   --  Non-Fader Volume: -26dB to +12dB / 2dB steps (L/R independent
       control)

   --  Loudness Control: 0db to -15dB / 1dB steps; f0 = 400Hz, 800Hz

   --  Bass: -14dB to +16dB / 2dB steps

       -- f0 = 50Hz, 80Hz, 120Hz

       -- Q = 1.0, 1.25. 1.5, 2.0

   --  Treble: -12dB to +12dB / 2dB steps; f0 = 8kHz, 12kHz

   --  Soft Mute Function