Description

The CXD2724AQ-1 is a CMOS LSI developed for Dolby Pro Logic Surround. A SRAM for short delay and AD/DA converters are built in, and all functions necessary for Dolby Pro Logic Surround such as an adaptive matrix, a passive decoder including BNR, auto input balance, a noise sequencer and center channel mode control are contained on a single chip. Further, this LSI also supports Dolby 3 Stereo and Virtual Dolby Surround.

Features

• Dolby Pro Logic Surround decoding with a single chip

• 2-channel 1-bit AD converter, decimation filter and prefilter operational amplifier

• 4-channel 1-bit DA converter, oversampling filter and post filter

• Analog switch for DSP bypass

• Analog electronic attenuator (+1.5 to –29.5dB) for center/surround channel trim

• 24K-bit SRAM for short delay

• No separation or other variance for digital processing

• External parts reduced by incorporating analog circuits

Functions

• Adaptive matrix

• Center channel mode control (Normal/Phantom/Wide)

• Dolby 3 Stereo

• Auto input balance control (ON/OFF)

• Noise sequencer

• Variable delay time (0 to 34.8ms)

• 7 kHz low-pass filter (12dB/Oct)

• Modified Dolby B-type NR

• Simple SFC function

• Virtual Dolby Surround

• SFC mode

• DSP bypass mode (L, R-channel through)

Applications

Equipment having Dolby Pro Logic Surround function such as AV amplifiers, receivers and compact music systems