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