SAA7708H

GENERAL DESCRIPTION

The CDSP-chip performs all the signal functions in front of the power amplifiers and behind the AM and FM_MPX demodulation of a car radio or the tape input. These functions are: interference absorption, stereo decoding, RDS decoding, FM and AM weak signal processing (soft-mute, sliding stereo, etc.), Dolby-B tape noise reduction and the audio controls (volume, balance, fader and tone). Some functions have been implemented in hardware (stereo decoder, RDS decoding and IAC for FM_MPX) and are not freely programmable. A digital audio signals from external sources with the Philips I2S and the LSB 16, 18 and 20 bit justified format or SPDIF format are accepted. There are four independent analog output channels..
The DSP contains a basic program which enables a set with AM/FM reception, sophisticated FM weak signal functions, MSS, Dolby-B tape noise reduction system, CD play with compressor function and separate bass and treble tone control and fader/balance control.

HARDWARE FEATURES

• Two 3rd order SCAD (switch cap analog to digital converters)
• D/A converters with four fold over sampling and noise shaping
• Digital stereo decoder for the FM_MPX signal
• Improved, digital IAC for FM
• RDS processing with optional 16 bit buffer via a separate channel.
• Phone input with common mode rejection. Can be mixed with DAC output of front channels or processed via an AD
• Auxiliary high CMRR analog CD input (CD-walkman, speech, economic CD-changer etc.)
• One separate full I2S and LSB justified format and two muxable SPDIF high performance input interfaces
• Audio output short circuit protected
• I2C bus controlled
• AM input or AM_Right and AM_Left input
• Phase Lock Loop to generate the high frequency DSP clock from common fundamental oscillator crystal
• Combined AM/FM level input
• Two analog single ended tape inputs
• -40 to +85°C operating temperature range

SOFTWARE FEATURES
• Improved FM weak signal processing
• Integrated 19 kHz MPX filter and de-emphasis
• Electronic adjustments: FM/AM level, FM channel separation, Dolby level
• Baseband Audio processing (treble/bass/balance/fader/volume)
• Dynamic loudness or bass boost
• Audio level meter
• Music Search detection for Tape (MSS)
• Dolby-B tape noise reduction
• CD dynamics compressor
• CD De-emphasis processing
• Improved AM processing with IAC
• Soft Audio Mute