AD74322
G61
REV. Pr D 03/00
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use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
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Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 Analog Devices, Inc., 1998
Low Cost, Low Power
Stereo Audio Analog Front End
Preliminary Technical Data
PRELIMINAR
Y
TECHNICAL
DA
T
A
FEATURES
2.5V Stereo Audio Codec with 3.3 V Tolerant Digital
Interface
Supports 96 kHz Sample Rates
Supports 16/18 /20/24-Bit Word Lengths
Multibit Sigma Delta Modulators with
“Perfect Differential Linearity Restoration” for
Reduced Idle Tones and Noise Floor
Data Directed Scrambling DACs - Least Sensitive to Jitter
Performance (20 Hz to 20 kHz)
90 dB ADC and DAC SNR
Digitally Programmable Input/Output Gain
On-chip Volume Controls Per Output Channel
Hardware and Software Controllable Clickless Mute
Supports 256xFs, 512xF
s
and 768xFs Master Mode Clocks
Master Clock Pre-Scaler for use with DSP master clocks
Flexible Serial Data Port with Right-Justified, Left-
Justified, I
2
S-Compatible and DSP Serial Port Modes
Supports Packed Data Mode (“TDM”) for cascading
devices.
On-Chip Reference
16, 20 and 24-Lead SOIC, SSOP and TSSOP Package
options.
APPLICATIONS
Digital Video Camcorders (DVC)
Portable Audio Devices (Walkman etc)
Audio Processing
Voice Processing
Conference Phones
General Purpose Analog I/O
FUNCTIONAL BLOCK DIAGRAM
GENERAL DESCRIPTION
The AD74322 is a front-end processor for general purpose
audio and voice applications. It features two multi-bit Σ∆
A/D conversion channels and two multi-bit Σ∆ D/A
conversion channels. Each ADC channel provides >85 dB
signal-to-noise ratio while each DAC channel provides
>90 dB, both over anG20 audio signal bandwidth.
The AD74322 is particularly suitable for a variety of ap-
plications where stereo input and output channels are
required, including audio sections of Digital Video
Camcorder, portable personal audio devices and the
analog front ends of conference phones . Its high quality
performance also make it suitable for speech and telephony
applications such as speech recognition and synthesis and
modern feature phones.
DGND AGNDREFCAP
CLKINDVDD2(INT)
AVDD
DVDD1(EXT)
Reference
CDIN
CDOUT
CCLK
CLATCH
SPI
Port
I
2
S
Port
Control
Block
ASDATA
DSDATA
LRCLK
BCLK
ADC
CHANNEL 1
ADC
CHANNEL 2
DAC
CHANNEL 2
DAC
CHANNEL 1
VIN1
VIN2
VOUT1
VOUT2
DGND AGNDREFCAP
CLKINDVDD2(INT)
AVDD
DVDD1(EXT)
Reference
Control
Block
Data
Port
SDO
SDI
SDIFS
SDOFS
SCLK
ADC
CHANNEL 1
ADC
CHANNEL 2
DAC
CHANNEL 2
DAC
CHANNEL 1
VIN1
VIN2
VOUT1
VOUT2
CDIN
CDOUT
CCLK
CLATCH
ASDATA/SDO
DSDATA/SDI
LRCLK/SDIFS
SDOFS
BCLK/SCLK
VIN1P
VIN1N
VIN2P
VIN2N
VOUT1P
VOUT1N
VOUT2P
VOUT2N
ADC
CHANNEL 1
ADC
CHANNEL 2
DAC
CHANNEL 2
DAC
CHANNEL 1
I
2
S
Port
DGND AGNDREFCAP
CLKINDVDD2(INT)
AVDD
DVDD1(EXT)
SPI
Port
Reference
Control
Block