a
Stereo, Single Supply
16-, 18- and 20-Bit Sigma-Delta DACs
AD1857/AD1858
PRODUCT OVERVIEW
FEATURES
Low Cost, High Performance Stereo DACs
128 Times Oversampling Interpolation Filter
Multibit
Modulator with Triangular PDF Dither
Discrete Time and Continuous Time Analog
Reconstruction Filters
Extremely Low Out-of-Band Energy
Buffered Outputs with 2 k Output Load Drive
94 dB Dynamic Range, –90 dB THD+N Performance
Digital De-emphasis and Mute
0.1 C Maximum Phase Linearity Deviation
Continuously Variable Sample Rate Support
Power-Down Mode
16-, 18- and 20-Bit I
2
S-Justified, Left-Justified Modes
Offered on AD1857
Accepts 24-Bit Word
16-Bit Right-Justified and DSP Serial Port Modes
Offered on AD1858
Single +5 V Supply
20-Pin SSOP Package
APPLICATIONS
Digital Cable TV and Direct Broadcast Satellite Set-Top
Decoder Boxes
Video Laser Disk, Video CD and CD-I Players
High Definition Televisions, Digital Audio Broadcast
Receivers
CD, CD-R, DAT, DCC and MD Players
Digital Audio Workstations, Computer Multimedia
Products
The AD1857/AD1858 are complete single-chip stereo digital
audio playback components. They each comprise an advanced
digital interpolation filter, a revolutionary “linearity-compensated”
multibit sigma-delta (∑∆) modulator with dither, a jitter-tolerant
DAC, switched capacitor and continuous time analog filters and
analog output drive circuitry. Other features include digital
de-emphasis processing and mute. The AD1857/AD1858
support continuously variable sample rates with essentially
linear phase response, and support 50/15
µs
digital de-emphasis
intended for “Redbook” 44.1 kHz sample frequency playback
from Compact Discs. The user must provide a master clock that
is synchronous with the left/right clock at 256 or 384 times the
intended sample frequency.
The AD1857/AD1858 have a simple but very flexible serial data
input port that allows for glueless interconnection to a variety of
ADCs, DSP chips, AES/EBU receivers and sample rate con-
verters. The AD1857 serial data input port can be configured
in either 16-bit, 18-bit or 20-bit left-justified or I
2
S-justified
modes. The AD1858 serial data input port can be configured in
either 16-bit right-justified or DSP serial port compatible modes.
The AD1857/AD1858 accept serial audio data in MSB first,
twos-complement format. A power-down mode is offered to
minimize power consumption when the device is inactive. The
AD1857/AD1858 operate from a single +5 V power supply.
They are fabricated on a single monolithic integrated circuit and
housed in 20-pin SSOP packages for operation over the
temperature range 0°C to +70°C.
FUNCTIONAL BLOCK DIAGRAM
DIGITAL
SUPPLY
2
COMMON
MODE
CLOCK
MODE
CLOCK
IN
16-/18-/20-BIT
DIGITAL
DATA INPUT
3
SERIAL DATA
INTERFACE
AD1857/AD1858
128x
INTERPOLATION
FILTER
128x
INTERPOLATION
FILTER
VOLTAGE
REFERENCE
CLOCK
CIRCUIT
SERIAL
MODE
MUTE
MULTIBIT
Σ∆
MODULATOR
DAC
ANALOG
FILTER
OUTPUT
BUFFER
ANALOG
OUTPUTS
MUTE
MULTIBIT
Σ∆
MODULATOR
DAC
ANALOG
FILTER
OUTPUT
BUFFER
4
DE-EMPHASIS
MUTE
POWER-DOWN/RESET
ANALOG
SUPPLY
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
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
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997
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