a
Stereo, Single Supply
16-, 18- and 20-Bit Sigma-Delta DACs
AD1857/AD1858
FEATURES
Low Cost, High Performance Stereo DACs
128 Times Oversampling Interpolation Filter
Multibit SD Modulator with Triangular PDF Dither
Discrete Time and Continuous Time Analog
Reconstruction Filters
Extremely Low Out-of-Band Energy
Buffered Outputs with 2 kV Output Load Drive
94 dB Dynamic Range, –90 dB THD+N Performance
Digital De-emphasis and Mute
60.18C Maximum Phase Linearity Deviation
Continuously Variable Sample Rate Support
Power-Down Mode
16-, 18- and 20-Bit I2S-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
PRODUCT OVERVIEW
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 converters. The AD1857 serial data input port can be configured
in either 16-bit, 18-bit or 20-bit left-justified or I2S-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
CLOCK
IN
CLOCK
MODE
COMMON
MODE
DIGITAL
SUPPLY
2
16-/18-/20-BIT
DIGITAL
DATA INPUT
SERIAL
MODE
3
SERIAL DATA
INTERFACE
AD1857/AD1858
128x
INTERPOLATION
FILTER
128x
INTERPOLATION
FILTER
MUTE
VOLTAGE
REFERENCE
MULTIBIT
Σ∆ MODULATOR
CLOCK
CIRCUIT
DAC
ANALOG
FILTER
DAC
ANALOG
FILTER
OUTPUT
BUFFER
ANALOG
OUTPUTS
MUTE
MULTIBIT
Σ∆ MODULATOR
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
AD1857/AD1858–SPECIFICATIONS
TEST CONDITIONS UNLESS OTHERWISE NOTED
Supply Voltages (AVDD, DVDD)
Ambient Temperature
Input Clock (FMCLK)
Input Signal
Input Sample Rate
Measurement Bandwidth
AD1857 Input Data Wordwidth
AD1858 Input Data Wordwidth
Load Capacitance
Load Impedance
Input Voltage HI (VIH)
Input Voltage LO (VIL)
+5.0 V
25°C
11.2896 MHz (256 × FS Mode)
1.0013 kHz
–0.5 dB Full Scale
44.1 kHz
20 Hz to 20 kHz
18 Bits
16 Bits
100 pF
47 kΩ
2.4 V
0.8 V
I2S-Justified Mode (Ref. Figure 7) for AD1857, Right-Justified Mode (Ref. Figure 8) for AD1858.
Performance of the right and left channels are identical (exclusive of the Interchannel Gain Mismatch and Interchannel Phase Deviation specifications).
Values in bold typeface are tested, all others are guaranteed, not tested.
ANALOG PERFORMANCE
Min
AD1857 Resolution
AD1858 Resolution
Dynamic Range (20 Hz to 20 kHz, –60 dB Input)
No A-Weight Filter
With A-Weight Filter
Total Harmonic Distortion + Noise
Analog Outputs
Single-Ended Output Range (± Full Scale)
Output Impedance at Each Output Pin
Output Capacitance at Each Output Pin
Out-of-Band Energy (0.5 × FS to 100 kHz)
CMOUT
DC Accuracy
Gain Error
Interchannel Gain Mismatch
Gain Drift
Interchannel Crosstalk (EIAJ method)
Interchannel Phase Deviation
Mute Attenuation
De-emphasis Gain Error
2.8
2.1
Typ
Max
Units
18
16
Bits
Bits
91
94
–90
0.003
dB
dB
dB
%
3.0
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