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© Analog Devices, Inc., 2002

AD1955

High Performance Multibit - DAC

with SACD Playback

FEATURES

5 V Power Supply Stereo Audio DAC System

Accepts 16-/18-/20-/24-Bit Data

Supports 24-Bit, 192 kHz Sample Rate PCM Audio Data

Supports SACD Bit Stream and External Digital Filter

Interface

Accepts a Wide Range of PCM Sample Rates Including:

32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, and

192 kHz

Multibit Sigma-Delta Modulator with "Perfect Differen-

tial Linearity Restoration" for Reduced Idle Tones and

Noise Floor

Data Directed Scrambling DAC––Low Sensitivity to Jitter

Supports SACD Playback with "Bit Expansion" Filter

Differential Current Output for Optimum Performance

8.64 mA p-p Differential Output

120 dB SNR/DNR (not muted) at 48 kHz Sample Rate

(A-Weighted Stereo)

123 dB SNR/DNR (Mono)

–110 dB THD + N

110 dB Stop-Band Attenuation with

0.0002 dB

Pass-Band Ripple

8

Oversampling Digital Filter

On-Chip Clickless Volume Control

Supports SACD-Mute Pattern Detection

Internal Digital Filter Pass-Through for External Filter

Hardware and Software Controllable Clickless Mute

Serial (SPI) Control for Serial Mode, Number of Bits,

Sample Rate, Volume, Mute, De-Emphasis, Mono Mode

Digital De-Emphasis for 32 kHz, 44.1 kHz, and 48 kHz

Sample Rates

Flexible Serial Data Port with Right-Justified, Left-

Justified, I

28-Lead SSOP Plastic Package

APPLICATIONS

High End DVD Audio

SACD

CD

Home Theater Systems

Automotive Audio Systems

Sampling Musical Keyboards

Digital Mixing Consoles

Digital Audio Effects Processors

FUNCTIONAL BLOCK DIAGRAM

AUTO-CLOCK

DIVIDER

SPI CONTROL

MASTER

CLOCK INPUT

CONTROL

DATA INPUT

3

DIGITAL

SUPPLY

DSD

BITSTREAM

INPUT

MUX

SERIAL DATA

INTERFACE

EXTERNAL

FILTER I/F

DIGITAL

FILTER ENGINE

S/H

MULTIBIT

-

MODULATOR

NOISE-SHAPED

SCRAMBLING

16-/20-/24-BIT

AUDIO DATA/

EXTERNAL

DIGITAL

FILTER INPUT

3/4

DSD FILTER

RESET

MUTE

ANALOG

SUPPLY

ZERO

FLAGS

I-DAC

L-CH

R-CH

DIFFERENTIAL

CURRENT OUTPUT

I-DAC

VOLTAGE

REFERENCE

4

PRODUCT OVERVIEW

The AD1955 is a complete, high performance, single-chip, stereo

digital audio playback system. It is comprised of a multibit sigma-

delta modulator, high performance digital interpolation filters,

and continuous-time differential current output DACs. Other

features include an on-chip clickless stereo attenuator and mute

capability, programmed through an SPI compatible serial control

port. The AD1955 is fully compatible with all known DVD audio

formats including 192 kHz as well as 96 kHz sample frequencies

and 24 bits. It is also backward compatible by supporting 50

µs/

15

µs digital de-emphasis intended for “redbook” compact discs,

as well as de-emphasis at 32 kHz and 48 kHz sample rates.

The AD1955 has a very flexible serial data input port that

allows for glueless interconnection to a variety of ADCs, DSPs,

SACD decoders, external digital filters, AES/EBU receivers, and

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