REV. A
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which may result from its use. No license is granted by implication or
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a
Low Cost Parallel-Port 16-Bit
SoundPort Stereo Codec
AD1846
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
FEATURES
Low Cost, Pin- and Register-Compatible Alternative to
AD1848
Single-Chip Integrated ∑∆ Digital Audio Stereo Codec
Supports the Microsoft Windows Sound System*
Multiple Channels of Stereo Input and Output
Analog and Digital Signal Mixing
Programmable Gain and Attenuation
On-Chip Signal Filters
Digital Interpolation and Decimation
Analog Output Low-Pass
Sample Rates from 5.5 kHz to 48 kHz
68-Lead PLCC Package
Operation from +5 V Supply
Byte-Wide Parallel Interface to ISA and EISA Buses
Supports One or Two DMA Channels and
Programmed I/O
It provides a direct, byte-wide interface to both ISA (“AT”) and
EISA computer buses for simplified implementation on a com-
puter motherboard or add-in card. The AD1846 generates en-
able and direction controls for IC buffers such as the 74_245.
The AD1846 SoundPort Stereo Codec supports a DMA re-
quest/grant architecture for transferring data with the host com-
puter bus. One or two DMA channels can be supported.
Programmed I/O (PIO) mode is also supported for control reg-
ister accesses and for applications lacking DMA control. Two
input control lines support mixed direct and indirect addressing
of twenty-one internal control registers over this asynchronous
interface.
External circuit requirements are limited to a minimal number
of low cost support components. Anti-imaging DAC output
filters are incorporated on-chip. DAC dynamic range exceeds
80 dB over the 20 kHz audio band. Sample rates from 5.5 kHz
to 48 kHz are supported from external crystals.
The Codec includes a stereo pair of ∑∆ analog-to-digital con-
verters and a stereo pair of ∑∆ digital-to-analog converters. In-
puts to the ADC can be selected from four stereo pairs of analog
signals: line, microphone (“mic”), auxiliary (“aux”) line #1, and
post-mixed DAC output. A software-controlled programmable
gain stage allows independent gain for each channel going into
the ADC. The ADCs’ output can be digitally mixed with the
DACs’ input.
(Continued on page 9)
PLAYBACK REQ
MUX
D A/D
CONVERTER
P
A
R
A
L
L
E
L
P
O
R
T
ANALOG
CRYSTALS
ANALOG
SUPPLY
DIGITAL
SUPPLY
L
R
GAIN
L
R
m /
A
L
A
W


OSCILLATORS
REFERENCE
L_MIC
R_MIC
R_LINE
L_LINE
R_AUX1
L_AUX1

R_OUT
GAIN/ATTEN/
MUTE
L_AUX2
R_AUX2

DIGITAL
m /
A
L
A
W
DATA7:0
ADR1:0
BUS DRIVER
CONTROL
CAPTURE REQ
HOST DMA
INTERRUPT
EXTERNAL
CONTROL
CONTROL
REGS
DIGITAL
MIX
16
D A/D
CONVERTER
16
D D/A
CONVERTER
D D/A
CONVERTER
ANALOG
FILTER
GAIN
ANALOG
FILTER
INTERPOL
INTERPOL
ATTENUATE
ATTENUATE
L_OUT
ATTEN/
MUTE
ATTEN/
MUTE
GAIN/ATTEN/
MUTE
AD1846
POWER DOWN
V
REF
PLAYBACK ACK
CAPTURE ACK
CS
WR
RD
PRODUCT OVERVIEW
The Parallel-Port AD1846 SoundPort
®
Stereo Codec integrates
key audio data conversion and control functions into a single in-
tegrated circuit. The AD1846 is intended to provide a complete,
single-chip audio solution for business audio and multimedia
applications requiring operation from a single +5 V supply.
*Windows Sound System is a trademark of Microsoft Corp.
SoundPort is a registered trademark of Analog Devices, Inc.
FUNCTIONAL BLOCK DIAGRAM