Low Cost Parallel-Port 16-Bit
SoundPort Stereo Codec
a
AD1846
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. T he AD1846 generates en-
able and direction controls for IC buffers such as the 74_245.
FEATURES
Low Cost, Pin- and Register-Com patible Alternative to
AD1848
Single-Chip Integrated ∑∆ Digital Audio Stereo Codec
Supports the Microsoft Window s Sound System *
Multiple Channels of Stereo Input and Output
Analog and Digital Signal Mixing
Program m able Gain and Attenuation
On-Chip Signal Filters
Digital Interpolation and Decim ation
Analog Output Low -Pass
Sam ple Rates from 5.5 kHz to 48 kHz
68-Lead PLCC Package
T he 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. T wo
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.
Operation from +5 V Supply
Byte-Wide Parallel Interface to ISA and EISA Buses
Supports One or Tw o DMA Channels and
Program m ed I/ O
P RO D UCT O VERVIEW
T he 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. T he ADCs’ output can be digitally mixed with the
DACs’ input.
T he Parallel-Port AD1846 SoundPort® Stereo Codec integrates
key audio data conversion and control functions into a single in-
tegrated circuit. T he 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.
(Continued on page 9)
FUNCTIO NAL BLO CK D IAGRAM
DIGITAL
SUPPLY
ANALOG
SUPPLY
CRYSTALS
POWER DOWN
ANALOG
DIGITAL
L_LINE
R_LINE
OSCILLATORS
PLAYBACK REQ
L
16
16
∑∆ A/D
CONVERTER
µ/
A
L
A
W
L_MIC
R_MIC
GAIN
GAIN
PLAYBACK ACK
CAPTURE REQ
P
A
R
A
L
L
E
L
MUX
L_AUX1
R_AUX1
R
∑∆ A/D
CONVERTER
CAPTURE ACK
ADR1:0
DATA7:0
AD1846
DIGITAL
MIX
GAIN/ATTEN/
MUTE
CS
L
WR
P
O
R
T
∑∆ D/A
CONVERTER
ATTEN/
MUTE
ANALOG
FILTER
L_OUT
R_OUT
∑
∑
µ/
A
L
A
W
INTERPOL
INTERPOL
ATTENUATE
ATTENUATE
RD
BUS DRIVER
CONTROL
R
∑∆ D/A
CONVERTER
ATTEN/
MUTE
ANALOG
FILTER
∑
∑
HOST DMA
INTERRUPT
CONTROL
REGS
REFERENCE
L_AUX2
R_AUX2
EXTERNAL
CONTROL
GAIN/ATTEN/
MUTE
V
REF
REV. A
Inform ation furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norw ood, MA 02062-9106, U.S.A.
Tel: 617/ 329-4700 Fax: 617/ 326-8703