Parallel-Port 16-Bit
SoundPort® Stereo Codec
a
AD1845
FEATURES
plete on-chip filtering, MPC Level-2 compliant analog mixing,
programmable gain, attenuation and mute, a variable sample
frequency generator, FIFOs, and supports advanced power-
down modes. It provides a direct, byte-wide interface to both
ISA (“AT ”) and EISA computer buses for simplified implemen-
tation on a computer motherboard or add-in card.
Single-Chip Integrated ∑∆ Digital Audio Stereo Codec
Microsoft® and Window s® Sound System Com patible
MPC Level-2+ Com pliant Mixing
16 m A Bus Drive Capability
Supports Tw o DMA Channels for Full Duplex Operation
On-Chip Capture and Playback FIFOs
Advanced Pow er-Dow n Modes
Program m able Gain and Attenuation
Sam ple Rates from 4.0 kHz to 50 kHz Derived from a
Single Clock or Crystal Input
68-Lead PLCC, 100-Lead TQFP Packages
Operation from +5 V Supplies
Byte-Wide Parallel Interface to ISA and EISA Buses
Pin Com patible w ith AD1848, AD1846, CS4248, CS4231
T he AD1845 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
register accesses and for applications lacking DMA control.
T wo input control lines support mixed direct and indirect ad-
dressing of thirty-seven internal control registers over this asyn-
chronous interface. T he AD1845 includes dual DMA count
registers for full duplex operation enabling the AD1845 to cap-
ture data on one DMA channel and play back data on a separate
channel. T he FIFOs on the AD1845 reduce the risk of losing
data when making DMA transfers over the ISA/EISA bus. T he
FIFOs buffer data transfers and allow for relaxed timing in
acknowledging requests for capture and playback data.
P RO D UCT O VERVIEW
T he Parallel Port AD1845 SoundPort Stereo Codec integrates
key audio data conversion and control functions into a single
integrated circuit. T he AD1845 provides a complete, single chip
computer audio solution for business audio and multimedia
applications. T he codec includes stereo audio converters, com-
(Continued on Page 9)
FUNCTIO NAL BLO CK D IAGRAM
ANALOG
POWER DOWN
RESET
ANALOG SUPPLY
DIGITAL SUPPLY
CLOCK SOURCE
DIGITAL
L_MIC
R_MIC
0 dB/
20 dB
VARIABLE SAMPLE
FREQUENCY GENERATOR
AD1845
PLAYBACK REQ
PLAYBACK ACK
CAPTURE REQ
CAPTURE ACK
ADR1:0
L_LINE
R_LINE
L_AUX1
R_AUX1
L
⌺⌬ A/D
CONVERTER
M
U
X
GAIN
-LAW
A-LAW
FIFO
R
⌺⌬ A/D
CONVERTER
LINEAR
GAIN
P
A
R
A
L
L
E
L
DATA7:0
DIGITAL MIX
ATTENUATE
GAM = GAIN
ATTENTUATE
GAM
GAM
GAM
CS
MUTE
RD
L
⌺⌬ D/A
CONVERTER
ATTENUATE
MUTE
⌺
⌺
⌺
⌺
P
O
R
T
L_OUT
M_OUT
R_OUT
WR
-LAW
A-LAW
LINEAR
MUTE
⌺
FIFO
BUS DRIVER
CONTROL
R
⌺⌬ D/A
CONVERTER
ATTENUATE
MUTE
HOST DMA
INTERRUPT
⌺
⌺
⌺
⌺
EXTERNAL
CONTROL
GAM
GAM
M_IN
L_AUX2
R_AUX2
REFERENCE
CONTROL
REGISTERS
V
V
REF
REF_F
SoundPort is a registered trademark of Analog Devices, Inc.
Microsoft and Windows are registered trademarks of Microsoft Corporation.
REV. C
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: 781/ 329-4700
Fax: 781/ 326-8703
World Wide Web Site: http:/ / w w w .analog.com
© Analog Devices, Inc., 1997