a
Parallel-Port 16-Bit
SoundPort® Stereo Codec
AD1845
FEATURES
Single-Chip Integrated ∑∆ Digital Audio Stereo Codec
Microsoft ® and Windows® Sound System Compatible
MPC Level-2+ Compliant Mixing
16 mA Bus Drive Capability
Supports Two DMA Channels for Full Duplex Operation
On-Chip Capture and Playback FIFOs
Advanced Power-Down Modes
Programmable Gain and Attenuation
Sample 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 Compatible with AD1848, AD1846, CS4248, CS4231
plete on-chip filtering, MPC Level-2 compliant analog mixing,
programmable gain, attenuation and mute, a variable sample
frequency generator, FIFOs, and supports advanced powerdown modes. It provides a direct, byte-wide interface to both
ISA (“AT”) and EISA computer buses for simplified implementation on a computer motherboard or add-in card.
LE
TE
The AD1845 SoundPort Stereo Codec supports a DMA request/grant architecture for transferring data with the host computer 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.
Two input control lines support mixed direct and indirect addressing of thirty-seven internal control registers over this asynchronous interface. The AD1845 includes dual DMA count
registers for full duplex operation enabling the AD1845 to capture data on one DMA channel and play back data on a separate
channel. The FIFOs on the AD1845 reduce the risk of losing
data when making DMA transfers over the ISA/EISA bus. The
FIFOs buffer data transfers and allow for relaxed timing in
acknowledging requests for capture and playback data.
PRODUCT OVERVIEW
B
SO
The Parallel Port AD1845 SoundPort Stereo Codec integrates
key audio data conversion and control functions into a single
integrated circuit. The AD1845 provides a complete, single chip
computer audio solution for business audio and multimedia
applications. The codec includes stereo audio converters, com-
(Continued on Page 9)
FUNCTIONAL BLOCK DIAGRAM
ANALOG
L_MIC
R_MIC
L_LINE
R_LINE
L_AUX1
R_AUX1
ANALOG SUPPLY
L
O
M_IN
GAM
⌺
GAM
⌺
⌺
GAIN
-LAW
A-LAW
LINEAR
DIGITAL MIX
GAM = GAIN
ATTENUATE
ATTENTUATE
MUTE
L ATTENUATE
⌺⌬ D/A
⌺
CONVERTER
MUTE
⌺
⌺
⌺
GAM
⌺
R
ATTENUATE
MUTE
⌺⌬ D/A
CONVERTER
DIGITAL
PLAYBACK REQ
PLAYBACK ACK
⌺⌬ A/D
CONVERTER
R
RESET
AD1845
⌺⌬ A/D
CONVERTER
GAIN
M
U
X
MUTE
POWER DOWN
VARIABLE SAMPLE
FREQUENCY GENERATOR
L_OUT
R_OUT
CLOCK SOURCE
0 dB/
20 dB
GAM
M_OUT
DIGITAL SUPPLY
-LAW
A-LAW
LINEAR
CAPTURE REQ
FIFO
P
A
R
A
L
L
E
L
FIFO
P
O
R
T
⌺
ADR1:0
DATA7:0
CS
RD
WR
BUS DRIVER
CONTROL
HOST DMA
INTERRUPT
EXTERNAL
CONTROL
GAM
L_AUX2
R_AUX2
CAPTURE ACK
REFERENCE
VREF_F
CONTROL
REGISTERS
VREF
SoundPort is a registered trademark of Analog Devices, Inc.
Microsoft and Windows are registered trademarks of Microsoft Corporation.
REV. C
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: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1997
