REV. B
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.
a
Serial-Port 16-Bit
SoundPort Stereo Codec
AD1847
® Analog Devices, Inc., 1996
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
FEATURES
Single-Chip Integrated SD Digital Audio Stereo Codec
Supports the Microsoft Windows Sound System*
Multiple Channels of Stereo Input
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
44-Lead PLCC and TQFP Packages
Operation from +5 V Supplies
Serial Digital Interface Compatible with ADSP-21xx
Fixed-Point DSP
I
S
A
B
U
S
ASIC AD1847
DSP
Figure 1. Example System Diagram
External circuit requirements are limited to a minimal number
of low cost support components. Anti-imaging DAC output
filters are incorporated on-chip. Dynamic range exceeds 70 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 (ADCs) and a stereo pair of ∑∆ digital-to-analog con-
verters (DACs). Inputs to the ADC can be selected from four
stereo pairs of analog signals: line 1, line 2, 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.
The pair of 16-bit outputs from the ADCs is available over a se-
rial interface that also supports 16-bit digital input to the DACs
and control/status information. The AD1847 can accept and
generate 16-bit twos-complement PCM linear digital data, 8-bit
unsigned magnitude PCM linear data, and 8-bit µ-law or A-law
companded digital data.
(Continued on page 7)
FUNCTIONAL BLOCK DIAGRAM
ANALOG
I/O
L
R
DIGITAL
I/O
CRYSTALS
2 2
2
S
E
R
I
A
L
P
O
R
T
OSCILLATORS
2.25V
REFERENCE
L
R
L
R
CLOCK
OUT
ATTEN
DIGITAL
SUPPLY
ANALOG
SUPPLY
M
U
X
L
R
L
R
L
R
L
R
BUS
MASTER
TIME SLOT
INPUT
TIME SLOT
OUTPUT
SERIAL DATA
OUTPUT
SERIAL DATA
INPUT
EXTERNAL
CONTROL
SERIAL BIT
CLOCK
FRAME
SYNC
RESET
LINE 1
INPUT
LINE 2
INPUT
AUX 1
INPUT
LINE
OUTPUT
AUX 2
INPUT
AD1847
∑
ATTEN/
MUTE
ATTEN
POWER
DOWN
µ/A
LAW
µ/A
LAW
ATTEN
∑
∑
∑
∑∆ D/A
CONVERTER
∑∆ D/A
CONVERTER
µ/A
LAW
µ/A
LAW
GAIN
GAIN
∑∆ A/D
CONVERTER
∑∆ A/D
CONVERTER
GAIN/ATTEN/MUTE
GAIN/ATTEN
/MUTE
GAIN/ATTEN
/MUTE
ATTEN/
MUTE
PRODUCT OVERVIEW
The AD1847 SoundPort
®
Stereo Codec integrates key audio
data conversion and control functions into a single integrated
circuit. The AD1847 is intended to provide a complete, low
cost, single-chip solution for business, game audio and multi-
media applications requiring operation from a single +5 V sup-
ply. It provides a serial interface for implementation on a
computer motherboard, add-in or PCMCIA card. See Figure 1
for an example system diagram.
*Windows Sound System is a registered trademark of Microsoft Corp.
SoundPort is a registered trademark of Analog Devices, Inc.
