AC ’97 SoundMAX
®
Codec

AD1985


Rev. A
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However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
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registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
AC ’97 2.3 COMPLIANT FEATURES
6 DAC channels for 5.1 surround
Greater than 90 dB dynamic range
20-bit resolution on all DACs
S/PDIF Output
Integrated stereo headphone amplifiers
Variable rate audio
Double rate audio (fS = 96 kHz)
Line-level mono phone input
High quality CD mixer input
Selectable MIC input with preamp
AUX and line in stereo inputs
External amplifier power down (EAPD)
Power management modes
Jack sensing and peripheral enumeration/identification
48-lead LQFP package
ENHANCED FEATURES
Integrated parametric equalizer (EQ)
Stereo microphone with preamplifiers
Integrated PLL for system clocking
Variable sample rate 7 kHz to 96 kHz
7 kHz to 48 kHz in 1 Hz increments
96 kHz for double rate audio
Advanced jack sense with auto topology switching
Software enabled VREFOUT for microphones and external
power amp
Software enabled outputs for jack sharing
Auto down-mix and channel spreading
Microphone to mono output
Stereo microphone analog passthrough to outputs
Built-in stereo microphone and Center/LFE pin sharing
Selectable Center/LFE tip/ring swapping to support various
speaker products

FUNCTIONAL BLOCK DIAGRAM
PCM L/R
ADC RATE
PCM C/LFE
DAC RATE
PCM FRONT
DAC RATE
PCM SURR
DAC RATE
DAC
SLOT
LOGIC
ADC
SLOT
LOGIC
AC '9
7
INTE
RFACE
V
2
.3
EQ C
OEF STOR
A
GE
AC '97
CONTROL
REGISTERS
EAPD
ANALOG MIXING
CONTROL
JACK SENSE
PLL
SPDIF
TX
ID0
ID1
RESET
SYNC
BITCLK
SDATA_OUT
SDATA_IN
JS0 JS1 JS2 JS3EAPD
16-BIT
16-BIT
Σ-∆ ADC
CODEC CORE
20-BIT
Σ-∆ DAC
20-BIT
Σ-∆ DAC
20-BIT
Σ-∆ DAC
20-BIT
Σ-∆ DAC
B
YPA
SS EQ
20-BIT
Σ-∆ DAC
B
YPA
SS
CS
W
P
CS
W
P
EQ
20-BIT
Σ-∆ DAC
Σ-∆ ADC
M
G = GAIN
A = ATTENUATION
M = MUTE
Z = HIGH Z
MG
M
Z
G
M GA
MGA
M GA
M GA
M GA
M GA
G
G
M
GA
M
GA
M
GA
MMM
GA
M
GA
M
GA
M
GA
M
GA
M
GA
M
M
M
MIC1
MIC2
PHONE_IN
CD_L
CD_GND
CD_R
AUX_L
AUX_R
LINE_IN_L
OM
S
OM
S
2CMIC
MS
CD
DIFF AMP
LINE_IN_R
SPR
D
MZ ALFE_OUT
SPR
D
MZ ACENTER_OUT
MZ ALINE_OUT_L
M AMONO_OUT
MZ ALINE_OUT_R
M A
SURR_OUT_L/
HP_OUT_L
M ASURR_OUT_R/
HP_OUT_R
HP
HP
LOSEL
LOSEL
M
I
X
H
PSEL
H
PSEL
V
REF
G
V
REFOUT
VOLTAGE
REFERENCE
AD1985
XTL_OUT XTL_IN SPDIF_OUT
PC BEEP
GENERATOR
Σ
Σ
Σ
M A
RE
CORD
SELEC
TOR
03610-A
-
001

Figure 1.