AC ’97 SoundMAX® Codec
AD1985
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
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
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
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
Jack sensing and peripheral enumeration/identification
48-lead LQFP package
FUNCTIONAL BLOCK DIAGRAM
V
V
XTL_OUT XTL_IN SPDIF_OUT
REF
REFOUT
AD1985
VOLTAGE
REFERENCE
MIC1
MIC2
G
Z
G
G
SPDIF
TX
CODEC CORE
PCM L/R
PHONE_IN
CD_L
PLL
ADC RATE
ID0
16-BIT
M
M
G
G
CD
Σ-∆ ADC
ADC
SLOT
LOGIC
CD_GND
CD_R
AUX_L
DIFF AMP
16-BIT
Σ-∆ ADC
ID1
AUX_R
LINE_IN_L
LINE_IN_R
PCM C/LFE
DAC RATE
RESET
SYNC
20-BIT
DAC
SLOT
LOGIC
M
M
GA
GA
Σ-∆ DAC
LFE_OUT
MZ
MZ
A
A
20-BIT
Σ-∆ DAC
CENTER_OUT
LINE_OUT_L
GA
GA
M
GA
M
GA
M
GA
M
BITCLK
SDATA_OUT
SDATA_IN
GA
M
GA
M
GA
M
GA
M
M
M
M
M M
MZ
A
PC BEEP
GENERATOR
A
M
M
MONO_OUT
LINE_OUT_R
A
A
PCM FRONT
DAC RATE
EQ
EQ
MZ
20-BIT
M
M
GA
GA
Σ
Σ-∆ DAC
Σ
20-BIT
Σ
AC '97
Σ-∆ DAC
SURR_OUT_L/
HP_OUT_L
A
A
M
M
HP
HP
CONTROL
REGISTERS
M
20-BIT
M
M
GA
GA
Σ-∆ DAC
M
SURR_OUT_R/
HP_OUT_R
ANALOG MIXING
CONTROL
JACK SENSE
20-BIT
Σ-∆ DAC
G = GAIN
EAPD
A = ATTENUATION
M = MUTE
PCM SURR
DAC RATE
Z = HIGH Z
EAPD JS0 JS1 JS2 JS3
Figure 1.
Rev. A
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