AD AD1885JST

a
AC’97 SoundMAX® Codec
AD1885
AC’97 2.1 FEATURES
Variable Sample Rate Audio
Multiple Codec Configuration Options
External Audio Power-Down Control
ENHANCED FEATURES
Full Duplex Variable Sample Rates from 7040 Hz to
48 kHz with 1 Hz Resolution
Jack Sense Pins Provide Automatic Output Switching
Software-Enabled VREFOUT Output for Microphones and
External Power Amp
Split Power Supplies (3.3 V Digital/5 V Analog)
Mobile Low-Power Mixer Mode
Extended 6-Bit Master Volume Control
Extended 6-Bit Headphone Volume Control
Digital Audio Mixer Mode
PHAT™ Stereo 3D Stereo Enhancement
AC’97 FEATURES
AC’97 2.1-Compliant
Greater than 90 dB Dynamic Range
Stereo Headphone Amplifier
Multibit ⌺⌬ Converter Architecture for Improved S/N
Ratio Greater than 90 dB
16-Bit Stereo Full-Duplex Codec
Four Analog Line-Level Stereo Inputs for:
LINE-IN, CD, VIDEO, and AUX
Two Analog Line-Level Mono Inputs for Speakerphone
and PC BEEP
Mono MIC Input w/Built-In 20 dB Preamp, Switchable
from Two External Sources
High Quality CD Input with Ground Sense
Stereo Line-Level Outputs
Mono Output for Speakerphone or Internal Speaker
Power Management Support
48-Terminal LQFP Package
FUNCTIONAL BLOCK DIAGRAM
ID0
ID1
JS0/EAPD
JS1
AD1885
JACK SENSES
AND EAPD CTRL
CHIP SELECT
MIC1
VREF
VREFOUT
0dB/
20dB
MIC2
LINE
SELECTOR
AUX
CD
VIDEO
PGA
16-BIT
⌺⌬ A/D
CONVERTER
PGA
16-BIT
⌺⌬ A/D
CONVERTER
RESET
PHONE_IN
SYNC
⌺
HP_OUT_L
LINE_OUT_L
LINE_OUT_R
HP_OUT_R
SAMPLE
RATE
GENERATORS
MMV
HV
MV
MV
HV
G
A
M
⌺
⌺
G
A
M
G
A
M
G
A
M
G
A
M
G
A
M
AC LINK
MONO_OUT
POP
BIT_CLK
SDATA_OUT
⌺
PHAT
STEREO
⌺
PHAT
STEREO
⌺
⌺
⌺
POP
A
M
PC_BEEP
⌺
⌺
⌺
⌺
⌺
⌺
NC
⌺
⌺
⌺
G = GAIN
A = ATTENUATE
M = MUTE
MV = MASTER VOLUME
HV = HEADPHONE VOLUME
NC
G
A
M
16-BIT
⌺⌬ D/A
CONVERTER
G
A
M
16-BIT
⌺⌬ D/A
CONVERTER
⌺
SDATA_IN
⌺
OSCILLATOR
XTL_OUT XTL_IN
SoundPort is a registered trademark and PHAT is a trademark of Analog Devices, Inc.
REV. 0
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., 2000
AD1885–SPECIFICATIONS
STANDARD TEST CONDITIONS UNLESS OTHERWISE NOTED
Temperature
Digital Supply (DVDD)
Analog Supply (AVDD)
Sample Rate (FS)
Input Signal
Analog Output Passband
25
°C
3.3
V
5.0
V
48
kHz
1008
Hz
20 Hz to 20 kHz
DAC Test Conditions
Calibrated
–3 dB Attenuation Relative to Full Scale
Input 0 dB
10 kΩ Output Load (LINE_OUT)
32 Ω Output Load (HP_OUT)
ADC Test Conditions
Calibrated
0 dB Gain
Input –3.0 dB Relative to Full Scale
ANALOG INPUT
Parameter
Min
Input Voltage (RMS Values Assume Sine Wave Input)
LINE_IN, AUX, CD, VIDEO, PHONE_IN, PC_BEEP
MIC with 20 dB Gain (M20 = 1)
MIC with 0 dB Gain (M20 = 0)
Input Impedance*
Input Capacitance*
Typ
Max
Unit
1
2.83
0.1
0.283
1
2.83
20
5
7.5
V rms
V p-p
V rms
V p-p
V rms
V p-p
kΩ
pF
Typ
Max
Unit
80
dB
dB
dB
dB
dB
dB
dB
Max
Unit
MASTER VOLUME
Parameter
Min
Step Size (0 dB to –94.5 dB); LINE_OUT_L, LINE_OUT_R
Output Attenuation Range Span*
Step Size (0 dB to –46.5 dB); MONO_OUT
Output Attenuation Range Span*
Step Size (+6 dB to –88.5 dB); HP_OUT_R, HP_OUT_L
Output Attenuation Range Span*
Mute Attenuation of 0 dB Fundamental*
1.5
–94.5
1.5
–46.5
1.5
–94.5
PROGRAMMABLE GAIN AMPLIFIER—ADC
Parameter
Min
Step Size (0 dB to 22.5 dB)
PGA Gain Range Span
Typ
1.5
22.5
dB
dB
ANALOG MIXER—INPUT GAIN/AMPLIFIERS/ATTENUATORS
Parameter
Min
Signal-to-Noise Ratio (SNR)
CD to LINE_OUT
Other to LINE_OUT
Step Size (+12 dB to –34.5 dB): (All Steps Tested)
MIC, LINE_IN, AUX, CD, VIDEO, PHONE_IN, DAC
Input Gain/Attenuation Range: MIC, LINE, AUX, CD, VIDEO, PHONE_IN, DAC
Step Size (0 dB to –45 dB): (All Steps Tested) PC_BEEP
Input Gain/Attenuation Range: PC_BEEP
Typ
Max
Unit
90
90
dB
dB
1.5
–46.5
3.0
–45
dB
dB
dB
dB
* Guaranteed, not tested.
–2–
REV. 0
AD1885
DIGITAL DECIMATION AND INTERPOLATION FILTERS*
Parameter
Min
Passband
Passband Ripple
Transition Band
Stopband
Stopband Rejection
Group Delay
Group Delay Variation Over Passband
0
Typ
0.4 × FS
0.6 × FS
–74
Max
Unit
0.4 × FS
± 0.09
0.6 × FS
∞
12/FS
0.0
Hz
dB
Hz
Hz
dB
sec
µs
Max
Unit
ANALOG-TO-DIGITAL CONVERTERS
Parameter
Min
Resolution
Total Harmonic Distortion (THD
Dynamic Range (–60 dB Input THD+N Referenced to Full Scale, A-Weighted)
Signal-to-Intermodulation Distortion* (CCIF Method)
ADC Crosstalk*
Line Inputs (Input L, Ground R, Read R; Input R, Ground L, Read L)
LINE_IN to Other
Gain Error (Full-Scale Span Relative to Nominal Input Voltage)
Interchannel Gain Mismatch (Difference of Gain Errors)
ADC Offset Error
84
Typ
16
–84
87
85
Bits
dB
dB
dB
–100
–90
–90
–85
± 10
± 0.5
±5
dB
dB
%
dB
mV
Typ
Max
Unit
DIGITAL-TO-ANALOG CONVERTERS
Parameter
Min
Resolution
Total Harmonic Distortion (THD) LINE_OUT
Total Harmonic Distortion (THD) HP_OUT (With 10 kΩ Load)
Dynamic Range LINE_OUT (–60 dB Input THD+N Referenced to Full Scale,
A-Weighted)
Signal-to-Intermodulation Distortion* (CCIF Method)
Gain Error (Full-Scale Span Relative to Nominal Input Voltage)
Interchannel Gain Mismatch (Difference of Gain Errors)
DAC Crosstalk* (Input L, Zero R, Measure R_OUT; Input R, Zero L,
Measure L_OUT)
Total Audible Out-of-Band Energy (Measured from 0.6 × FS to 20 kHz)*
85
16
–85
–75
Bits
dB
dB
90
–100
± 10
dB
dB
%
dB
± 0.7
–80
dB
dB
Max
Unit
–40
ANALOG OUTPUT
Parameter
Min
Full-Scale Output Voltage; LINE_OUT
1
2.83
Output Impedance*
External Load Impedance*
Output Capacitance*
External Load Capacitance
Full-Scale Output Voltage; HP_OUT (0 dB Gain)
Output Capacitance*
External Load Capacitance
VREF
VREFOUT
VREFOUT Current Drive
Mute Click (Muted Output Minus Unmuted Midscale DAC Output)
*Guaranteed, not tested.
REV. 0
Typ
–3–
800
10
15
100
1
2.05
2.25
2.25
100
32
2.45
5
±5
V rms
V p-p
Ω
kΩ
pF
pF
V rms
pF
Ω
V
V
mA
mV
AD1885–SPECIFICATIONS
STATIC DIGITAL SPECIFICATIONS*
Parameter
Min
Typ
High-Level Input Voltage (VIH): Digital Inputs
Low-Level Input Voltage (VIL)
High-Level Output Voltage (VOH), IOH = 2 mA
Low-Level Output Voltage (VOL), IOL = 2 mA
Input Leakage Current
Output Leakage Current
0.65 × DVDD
Max
Unit
V
0.35 × DVDD V
V
0.1 × DVDD V
10
µA
10
µA
0.9 × DVDD
–10
–10
POWER SUPPLY
Parameter
Min
Power Supply Range—Analog (AVDD)
Power Supply Range—Digital (DVDD)
Power Dissipation—5 V/3.3 V
Analog Supply Current—5 V (AVDD)
Digital Supply Current—3.3 V (DVDD)
Power Supply Rejection (100 mV p-p Signal @ 1 kHz)*
(At Both Analog and Digital Supply Pins, Both ADCs and DACs)
4.75
3.15
Typ
Max
Unit
5.25
3.45
V
V
mW
mA
mA
dB
355
50
21
40
CLOCK SPECIFICATIONS
Parameter
Min
Typ
Max
Unit
Input Clock Frequency
Recommended Clock Duty Cycle
40
24.576
50
60
MHz
%
POWER-DOWN MODE*
Parameter
Set Bits
DVDD (3.3 V)
Typ
AVDD (5 V)
Typ
Unit
ADC
DAC
ADC and DAC
ADC + DAC + Mixer (Analog CD On)
Mixer
ADC + Mixer
DAC + Mixer
ADC + DAC + Mixer
Analog CD Only (AC-Link On)
Analog CD Only (AC-Link Off)
Standby
Headphone Standby
PR0
PR1
PR1, PR0
LPMIX, PR1, PR0
PR2
PR2, PR0
PR2, PR1
PR2, PR1, PR0
LPMIX, PR5, PR1, PR0
LPMIX, PR1, PR0, PR4, PR5
PR5, PR4, PR3, PR2, PR1, PR0
PR6
20
20
8
8
21
19
19
8
7
0
0
21
44
41
35
26
23
18
15
10
22
12
0.1
38
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
NOTES
*Guaranteed, not tested.
Output jitter is directly dependent on crystal input jitter.
Specifications subject to change without notice.
–4–
REV. 0
AD1885
TIMING PARAMETERS (GUARANTEED OVER OPERATING TEMPERATURE RANGE)
Parameter
Symbol
RESET Active Low Pulsewidth
RESET Inactive to BIT_CLK Startup Delay
SYNC Active High Pulsewidth
SYNC Low Pulsewidth
SYNC Inactive to BIT_CLK Startup Delay
BIT_CLK Frequency
BIT_CLK Period
BIT_CLK Output Jitter*
BIT_CLK High Pulsewidth
BIT_CLK Low Pulsewidth
SYNC Frequency
SYNC Period
Setup to Falling Edge of BIT_CLK
Hold from Falling Edge of BIT_CLK
BIT_CLK Rise Time
BIT_CLK Fall Time
SYNC Rise Time
SYNC Fall Time
SDATA_IN Rise Time
SDATA_IN Fall Time
SDATA_OUT Rise Time
SDATA_OUT Fall Time
End of Slot 2 to BIT_CLK, SDATA_IN Low
Setup to Trailing Edge of RESET (Applies to SYNC, SDATA_OUT)
Rising Edge of RESET to HI-Z Delay
Propagation Delay
RESET Rise Time
Output Valid Delay from Rising Edge of BIT_CLK to SDI Valid
tRST_LOW
tRST2CLK
tSYNC_HIGH
tSYNC_LOW
tSYNC2CLK
NOTES
*Output jitter is directly dependent on crystal input jitter.
Specifications subject to change without notice.
REV. 0
–5–
Min
Typ
Max
1.0
162.8
1.3
19.5
162.8
12.288
81.4
tCLK_PERIOD
tCLK_HIGH
tCLK_LOW
32.56
32.56
tSYNC_PERIOD
tSETUP
tHOLD
tRISECLK
tFALLCLK
tRISESYNC
tFALLSYNC
tRISEDIN
tFALLDIN
tRISEDOUT
tFALLDOUT
tS2_PDOWN
tSETUP2RST
tOFF
5
5
2
2
2
2
2
2
2
2
0
15
42
38
48.0
20.8
2.5
4
4
4
4
4
4
4
4
750
48.84
48.84
10
10
10
10
10
10
10
10
10
25
15
50
15
Unit
µs
ns
µs
µs
ns
MHz
ns
ps
ns
ns
kHz
µs
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ms
ns
ns
ns
ns
ns
AD1885
tRST_LOW
tRST2CLK
BIT_CLK
RESET
tRISECLK
tFALLCLK
BIT_CLK
SYNC
Figure 1. Cold Reset
tRISESYNC
tFALLSYNC
SDATA_IN
tRISEDIN
tRST2CLK
tSYNC_HIGH
SYNC
tFALLDIN
SDATA_OUT
BIT_CLK
tRISEDOUT
Figure 2. Warm Reset
tFALLDOUT
Figure 5. Signal Rise and Fall Time
tCLK_LOW
BIT_CLK
SYNC
tCLK_HIGH
tCLK_PERIOD
SLOT 1
SLOT 2
WRITE
TO 0x26
DATA
PR4
BIT_CLK
tSYNC_LOW
SDATA_OUT
SYNC
DON’T
CARE
tS2_PDOWN
tSYNC_HIGH
tSYNC_PERIOD
SDATA_IN
NOTE: BIT_CLK NOT TO SCALE
Figure 3. Clock Timing
Figure 6. AC-Link Low Power Mode Timing
tSETUP
RESET
BIT_CLK
SDATA_OUT
SYNC
tSETUP2RST
SDATA_OUT
SDATA_IN, BIT_CLK
HI-Z
tOFF
tHOLD
Figure 4. Data Setup and Hold
Figure 7. ATE Test Mode
–6–
REV. 0
AD1885
ABSOLUTE MAXIMUM RATINGS*
Parameter
Power Supplies
Digital (AVDD)
Analog (DVDD)
Input Current (Except Supply Pins)
Analog Input Voltage (Signal Pins)
Digital Input Voltage (Signal Pins)
Ambient Temperature (Operating)
Storage Temperature
ORDERING GUIDE
Min
–0.3
–0.3
–0.3
–0.3
0
–65
Max
Unit
+3.6
+6.0
± 10
AVDD + 0.3
DVDD + 0.3
70
+150
V
V
mA
V
V
°C
°C
Model
Temperature
Range
Package
Description
Package
Option*
AD1885JST
0°C to 70°C
48-Lead LQFP
ST-48
*ST = Thin Quad Flatpack.
ENVIRONMENTAL CONDITIONS
Ambient Temperature Rating
TAMB = TCASE – (PD × θCA)
TCASE = Case Temperature in °C
PD = Power Dissipation in W
θCA = Thermal Resistance (Case-to-Ambient)
θJA = Thermal Resistance (Junction-to-Ambient)
θJC = Thermal Resistance (Junction-to-Case)
*Stresses greater than those listed under Absolute Maximum Ratings may cause
permanent damage to the device. This is a stress rating only; functional operation
of the device at these or any other conditions above those indicated in t he
operational section of this specification is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device reliability.
Package
␪JA
␪JC
␪CA
LQFP
76.2°C/W
17°C/W
59.2°C/W
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD1885 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
MONO_OUT
HP_OUT_L
AVDD2
NC
HP_OUT_R
AVSS2
ID0
AVSS3
AVDD3
ID1
JS0 (EAPD)
JS1
PIN CONFIGURATION
48 47 46 45 44 43 42 41 40 39 38 37
DVDD1 1
XTL_IN 2
36 LINE_OUT_R
PIN 1
IDENTIFIER
35 LINE_OUT_L
XTL_OUT 3
DVSS1 4
34 CX3D
33 RX3D
SDATA_OUT 5
32 FILT_L
AD1885
BIT_CLK 6
DVSS2 7
31 FILT_R
TOP VIEW
(Not to Scale)
SDATA_IN 8
DVDD2 9
30 AFILT2
29 AFILT1
28 VREFOUT
27 VREF
SYNC 10
RESET 11
PC_BEEP 12
26 AVSS1
25 AVDD1
NC = NO CONNECT
REV. 0
–7–
MIC2
LINE_IN_L
LINE_IN_R
CD_GND_REF
CD_R
MIC1
VIDEO_R
CD_L
AUX_R
VIDEO_L
PHONE_IN
AUX_L
13 14 15 16 17 18 19 20 21 22 23 24
WARNING!
ESD SENSITIVE DEVICE
AD1885–SPECIFICATIONS
PIN FUNCTION DESCRIPTIONS
Digital I/O
Pin Name
LQFP
I/O
Description
XTL_IN
XTL_OUT
SDATA_OUT
BIT_ CLK
SDATA_IN
SYNC
RESET
2
3
5
6
8
10
11
I
O
I
O/I
O
I
I
Crystal (or Clock) Input, 24.576 MHz.
Crystal Output.
AC-Link Serial Data Output, AD1885 Input Stream.
AC-Link Bit Clock. 12.288 MHz Serial Data Clock. Daisy Chain Input Clock.
AC-Link Serial Data Input. AD1885 Output Stream.
AC-Link Frame Sync.
AC-Link Reset. AD1885 Master H/W Reset.
Pin Name
LQFP
Type
Description
ID0
ID1
45
46
I
I
Chip Select Input 0 (Active Low).
Chip Select Input 1 (Active Low).
CHIP SELECTS
JACK SENSES/EAPD/GENERAL-PURPOSE DIGITAL OUTPUTS
These signals can sense the presence of audio jacks in the line-out or headphones outputs, and automatically mute the other audio
outputs. JS0 can also be programmed for EAPD control. Alternatively, both pins can be programmed as general-purpose digital outputs.
Pin Name
LQFP
Type
Description
JS0
JS1
47
48
I/O
I/O
JACK Sense Input 0 (Mutes Mono Output).
JACK Sense Input 1 (Mutes Line_Out and Mono Outputs, or Line_Out Only).
Analog I/O
These signals connect the AD1885 component to analog sources and sinks, including microphones and speakers.
Pin Name
LQFP
I/O
Description
PC_BEEP
PHONE_IN
AUX_L
AUX_R
VIDEO_L
VIDEO_R
CD_L
CD_GND_REF
CD_ R
MIC1
MIC2
LINE_IN_L
LINE_IN_R
LINE_OUT_L
LINE_OUT_R
MONO_OUT
HP_OUT_L
HP_OUT_R
12
13
14
15
16
17
18
19
20
21
22
23
24
35
36
37
39
41
I
I
I
I
I
I
I
I
I
I
I
I
I
O
O
O
O
O
PC Beep. PC speaker beep passthrough.
Phone Input. From telephony subsystem speakerphone or handset.
Auxiliary Input Left Channel.
Auxiliary Input Right Channel.
Video Audio Left Channel.
Video Audio Right Channel.
CD Audio Left Channel.
CD Audio Analog Ground Reference for Differential CD Input.
CD Audio Right Channel.
Microphone 1. Desktop microphone input.
Microphone 2. Second microphone input.
Line In Left Channel.
Line In Right Channel.
Line Out Left Channel.
Line Out Right Channel.
Monaural Output to Telephony Subsystem Speakerphone.
Headphones Out Left Channel.
Headphones Out Right Channel.
–8–
REV. 0
AD1885
Filter/Reference
These signals are connected to resistors, capacitors, or specific voltages.
Pin Name
LQFP
I/O
Description
VREF
VREFOUT
AFILT1
AFLIT2
FILT_R
FILT_L
RX3D
CX3D
27
28
29
30
31
32
33
34
O
O
O
O
O
O
O
I
Voltage Reference Filter.
Voltage Reference Output 5 mA Drive (Intended for Mic Bias).
Antialiasing Filter Capacitor—ADC Right Channel.
Antialiasing Filter Capacitor—ADC Left Channel.
AC-Coupling Filter Capacitor—ADC Right Channel.
AC-Coupling Filter Capacitor—ADC Left Channel.
3D PHAT Stereo Enhancement—Resistor.
3D PHAT Stereo Enhancement—Capacitor.
Power and Ground Signals
Pin Name
LQFP
Type
Description
DVDD1
DVSS1
DVSS2
DVDD2
AVDD1
AVSS1
AVDD2
AVSS2
AVDD3
AVSS3
1
4
7
9
25
26
38
40
43
44
I
I
I
I
I
I
I
I
I
I
Digital VDD 3.3 V
Digital GND
Digital GND
Digital VDD 3.3 V
Analog VDD 5.0 V
Analog GND
Analog VDD 5.0 V
Analog GND
Analog VDD 5.0 V
Analog GND
Pin Name
LQFP
Type
Description
NC
42
No Connects
No Connect
ID0
ID1
JS0/EAPD
JACK SENSE
AND EAPD CTRL
CHIP SELECT
0dB/20dB
M20 0x0E
MS
MIC2
1
LS/RS (0)
S 0ⴛ20
LS (4)
RS (4) S
E
LS (3)
L
RS (3)
E
LS (1) C
RS (1) T
LS (2) O
RS (2) R
LS/RS (7)
LINE
AUX
CD
VIDEO
PHONE_IN
STEREO MIX (L)
MONO MIX
STEREO MIX (R)
MONO_OUT
LS (5)
LS/RS (6)
RS (5)
MV
MIX
0x20
0x04
0x04
HPM
LHV
HP_OUT_L
GA
0x0C
PHV
GA
0x0E
MCV
GA
0x10
LLV
RLV
GA
0x12
LCV
RCV
GA
0x16
LAV
RAV
GA
0x14
LVV
RVV
M
0x0C
PHM
M
0x0E
MCM
M
0x10
LM
M
0x12
CM
M
0x16
AM
M
0x14
VM
0x02
0x02
MM
LMV
0x02
0x02
MM
LMV
0x04
0x04
HPM
RHV
LINE_OUT_R
GAM
0x1C
RIV
IM
RESET
S 0x1A
AD1885
D
A
M
0x22
PHAT
DP
0x20
0x22
PHAT
DP
0x20
NC
GAM
0x18
LOV
OM
⌺
3D 0x20
SWITCH
NC
B
M
0x0A
PCM
A
0x0A
PCV
G = GAIN
A = ATTENUATION
M = MUTE
S = SELECTOR
GAM
0x18
ROV
OM
⌺
OSCILLATORS
PC_BEEP
XTL_OUT
Figure 8. Block Diagram Register Map
REV. 0
SYNC
BIT_CLK
SDATA_OUT
A
POP
HP_OUT_R
GAM
0x1C
LIV
IM
SDATA_IN
POP
LINE_OUT_L
VREFOUT
VREF
0
AC-LINK
MIC1
JS1
–9–
XTL_IN
AD1885
PRODUCT OVERVIEW
Sample Rates and D2S
The AD1885 Codec meets the Audio Codec ’97 2.1 Extensions,
adding support for multiple Codecs and variable sample rates.
In addition, the AD1885 SoundPort Codec is designed to meet
all requirements of the Audio Codec ’97, Component Specification,
Revision 1.03, © 1996, Intel Corporation, found at www.Intel.com.
The AD1885 also includes other Codec enhanced features such
as communicating to three Codecs on the same link, integrated
headphone driver and built-in PHAT Stereo 3D enhancement.
The AD1885 default mode sets the Codec to operate at 48 kHz
sample rates. The converter pairs may process left and right
channel data at different sample rates. The AD1885 sample rate
generator allows the Codec to instantaneously change and process
sample rates from 7040 Hz to 48 kHz with a resolution of 1 Hz.
The in-band integrated noise and distortion artifacts introduced
by rate conversions are below –90 dB. The AD1885 uses a 4-bit
Σ∆ structure and D2S to enhance noise immunity on motherboards and in PC enclosures, and to suppress idle tones below
the device’s quantization noise floor. The D2S process pushes
noise and distortion artifacts caused by errors in the multibit
DAC to frequencies beyond the auditory response of the human
ear and then filters them.
The AD1885 is an analog front end for high-performance PC
audio, modem, or DSP applications. The AC’97 architecture
defines a 2-chip audio solution comprising a digital audio
controller, plus a high-quality analog component that includes
Digital-to-Analog Converters (DACs), Analog-to-Digital Converters (ADCs), mixer, and I/O.
Digital-to-Analog Signal Path
The analog output of the DAC may be gained or attenuated
from +12 dB to –34.5 dB in 1.5 dB steps, and summed with any
of the analog input signals. The summed analog signal enters
the Master Volume stage where each channel of the mixer output may be attenuated from 0 dB to –94.5 dB in 1.5 dB steps
or muted.
The main architectural features of the AD1885 are the high
quality analog mixer section, two channels of Σ∆ ADC conversion, two channels of Σ∆ DAC conversion and Data Direct
Scrambling (D2S) rate generators.
FUNCTIONAL DESCRIPTION
This section overviews the functionality of the AD1885 and is
intended as a general introduction to the capabilities of the
device. Detailed reference information may be found in the
descriptions of the Indexed Control Registers.
Analog Outputs
Analog Inputs
Host-Based Echo Cancellation Support
The Codec contains a stereo pair of Σ∆ ADCs. Inputs to the
ADC may be selected from the following analog signals: telephony (PHONE_IN), mono microphone (MIC1 or MIC2),
stereo line (LINE_IN), auxiliary line input (AUX), stereo CD
ROM (CD), stereo audio from a video source (VIDEO) and
post-mixed stereo or mono line output (LINE_OUT).
The AD1885 supports time correlated I/O data format by presenting mic data on the left channel of the ADC and the mono
summation of left and right output on the right channel. The
ADC is splittable; left and right ADC data can be sampled at
different rates.
Analog Mixing
The AD1885 contains a V.34-capable analog front end for supporting host-based and data pump modems. The modem DAC
typical dynamic range is 90 dB over a 4.2 kHz analog output
passband where FS = 12.8 kHz. The left channel of the ADC
and DAC may be used to convert modem data at the same
sample rate in the range between 7040 Hz and 48 kHz. All programmed sample rates have a resolution of 1 Hz. The AD1885
supports irrational V.34 sample rates with 8/7 and 10/7 selectable multiplier coefficients.
The AD1885 offers a line output controlled by the Master Volume
control and an integrated headphone driver with independent
control.
PHONE_IN, MIC1 or MIC2, LINE_IN, AUX, CD, and VIDEO
can be mixed in the analog domain with the stereo output from the
DACs. Each channel of the stereo analog inputs may be independently gained or attenuated from +12 dB to –34.5 dB in 1.5 dB
steps. The summing path for the mono inputs (PHONE_IN, MIC1,
and MIC2 to LINE_OUT and HP_OUT) duplicates mono channel data on both the left and right LINE_OUT and HP_OUT.
Additionally, the PC attention signal (PC_BEEP) may be mixed
with the line output and headphone. A switch allows the output
of the DACs to bypass the PHAT Stereo 3D enhancement.
Digital Audio Mode
The AD1885 is designed with a Digital Audio Mode (DAM)
that allows mixing of all analog inputs, independent of the DAC
output signal path. Mixed analog input signals may be sent to
the ADCs for processing by the DC ’97 controller or the host,
and may be used during simultaneous capture and playback at
different sample rates.
Telephony Modem Support
Power Management Modes
The AD1885 is designed to meet notebook and ACPI power
consumption requirements through flexible power management
control of all internal resources. The following subsections may
be independently controlled:
Analog-to-Digital Signal Path
The selector sends left and right channel information to the
programmable gain amplifier (PGA). The PGA following the
selector allows independent gain control for each channel entering the ADC from 0 dB to +22.5 dB in 1.5 dB steps. Each
channel of the ADC is independent, and can process left and
right channel data at different sample rates.
–10–
ADCs and Input Mux Power-Down
DACs Power-Down
Analog Mixer Power-Down
Digital Interface Power-Down
Internal Clocks Disabled
ADC and DAC Power-Down
VREF Standby Mode
Low-Power Mixer Mode—CD Mixer Alive Only Mode
Mixer Bypass Mode (Digital Audio)
Headphone
REV. 0
AD1885
Indexed Control Registers
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Default
00h
Reset
X
SE4
SE3
SE2
SE1
SE0
ID9
ID8
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0410h
02h
Master Volume
MM
X
LMV5
LMV4 LMV3 LMV2 LMV1
LMV0 X
X
RMV5
RMV4
RMV3 RMV2 RMV1 RMV0
8000h
04h
Headphones Volume
HPM
X
LHV5
LHV4 LHV3 LHV2
LHV1
LHV0
X
X
RHV5
RHV4
RHV3 RHV2
RHV1 RHV0
8000h
06h
Master Volume Mono
MMM
X
X
X
X
X
X
X
X
MMV
MMV MMV
MMV MMV
8000h
4
3
2
1
0
X
X
08h
Reserved
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0Ah
PC Beep Volume
PCM
X
X
X
X
X
X
X
X
X
X
PCV3
PCV2
PCV1
PCV0
X
8000h
0Ch
Phone In Volume
PHM
X
X
X
X
X
X
X
X
X
X
PHV4
PHV3 PHV2
0Eh
MIC Volume
MCM
X
X
X
X
X
X
X
X
M20
X
MCV4 MCV3 MCV2 MCV1 MCV0 8008h
10h
Line In Volume
LM
X
X
LLV4
LLV3 LLV2
LLV1
LLV0
X
X
X
RLV4
RLV3
12h
CD Volume
CVM
X
X
LCV4 LCV3 LCV2
LCV1
LCV0
X
X
X
RCV4
14h
Video Volume
VM
X
X
LVV4
LVV3 LVV2
LVV1
LVV0
X
X
X
16h
Aux Volume
AM
X
X
LAV4
LAV3 LAV2
LAV1
LAV0
X
X
18h
PCM Out Volume
OM
X
X
LOV4 LOV3 LOV2
LOV1
LOV0
X
1Ah
Record Select
X
X
X
X
X
LS1
LS0
1Ch
Record Gain
IM
X
X
X
LIM3 LIM2
LIM1
1Eh
Reserved
X
X
X
X
X
X
20h
General Purpose
POP
X
3D
X
X
22h
3D Control
X
X
X
X
26h
Power-Down Cntrl/Stat
X
X
PR5
28h
Extended Audio ID
ID1
ID0
2Ah
Extended Audio Stat/Ctrl X
X
2Ch/
PCM DAC Rate (SR1)
SR15
PCM ADC Rate (SR0)
34h
8808h
RCV3 RCV2
RCV1 RCV0
8808h
RVV4
RVV3
RVV1
RVV0
8808h
X
RAV4
RAV3 RAV2
RAV1 RAV0
8808h
X
X
ROV4
ROV3 ROV2
ROV1 ROV0
8808h
X
X
X
X
X
RS2
RS1
RS0
0000h
LIM0
X
X
X
X
RIM3
RIM2
RIM1
RIM0
8000h
X
X
X
X
X
X
X
X
X
X
X
X
MIX
MS
LPBK X
X
X
X
X
X
X
0000h
X
X
X
X
X
X
X
X
DP3
DP2
DP1
DP0
0000h
PR4
PR3
PR2
PR1
PR0
X
X
X
X
REF
ANL
DAC
ADC
000Xh
X
X
X
X
X
X
X
X
X
X
X
X
X
VRA
0001h
X
X
X
X
X
X
X
X
X
X
X
X
X
VRA
0000h
SR14 SR13
SR12
SR11
SR10
SR9
SR8
SR7
SR6
SR5
SR4
SR3
SR2
SR1
SR0
BB80h
SR15
SR14 SR13
SR12
SR11
SR10
SR9
SR8
SR7
SR6
SR5
SR4
SR3
SR2
SR1
SR0
BB80h
Reserved
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
72h
Jack Sense/Audio
JS1_OUT JS0_
JS1
JS0
JS1_
JS0
JS1
JS0
JS1
JS0_
JS1
JS0
AUD
JS1
JS0
JS
0000h
Interrupt/Status
FUNCT
OUT PUDIS PUDIS OE
OE
DIS
DIS
CLR
CLR
MODE MODE INT
SLOT
REG
REG
REG
X
X
DHWR X
X
X
16
M2
M1
M0
DMS
DLSR
X
RVV2
RLV1
8008h
RLV0
LS2
RLV2
PHV1 PHV0
(7Ah)*
32h/
(78h)*
74h
76h
Serial Configuration
Miscellaneous Control
DAC
LPMI X
Bits
Z
X
DAM
7Ch
Vendor ID1
F7
F6
F5
F4
F3
F2
F1
7Eh
Vendor ID2
T7
T6
T5
T4
T3
T2
T1
NOTES
All registers not shown and bits containing an X are assumed to be reserved.
Odd register addresses are aliased to the next lower even address.
Reserved registers should not be written.
Zeros should be written to reserved bits.
*Indicates Aliased register for AD1819B backward compatibility.
REV. 0
–11–
ALSR
MOD SRX1 SRX8
EN
0D7
D7
F0
S7
S6
S5
T0
REV7 REV6 REV5
INT
X
X
X
X
X
S4
REV4
X
X
7000h
DRSR X
ARSR
0404h
S3
S2
S1
S0
4144h
REV3
REV2
REV1
REV0
5360h
AD1885
Reset (Index 00h)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
00h
X
SE4
SE3
SE2
SE1
SE0
ID9
ID8
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0410h
Reset
Note: Writing any value to this register performs a register reset, which causes all registers to revert to their default values (except
74h, which forces the serial configuration). Reading this register returns the ID code of the part and a code for the type of 3D Stereo
Enhancement.
ID[9:0] Identify Capability. The ID decodes the capabilities of AD1885 based on the following:
Bit = 1
Function
AD1885
ID0
ID1
ID2
ID3
ID4
ID5
ID6
ID7
ID8
ID9
Dedicated MIC PCM In Channel
Modem Line Codec Support
Bass and Treble Control
Simulated Stereo (Mono to Stereo)
Headphone Out Support
Loudness (Bass Boost) Support
18-Bit DAC Resolution
20-Bit DAC Resolution
18-Bit ADC Resolution
20-Bit ADC Resolution
0
0
0
0
1
0
0
0
0
0
SE[4:0] Stereo Enhancement. The 3D stereo enhancement identifies the Analog Devices 3D stereo enhancement.
Master Volume Registers (Index 02h)
Reg
Num
Name
D15
D14
D13
02h
Master
Volume
MM
MM
X
LMV5 LMV4 LMV3 LMV2 LMV1 LMV0 X
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
X
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
RMV5 RMV4 RMV3 RMV2 RMV1 RMV0 8000h
RMV[5:0]
Right Master Volume Control. The least significant bit represents 1.5 dB. This register controls the output from
0 dB to a maximum attenuation of –94.5 dB.
LMV[5:0]
Left Master Volume Control. The least significant bit represents 1.5 dB. This register controls the output from 0 dB to
a maximum attenuation of –94.5 dB.
MM
Master Volume Mute. When this bit is set to “1,” the channel is muted.
MM
xMV5 . . . xMV0
Function
0
0
0
1
00 0000
01 1111
11 1111
xx xxxx
0 dB Attenuation
–46.5 dB Attenuation
–94.5 dB Attenuation
–∞ dB Attenuation
–12–
REV. 0
AD1885
Headphones Volume Registers (Index 04h)
Reg
Num
Name
04h
Headphones Volume HPM X
D15
D14 D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
LHV5 LHV4 LHV3 LHV2 LHV1 LHV0 X
D6
D6
X
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
RHV5 RHV4 RHV3 RHV2 RHV1 RHV0 8000h
RHV[5:0]
Right Headphone Volume Control. The least significant bit represents 1.5 dB. This register controls the output from +6 dB to a maximum attenuation of –88.5 dB.
LHV[5:0]
Left Headphone Volume Control. The least significant bit represents 1.5 dB. This register controls the output
from +6 dB to a maximum attenuation of –88.5 dB.
HPM
Headphone Volume Mute. When this bit is set to “1,” the channel is muted.
HPM
xHV5 . . . xHV0
Function
0
0
0
1
00 0000
01 1111
11 1111
xx xxxx
6 dB Gain
–40.5 dB Attenuation
–88.5 dB Attenuation
–∞ dB Attenuation
Master Volume Mono (Index 06h)
Reg
Num
Name
06h
Master Volume
MMM X
Mono
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
X
X
X
X
X
X
X
MMV4 MMV3 MMV2 MMV1 MMV0 8000h
MMV[4:0]
Mono Master Volume Control. The least significant bit represents 1.5 dB. This register controls the output from
0 dB to a maximum attenuation of 46.5 dB.
MMM
Mono Master Volume Mute. When this bit is set to “1,” the channel is muted.
PC Beep Register (Index 0Ah)
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
0Ah
PC_BEEP Volume
PCM
X
X
X
X
X
X
X
D7
D7
D6
D6
X
X
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
X
PCV3 PCV2 PCV1 PCV0 X
Default
8000h
PCV[3:0]
PC Beep Volume Control. The least significant bit represents 3 dB attenuation. This register controls the output
from 0 dB to a maximum attenuation of –45 dB. The PC Beep is routed to Left and Right Line outputs even when
AD1885 is in a RESET state. This is so that Power-On Self-Test (POST) codes can be heard by the user in case
of a hardware problem with the PC.
PCM
PC Beep Mute. When this bit is set to “1,” the channel is muted.
REV. 0
PCM
PCV3 . . . PCV0
Function
0
0
1
0000
1111
xxxx
0 dB Attenuation
–45 dB Attenuation
∞ dB Attenuation
–13–
AD1885
Phone Volume (Index 0Ch)
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
0Ch
Phone Volume
PHM
X
X
X
X
X
X
X
X
X
X
PHV4 PHV3 PHV2 PHV1 PHV0 8008h
D3
D3
D2
D2
D1
D1
D0
D0
Default
PHV[4:0]
Phone Volume. Allows setting the Phone Volume Attenuator in 32 steps. The LSB represents 1.5 dB, and the
range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
PHM
Phone Mute. When this bit is set to “1,” the channel is muted.
MIC Volume (Index 0Eh)
Reg
Name
Num
0Eh
MIC
Volume
D15
D14
MCM X
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
X
X
X
X
X
M20
X
MCV4
MCV3
MCV2
MCV1
MCV0
8008h
MCV[4:0]
MIC Volume Gain. Allows setting the MIC Volume attenuator in 32 steps. The LSB represents 1.5 dB, and the
range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
M20
Microphone 20 dB Gain Block
0 = Disabled; Gain = 0 dB
1 = Enabled; Gain = 20 dB.
MCM
MIC Mute. When this bit is set to “1,” the channel is muted.
Line In Volume (Index 10h)
Reg
Name
Num
10h
D15
Line In Volume LM
LM
D14 D13 D12
X
X
D11
D10
D9
D9
D8
D8
D7
D7
LLV4 LLV3 LLV2 LLV1 LLV0
X
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
RLV4
RLV3
RLV2
RLV1
RLV0
8808h
RLV[4:0]
Right Line In Volume. Allows setting the Line In right channel attenuator in 32 steps. The LSB represents 1.5 dB,
and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
LLV[4:0]
Line In Volume Left. Allows setting the Line In left channel attenuator in 32 steps. The LSB represents 1.5 dB, and
the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
LM
Line In Mute. When this bit is set to “1,” the channel is muted.
CD Volume (Index 12h)
Reg
Name
Num
12h
D15
D14
CD Volume CVM X
D13
D12
D11
D10
D9
D9
D8
D8
X
LCV4 LCV3 LCV2 LCV1 LCV0
D7
D7
X
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
RCV4 RCV3 RCV2 RCV1 RCV0 8808h
RCV[4:0]
Right CD Volume. Allows setting the CD right channel attenuator in 32 steps. The LSB represents 1.5 dB, and
the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
LCV[4:0]
Left CD Volume. Allows setting the CD left channel attenuator in 32 steps. The LSB represents 1.5 dB, and the
range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
CVM
CD Volume Mute. When this bit is set to “1,” the channel is muted.
–14–
REV. 0
AD1885
Video Volume (Index 14h)
Reg
Name
Num
14h
D15
Video Volume VM
VM
D14
D13
D12
D11
D10
D9
D9
D8
D8
X
X
LVV4 LVV3 LVV2 LVV1 LVV0
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
X
RVV4 RVV3 RVV2 RVV1 RVV0 8808h
RVV[4:0]
Right Video Volume. Allows setting the Video right channel attenuator in 32 steps. The LSB represents 1.5 dB,
and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
LVV[4:0]
Left Video Volume. Allows setting the Video left channel attenuator in 32 steps. The LSB represents 1.5 dB, and
the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
VM
Video Mute. When this bit is set to “1,” the channel is muted.
AUX Volume (Index 16h)
Reg
Name
Num
D15
D14
D13
D12
16h
AM
AM
X
X
LAV4 LAV3 LAV2 LAV1 LAV0
Aux Volume
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
X
RAV4 RAV3 RAV2 RAV1 RAV0 8808h
RAV[4:0]
Right Aux Volume. Allows setting the Aux right channel attenuator in 32 steps. The LSB represents 1.5 dB, and
the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
LAV[4:0]
Left Aux Volume. Allows setting the Aux left channel attenuator in 32 steps. The LSB represents 1.5 dB, and the
range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
AM
Aux Mute. When this bit is set to “1,” the channel is muted.
PCM Out Volume (Index 18h)
Reg
Name
Num
18h
PCM Out
Volume
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
OM
OM
X
X
LOV4 LOV3 LOV2 LOV1 LOV0
D7
D7
X
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
ROV4 ROV3 ROV2 ROV1 ROV0 8808h
ROV[4:0]
Right PCM Out Volume. Allows setting the PCM right channel attenuator in 32 steps. The LSB represents 1.5 dB,
and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
LOV[4:0]
Left PCM Out Volume. Allows setting the PCM left channel attenuator in 32 steps. The LSB represents 1.5 dB,
and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
OM
PCM Out Volume Mute. When this bit is set to “1,” the channel is muted.
Volume Table
REV. 0
xM
x4 . . . x0
Function
0
0
0
1
00000
01000
11111
xxxxx
+12 dB Gain
0 dB Gain
–34.5 dB Gain
–∞ dB Gain
–15–
AD1885
Record Select Control Register (Index 1Ah)
Reg
Name
Num
1Ah
D15
Record Select X
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
X
X
LS2
LS1
LS0
X
X
X
X
X
RS2
RS1
RS0
0000h
RS[2:0]
Right Record Select
LS[2:0]
Left Record Select.
Used to select the record source independently for right and left. See table for legend.
The default value is 0000h, which corresponds to MIC in.
RS2 . . . RS0
Right Record Source
0
1
2
3
4
5
6
7
MIC
CD_R
VIDEO_R
AUX_R
LINE_IN_R
Stereo Mix (R)
Mono Mix
PHONE_IN
LS2 . . . LS0
Left Record Source
0
1
2
3
4
5
6
7
MIC
CD_L
VIDEO_L
AUX_L
LINE_IN_L
Stereo Mix (L)
Mono Mix
PHONE_IN
Record Gain (Index 1Ch)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
1Ch
IM
IM
X
X
X
LIM3
LIM2
LIM1
LIM0
X
X
X
X
RIM3
RIM2
RIM1
RIM0
8000h
Record Gain
RIM[3:0]
Right Input Mixer Gain Control. Each LSB represents 1.5 dB, 0000 = 0 dB and the range is 0 dB to +22.5 dB.
LIM[3:0]
Left Input Mixer Gain Control. Each LSB represents 1.5 dB, 0000 = 0 dB and the range is 0 dB to +22.5 dB.
IM
Input Mute.
0 = Unmuted,
1 = Muted or –∞ dB gain.
IM
xIM3 . . . xIM0
Function
0
0
1
1111
0000
xxxxx
+22.5 dB Gain
0 dB Gain
–∞ dB Gain
–16–
REV. 0
AD1885
General-Purpose Register (Index 20h)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
20h
POP
X
3D
3D
X
X
X
MIX
MS
MS
LPBK
X
X
X
X
X
X
X
0000h
General-Purpose
Note: This register should be read before writing to generate a mask for only the bit(s) that need to be changed.
LPBK
Loopback Control. ADC/DAC Digital Loopback Mode
MS
MIC Select
0 = MIC1
1 = MIC2.
MIX
Mono Output Select
0 = Mix
1 = MIC.
3D
3D PHAT Stereo Enhancement
0 = PHAT Stereo is off.
1 = PHAT Stereo is on.
POP
PCM Output Path and Mute. The POP bit controls the optional PCM out 3D bypass path (the pre- and post-3D
PCM out paths are mutually exclusive).
0 = pre-3D
1 = post-3D.
3D Control Register (Index 22h)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
22h
X
X
X
X
X
X
X
X
X
X
X
X
DP3
DP2
DP1
DP0
0000h
3D Control
DP[2:0]
REV. 0
Depth Control. Sets 3D “Depth” PHAT Stereo enhancement according to table below.
DP3 . . . DP0
Depth
0000
0001
.
.
14
15
0%
6.67%
.
.
93.33%
100%
–17–
AD1885
Subsection Ready Register (Index 26h)
Reg
Name
Num
26h
D15
D14
Power-Down Cntrl/Stat EAPD PR6
D13 D12 D11 D10 D9
D9
D8
D8
D7
D7
PR5 PR4 PR3 PR2 PR1 PR0 X
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
X
REF
ANL
DAC ADC 000xh
Note: The ready bits are read only, writing to REF, ANL, DAC, ADC will have no effect. These bits indicate the status for the
AD1885 subsections. If the bit is a one, then that subsection is “ready.” Ready is defined as the subsection able to perform in
its nominal state.
ADC
ADC section ready to transmit data.
DAC
DAC section ready to accept data.
ANL
Analog gainuators, attenuators, and mixers ready.
REF
Voltage References, VREF and VREFOUT up to nominal level.
PR[5:0]
AD1885 Power-Down Modes. The first three bits are to be used individually rather than in combination with each
other. The last bit PR3 can be used in combination with PR2 or by itself. The mixer and reference cannot be
powered down via PR3 unless the ADCs and DACs are also powered down. Nothing else can be powered up until
the reference is up.
PR0 – Power-Down ADC
PR1 – Power-Down DAC
PR2 – Power-Down Analog Mixer
PR3 – Power-Down VREF and VREFOUT
PR4 – Power-Down AC-Link
PR5 – Power-Down Internal Clock
PR6 – Power-Down Headphone
EAPD – External AMP Power-Down Control Signal
PR5 has no effect unless all ADCs, DACs, and the AC-Link are powered down. The reference and the mixer can
either be up or down, but all power-up sequences must be allowed to run to completion before PR5 and PR4 are
both set.
In multiple-codec systems, the master codec’s PR5 and PR4 bits control the slave codec. PR5 is also effective in
the slave codec if the master’s PR5 bit is clear, but the PR4 bit has no effect except to enable or disable PR5.
Power-Down State
EAPD PR6
PR5
PR4
PR3
PR2
PR1
PR0
ADC Power-Down
DAC Power-Down
ADC and DAC Power-Down
Mixer Power-Down
ADC + Mixer Power-Down
DAC + Mixer Power-Down
ADC + DAC + Mixer Power-Down
Standby
X
X
X
X
X
X
X
X
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
1
1
1
1
1
0
1
1
0
0
1
1
1
1
0
1
0
1
0
1
1
0
0
0
0
0
0
0
1
Extended Audio ID Register (Index 28h)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
28h
ID1
ID0
X
X
X
X
X
X
X
X
X
X
X
X
X
VRA
0001h
Extended Audio ID
Note: The Extended Audio ID is a read only register.
VRA
Variable Rate Audio. VRA = 1 indicates support for Variable Rate Audio.
ID[1:0]
ID1, ID0 is a 2-bit field that indicates the codec configuration: Primary is 00; Secondary is 01.
–18–
REV. 0
AD1885
Extended Audio Status and Control Register (Index 2Ah)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
2Ah
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
VRA
0000h
Extended Audio St/Ctrl
Note: The Extended Audio Status and Control Register is a read/write register that provides status and control of the extended audio
features.
VRA
Variable Rate Audio. VRA = 1 enables support for Variable Rate Audio mode (sample rate control registers and
SLOTREQ signaling).
PCM DAC Rate Register (Index 2Ch)
Reg
Num
Name
2Ch/(7Ah) PCM DAC Rate
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
SR15
SR14
SR13
SR12
SR11
SR10
SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h
Note: 2Ch is an alias for 7Ah. The VRA bit in register 2Ah must be set for the alias to work; if a zero is written to VRA, both sample
rates are reset to 48 kHz.
SR[15:0]
Writing to this register allows programming of the sampling frequency from 7040 Hz (1B80h) to 48 kHz (BB80h)
in 1 Hz increments. Programming a value outside of the range 7040 Hz (1b80h) to 48000 Hz (BB80h) causes the
codec to saturate. For all rates, if the value written to the register is supported, that value will be echoed back
when read, otherwise the closest rate supported is returned.
PCM ADC Rate Register (Index 32h)
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D9
32h/(78h)
PCM ADC Rate
SR15
SR14
SR13
SR12
SR11
SR10
SR9 SR8 SR7 SR6 SR5 SR4 SR3 SR2 SR1 SR0 BB80h
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
Note: 32h is an alias for 78h. The VRA bit in register 2Ah must be set for the alias to work; if a zero is written to VRA, both sample
rates are reset to 48 kHz.
SR[15:0]
Writing to this register allows programming of the sampling frequency from 7040 Hz (1B80h) to 48 kHz (BB80h)
in 1 Hz increments. Programming a value outside of the range 7040 Hz (1b80h) to 48000 Hz (BB80h) causes the
codec to saturate. For all rates, if the value written to the register is supported, that value will be echoed back
when read; otherwise, the closest rate supported is returned.
Jack Sense/Audio Interrupt/Status Register (Index 72h)
Reg
Num
Name
72h
Jack Sense/Audio JS1_OUT/
Interrupt/Status FUNCT
D15
D14
D13
D12
D11
D10
D9
D9
JS0_
OUT
JS1
JS0
JS1_ JS0_ JS1
PUDIS PUDIS OE
OE OE
OE DIS
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
JS0 JS1
JS0
JS1
JS0
AUD
DIS CLR CLR MODE MODE INT
D2
D2
D1
D1
JS1 JS0
D0
D0
Default
JS
JS
INT
0000h
Note: all register bits are read/write except for AUDINT, JSINT, JS0 and JS1, which are read only.
JSINT
Indicates that a jack sense interrupt has been generated by JS0 or JS1. Remains set until all JS enabled interrupts
are cleared.
JS0
Indicates Pin JS0 state.
JS1
Indicates Pin JS1 state.
AUDINT
Indicates the Codec has generated audio interrupt. Remains set until software clears all pending interrupts.
JS0MODE
Sets JS0 pin input mode, 1 = Interrupt 0 = Jack Sense.
JS1MODE
Sets JS1 pin input mode, 1 = Interrupt 0 = Jack Sense.
JS0CLR
This bit is set by the Codec when there is a pending JS0 interrupt. Software must clear this bit to clear the JS0
interrupt status bit.
JS1CLR
This bit is set by the Codec when there is a pending JS1 interrupt. Software must clear this bit to clear the JS1
interrupt status bit.
JS0DIS
If the JS0DIS bit is set, the Codec ignores Jack Sense pin JS0.
JS1DIS
If the JS1DIS bit is set, the Codec ignores Jack Sense pin JS1.
REV. 0
–19–
AD1885
JS0_OE
Enables JS0 pin as a general-purpose output.
JS1_OE
Enables JS1 pin as a general-purpose output.
JS0PUDIS
Setting the JS0PUDIS bit disables the JS0 pin internal pull-up.
JS1PUDIS
Setting the JS1PUDIS bit disables the JS1 pin internal pull-up.
JS0_OUT
When enabled as GPO, the JS0 pin reflects the state of the JS0_OUT bit.
JS1_OUT/FUNCT When enabled as GPO, the JS1 pin reflects the state of the JS1_OUT bit, otherwise this bit can be set to change
the functionality of JS1 so that only LINE_OUT is muted when JS1 is high.
Serial Configuration (Index 74h)
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
74h
Serial
Configuration
SLOT
16
16
REGM2
REGM1
REGM0
X
X
DHWR
X
X
X
X
X
X
X
X
X
X
Note: this register is not reset when the reset register (register 00h) is written.
DHWR
Disable Hardware Reset.
REGM0
Master Codec register mask.
REGM1
Slave 1 Codec register mask.
REGM2
Slave 2 Codec register mask.
SLOT16
Enable 16-bit slots.
If your system uses only a single AD1885, you can ignore the register mask.
SLOT16 makes all AC-Link slots 16 bits in length, formatted into 16 slots.
Miscellaneous Control Bits (Index 76h)
Reg
Name
Num
D15
D14
D13 D12
76h
DAC
Z
LPMI
X
X
Misc Control Bits
D11
D10
D9
D9
DAM DMS DLSR X
ARSR
ADC right sample generator select
0 = SR0 Selected (32h)
1 = SR1 Selected (2Ch).
DRSR
DAC right sample generator select
0 = SR0 Selected (32h)
1 = SR1 Selected (2Ch).
SRX8D7
Multiply SR1 rate by 8/7.
D8
D8
D7
D7
D6
D6
D5
D5
ALSR
MOD
EN
EN
SRX10 SRX8
D7
D7
D7
D7
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
X
X
DRSR
X
ARSR
0000h
SRX10D7
Multiply SR1 rate by 10/7. SRX10D7 and SRX8D7 are mutually exclusive.
MODEN
Modem filter enable (left channel only). Change only when DACs and ADCs are powered down.
ALSR
ADC left sample generator select
0 = SR0 Selected (32h)
1 = SR1 Selected (2Ch).
DLSR
DAC left sample generator select
0 = SR0 Selected (32h)
1 = SR1 Selected (2Ch).
DMS
Digital Mono Select.
0 = Mixer
1 = Left DAC and Right DAC.
DAM
Digital Audio Mode. DAC Outputs bypass analog mixer and sent directly to the codec output.
LPMIX
Low Power Mixer.
DACZ
Zero fill (vs. repeat) if DAC is starved for data.
–20–
REV. 0
AD1885
Sample Rate 0 (Index 78h)
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D2
D2
D1
D1
D0
D0
Default
(32h)/78h Sample Rate 0 SR015 SR014 SR013 SR012 SR011 SR010 SR09 SR08 SR07 SR06 SR05 SR04 SR03 SR02 SR01 SR00 BB80h
Note: 32h is an alias for 78h. The VRA bit in register 2Ah must be set for the alias to work; if a zero is written to VRA, both
sample rates are reset to 48 kHz.
SR0[15:0]
Writing to this register allows the user to program the sampling frequency from 7 kHz (1B58h) to 48 kHz (BB80h)
in 1 Hertz increments. Programming a value greater than 48 kHz or less than 7 kHz may cause unpredictable
results.
Sample Rate 1 (Index 7Ah)
Reg
Num
Name
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D2
D2
D1
D1
D0
D0
Default
(2Ch)/7Ah Sample Rate 1 SR115 SR114 SR113 SR112 SR111 SR110 SR19 SR18 SR17 SR16 SR15 SR14 SR13 SR12 SR11 SR10 BB80h
Note: 2Ch is an alias for 7Ah. The VRA bit in register 2Ah must be set for the alias to work; if a zero is written to VRA, both sample
rates are reset to 48 kHz.
SR1[15:0]
Writing to this register allows the user to program the sampling frequency from 7 kHz (1B58h) to 48 kHz (BB80h)
in 1 Hertz increments. Programming a value greater than 48 kHz or less than 7 kHz may cause unpredictable results.
Vendor ID Registers (Index 7Ch–Eh)
Reg
Name
Num
D15
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
D6
D6
D5
D5
D4
D4
D3
D3
D2
D2
D1
D1
D0
D0
Default
7Ch
F7
F7
F6
F6
F5
F5
F4
F4
F3
F3
F2
F2
F1
F1
F0
F0
S7
S7
S6
S6
S5
S5
S4
S4
S3
S3
S2
S2
S1
S1
S0
S0
4144h
D2
D2
D1
D1
Vendor ID1
S[7:0]
This register is ASCII encoded to “S.”
F[7:0]
This register is ASCII encoded to “D.”
Reg
Name
Num
7Eh
D15
Vendor ID2 T7
T7
D14
D13
D12
D11
D10
D9
D9
D8
D8
D7
D7
T6
T6
T5
T5
T4
T4
T3
T3
T2
T2
T1
T1
T0
T0
REV7 REV6 REV5 REV4 REV3 REV2 REV1 REV0 5360h
T[7:0]
This register is ASCII encoded to “S.”
REV[7:0]
Revision Register field contains the revision number.
D6
D6
D5
D5
These bits are read-only and should be verified before accessing vendor defined features.
REV. 0
–21–
D4
D4
D3
D3
D0
D0
Default
AD1885
APPLICATIONS CIRCUITS
The AD1885 has been designed to require a minimum amount of external circuitry. The recommended applications circuits are shown in
Figures 9–18. Reference designs for the AD1885 are available and may be obtained by contacting your local Analog Devices
sales representative or authorized distributor. Example shell programs for establishing a communications path between the AD1885
and an ADSP-21xx or ADSP-21xxx are also available.
AVDD
22pF
24.576MHz
SDATA_OUT
SDATA_IN
SYNC
RESET
BIT_CLK
47pF
DVDD1
XTL_IN
XTL_OUT
DVSS1
SDATA_OUT
BIT_CLK
DVSS2
SDATA_IN
DVDD2
SYNC
RESET
PC_BEEP
AD1885
LINE_OUT_R
LINE_OUT_L
CX3D
RX3D
FILT_L
FILT_R
AFILT2
AFILT1
VREFOUT
VREF
AVSS1
AVDD1
36
35
34
33
32
31
30
29
28
27
26
25
47nF
+
270pF NPO
+
270pF NPO
+
AVDD
13
14
15
16
17
18
19
20
21
22
23
24
10k
PC_BEEP
1
2
3
4
5
6
7
8
9
10
11
12
PHONE_IN
AUX_L
AUX_R
VIDEO_L
VIDEO_R
CD_L
CD_GND_REF
CD_R
MIC1
MIC2
LINE_IN_L
LINE_IN_R
+
22pF
NC
JS1
JSO/EAPD
ID1
ID0
AVSS3
AVDD3
NC
HP_OUT_R
AVSS2
HO_OUT_L
AVDD2
MONO_OUT
48
47
46
45
44
43
42
41
40
39
38
37
DVDD
NC
NC
+
NOTE:
IF NOT USED, GROUND
JACK SENSE PINS.
FB 600Z
NOTE:
ALL “UNUSED” ANALOG INPUTS
(LINE_IN_L/R, AUX_L/R, VIDEO_L/R,
MIC1, MIC2, PC_BEEP, PHONE_IN
AND CD_L/R/GND) MUST BE LEFT
UNCONNECTED.
Figure 9. Recommended One-Codec PWR/Decoupling and AC‘97 Connections
–22–
REV. 0
AD1885
JACK SENSE OPERATION
The AD1885 features two Jack Sense pins (JS0 and JS1) that can be used to automatically mute the LINE_OUT and/or MONO_OUT
audio outputs. When the Jack Sense pins are connected to the output jacks, the AD1885 can sense whether an audio plug has been
inserted into a particular output jack and automatically mute the other unnecessary audio outputs.
The JS1 pin should normally be connected to the HP_OUT jack to automatically mute the MONO_OUT and LINE_OUT audio
signals, while the JS0 pin should normally be connected to the LINE_OUT jack to automatically mute the MONO_OUT signal. It is
also possible to set the D15 bit in the Jack Sense Index Register (72h), which causes JS1 to only mute the LINE_OUT signal. This
option may be desirable in certain audio configurations. Table I summarizes the Jack Sense operation.
Table I. Jack Sense Operation Table
HP_OUT Plug
(JS1)
LINE_OUT Plug
(JS0)
Audio Output States
(REG 72h, D15 = 0)
Audio Output States
(REG 72h, D15 = 1)
OUT
OUT
OUT
IN
IN
OUT
IN
IN
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = ON
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = ON
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = ON
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = MUTE
NOTE: PLUG IN = JACK SENSE HIGH, PLUG OUT = JACK SENSE LOW.
The Jack Sense inputs are active high and their functionality is enabled by default on CODEC power-up. If necessary, the Jack Sense
inputs can be individually disabled by writing to the D8 and D9 bits on the CODEC Jack Sense Index Register (72h).
The Jack Sense pins contain active internal pull-ups. If the Jack Sense inputs are not being used, they should be pulled down to
digital ground using 10 kΩ resistors. This prevents LINE_OUT and MONO_OUT from becoming muted while the Jack Senses are
enabled.
CONNECTING THE JACK SENSES TO THE OUTPUT JACKS
Headphone Jack
The diagram on Figure 10 shows the preferred method to connect the JS1 Jack Sense line to the HP_OUT jack. This scheme requires
a stereo jack with a normally closed and isolated single switch. The switch holds the Jack Sense line low (grounded) until an audio
plug is inserted, causing the switch to open and the Jack Sense line to go high due to the CODEC internal pull-up. The R2 and R3
resistors keep the electrolytic output caps properly polarized while the HP_OUT jack is not used.
NOTE: LOCATE R1 CLOSE TO CODEC.
JACK SENSE LINE
TO CODEC JS1 (PIN 48)
OPTIONAL EMC
COMPONENTS
FROM CODEC HP_OUT_R (PIN 41)
+
L1 600Z
FROM CODEC HP_OUT_L (PIN 39)
+
L2 600Z
C1
470pF
C4
470pF
5
4
3
ISOLATED
NC SWITCH
2
1
HEADPHONE OUT
Figure 10. Jack Sense Connection to HP_OUT Jack, Using Isolated Switch
Alternatively, when an audio output jack containing an isolated switch is not available, the circuit shown on Figure 11 can be used.
While the audio plug is out, this circuit keeps the Jack Sense line state low, by the pull-down affect of R2 (with no audio present) or
by tracking the lower peaks of the HP_OUT audio signal. Once an audio plug is inserted and the jack switch opens, the Jack Sense
line switches to a high state due to the CODEC internal pull-up, which quickly charges C1 to DVDD.
The R2 and R3 resistors also keep the electrolytic output caps properly polarized while the HP_OUT jack is not used.
REV. 0
–23–
AD1885
NOTE: LOCATE R1 AND C1 CLOSE TO CODEC.
JACK SENSE
D1
TO CODEC JS1 (PIN 48)
MMBD914
OPTIONAL EMC
COMPONENTS
L1 600Z
FROM CODEC HP_OUT_R (PIN 41)
+
C4
470pF
1
2
3
4
5
L2 600Z
FROM CODEC HP_OUT_L (PIN 39)
+
C5
470pF
J1
HEADPHONE OUT
Figure 11. Jack Sense Connection to HP_OUT Jack, Using Nonisolated Switch
LINE_ OUT Jack
Although not shown, if a LINE_OUT jack is used and the jack sense functionality is desired, the LINE_OUT jack should be wired
in a similar configuration as shown above for the HP_OUT jack (preferably Figure 10). The LINE_OUT jack should normally
be connected to the JS0 input, in order to mute the MONO_OUT signal. We recommend that in this case the output coupling
caps (C2, C3) be set to 2.2 µF. All other values should be kept the same.
APPLICATION CIRCUITS
CD-ROM CONNECTIONS
Typical CD-ROM drives generate 2 V rms output and require a voltage divider for compatibility with the Codec input (1 V rms
range). The recommended circuit is basically a group of divide-by-two voltage dividers as shown on Figure 12.
The CD_GND_REF pin is used to cancel differential ground noise from the CD-ROM. For optimum noise cancellation, this section of the divider should have approximately half the impedance of the right and left channel section dividers.
VOLTAGE DIVIDER
AC-COUPLING
TO CODEC CD_L INPUT
HEADER FOR
CD ROM AUDIO
(LGGR)
1
2
3
4
TO CODEC CD_GND_REF INPUT
TO CODEC CD_R INPUT
Figure 12. Typical CD-ROM Audio Connections
LINE_IN, AUX AND VIDEO INPUT CONNECTIONS
Most of these audio sources also generate 2 V rms audio level and require a –6 dB input voltage divider to be compatible with the
Codec inputs. Figure 13 shows the recommended application circuit. For applications requiring EMC compliance, the EMC components should be configured and selected to provide adequate RF immunity and emissions control.
EMC
COMPONENTS
LINE/AUX/VIDEO INPUT
J1
1
2
3
4
5
VOLTAGE DIVIDER
AC-COUPLING
L2 600Z
TO CODEC RIGHT CHANNEL INPUT
C1
470pF
L1 600Z
TO CODEC LEFT CHANNEL INPUT
C2
470pF
Figure 13. LINE_IN, AUX, and Video Input Connections
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REV. 0
AD1885
MICROPHONE CONNECTIONS
The AD1885 contains an internal microphone preamp with 20 dB gain; in most cases a direct microphone connection as shown in
Figure 14 is adequate. If the microphone level is too low, an external preamp can be added as shown in Figure 15. In either case the
microphone bias can be derived from the Codec’s internal reference (VREFOUT) using a 2.2 kΩ resistor. For the preamp circuit,
the VREFOUT signal can also provide the midpoint bias for the amplifier.
To meet the PC99 1.0A requirements, the MIC signal should be placed on the microphone jack tip and the bias on the ring. This
configuration supports electret microphones with three conductor plugs, as well as dynamic microphones with two conductor plugs
(ring and sleeve shorted together).
Additional filtering may be required to limit the microphone response to the audio band of interest.
EMC
COMPONENTS
J1
L1 600Z
1
2
3
4
5
AC-COUPLING
C2
470pF
L2 600Z
TO CODEC MIC1 OR MIC2 INPUT
C1
470pF
MIC BIAS
MIC INPUT
FROM CODEC VREFOUT
Figure 14. Recommended Microphone Input Connections
PREAMP
EMC
COMPONENTS
J1
L1 600Z
1
2
3
4
5
AC-COUPLING
C2
470pF
AVDD
4
L2 600Z
C1
470pF
U1
MIC INPUT
MIC BIAS
TO CODEC MIC1 OR MIC2 INPUT
AD8531
FROM CODEC VREFOUT
Figure 15. Microphone with Additional External Preamp (20 dB Gain)
LINE OUTPUT CONNECTIONS
The AD1885 Codec provides stereo LINE_OUT signals at a standard 1 V rms level. These signals must be ac-coupled before they
can be connected to an external load. After the ac-coupling, a minimal resistive load is recommend to keep the capacitors properly
biased and reduce click and pop when plugging stereo equipment into the output jack. The capacitor values should be selected to
provide a desired frequency response, taking into account the nominal impedance of the external load. To meet the PC99 specification for PCs, testing must be performed with a 10 kΩ load, therefore a 1 µF value is recommended to achieve less than –3 dB
roll-off at 20 Hz.
EMC
COMPONENTS
AC-COUPLING
STEREO LINE_OUT JACK
J1
L2 600Z
FROM CODEC LINE_OUT_R
C1
470pF
L1 600Z
FROM CODEC LINE_OUT_L
C2
470pF
NOTE:
IF AN OUTPUT AMP IS USED, THE
AC-COUPLING CAP VALUES WILL
DEPENDEND ON THE AMP DESIGN.
Figure 16. Recommended LINE_OUT Connections
REV. 0
–25–
AD1885
PC_BEEP INPUT CONNECTIONS
The recommended PC_BEEP input circuit is shown below. Under most cases the PC_BEEP signal should be attenuated, filtered and
then ac-coupled into the Codec.
PC_BEEP (FROM ICH)
TO CODEC PC_BEEP INPUT
Figure 17. Recommended PC_BEEP Connections
GROUNDING AND LAYOUT
To reduce noise and emissions, Analog Devices recommends a split ground plane as shown in Figure 18. The purpose of splitting
the ground plane is to create a low noise analog area that is somewhat isolated from the digital ground current noise generated
by the system’s logic. All the analog circuitry should be placed on the analog ground plane area.
For reference purposes, and to return power supply currents, the analog and digital ground planes must be connected at some point,
ideally a small bridge under or near the Codec should be provided. A 0 Ω resistor or a ferrite bead should also be considered since
these allow some flexibility in optimizing the layout to meet EMC requirements.
DIGITAL
GROUND PLANE
CONNECT SPLIT GROUND
PLANES AT OR NEAR CODEC.
PIN 1
ISOLATION
TRENCH
AD1885
ANALOG
GROUND PLANE
Figure 18. Recommended Split Ground Plane
ANALOG POWER SUPPLY
To minimize audio noise, the Codec analog power supply (AVDD) should be well decoupled and regulated. In PC systems it is recommended that the analog supply be derived from the 12 V PC power supply using a localized linear voltage regulator. Preferably,
the analog power supply should be connected to the Codec’s analog section using a ferrite bead.
If a power plane layer is being used in the system design, it is recommended that the analog power plane for the Codec also be split
(mirroring the analog ground plane). In this case, the analog power supply ferrite bead should bridge the isolation trench, close to
the Codec location.
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AD1885
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
0.063 (1.60) MAX
0.354 (9.00) BSC
0.030 (1.45)
(0.75)
0.057
0.018 (1.35)
(0.45)
0.053
0.276 (7.0) BSC
0.276 (7.0) BSC
37
36
48
1
SEATING
PLANE
TOP VIEW
(PINS DOWN)
0.006 (0.15)
0.002 (0.05)
0.007 (0.18)
0.004 (0.09)
12
13
0.019685 (0.5)
BSC
25
24
0.011 (0.27)
0.006 (0.17)
PRINTED IN U.S.A.
0 –7
0 MIN
0.354 (9.00) BSC
0.030 (0.75)
0.018 (0.45)
C00753–2.5–7/00 (rev. 0)
48-Lead Thin Plastic Quad Flatpack (LQFP)
(ST-48)
REV. 0
–27–