AD AD1849KPZ

a
Serial-Port 16-Bit
SoundPort ® Stereo Codec
AD1849K
(mono) speaker and stereo headphone drive circuits that require
no additional external components. Dynamic range exceeds
80 dB over the 20 kHz audio band. Sample rates from 5.5 kHz
to 48 kHz are supported from external crystals, from an external
clock, or from the serial interface bit clock.
FEATURES
Single-Chip Integrated ⌺⌬ Digital Audio Stereo Codec
Multiple Channels of Stereo Input and Output
Digital Signal Mixing
On-Chip Speaker and Headphone Drive Capability
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 Package
Operation from 5 V and Mixed 5 V/3.3 V Supplies
Serial Interface Compatible with ADSP-21xx FixedPoint DS␮Ps
Compatible with CS4215 (See Text)
TE
The Codec includes a stereo pair of Σ∆ analog-to-digital converters
and a stereo pair of Σ∆ digital-to-analog converters. Analog signals
can be input at line levels or microphone levels. 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 left and right channel 16-bit outputs from the ADCs are
available over a single bidirectional serial interface that also supports 16-bit digital input to the DACs and control information.
The AD1849K can accept and generate 8-bit µ-law or A-law
companded digital data.
PRODUCT OVERVIEW
LE
The Serial-Port AD1849K SoundPort Stereo Codec integrates
the key audio data conversion and control functions into a single
integrated circuit. The AD1849K is intended to provide a complete, single-chip audio solution for multimedia applications
requiring operation from a single 5 V supply. External signal
path circuit requirements are limited to three low tolerance
capacitors for line level applications; anti-imaging filters are
incorporated on-chip. The AD1849K includes on-chip monaural
B
SO
The Σ∆ DACs are preceded by a digital interpolation filter. An
attenuator provides independent user volume control over each
DAC channel. Nyquist images and shaped quantization noise
are removed from the DACs’ analog stereo output by on-chip
switched-capacitor and continuous-time filters. Two independent
stereo pairs of line-level (or one line-level and one headphone)
outputs are generated, as well as drive for a monaural speaker.
FUNCTIONAL BLOCK DIAGRAM
DIGITAL
SUPPLY
ANALOG
SUPPLY
CRYSTALS
2
ANALOG
IN
MIC L
MIC R
20
dB
OSCILLATORS
GAIN
⌺⌬ A/D
CONVERTER
␮/A
LAW
GAIN
⌺⌬ A/D
CONVERTER
␮/A
LAW
LOOPBACK
MONITOR MIX
L
LINE 0 L
MUTE
R
LINE 0 R
ANALOG
OUT
DATA/CONTROL
MODE
DATA/CONTROL
TRANSMIT
MUX
R
O
2
DIGITAL
I/O
LINE L
LINE R
L
POWER-DOWN
L
ANALOG
FILTER
ATTENUATE
⌺⌬ D/A
CONVERTER
INTERPOL
ATTENUATE
ANALOG
FILTER
ATTENUATE
⌺⌬ D/A
CONVERTER
INTERPOL
ATTENUATE
⌺
⌺
␮/A
LAW
␮/A
LAW
S
E
R
I
A
L
P
O
R
T
L
O
O
P
B
A
C
K
2
LINE 1 L
HEADPHONE RETURN
LINE 1 R
MUTE R
⌺
MUTE
REFERENCE
OUT
AD1849K
DATA/CONTROL
RECEIVE
PARALLEL I/O
BIT CLOCK
FRAME SYNC
RESET
RETURN
MONO SPEAKER
2.25V
CHAINING
OUTPUT
CHAINING
INPUT
SoundPort is a registered trademark of Analog Devices, Inc.
REV. A
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
AD1849K–SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
STANDARD TEST CONDITIONS UNLESS OTHERWISE NOTED
25
5.0
5.0
256
256 Bits per Frame
48
1
20 Hz to 20 kHz
2.4
0.8
10
°C
V
V
FS
48
Ω
100
pF
DAC Input Conditions
0 dB Attenuation
Full-Scale Digital Inputs
16-Bit Linear Mode
OLB = 1
ADC Input Conditions
0 dB PGA Gain
–3.0 dB Relative to Full Scale
Line Input
16-Bit Linear Mode
kHz
kHz
V
V
kΩ
All tests are performed on all ADC and DAC channels.
TE
Temperature
Digital Supply (VDD)
Analog Supply (VCC)
Clock (SCLK)
Master Mode
Word Rate (FS)
Input Signal
Analog Output Passband
VIH
VIL
External Load Impedance
(Line 0)
External Load Impedance
(Line 1)
External Load Capacitance
(Line 0, 1)
ANALOG INPUT
Input Voltage*
(RMS Values Assume Sine Wave Input)
Line and Mic with 0 dB Gain
Mic with 20 dB Gain
Max
Unit
0.99
2.80
0.099
0.280
1.04
2.94
0.104
0.294
15
V rms
V p-p
V rms
V p-p
pF
Min
Typ
Max
Unit
1.3
1.5
1.7
dB
+22.7
42.7
dB
dB
Min
Max
Unit
0
0.45 × FS
± 0.1
0.55 × FS
Hz
dB
Hz
Hz
dB
0 94
2.66
0.094
0.266
B
SO
Input Capacitance
Typ
LE
Min
*Accounts for Sum of Worst Case Reference Errors and Worst Case Gain Errors.
PROGRAMMABLE GAIN AMPLIFIER—ADC
Step Size (0 dB to 22.5 dB)
(All Steps Tested, –30 dB Input)
PGA Gain Range*
Line and Mic with 0 dB Gain
Mic with 20 dB Gain
–0.2
19.8
O
DIGITAL DECIMATION AND INTERPOLATION FILTERS*
Passband
Passband Ripple
Transition Band
Stopband
Stopband Rejection
Group Delay
Group Delay Variation Over Passband
0.45 × FS
≥0.55 × FS
74
30/FS
0.0
–2–
µs
REV. A
AD1849K
ANALOG-TO-DIGITAL CONVERTERS
Min
Resolution*
ADC Dynamic Range, A-Weighted
Line and Mic with 0 dB Gain (–60 dB Input,
THD+N Referenced to Full Scale)
Mic with 20 dB Gain (–60 dB Input,
THD+N Referenced to Full Scale)
Typ
Bits
74
83
dB
72
74
dB
0.013
–78
0.032
–70
ADC Crosstalk
Line to Line (Input L, Ground R,
Read R; Input R, Ground L, Read L)
Line to Mic (Input LINL & R,
Ground and Select MINL & R,
Read Both Channels)
LE
Gain Error (Full-Scale Span Relative to Nominal)
ADC Interchannel Gain Mismatch (Line and Mic)
(Difference of Gain Errors)
B
SO
Min
DAC Dynamic Range
(–60 dB Input, THD+N Referenced to Full Scale)
0.020
–72
0.056
–65
TE
Mic with 20 dB Gain
Resolution*
Unit
16
ADC THD+N, (Referenced to Full Scale)
Line and Mic with 0 dB Gain
DIGITAL-TO-ANALOG CONVERTERS
Max
80
DAC THD+N (Referenced to Full Scale)
Line 0 and 1 (10 kΩ Load)
Typ
%
dB
%
dB
–80
dB
–60
dB
0.75
dB
0.3
dB
Max
Unit
16
Bits
86
dB
0.020
–74
0.100
–60
0.100
–60
%
dB
%
dB
%
dB
DAC Crosstalk (Input L, Zero R, Measure
LOUT0R and 1R; Input R, Zero L,
Measure LOUT0L and 1L)
–80
dB
Gain Error (Full-Scale Span Relative to Nominal)
0.75
dB
DAC Interchannel Gain Mismatch (Line 0 and 1)
(Difference of Gain Errors)
0.3
dB
Total Out-of-Band Energy*
(Measured from 0.55 × FS to 100 kHz)
–60
dB
Audible Out-of-Band Energy*
(Measured from 0.55 FS to 22 kHz,
All Selectable Sampling Frequencies)
–72
dB
Line 1 (48 Ω Load)
O
Mono Speaker (48 Ω Load)
*Guaranteed, not tested.
REV. A
–3–
0.010
–80
0.022
–73
0.045
–67
AD1849K
MONITOR MIX ATTENUATOR
Step Size (0.0 dB to –60 dB)*
Step Size (–61.5 dB to –94.5 dB)*
Output Attenuation*
Min
Typ
Max
Unit
1.3
1.0
–95
1.5
1.5
1.7
2.0
0.2
dB
dB
dB
Min
Typ
Max
Unit
1.3
1.5
1.7
dB
1.0
–95
1.5
2.0
0.2
dB
dB
Max
Unit
+0.2
dB
± 0.9
5
LSB
Degrees
Max
Unit
Step Size (0.0 dB to –60 dB)
(Tested at Steps –1.5 dB, –19.5 dB,
–39 dB and –60 dB)
Step Size (–61.5 dB to –94.5 dB)*
Output Attenuation*
TE
DAC ATTENUATOR
SYSTEM SPECIFICATIONS
Min
ANALOG OUTPUT
–0.5
LE
System Frequency Response*
(Line In to Line Out,
0 to 0.45 × FS)
Differential Nonlinearity*
Phase Linearity Deviation*
Typ
Min
B
SO
Full-Scale Output Voltage (Line 0 & 1)
[OLB = 1]
Full-Scale Output Voltage (Line 0)
[OLB = 0]
Full-Scale Output Voltage (Line 1)
[OLB = 0]
Full-Scale Output Voltage (Mono Speaker)
[OLB = 1]
Full-Scale Output Voltage (Mono Speaker)
[OLB = 0]
CMOUT Voltage (No Load)
CMOUT Current Drive*
CMOUT Output Impedance
Mute Attenuation of 0 dB
Fundamental* (LINE 0, 1, and MONO)
Typ
1.85
2.1
V rms
V p-p
V rms
V p-p
V p-p
4.0
V p-p
8.0
V p-p
2.25
100
4
–80
V
µA
kΩ
dB
Min
Max
Unit
2.4
2.4
–0.3
2.4
(VDD+) + 0.3
(VDD+) + 0.3
+0.8
O
1.80
0.707
2.0
1.0
2.8
4.0
2.50
STATIC DIGITAL SPECIFICATIONS
High Level Input Voltage (VIH)
Digital Inputs
XTAL1/2I
Low Level Input Voltage (VIL)
High Level Output Voltage (VOH) at IOH = –2 mA
Low Level Output Voltage (VOL) at IOL = 2 mA
Input Leakage Current
(GO/NOGO Tested)
Output Leakage Current
(GO/NOGO Tested)
–10
0.4
+10
V
V
V
V
V
µA
–10
+10
µA
*Guaranteed, not tested.
–4–
REV. A
AD1849K
DIGITAL TIMING PARAMETERS (Guaranteed over 4.75 V to 5.25 V, 0ⴗC to 70ⴗC)
Min
POWER SUPPLY
Unit
ns
s
1/(FS × Bits per Frame)
25
ns
25
13.5
30
30
27
TE
15
10
25
0
15
20
50
100
Min
Typ
ns
MHz
ns
ns
MHz
ns
ns
ns
ns
ns
ns
ms
ns
Max
Unit
5.25
V
100
130
mA
20
200
µA
dB
Min
Max
Unit
5.5125
27
± 10
50
MHz
%
kHz
4.75
B
SO
Power Supply Voltage Range*
–Digital and Analog
Power Supply Current—Operating
(50% IVDD, 50% IVCC, Unloaded Outputs)
Power Supply Current—Power Down
Power Supply Rejection (@ 1 kHz)*
(At Both Analog and Digital
Supply Pins, Both ADCs and DACs)
Max
80
LE
SCLK Period (tCLK)
Slave Mode, MS = 0
Master Mode, MS = 1*
SCLK HI (tHI)*
Slave Mode, MS = 0
SCLK LO (tLO)*
Slave Mode, MS = 0
CLKIN Frequency
CLKIN HI
CLKIN LO
Crystals Frequency
Input Setup Time (tS)
Input Hold Time (tIH)
Output Delay (tD)
Output Hold Time (tOH)
Output Hi-Z to Valid (tZV)
Output Valid to Hi-Z (tVZ)
Power Up RESET LO Time
Operating RESET LO Time
Typ
40
CLOCK SPECIFICATIONS*
Input Clock Frequency, Crystals
Clock Duty Cycle Tolerance
Sample Rate (FS)
O
*Guaranteed, not tested.
Specifications subject to change without notice.
REV. A
–5–
AD1849K
± 10.0
6
COUT1
VDD
mA
TSIN
FSYNC
TSOUT
SCLK
SDTX
V
V
GNDD
+6.0
+6.0
SDRX
–0.3
–0.3
CLKOUT
Unit
CIN1
Max
40
1
7
39
CIN2
V
V
°C
°C
V
PIO0
COUT2
AD1849KP
D/C
RESET
SOUNDPORT
STEREO CODEC
N/C
PDN
LOUT0R
LOUT0L
C0
MINR
LOUT1L
LINR
LOUT1C
TE
MINL
of MIL-STD-883B)
17
29
MOUT
N/C
VCC
GNDA
VCC
VREF
GNDA
LINL
*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 the
operational section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
LOUT1R
28
18
MOUTR
(VCC+) + 0.3
(VDD+) + 0.3
70
+150
C1
–0.3
–0.3
0
–65
500
GNDD
VDD
PIO1
GNDD
CMOUT
Power Supplies
Digital (VDD)
Analog (VCC)
Input Current
(Except Supply Pins and MOUT,
MOUTR, LOUT1R, LOUT1L,
LOUT1C)
Analog Input Voltage (Signal Pins)
Digital Input Voltage (Signal Pins)
Ambient Temperature (Operating)
Storage Temperature
ESD Tolerance (Human Body
Model per Method 3015.2
Min
CLKIN
VDD
PIN CONFIGURATION
44-Lead Plastic Leaded Chip Carrier
ABSOLUTE MAXIMUM RATINGS*
N/C = NO CONNECT
ORDERING GUIDE
LE
WARNING: CMOS device. May be susceptible to high-voltage
transient-induced latchup.
Model
Temperature
Range
B
SO
AD1849KP 0°C to 70°C
Package
Option
44-Lead PLCC
P-44A
WARNING!
ESD SENSITIVE DEVICE
O
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 AD1849K 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.
Package
Description
–6–
REV. A
AD1849K
PIN FUNCTION DESCRIPTIONS
Digital Signals
PLCC
I/O
Description
SDRX
SDTX
SCLK
FSYNC
TSOUT
TSIN
D/C
CIN1
COUT1
CIN2
COUT2
CLKIN
CLKOUT
PDN
RESET
PIO1
PIO0
1
44
43
42
41
40
35
6
7
10
11
4
5
13
12
37
36
I
O
I/O
O
O
I
I
I
O
I
O
I
O
I
I
I/O
I/O
Receive Serial Data Pin
Transmit Serial Data Pin
Bidirectional Serial Bit Clock
Frame Sync Output Signal
Chaining Word Output
Chaining Word Input
Data/Control Select Input
Crystal 1 Input
Crystal 1 Output
Crystal 2 Input
Crystal 2 Output
External Sample Clock Input (256 × FS)
External Sample Clock Output (256 × FS)
Power Down Input (Active HI)
Reset Input (Active LO)
Parallel Input/Output Bit 1
Parallel Input/Output Bit 0
LE
Analog Signals
TE
Pin Name
PLCC
I/O
Description
LINL
LINR
MINL
MINR
LOUT0L
LOUT0R
LOUT1L
LOUT1R
LOUT1C
MOUT
MOUTR
C0
C1
N/C
N/C
VREF
CMOUT
18
16
17
15
32
33
31
29
30
27
28
14
20
26
34
21
19
I
I
I
I
O
O
O
O
I
O
I
O
O
Left Channel Line Input
Right Channel Line Input
Left Channel Microphone Input (–20 dB from Line Level if MB = 0 or Line Level if MB = 1)
Right Channel Microphone Input (–20 dB from Line Level if MB = 0 or Line Level if MB = 1)
Left Channel Line Output 0
Right Channel Line Output 0
Left Channel Line Output 1
Right Channel Line Output 1
Common Return Path for Large Current from External Headphones
Mono Speaker Output
Mono Speaker Output Return
External 1.0 µF Capacitor (± 10%) Connection
External 1.0 µF Capacitor (± 10%) Connection
No Connect (Do Not Connect)
No Connect (Do Not Connect)
Voltage Reference (Connect to Bypass Capacitor)
Common Mode Reference Datum Output (Nominally 2.25 V)
B
SO
Pin Name
O
O
O
Power Supplies
Pin Name
PLCC
I/O
Description
VCC
GNDA
VDD
GNDD
23 and 24
22 and 25
3, 8, 38
2, 9, 39
I
I
I
I
Analog Supply Voltage (5 V)
Analog Ground
Digital Supply Voltage (5 V)
Digital Ground
REV. A
–7–
AD1849K
FUNCTIONAL DESCRIPTION
Monitor Mix
This section overviews the functionality of the AD1849K and
is intended as a general introduction to the capabilities of the
device. As much as possible, detailed reference information has
been placed in “Control Registers” and other sections. The user
is not expected to refer repeatedly to this section.
A monitor mix is supported that digitally mixes a portion of the
digitized analog input with the analog output (prior to digitization). The digital output from the ADCs going out of the serial
data port is unaffected by the monitor mix. Along the monitor
mix datapath, the 16-bit linear output from the ADCs is attenuated
by an amount specified with control bits. Both channels of
the monitor data are attenuated by the same amount. (Note
that internally the AD1849K always works with 16-bit PCM
linear data, digital mixing included; format conversions take
place at the input and output.)
The AD1849K SoundPort Stereo Codec accepts stereo line-level
and mic-level inputs. These analog stereo signals are multiplexed
to the internal programmable gain amplifier (PGA) stage. The
mic inputs can be amplified by 20 dB prior to the PGA to compensate for the voltage swing difference between line levels and
typical condenser microphones. The mic inputs can bypass the
20 dB fixed gain block and go straight to the input multiplexer,
which often results in an improved system signal-to-noise ratio.
The PGA following the input multiplexer allows independent
selectable gains for each channel from 0 to 22.5 dB in 1.5 dB
steps. The Codec can operate either in a global stereo mode or
in a global mono mode with left-channel inputs appearing at
both channel outputs.
Analog-to-Digital Datapath
The attenuated monitor data is digitally summed with the DAC
input data prior to the DACs’ datapath attenuators. Because
both stereo signals are mixed before the output attenuators,
mix data is attenuated a second time by the DACs’ datapath
attenuators. The digital sum of digital mix data and DAC
input data is clipped at plus or minus full scale and does not
wrap around.
LE
The AD1849K Σ∆ ADCs incorporate a proprietary fourth-order
modulator. A single pole of passive filtering is all that is required
for antialiasing the analog input because of the ADC’s high 64
times oversampling ratio. The ADCs include linear-phase digital
decimation filters that low-pass filter the input to 0.45 × FS
(“FS” is the word rate or “sampling frequency”). ADC input
overrange conditions will cause a sticky bit to be set that can be
read.
Sixteen steps of –6 dB attenuation are supported to –94.5 dB. A
“0” implies no attenuation, while a “14” implies 84 dB of
attenuation. Specifying full scale “15” completely mutes the
monitor datapath, preventing any mixing of the analog input
with the digital input. Note that the level of the mixed output
signal is also a function of the input PGA settings since they
affect the ADCs’ output.
TE
Analog Inputs
Analog Outputs
B
SO
One stereo line-level output, one stereo headphone output, and
one monaural (mono) speaker output are available at external
pins. Each of these outputs can be independently muted. Muting
either the line-level stereo output or the headphone stereo
output mutes both left and right channels of that output. When
muted, the outputs will settle to a dc value near CMOUT,
the midscale reference voltage. The mono speaker output is
differential. The chip can operate either in a global stereo mode
or in a global mono mode with left channel inputs appearing at
both outputs.
Digital-to-Analog Datapath
O
The Σ∆ DACs are preceded by a programmable attenuator and
a low-pass digital interpolation filter. The attenuator allows
independent control of each DAC channel from 0 dB to –94.5 dB
in 1.5 dB steps plus full digital mute. The anti-imaging interpolation filter oversamples by 64 and digitally filters the higher
frequency images. The DACs’ Σ∆ noise shapers also oversample
by 64 and convert the signal to a single-bit stream. The DAC
outputs are then filtered in the analog domain by a combination
of switched-capacitor and continuous-time filters. They remove
the very high frequency components of the DAC bitstream
output, including both images at the oversampling rate and
shaped quantization noise. No external components are required.
Phase linearity at the analog output is achieved by internally
compensating for the group delay variation of the analog output
filters.
Attenuation settings are specified by control bits in the data
stream. Changes in DAC output level take effect only on zero
crossings of the digital signal, thereby eliminating “zipper”
noise. Each channel has its own independent zero-crossing
detector and attenuator change control circuitry. A timer
guarantees that requested volume changes will occur even in the
absence of an input signal that changes sign. The time-out
period is 10.7 milliseconds at a 48 kHz sampling rate and 64
milliseconds at an 8 kHz sampling rate (Time-out [ms] ≈ 512/
Sampling Rate [kHz]).
Digital Data Types
The AD1849K supports four global data types: 16-bit twoscomplement linear PCM, 8-bit unsigned linear PCM, 8-bit
companded µ-law, and 8-bit companded A-law, as specified by
control register bits. Data in all four formats is always transferred MSB first. Sixteen-bit linear data output from the ADCs
and input to the DACs is in twos-complement format. Eight-bit
data is always left-justified in 16-bit fields; in other words, the
MSBs of all data types are always aligned; in yet other words,
full-scale representations in all three formats correspond to
equivalent full-scale signals. The eight least-significant bit positions
of 8-bit linear and companded data in 16-bit fields are ignored
on input and zeroed on output.
The 16-bit PCM data format is capable of representing 96 dB of
dynamic range. Eight-bit PCM can represent 48 dB of dynamic
range. Companded µ-law and A-law data formats use nonlinear
coding with less precision for large-amplitude signals. The loss
of precision is compensated for by an increase in dynamic range
to 64 dB and 72 dB, respectively.
–8–
REV. A
AD1849K
On input, 8-bit companded data is expanded to an internal
linear representation, according to whether µ-law or A-law was
specified in the Codec’s internal registers. Note that when µ-law
compressed data is expanded to a linear format, it requires 14
bits. A-law data expanded requires 13 bits, see Figure 1.
15
COMPRESSED
INPUT DATA
MSB
0
8 7
3/2
MSB
2/1
0
2/1
0
During the autocalibration sequence, the serial data output from
the ADCs is meaningless and the ADI bit is asserted. Serial data
inputs to the DACs are ignored. Even if the user specified the
muting of all analog outputs, near the end of the autocalibration
sequence, dc analog outputs very close to CMOUT will be
produced at the line outputs and mono speaker output.
LSB
15
DAC INPUT
The AD1849K supports an autocalibration sequence to eliminate
DAC and ADC offsets. The autocalibration sequence is
initiated in the transition from Control Mode to Data Mode,
regardless of the state of the AC bit. The user should specify
that analog outputs be muted to prevent undesired outputs.
Monitor mix will be automatically disabled by the Codec.
LSB
15
EXPANSION
Autocalibration
3/2
MSB
LSB
000/00
An autocalibration sequence is also performed when the
AD1849K leaves the reset state (i.e., RESET goes HI). The
RESET pin should be held LO for 50 ms after power up or after
leaving power-down mode to delay the onset of the autocalibration
sequence until after the voltage reference has settled.
TE
Figure 1. A-Law or µ -Law Expansion
When 8-bit companding is specified, the ADCs’ linear output is
compressed to the format specified prior to output. See Figure 2.
Note that all format conversions take place at input or output.
Internally, the AD1849K always uses 16-bit linear PCM
representations to maintain maximum precision.
0
MSB
LSB
15
TRUNCATION
3/2
MSB
15
MSB
LSB
8 7
LSB
2/1
Analog loopback mode D-A-D is enabled by setting the ADL
bit (Control Word Bit 32) to a “1” when ENL is a “1.” In this
mode, the DACs’ analog outputs are re-input to the PGAs prior
to the ADCs, allowing digital inputs to be compared to digital
outputs. The monitor mix will be automatically disabled by the
Codec during D-A-D loopback. The analog outputs can be
individually attenuated, and the analog inputs are internally
disconnected. Note that muting the line 0 output mutes the
looped-back signal in this mode.
0
0
00000000
B
SO
COMPRESSION
Digital and analog loopback modes are supported for device and
system testing. The monitor mix datapath is always available for
loopback test purposes. Additional loopback tests are enabled by
setting the ENL bit (Control Word Bit 33) to a “1.”
LE
15
ADC OUTPUT
Loopback
Figure 2. A-Law or µ -Law Compression
Power Supplies and Voltage Reference
The AD1849K operates from 5 V power supplies. Independent
analog and digital supplies are recommended for optimal
performance, though excellent results can be obtained in single
supply systems. A voltage reference is included on the Codec
and its 2.25 V buffered output is available on an external pin
(CMOUT). The CMOUT output can be used for biasing op
amps used in dc coupling. The internal reference is externally
bypassed to analog ground at the VREF pin. Note that VREF
should only be connected to its bypass capacitors.
O
Digital loopback mode D-D is enabled by resetting the ADL bit
(Control Word Bit 32) to a “0” when ENL is a “1.” In this mode,
the control and data bit pattern presented on the SDRX pin is
echoed on the SDTX pin with a two frame delay, allowing the
host controller to verify the integrity of the serial interface starting
on the third frame after D-D loopback is enabled. During digital
loopback mode, the output DACs are operational.
REV. A
–9–
AD1849K
The loopback modes are shown graphically in Figure 3.
GAIN
A/D
AD1849K
␮/A-LAW
ENCODE
SDTX
␮/A-LAW
DECODE
SDRX
MONITOR
DISABLE
MUTE
LINE 0,
OUTPUT
LINE 1
FUNCTIONAL
0
1
D/A
Analog Loopback D-A-D
LINE, MIC
INPUT
GAIN
A/D
AD1849K
LINE 0,
LINE 1
OUTPUT
FUNCTIONAL
MUTE
␮/A-LAW
ENCODE
SDTX
␮/A-LAW
ENCODE
SDRX
MONITOR
D/A
The AD1849K can operate from external crystals, from a 256 ×
FS input clock, from an input clock with a programmable divide
factor, or from the serial port’s bit clock (at 256 × FS), selected
under software control. Two crystal inputs are provided to
generate a wide range of sample rates. The oscillators for these
crystals are on the AD1849K, as is a multiplexer for selecting
between them. They can be overdriven with external clocks by
the user, if so desired. The recommended crystal frequencies are
16.9344 MHz and 24.576 MHz. From them the following sample
rates can be internally generated: 5.5125, 6.615, 8, 9.6, 11.025,
16, 18.9, 22.05, 27.42857, 32, 33.075, 37.8, 44.1, 48 kHz.
Regardless of clock input source, a clock output of 256 × FS is
generated (with some skew). If an external input clock or the
serial port’s bit clocks are selected to drive the AD1849K’s
internal operation, they should be low jitter clocks. If no external
clock will be used, Analog Devices recommends tying the clock
input pin (CLKIN) to ground. If either external crystal is not
used, Analog Devices recommends tying its input (CIN1 and/or
CIN2) to ground.
TE
LINE, MIC
INPUT
DISCONNECTED
Clocks and Sample Rates
O
B
SO
Figure 3. Loopback Modes
LE
Digital Loopback D-D
–10–
REV. A
AD1849K
CONTROL REGISTERS
The AD1849K SoundPort Stereo Codec accepts control information through its serial port when in Control Mode. Some control
information is also embedded in the data stream when in Data Mode. (See Figure 8.) Control bits can also be read back for system
verification. Operation of the AD1849K is determined by the state of these control bits. The 64-bit serial Control Mode and Data
Mode control registers have been arbitrarily broken down into bytes for ease of description. All control bits initialize to default states
after RESET or Power Down. Those control bits that cannot be changed in Control Mode are initialized to defaults on the transition
from Data Mode to Control Mode. See below for a definition of these defaults.
Control Mode Control Registers
Control Byte 1, Status Register
Data 4
Data 3
Data 2
Data 1
Data 0
0
0
1
MB
OLB
DCB
0
AC
63
62
61
60
59
58
57
56
Mic bypass:
0
Mic inputs applied to 20 dB fixed gain block.
1
Mic inputs bypass 20 dB fixed gain block.
Output level bit:
0
Full-scale line 0 output is 2.8 V p-p (1 V rms).
Full-scale line 1 output is 4.0 V p-p.
Full-scale mono speaker output is 8.0 V p-p.
1
Full-scale line 0 output is 2.0 V p-p.
Full-scale line 1 output is 2.0 V p-p.
Full-scale mono speaker output is 4.0 V p-p.
Data/control bit. Used for handshaking in data/control transitions. See “DCB Handshake Protocol.”
Autocalibration.
Autocalibration will always occur on the Control-to-Data mode transition. The AC bit is ignored. Autocalibration
requires an interval of 194 frames. Offsets for all channels of ADC and DAC are zeroed. The user should specify that
analog outputs are muted to prevent undesired outputs, i.e., OM0 = “0,” OM1 = “0,” and SM =“0.” Monitor mix will
be automatically disabled by the Codec.
O
B
SO
DCB
AC
Data 5
TE
OLB
Data 6
LE
MB
Data 7
REV. A
–11–
AD1849K
Control Byte 2, Data Format Register
DF1:0
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
0
0
DFR2
DFR1
DFR0
ST
DF1
DF0
55
54
53
52
51
50
49
48
Data conversion frequency (FS) select tin kHz:
DFR
Divide Factor
0
3072
1
1536
2
896
3
768
4
448
5
384
6
512
7
2560
ITS
47
B
SO
Data 7
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
MCK2
MCK1
MCK0
FSEL1
FSEL0
MS
TXDIS
46
45
44
43
42
41
40
Immediate three-state:
0
FSYNC, SDTX and SCLK three-state within 3 SCLK cycles after D/C goes LO
1
FSYNC, SDTX and SCLK three-state immediately after D/C goes LO
Clock source select for Codec internal operation:
0
Serial bit clock (SCLK) is the master clock at 256 × FS
1
24.576 MHz crystal (XTAL1) is the clock source
2
16.9344 MHz crystal (XTAL2) is the clock source
3
External clock (CLKIN) is the clock source at 256 × FS
4
External clock (CLKIN) is the clock source, divided by the factor selected by DFR2:0
(External clock must be stable and valid within 2000 periods after it is selected.)
Frame size select:
0
64 bits per frame
1
128 bits per frame
2
256 bits per frame
3
Reserved
Note that FSEL is overridden in Data Mode when SCLK is the clock source (MCK = “0”). When SCLK is providing
the 256 × FS clock for internal Codec operation, 256 bits per frame is effectively selected, regardless of FSEL’s contents.
Master/slave mode for the serial interface:
0 Receive serial clock (SCLK) and TSIN from an external device (“slave mode”)
1 Transmit serial clock (SCLK) and frame sync (FSYNC) to external devices (“master mode”)
Note that MS is overridden when SCLK is the clock source (MCK = “0”). When SCLK is providing the clock for
internal Codec operation, slave mode is effectively selected, regardless of the contents of MS.
Transmitter disable:
0
Enable serial output
1
Three-state serial data output (high impedance)
Note that Control Mode overrides TXDIS. In Control Mode, the serial output is always enabled.
O
MCK2:0
XTAL2 (16.9344 MHz)
5.5125
11.025
18.9
22.05
37.8
44.1
33.075
6.615
Note that the AD1849K’s internal oscillators can be overdriven by external clock sources at the crystal input pins. If an
external clock source is used, it should be applied to the crystal input pin (CIN1 or CIN2), and the crystal output pin
(COUT1 or COUT2) should be left unconnected. The external clock source need not be at the recommended crystal
frequencies, and it will be divided down by the selected Divide Factor.
Global stereo mode. Both converters are placed in the same mode.
0
Mono mode. The left analog input appears at both ADC outputs. The left digital input appears at both DAC outputs.
1
Stereo mode
Codec data format selection:
0
16-bit twos-complement PCM linear
1
8-bit µ-law companded
2
8-bit A-law companded
3
8-bit unsigned PCM linear
Control Byte 3, Serial Port Control Register
ITS
XTAL1 (24.576 MHz)
8
16
27.42857
32
N/A
N/A
48
9.6
TE
ST
Data 6
LE
DFR2:0
Data 7
FSEL1:0
MS
TXDIS
–12–
REV. A
AD1849K
Control Byte 4, Test Register
ENL
ADL
Data 7
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
0
0
0
0
0
0
ENL
ADL
39
38
37
36
35
34
33
32
Enable loopback testing:
0
Disabled
1
Enabled
Loopback mode:
0
Digital loopback from Data/Control receive to Data/Control transmit (D-D)
1
Analog loopback from DACs to ADCs (D-A-D)
TE
Control Byte 5, Parallel Port Register
Data 7
Data 6
Data 5
Data 4
PIO1
PIO0
0
0
31
30
29
28
Data 3
Data 2
Data 1
Data 0
0
0
0
0
27
26
25
24
Data 4
Data 3
Data 2
Data 1
Data 0
0
0
0
0
0
20
19
18
17
16
PIO1:0 Parallel I/O bits for system signaling. PIO bits do not affect Codec operation.
Data 7
Data 6
Data 5
0
0
0
23
22
21
Reserved bits should be written as 0.
B
SO
Control Byte 7, Revision Register
LE
Control Byte 6, Reserved Register
Data 7
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
0
0
1
0
REVID3
REVID2
REVID1
REVID0
15
14
13
12
11
10
9
8
REVID3:0
Silicon revision identification. Reads greater than or equal to 0010 (i.e., 0010, 0011, etc.) for the AD1849K.
Control Byte 8, Reserved Register
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
0
0
0
0
0
0
0
0
5
4
3
2
1
0
O
Data 7
7
6
Reserved bits should be written as 0.
REV. A
–13–
AD1849K
Data Mode Data and Control Registers
Data Byte 1, Left Audio Data—Most Significant 8 Bits
Data 7
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
L15
L14
L13
L12
L11
L10
L9
L8
63
62
61
60
59
58
57
56
In 16-bit linear PCM mode, this byte contains the upper eight bits of the left audio data sample. In the 8-bit companded and linear
modes, this byte contains the left audio data sample. In mono mode, only the left audio data is used. MSB first format is used in all
modes, and twos-complement coding is used in 16-bit linear PCM mode.
Data Byte 2, Left Audio Data—Least Significant 8 Bits
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
L7
L6
L5
L4
L3
L2
L1
L0
55
54
53
52
51`
50
49
48
TE
Data 7
LE
In 16-bit linear PCM mode, this byte contains the lower eight bits of the left audio data sample. In the 8-bit companded and linear
modes, this byte is ignored on input, zeroed on output. In mono mode, only the left audio data is used. MSB first format is used in
all modes, and twos-complement coding is used in 16-bit linear PCM mode.
Data Byte 3, Right Audio Data—Most Significant 8 Bits
Data 6
Data 5
R15
R14
R13
47
46
45
Data 4
Data 3
Data 2
Data 1
Data 0
R12
R11
R10
R9
R8
44
43
42
41
40
B
SO
Data 7
In 16-bit linear PCM mode, this byte contains the upper eight bits of the right audio data sample. In the 8-bit companded and linear
modes, this byte contains the right audio data sample. In mono mode, this byte is ignored on input, zeroed on output. MSB first
format is used in all modes, and twos complement coding is used in 16-bit linear PCM mode.
Data Byte 4, Right Audio Data—Least Significant 8 Bits
Data 7
R7
39
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
R6
R5
R4
R3
R2
R1
R0
38
37
36
35
34
33
32
O
In 16-bit linear PCM mode, this byte contains the lower eight bits of the right audio data sample. In the 8-bit companded and linear
modes, this byte is not used. In mono mode, this byte is ignored on input, zeroed on output. MSB first format is used in all modes,
and twos-complement coding is used in 16-bit linear PCM mode.
Data Byte 5, Output Setting Register 1
OM1
OM0
LO5:0
Data 7
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
OM1
OM0
LO5
LO4
LO3
LO2
LO1
LO0
31
30
29
28
27
26
25
24
Output Line 1 Analog Mute:
0
Mute Line 1
1
Line 1 on
Output Line 0 Analog Mute:
0
Mute Line 0
1
Line 0 on
Output attenuation setting for the left DAC channel; “0” represents no attenuation. Step size is 1.5 dB; “62” represents
93 dB of attenuation. Attenuation = 1.5 dB × LO, except for LO = “63,” which represents full digital mute.
–14–
REV. A
AD1849K
Data Byte 6, Output Setting Register 2
ADI
SM
RO5:0
Data 7
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
ADI
SM
RO5
RO4
RO3
RO2
RO1
RO0
23
22
21
20
19
18
17
16
ADC Invalid. This bit is set to “1” during the autocalibration sequence, indicating that the serial data output from the
ADCs is meaningless.
Mono Speaker Analog Mute:
0
Mute mono speaker
1
Mono speaker on
Output attenuation setting for the right DAC channel; “0” represents no attenuation. Step size is 1.5 dB; “62”
represents 93 dB of attenuation. Attenuation = 1.5 dB × RO, except for RO = “63,” which represents full digital mute.
LG3:0
Data 5
Data 4
PIO1
PIO0
OVR
IS
15
14
13
12
Data 3
Data 2
Data 1
Data 0
LG3
LG2
LG1
LG0
11
10
9
8
Parallel I/O bits for system signaling. PIO bits do not affect Codec operation.
ADC input overrange. This bit is set to “1” if either ADC channel is driven beyond the specified input range. It is
“sticky,” i.e., it remains set until explicitly cleared by writing a “0” to OVR. A “1” written to OVR is ignored,
allowing OVR to remain “0” until an overrange condition occurs.
Input selection:
0
Line-level stereo inputs
1
Microphone (condenser-type) level inputs if MB = 0 (20 dB gain), or line-level stereo inputs if MB = 1
(0 dB gain).
Input gain for left channel. “0” represents no gain. Step size is 1.5 dB; “15” represents 22.5 dB of input gain.
Gain = 1.5 dB × LG.
LE
IS
Data 6
B
SO
PIO1:0
OVR
Data 7
TE
Data Byte 7, Input Setting Register 1
Data Byte 8, Input Setting Register 2
MA3:0
Data 6
Data 5
Data 4
Data 3
Data 2
Data 1
Data 0
MA3
MA2
MA1
MA0
RG3
RG2
RG1
RG0
7
6
5
4
3
2
1
0
Monitor mix. “0” represents no attenuation, i.e., the ADCs’ output is fully mixed with the DACs’ input. Step size
is 6 dB; “14” represents an attenuation of both channels of the ADCs’ output along the monitor datapath of
84 dB. Mix attenuation = 6 dB × MA, except for MA = “15,” which disables monitor mix entirely.
Input gain for right channel. “0” represents no gain. Step size is 1.5 dB; “15” represents 22.5 dB of input gain.
Gain = 1.5 dB × RG.
O
RG3:0
Data 7
REV. A
–15–
AD1849K
Control Register Defaults
Upon coming out of RESET or Power Down, internal control registers will be initialized to the following values:
Defaults Calming Out of RESET or Power Down
1
0
0
0
1
0
0
2
0
1
0
0
3
0
63
1
0
63
0
0
0
15
0
TE
DCB
AC
DFR2:0
ST
DF1:0
ITS
MCK2:0
FSEL1:0
MS
TXDIS
ENL
ADL
PIO1:0
OM1:0
LO5:0
ADI
SM
RO5:0
OVR
IS
LG3:0
MA3:0
RG3:0
Mic Input Applied to 20 dB Fixed Gain Block
Full-Scale Line 0 Output 2.8 V p-p, Full-Scale Line 1 Output 4.0 V p-p, Full-Scale Mono Speaker
Output 8.0 V p-p
Data/Control Bit HI
Autocalibration Disabled
8 or 5.5125 kHz
Monophonic Mode
8-Bit µ-Law Data
FSYNC, SDTX and SCLK Three-State within 3 SCLK Cycles after D/C Goes LO
Serial Bit Clock [SCLK] is the Master Clock
256 Bits per Frame
Slave Mode
Three-State Serial Data Output
Loopback Disabled
Digital Loopback
“1”s, i.e., Three-State for the Open Collector Outputs
Mute Line 0 and Line 1 Outputs
Mute Left DAC
ADC Data Invalid, Autocalibration in Progress
Mute Mono Speaker
Mute Right DAC
No Overrange
Line-Level Stereo Inputs
No Gain on Left Channel
No Mix
No Gain on Right Channel
LE
0
0
B
SO
MB
OLB
Also, when making a transition from Control Mode to Data Mode, those control register values that are not changeable in Control
Mode get reset to the defaults above (except PIO). The control registers that can be changed in Control Mode will have the values
they were just assigned. The subset of the above list of control registers that are assigned default values on the transition from
Control Mode to Data Mode are:
Defaults at a Control-to-Data Mode Transition
0
63
0
63
0
0
0
15
0
Mute Line 0 and Line 1
Mute Left DAC
Mute Mono Speaker
Mute Right DAC
No Overrange
Line-Level Stereo Inputs
No Gain
No Mix
No Gain
O
OM1:0
LO5:0
SM
RO5:0
OVR
IS
LG3:0
MA3:0
RG3:0
Note that all these defaults can be changed with control information in the first Data Word. Note also that the PIO bits in the output
serial streams always reflect the values most recently read from the external PIO pins. (See “Parallel I/O Bits” below for timing
details.) A Control-to-Data Mode transition is no exception.
An important consequence of these defaults is that the AD1849K Codec always comes out of reset or power down in slave mode with an
externally supplied serial bit clock (SCLK) as the clock source. An external device must supply the serial bit clock and the chaining word
input signal (TSIN) initially. (See “Codec Startup, Modes, and Transitions” below for more details.)
–16–
REV. A
AD1849K
A single serial interface on the AD1849K provides for the transfer of both data and control information. This interface is similar to AT&T’s Concentrated Highway Interface (CHI), allowing
simple connection with ISDN and other telecommunication
devices. The AD1849K’s implementation also allows a no-glue
direct connection to members of Analog Devices’ family of
fixed-point DSP processors, including the ADSP-2101, the
ADSP-2105, the ADSP-2111, and the ADSP-2115.
Frames and Words
The AD1849K serial interface supports time-division multiplexing. Up to four AD1849K Codecs or compatible devices
can be daisy-chained on the same serial lines. A “frame” can
consist of one, two, or four 64-bit “words.” Thus, frames can be
64, 128, or 256 bits in length as specified by the FSEL bits in
Control Byte 3. Only 64 bits of each frame, a “word,” contain
meaningful data and/or control information for a particular
Codec. See Figure 4 below.
TWO WORDS/FRAME
0
FOUR WORDS/FRAME
Input data (except PIO) is clocked by the falling edge of SCLK.
Data outputs (except PIO) begin driving on the rising edge of
SCLK and are always valid well before the falling edge of
SCLK.
63
WORD #1
WORD #2
63 64
WORD #1
0
In master mode, the SCLK output frequency is determined by
the number of bits per frame selected (FSEL) and the sampling
frequency, FS. In short, SCLK = FSEL × FS in master mode.
Timing Relationships
WORD #1
0
The internal oscillators or CLKIN can be the clock source when
the serial interface is in slave mode provided that all clocks
applied to the AD1849K SoundPort Codec are derived from the
same external source. Precise phase alignment of the clocks is
not necessary, rather the requirement is that there is no
frequency drift between the clocks.
127
WORD #2
63 64
LE
ONE WORD/FRAME
Recommended modes are indicated above by “yes.” Note that
Codec performance is improved with a clean clock source, and
in many systems the lowest jitter clocks available will be those
generated by the Codec’s internal oscillators. Conversely, SCLK
in many systems will be the noisiest source. The master/SCLK
clock source combination is impossible because selecting SCLK
as the clock source overrides the MS control bit, forcing slave
mode. (The SCLK pin cannot be driving out if it is simultaneously receiving an external clock.)
TE
SERIAL INTERFACE
WORD #3
127 128
WORD #4
191 192
Figure 4. Frames and Words
255
B
SO
The AD1849K supports two types of words: Data Words and
Control Words. The proper interpretation of a word is determined by the state of the asynchronous Data/Control (D/C) pin.
The D/C pin establishes whether the SoundPort Codec is in the
“Data” mode or “Control” mode. Transitions between these
modes require an adherence to a handshaking protocol to prevent ambiguous bus ownership. The Data/ Control transition
protocol is described below in a separate section.
Word chaining input, TSIN, indicates to a particular Codec the
beginning of its word within a frame in both slave and master
modes. The master mode Codec will generate a FSYNC output
which indicates the beginning of a frame. In single Codec
systems, the master’s FSYNC output should be tied to the
master’s TSIN input to indicate that the beginning of the frame
is also the beginning of its word. In multiple Codec daisy-chain
systems, the master’s FSYNC output should be tied to the
TSIN input of the Coded (either the master or one of the
slaves) which is intended to receive the first word in the frame.
FSYNC and TSIN are completely independent, and nothing
about the wiring of FSYNC to TSIN is determined by master or
slave status (i.e., the master can own any one of the words in the
frame). The master Codec’s FSYNC can also be tied to all of
the slave Codecs’ FSYNC pins. When a slave, a Codec’s
FSYNC output is three-stated. Thus, it can be connected to a
master’s FSYNC without consequence. See “Daisy-Chaining
Multiple Codecs” below for more details.
Clocks and the Serial Interface
O
The primary pins of the AD1849K’s serial interface are the
serial data receive (SDRX) input pin. The serial data transmit
(SRTX) pin, the serial data bit clock (SCLK) pin, the frame
sync output (FSYNC) pin, the chaining word input (TSIN) pin,
and the chaining word output (TSOUT) pin. The AD1849K
can operate in either master mode—in which case SCLK and
FSYNC are outputs and TSIN is an input—or in slave mode—
in which case SCLK and TSIN are inputs and FSYNC is threestated. If the AD1849K is in master mode, the internally
selected clock source is used to drive SCLK and FSYNC. Note
that in Control Mode, the Codec always behaves as a slave,
regardless of the current state of the MS (Master/Slave) bit.
The five possible combinations of clock source and master/slave
are summarized in Figure 5.
MASTER
SLAVE
INTERNAL OSCILLATORS
CLKIN
SCLK
YES
YES
IMPOSSIBLE
CONDITIONAL
CONDITIONAL
YES
The FSYNC rate is always equal to the data conversion sampling
frequency, FS. In Data Mode, the key significance of “frames” are
to synchronize the transfer of digital data between an AD1849K’s
internal ADCs and DACs and its serial interface circuitry. If, for
example, a Codec has been programmed for two words per
frame (FSEL = “1”), then it will trigger the data converters and
transfer data between the converters and the interface every 128
SCLKs. The TSIN input signals the Codec where its word
begins within the frame. In Control Mode, frame size is
irrelevant to the operation of any particular Codec; TSIN and
TSOUT are sufficient to convey all the information required.
Figure 5. Clock Source and Master/Slave Combinations
REV. A
–17–
AD1849K
TSIN is sampled on the falling edge of SCLK. A LO-to-HI
transition of TSIN defines the beginning of the word to occur at
the next rising edge of SCLK (for driving output data). The
LO-to-HI transition is defined by consecutive LO and HI
samples of TSIN at the falling edges of SCLK. Both input and
output data will be valid at the immediately subsequent falling
edge of SCLK. See Figures 6 and 7.
t CLK
t HI
t LO
SCLK
t IH
tS
SDRX AND TSIN
INPUTS
SCLK
t ZV
SDTX CONTROL
OR DATA BYTE 1,
BIT 7 OUTPUT
FSYNC, TSIN, &
TSOUT
t OH
tD
SDTX, FSYNC, AND
TSOUT OUTPUTS
t VZ
TE
SDTX CONTROL
OR DATA BYTE 8,
BIT 0 OUTPUT
SDRX & SDTX
tS
FIRST DATA BIT
OF WORD
t IH
PIO INPUTS
Figure 6. Timing Relationships
tD
PIO OUTPUTS
After the beginning of a word has been recognized, TSIN is a
“don’t care”; its state will be ignored until one SCLK period
before the end of the current word.
t OH
LE
Figure 7. Timing Parameters
B
SO
The AD1849K comes out of reset with the default conditions
specified in “Control Register Defaults.” It will be in the mode
specified by the D/C pin. If in Control Mode, the SoundPort
Codec can be configured by the host for operation. Subsequent
transitions to Control Mode after initialization are expected to
be relatively infrequent. Control information that is likely to
change frequently, e.g., gain levels, is transmitted along with the
data in Data Mode. See Figure 8 for a complete map of the data
and control information into the 64-bit Data Word and the
64-bit Control Word.
16-BIT STEREO DATA WORD
63
48 47
Left-Channel Audio
32 31 30 29 24 23
Right-Channel Audio
OM
LO
22 21
ADI SM
16 15 14
RO
PIO
13
OVR
12 11 8 7 4 3
IS
LG
MA
0
RG
16-BIT MONO DATA WORD
48 47
32 31 30 29 24 23
O
63
Left-Channel Audio
Left-Channel Audio
OM
LO
22 21
ADI SM
16 15 14
RO
PIO
13
OVR
12 11 8 7 4 3
IS
LG
MA
0
0000
8-BIT STEREO DATA WORD
63
56 55
48 47
40 39
32 31 30 29 24 23
Left Audio 0000 0000 Right Audio 0000 0000 OM
LO
22 21
ADI SM
16 15 14
RO
PIO
13
OVR
12 11 8 7 4 3
IS
LG
MA
0
RG
8-BIT MONO DATA WORD
63
56 55
32 31
Left Audio 0000 0000 Left Audio 0000 0000
30 29 24 23
OM
LO
22 21
ADI SM
16 15 14
RO
PIO
13
OVR
12 11 8 7 4 3
IS
LG
MA
0
0000
CONTROL WORD
63 61 60
59
58 57 56 55 54 53 51 50 49 48 47 46 44 43 42 41
001 MB OLB DCB 0 AC
00
DFR ST
DF
40
39
34
33
32 31 30 29 24 23
16 15 12 11
8 7
0
ITS MCK FSEL MS TXDIS 0000 00 ENL ADL PIO 00 0000 0000 0000 0010 REVID 0000 0000
Figure 8. Bit Positions for Data and Control
–18–
REV. A
AD1849K
frame, and SCLK as an input. The slaves FSYNC out-puts will
be three-stated and thus can be connected to the master’s FSYNC
without contention.
Up to four SoundPort Codecs can be daisy-chained with frame
sizes in multiples of 64 bits. The serial data is time-division
multiplexed (TDM), allocating each Codec its own 64-bit word
in the frame.
The pins that support TDM daisy-chaining of multiple Codecs
are the word chaining input (TSIN) and the word chaining output (TSOUT). As described above, TSIN is used to indicate
the position of the first bit of a particular Codec’s 64-bit word
within the total frame.
The word chaining output (TSOUT) is generated by every Codec
during the transmission of the last bit of its 64-bit word. The
first device in any Codec chain uses an externally generated or
self-generated FSYNC signal as an input to TSIN. The TSOUT
of the first Codec is wired directly to the TSIN of the second
Codec and so on. The waveform of TSOUT is a pulse of one
SCLK period in duration. All Codecs share the same SCLK,
FSYNC, SDRX, and SDTX lines since they are selecting
different words from a common frame.
EXTERNAL
DEVICE
SCLK
SCLK
SDTX
SDRX
SDRX
SDTX
AD1849K #1
MASTER
FSYNC
Both Data and Control Words allocate Bit positions for “parallel
I/O,” PIO1:0. This provides a convenient mechanism for transferring signaling information between the serial data and control
streams and the external pair of bidirectional pins also named
“PIO1” and “PIO0.” The states of the parallel I/O bits and pins
do not affect the internal operation of the Codec in any way;
their exclusive use is for system signaling.
The PIO pins are open-drain and should be pulled HI externally.
They can be read (through serial output data) in either Control
or Data Mode and can be written (through serial input data) in
Data Mode exclusively. The values in the PIO field of the Control
Word serial input in Control Mode will be ignored. An external
device may drive either PIO pin LO even when written HI by
the Codec, since the pin outputs are open-drain. Thus, a PIO
value read back as a serial output bit may differ from the value
just written as a serial input bit.
The PIO pins are read on the rising edge of SCLK five (5) SCLK
periods before the first PIO bit is transmitted out over the serial
interface. In Data Mode, the PIO pins are sampled as Bit 20 starts
to be driven out. In Control Mode, the PIO pins are sampled
as Bit 36 starts being driven out. Timing para-meters are as
shown in Figure 7; PIO pin input data is relative to the rising
edge of SCLK. (Note that only the PIO pins are read on SCLK
rising edges.)
B
SO
FSYNC
Parallel I/O Bits
LE
Note that a powered-down Codec immediately echoes TSIN on
TSOUT. Thus, a Codec can be added or removed from the
chain simply by using the PDN pin. See “Reset and Power
Down” below for more details. See Figure 9 for an illustration
of daisy-chained Codecs.
If SCLK is the clock source, it must run at 256 × FS, and therefore
the frame size must be 256 bits, i.e., four words. By contrast, if
the master Codec’s CLKOUT is used as the clock source, then
it can run at either 256 × FS or 128 × FS.
TE
Daisy-Chaining Multiple Codecs
TSIN
D/C
PDN1
PDN2
CLKOUT
TSOUT
D/C
RESET
PDN
RESET
SCLK
SDRX
SDTX
AD1849K #2
FSYNC
SLAVE
TSIN
O
TSOUT
CLKIN
D/C
PDN
RESET
Figure 9. Daisy-Chaining
Note that at most, one Codec in a daisy-chain can be in master
mode without contention. All other Codecs must be in slave
mode, receiving SCLK and TSIN externally.
Each slave can use SCLK as its clock source. However, as an
alternative, it is possible to connect the CLKOUT pin of the
master Codec to the CLKIN pins of the slaves, so that the
sam-ple frequency selected by the master (from one of its two
crystals) will be automatically applied to the slaves. The master
must be programmed for the desired sample frequency and the
correct number of bits per frame. The slaves must be programmed
for CLKIN as the clock source, the correct number of bits per
REV. A
The PIO pins are driven very shortly after the PIO data bits in
the input Data Word are read (Data Mode only). They are driven
on the falling edge of SCLK (unlike any other output). The PIO
data bits in the input are located at Bits 15 and 14 in the Data
Word and at Bits 31 and 30 in the Control Word (Figure 8).
Due to the five (5) SCLK period delay, the PIO pins will be
driven out with new values for Data Mode on the SCLK falling
edge when Bit 8 is read in, and for Control Mode on the SCLK
falling edge when Bit 24 is read in.
CODEC STARTUP, MODES, AND TRANSITIONS
Reset and Power-Down
The AD1849K stereo codec can be reset by either of two closely
related digital input signals, RESET and Power-Down (PDN).
RESET is active LO and PDN is active HI. Asserting PDN is
equivalent to asserting RESET with two exceptions. First, if
PDN is asserted (when RESET is HI), then the TSIN and
TSOUT chaining pins remain active. TSOUT will immediately
echo whatever signal is applied to TSIN during power down.
This feature allows a very simple system test to detect “life”
even in a power-down state. It also allows the user to selectively
shut off codecs in a daisy chain by powering down the unwanted
codecs. The down-stream codecs will simply move up a word
position in frame. The second difference is that power consumption
will be lower in power-down mode than in exclusive reset mode.
The CMOUT and LOUT1C pins will not supply current while
the AD1849K is in the power-down state since all outputs
collapse to ground.
–19–
AD1849K
RESET should be asserted when power is first applied to the
AD1849K. RESET should be asserted for a minimum of 50 ms
at power-up or when leaving the power-down mode to allow the
power supplies and the voltage reference to settle. Any time
RESET is asserted during normal operation, it should remain
asserted for a minimum of 100 ns to insure a complete reset.
Note that an autocalibration sequence will always occur when
RESET is deasserted, in addition to on the Control Mode to
Data Mode transition.
protocol to ensure a smooth transition between serial bus
masters (i.e., the external controller and the Codec) and
guarantee unambiguous serial bus ownership. This software
handshake protocol for Control Mode to Data Mode transitions
makes use of the Data/Control Bit (DCB) in the Control Mode
Control Word (Bit 58). Prior to initiating the change to Control
Mode, the external controller should gradually attenuate the
audio outputs. The DCB handshake protocol requires the
following steps:
Coming out of either reset or power down, the state of the Data/
Control pin (D/C) will determine whether the Codec is in Data
Mode or Control Mode. In the unlikely event that the control
register defaults are desired for Codec operation, it is possible to
go directly from reset or power down to Data Mode and begin
audio operation.
Enter Control Mode
LE
More typically, users coming out of reset or power down will
want to change the control register defaults by transmitting a
Control Word in Control Mode. The user of the AD1849K
SoundPort Codec can also enter Control Mode at any time
during normal Data Mode operation. The D/C pin is provided
to make this possible. The Codec enters Control Mode when
the D/C pin is driven LO or held LO when coming out of reset
and/or power down.
When ITS = 0 (Control Word Bit 47) and the Codec was operating as the master in the preceding Data Mode, immediately
after D/C goes LO, the Codec will drive FSYNC and TSOUT
LO for one SCLK period, then three-state FSYNC. SDTX is
three-stated immediately after D/C goes LO. TSOUT is not
three-stated. The Codec will drive SCLK for three (3) SCLK
periods after D/C goes LO and then three-state SCLK. The
external controller must wait at least three (3) SCLK periods
after it drives D/C LO, and then start driving SCLK.
TE
Control Mode
The external controller drives the D/C pin LO, forcing the
Codec into Control Mode as a slave. The DCB transmitted
from the external controller to the Codec may be “0” or “1”
at this point in the handshake.
When ITS = 1 (Control Word Bit 47) and the Codec was
operating as the master in the preceding Data Mode, the Codec
will three-state FSYNC, SDTX, and SCLK immediately after
D/C goes LO. TSOUT is driven LO immediately after D/C
goes LO and is not three-stated. The external controller may
start driving SCLK immediately.
B
SO
In Control Mode, the location of a word within a frame is
determined solely by the behavior of the TSIN and TSOUT
signals. Each Codec by itself does not care where the frame
boundaries fall as defined by the system. The contents of the
frame size select (FSEL1:0, Control Word Bits 43 and 42) bits
are irrelevant to the operation of each AD1849K in Control
Mode. In Control Mode, a Codec requires 64 SCLK cycles to
be fully programmed. Additional SCLK cycles (more than 64)
that occur before the end of the frame will be ignored.
If four Codecs, for example, were daisy-chained, then each Codec
would receive TSIN every 256 bits. In this case, Codec #2’s
input Control Word will be positioned between Bit 64 and Bit
127 in the input frame.
Control Word Echo
O
While in Control Mode, the AD1849K Codec will echo the
Control Word received as a serial input on the SDRX pin as a
serial output in the next frame on the SDTX pin. (SDTX will
be enabled regardless of the setting of the TXDIS bit, Control
Word Bit 40.) This echoing of the control information allows
the external controller to confirm that the Codec has received
the intended Control Word. For the four Codec daisy chain
example above, the Control Word will be echoed bit for bit as
an output between Bit 64 and Bit 127 in the next output frame.
In general, in Control Mode, the location of the echo Control
Word within a frame will be at the same word location as the
input Control Word.
In the first frame of Control Mode, the AD1849K will output a
Control Word that reflects the control register values operative
during the most recent Data Mode operation. If Control Mode
was entered prior to any Data Mode operation, this first output
word will simply reflect the standard default settings. DCB will
always be “1” in the first output echoed Control Word.
DCB Handshaking Protocol
The D/C pin can make transitions completely asynchronously to
internal Codec operation. This fact necessitates a handshaking
When ITS = 0 and the external controller was operating as the
master in the preceding Data Mode, the external controller
must continue to supply SCLK to the slave Codec for at least
three (3) SCLK periods after D/C goes LO before a Control
Mode TSIN is issued to the Codec. TSIN must be held LO
externally until the first Control Word in Control Mode is
supplied by the external controller. This prevents false starts
and can be easily accomplished by using a pull-down resistor on
TSIN as recommended. The slave Codec drives TSOUT and
SDTX LO, then three-states SDTX, all within 1 1/2 (one and
one half) SCLK periods after D/C goes LO. TSOUT is not
three-stated.
When ITS = 1 and the external controller was operating as the
master in the preceding Data Mode, the external controller
must continue to supply SCLK to the slave Codec. A Control
Mode TSIN should be issued to the Codec three or more SCLK
periods after D/C goes LO. The slave Codec drives TSOUT LO
and three-states SDTX immediately after D/C goes LO.
TSOUT is not three-stated.
The Codec initializes its Data Mode Control Registers to the
defaults identified above, which among other actions, mutes all
audio outputs.
First DCB Interlock
When the external controller is ready to continue with the DCB
handshake, the Control Word sent by the external controller
should have the DCB reset to “0” along with arbitrary control
information (i.e., the control information does not have to be
valid, although if it is valid, it allows the external controller to
verify that the echoed Control Word is correct). The external
controller should continue to transmit this bit pattern with
–20–
REV. A
AD1849K
DCB = “0” until the echoed DCB from the Codec also is reset
to “0” (i.e., it must poll DCB until a “0” is read). This is the
first interlock of the DCB handshake.
The DCB = “0” is echoed on SDTX in the next frame after it
was received on SDRX if a sample rate has been consistently
selected AND the clock source is generated using the internal
oscillator. Otherwise DCB = “0” will be echoed on SDTX in
the frame after at least 2 ms of consistent sample rate selection
expires. If SCLK or CLKIN is used as the clock source, the user
must guarantee that the source selection and sample rate are stable
for 2 ms before D/C is driven HI.
edge of SCLK. This allows external devices driven by SCLK to
recognize a complete FSYNC LO-to-HI transition. If an
AD1849K Codec enters Data Mode as a slave, it can recognize
a TSIN LO-to-HI transition even if SCLK is simultaneously
making its first LO-to-HI transition. In fact, the AD1849K
serial interface will operate properly even if D/C, SCLK, and
TSIN all go HI at the same time.
See Figure 10 for a flow chart representation of a typical startup
sequence, including the DCB handshake.
Apply power while RESET is pulled LO
and wait 50 milliseconds
Note that after sending a Control Word with DCB = “0,” the
external controller must take care not to set (or glitch) DCB =
“1” until after the echoed DCB = “0” has been received from
the Codec.
Second DCB Interlock
After it sees the DCB = “0” (and has optionally verified that
the echoed Control Word is correct), and when it is ready to
continue with the DCB handshake, the external controller
should transmit the desired and valid control information, but
now with DCB set to “1.” The external controller can then
transmit arbitrary control information until the echoed DCB
from the Codec is also set to “l” (i.e., it must poll DCB until a
“l” is read). After this Control Word with DCB = “1,” all future
control information received by the Codec during Control Mode
(i.e., while D/C is LO) will be ignored. This is the second and
final interlock of the DCB handshake.
Transmit a Control Word
to Codec with DCB LO
Wait for Codec to transmit
back a DCB LO
LE
O
Exit Control Mode
Control mode DCB handshake is now complete. The Codec
will remain inactive until D/C goes HI or RESET and or PDN
are asserted.
Note that if a sample rate and a clock source have been consistently selected throughout the handshake, the AD1849K and the
CS4215 DCB protocols are equivalent.
Control Mode to Data Mode Transition and Autocalibration
The AD1849K will enter Data Mode when the asynchronous
D/C signal goes HI. The serial interface will become active
immediately and begin receiving and transmitting Data Words
in accordance with the SCLK, FSYNC, TSIN, and TSOUT
signals as shown in Figure 6. If the Codec enters Data Mode as
a master, it will generate one complete SCLK period before it
drives FSYNC HI; FSYNC will go HI with the second rising
REV. A
FIRST DCB INTERLOCK
0 – 2ms
Transmit desired Control Word
to Codec with DCB HI
Wait for Codec to transmit
back a DCB HI
Bring D/C HI
B
SO
The Codec will echo DCB = “l” in the next frame after it was
received on SDRX if a sample rate has been consistently selected
AND the clock source is generated using the internal oscillator.
Otherwise DCB = “1” will be echoed on SDTX once one sample
rate selection has been held constant for at least 2 ms. If SCLK
or CLKIN is used as the clock source, the user must guarantee
that the source selection and sample rate are stable for 2 ms
before D/C is driven HI. The Codec will transmit the full 64-bit
Control Word with DCB = “1” and then three-state the SDTX
pin. The external controller must continue to supply SCLK to
the Codec until all 64 bits of the Control Word with DCB = “1”
have been transmitted by the Codec, plus at least one [1] more
SCLK after this 64-bit Control Word (i.e., at least 65 SCLKs).
Note that echoing the full 64-bit Control Word makes the
AD1849K match the behavior of the CS4215.
ENTER CONTROL MODE
TE
Provide TSIN and SCLK
signals to Codec. Drive RESET
HI (inactive) while D/C is LO
Transmit 194 Data Words
to Codec
SECOND DCB INTERLOCK
0 – 2ms
EXIT CONTROL MODE
AUTOCALIBRATION
Begin audio operation
Figure 10. Typical Startup Sequence
APPLICATIONS CIRCUITS
The AD1849K Stereo Codec has been designed to require a
minimum of external circuitry. The recommended circuits are
shown in Figures 11 through 20 and summarized in Figure 21.
Analog Devices estimates that the total cost of all the components shown in these Figures, including crystals, to be less than
$5 in 10,000 piece quantities.
Industry-standard compact disc “line-levels” are 2 V rms
centered around analog ground. (For other audio equipment,
“line level” is much more loosely defined.) The AD1849K
SoundPort is a 5 V only powered device. Line level voltage swings
for the AD1849K are defined to be 1 V rms for ADC input and
0.707 V rms for DAC output. Thus, 2 V rms input analog signals
must be attenuated and either centered around the reference
voltage intermediate between 0 V and 5 V or ac-coupled. The
CMOUT pin will be at this intermediate voltage, nominally
2.25 V. It has limited drive but can be used as a voltage datum to
an op amp input. Note, however, that dc-coupled inputs are not
recommended, as they provide no performance benefits with
the AD1849K architecture. Furthermore, dc offset differences
between multiple dc-coupled inputs create the potential for
“clicks” when changing the input mux selection.
–21–
AD1849K
A circuit for 2 V rms line-level inputs is shown in Figure 11.
Note that this is approximately a divide-by-two resistive divider.
1␮F
LOUT0L
47k⍀
0.33␮F
5.1k⍀
LINL
5.1k⍀
560pF
1␮F
LOUT0R
NPO
47k⍀
0.33␮F
5.1k⍀
LINR
Figure 13. Line Output Connections
5.1k⍀
560pF
A circuit for headphone drive is illustrated in Figure 14. Drive is
supplied by 5 V operational amps. The circuit shown ac couples
the headphones to the line output.
NPO
Figure 11. 2 V rms Line-Level Input Circuit
8.66k⍀
An external passive antialias filter is required. If line-level inputs
are already at the 1 V rms levels expected by the AD1849K, the
resistors in parallel with the 560 pF capacitors should be
omitted and the series 5.1 kΩ resistor should be decreased to
2.5 kΩ.
10k⍀
TE
470␮F
HEADPHONE
LEFT
SSM2135
LOUT1C
10k⍀
LOUT1R
470␮F
HEADPHONE
RIGHT
8.66k⍀
LE
The AD1849K Codec contains a bypassable 20 dB gain block
to accommodate condenser microphones. Particular system
requirements will depend upon the characteristics of the
intended microphone. Figure 12 illustrates one example of how
an electret condenser mike requiring phantom power could be
connected to the AD1849K. CMOUT is shown buffered by an
op amp; a transistor like a 2N4124 will also work fine for this
purpose. Note that if a battery-powered microphone is used, the
buffer and R2s are not needed. The values of R1, R2, and C
should be chosen in light of the mic characteristics and intended
gain. Typical values for these might be R1 = 20 kΩ, R2 = 2 kΩ,
and C = 220 pF.
LOUT1L
The AD1849K has a common return path LOUT1C which is
biased up to the CMOUT voltage, nominally 2.25 V. The
AD1849K allows for 6 dB larger output voltage swings by
resetting the OLB bit (Bit 59 of the Control Word) to “0.”
Figure 15 illustrates an alternative headphone connection for
the AD1849K which uses the LOUT1C pin to eliminate the
need for ac coupling. The 12 Ω resistors minimize output level
variations caused by different headphone impedances. LOUT1L,
LOUT1R and LOUT1C are short-circuit protected. Note that
driving headphones directly as shown in Figure 15 with OLB =
0 will cause clipping for large input signals and will only work
with very efficient “Walkman-type” headphones. For high
quality headphone listening, Analog Devices recommends the
circuit shown in Figure 14 with OLB = 1.
B
SO
C
R1
1␮F
5k⍀
0.33␮F
MINL
1/2 SSM2135
OR AD820
R2
LEFT ELECTRET
CONDENSER
MICROPHONE
INPUT
Figure 14. Headphone Drive Connections
CMOUT
1/2 SSM2135
OR AD820
C
R2
LOUT1L
R1
5k⍀
O
1␮F
RIGHT ELECTRET
CONDENSER
MICROPHONE
INPUT
LOUT1R
0.33␮F
12⍀ 1/2W
HEADPHONE
LEFT
12⍀ 1/2W
HEADPHONE
RIGHT
MINR
1/2 SSM2135
OR AD820
LOUT1C
CMOUT
HEADPHONE
RETURN
Figure 15. Optional Headphone Drive Connections
Figure 12. “Phantom-Powered” Microphone Input Circuit
Figure 13 shows ac-coupled line outputs. The resistors are
used to center the output signals around analog ground. If
dc-coupling is desired, CMOUT could be used with op amps
as mentioned below.
–22–
REV. A
AD1849K
No external circuitry is required for driving a single speaker
from the AD1849K’s mono outputs as shown in Figure 16.
Note that this output is differential. Analog Devices guarantees
specified distortion performance for speaker impedances of 48 Ω
or greater. Lower impedance speakers can be used, but at the
cost of some distortion. When driving speakers much less than
48 Ω, a power amp should be used. The AD1849K can drive
speakers of 32 Ω or greater.
MOUT
Zⱖ32⍀
The crystals shown in the crystal connection circuitry of Figure 19
should be fundamental-mode and parallel-tuned. Two sources for
the exact crystals specified are Component Marketing Services
in Massachusetts, U.S. at 617-762-4339 and Cardinal Components in New Jersey, U.S. at 201-746-0333. Note that using the
exact data sheet frequencies is not required and that external
clock sources can be used to overdrive the AD1849K’s internal
oscillators. (See the description of the MCK1:0 control bits above.)
If using an external clock source, apply it to the crystal input pins
while leaving the crystal output pins unconnected. Attention
should be paid to providing low jitter external input clocks.
CIN1
COUT1
CIN2
COUT2
MOUTR
20–64pF
Figure 17 illustrates reference bypassing. VREF should only be
connected to its bypass capacitors, which should be located as
close to Pin 21 as possible (especially the 0.1 µF capacitor).
VREF
CMOUT
10␮F
0.1␮F
20–64pF
20–64pF
16.9344MHz
20–64pF
Figure 19. Crystal Connections
Good, standard engineering practices should be applied for
power-supply decoupling. Decoupling capacitors should be
placed as close as possible to package pins. If a separate analog
power supply is not available, we recommend the circuit shown
in Figure 20 for using a single 5 V supply. Ferrite beads suffice
for the inductors shown. This circuitry should be as close to the
supply pins as is practical.
LE
10␮F
24.576MHz
TE
Figure 16. External Mono Speaker Connector
FERRITE
5V SUPPLY
Figure 17. Voltage Reference Bypassing
0.1␮F
1␮F
0.1␮F
B
SO
Figure 18 illustrates signal-path filtering capacitors, C0 and C1.
The AD1849K must use 1.0 µF capacitors.
C0
1␮F
C1
1␮F
REV. A
0.1␮F
VDD
VDD
0.1␮F
VDD
1.6⍀
1␮F
1␮F
0.1␮F
VCC
VCC
Figure 20. Recommended Power Supply Bypassing
The two PIO pins must be pulled HI, as they have open drain
outputs. Analog Devices also recommends pull-down resistors
for SCLK, FSYNC, SDTX, SDRX, and TSIN to provide
margin against system noise. CLKIN, CIN1, and CIN2, if not
used, should be grounded. A typical connection diagram is
shown in Figure 21, which serves to summarize the preceding
application circuits.
O
Figure 18. External Filter Capacitor Connections
FERRITE
0.1␮F
–23–
AD1849K
0.1␮F
FERRITE
0.1␮F
0.33␮F
VDD
0.1␮F
Note that the interface to the Texas Instruments TMS320C25
must be significantly more complicated than these three examples
because the C25’s serial port cannot be a master, which is
required of the external controller during Control Mode.
0.1␮F
VDD
VDD
VCC
LINL
5.1k⍀
1␮F
VCC
LINE IN
MOUT
LINR
560pF
NPO
MONO
SPEAKER
MOUTR
5.1k⍀
1␮F
PREFERRED
MICROPHONE
INPUT CIRCUIT
MINL
47k⍀
LINE
OUT 0
LOUT0R
1␮F
MINR
AD1849K
47k⍀
CMOUT
10␮F
LOUT1L
VREF
0.1␮F
LOUT1R
LOUT1C
LINE OUT 1 OR
PREFERRED
HEADPHONE
CIRCUIT
PDN
COUT1
C0
CIN1
C1
GNDA
16.9344MHz
CIN2
GNDA
PIO0
TSIN
RESET
FSYNC
PIO1
SCLK
VDD
SCLK
FSYNC
TSIN
SCLK0
RFS0
ADSP-2111
B
SO
PDN
47k⍀
Figure 22. Recommended Ground Plane
20–64pF
COUT2
C0
LE
24.576MHz
1␮F
1␮F
LOUT0R
NC
LOUT0L
AD1849K
10␮F
ANALOG GROUND PLANE
DIGITAL GROUND PLANE
0.33␮F
5.1k⍀
0.1␮F
TE
560pF
NPO
1␮F
1␮F
0.1␮F
5.1k⍀
Representative or on the Analog Devices DSP Bulletin Board.
The DSP Bulletin Board telephone number is 781-461-4258,
8 data bits, no parity, 1 stop bit, 300 to 2400 baud.
1.6⍀
FERRITE
5V
SUPPLY
AD1849K
SDRX
SDTX
D/C
DT0
DR0
FL0
SDTX
GNDD GNDD GNDD SDRX
20k⍀
Figure 21. Typical Connection Diagram
O
Analog Devices recommends a split ground plane as shown in
Figure 22. The analog plane and the digital plane are connected
directly under the AD1849K. Splitting the ground plane directly
under the SoundPort Codec is optimal because analog pins will
be located above the analog ground plane and digital pins will
be located directly above the digital ground plane for the best
isolation. The digital ground and analog grounds should be tied
together in the vicinity of the AD1849K. Other schemes may
also yield satisfactory results.
Figure 23 illustrates the “zero-chip” interfaces of the AD1849K
SoundPort Codec to four of Analog Devices’ Fixed-Point DSµPs.
The ADSP-2111, ADSP-2101 and ADSP-2115 use their multichannel serial port for the data interface and flag outputs for
D/C. The ADSP-2105 has a single serial port which operates in
its frameless mode. Because the ADSP-2105 lacks a flag output, it
alone does require additional circuitry to generate D/C. Shown is
an implementation using a single D-flop, an OR-gate, and two
pull-down resistors.
SCLK
FSYNC
TSIN
SCLK0
RFS0
UNUSED INPUTS SHOULD BE GROUNDED AND NC'S LEFT UNCONNECTED
ADSP-2101
AD1849K
ADSP-2115
DT0
DR0
FO
SDRX
SDTX
D/C
10k⍀
SCLK
SCLK
RFS
TFS
FSYNC
10k⍀
TSIN
AD1849K
ADSP-2105
DT
DR
D8
RESET
WR
DMS
D
Q
SDRX
SDTX
D/C
CLR
RESET
Figure 23. Interfaces to Analog Devices’ Fixed-Point
DS µPs
Low level ADSP-21xx software drivers for the AD1849K are
supplied with the AD1849K Evaluation Board. Source and
object codes arc available from your Analog Devices Sales
–24–
REV. A
AD1849K
CS4215 COMPATIBILITY
The Analog Devices AD1849K SoundPort Stereo Codec is pincompatible with the CS4215. These chips were independently
codeveloped to a common specification provided by Sun
Microsystems, Inc. Because of their independent development,
they will differ in performance and in minor details. A board can
be designed to accommodate either chip by attending to a few
differences in their required support circuitry.
• The Analog Devices AD1849K uses two external capacitors
to complete its internal input filter as shown in Figure 18.
The CS4215 calls the two pins on the AD1849K for these
capacitor connections, “no connects.” By laying out a board
with these capacitors, either chip will work.
• Analog Devices recommends a 10 µF bypass capacitor on the
voltage reference output, CMOUT (Pin 19). Using a 0.47 µF
capacitor may be acceptable in many systems, however DAC
performance at low sample rates will be improved with the
larger capacitor.
O
B
SO
LE
• The AD1849K requires an external passive antialias filter as
shown in Figure 11. In contrast, the recommended input
circuit for the CS4215 is a single-pole active filter requiring a
dual op amp. Though overkill for the AD1849K, this input
circuit will work with the AD1849K as well.
• While it is not required, it is strongly recommended that pin 38
on the AD1849K be connected to the digital power supply
and pin 39 be connected to digital ground. As these pins are
“no connect” on the CS4215, either chip will work in this
configuration.
TE
• If consistent control information is transmitted to the Codec
during Control Mode, the AD1849K DCB handshake is
compatible with the CS4215. See text for more details.
• The AD1849K was designed to require no external low-pass
filters on analog outputs. As shown in Figure 13, the AD1849K
only requires ac-coupling capacitors and resistors to line-level dc
bias. In contrast, the CS4215 has a single-pole passive filter for
its recommended line-level output circuit. Though overkill for
the AD1849K, this output circuit will work with the AD1849K
as well.
REV. A
–25–
AD1849K
FREQUENCY RESPONSE PLOTS
10
0
0
–10
–10
–20
–20
–30
–30
–40
–40
–50
–50
dB
–60
–70
–80
–80
–90
–90
–100
–100
–110
–110
–120
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
–120
0.0
1.0
Figure 24. Analog-to-Digital Frequency Response to FS (FullScale Line-Level Inputs, 0 dB Gain)
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Figure 26. Digital-to-Analog Frequency Response (Full-Scale
Inputs, 0 dB Attenuation)
10
10
0
LE
0
–10
–10
–20
–20
–30
–30
–40
–40
dB
–50
–60
–50
–60
–70
–80
–90
–100
–110
0.42
B
SO
–70
–120
0.40
0.1
SAMPLE FREQUENCY – FS
SAMPLE FREQUENCY – FS
dB
–60
–70
TE
dB
10
0.44
0.46
0.48
0.50
0.52
0.54
0.56
0.58
0.60
SAMPLE FREQUENCY – FS
–80
–90
–100
–110
–120
0.40
0.42
0.44
0.46 0.48 0.50 0.52 0.54
SAMPLE FREQUENCY – FS
0.56
0.58
0.60
Figure 27. Digital-to-Analog Frequency Response—
Transition Band (Full-Scale Inputs, 0 dB Attenuation)
O
Figure 25. Analog-to-Digital Frequency Response—
Transition Band (Full-Scale Line-Level Inputs, 0 dB Gain)
–26–
REV. A
AD1849K
O
B
SO
LE
TE
INDEX
PAGE
PRODUCT OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . 1
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . 6
PIN CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . 6
PIN FUNCTION DESCRIPTIONS . . . . . . . . . . . . . . . . . 7
FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . 8
Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Analog-to-Digital Datapath . . . . . . . . . . . . . . . . . . . . . . . 8
Digital-to-Analog Datapath . . . . . . . . . . . . . . . . . . . . . . . 8
Monitor Mix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Analog Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Digital Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Power Supplies and Voltage Reference . . . . . . . . . . . . . . . 9
Autocalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Loopback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Clocks and Sample Rates . . . . . . . . . . . . . . . . . . . . . . . . 10
CONTROL REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . 11
Control Mode Control Registers . . . . . . . . . . . . . . . . . . 11
Data Mode Data and Control Registers . . . . . . . . . . . . . 14
Control Register Defaults . . . . . . . . . . . . . . . . . . . . . . . . 16
SERIAL INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Frames and Words . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Clocks and the Serial Interface . . . . . . . . . . . . . . . . . . . . 17
Timing Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Daisy-Chaining Multiple Codecs . . . . . . . . . . . . . . . . . . 19
Parallel I/O Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
CODEC STARTUP, MODES, AND TRANSITIONS . . 19
Reset and Power-Down . . . . . . . . . . . . . . . . . . . . . . . . . 19
Control Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Control Word Echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
DCB Handshaking Protocol . . . . . . . . . . . . . . . . . . . . . . 20
Control Mode to Data Mode Transition
and Autocalibration . . . . . . . . . . . . . . . . . . . . . . . . . . 21
APPLICATIONS CIRCUITS . . . . . . . . . . . . . . . . . . . . . 21
CS4215 COMPATIBILITY . . . . . . . . . . . . . . . . . . . . . . . 25
FREQUENCY RESPONSE PLOTS . . . . . . . . . . . . . . . . 26
OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . 28
REV. A
–27–
AD1849K
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
C00729–0–10/00 (rev. A)
44-Lead Plastic Leaded Chip Carrier (PLCC)
(P–44A)
0.180 (4.57)
0.165 (4.19)
0.048 (1.21)
0.042 (1.07)
0.056 (1.42)
0.042 (1.07)
6
7
PIN 1
IDENTIFIER
0.025 (0.63)
0.015 (0.38)
40
39
0.050
(1.27)
BSC
17
BOTTOM VIEW
(PINS UP)
0.040 (1.01)
0.025 (0.64)
0.656 (16.66)
SQ
0.650 (16.51)
0.110 (2.79)
0.085 (2.16)
PRINTED IN U.S.A.
O
B
SO
LE
0.695 (17.65)
SQ
0.685 (17.40)
PIN 1
IDENTIFIER
0.032 (0.81)
0.026 (0.66)
29
28
18
0.020
(0.50)
R
0.63 (16.00)
0.59 (14.99)
0.021 (0.53)
0.013 (0.33)
TOP VIEW
(PINS DOWN)
0.020
(0.50)
R
TE
0.048 (1.21)
0.042 (1.07)
–28–
REV. A