TI PCM1795DBR

PCM1795
www.ti.com ........................................................................................................................................................................................................ SLES248 – MAY 2009
32-Bit, 192-kHz Sampling, Advanced Segment,
Stereo Audio Digital-to-Analog Converter
FEATURES
APPLICATIONS
• 32-Bit Resolution
• Analog Performance:
– Dynamic Range: 123 dB
– THD+N: 0.0005%
• Differential Current Output: 3.9 mAPP
• 8× Oversampling Digital Filter:
– Stop Band Attenuation: –98 dB
– Passband Ripple: ±0.0002 dB
• Sampling Frequency: 10 kHz to 200 kHz
• System Clock: 128, 192, 256, 384, 512, or
768 fS With Autodetect
• Accepts 16-, 24-, and 32-Bit Audio Data
• PCM Data Formats: Standard, I2S™, and
Left-Justified
• DSD Format Interface Available
• Interface Available for Optional External Digital
Filter or DSP
• TDMCA or Serial Port (SPI™/I2C™)
• User-Programmable Mode Controls:
– Digital Attenuation: 0 dB to –120 dB,
0.5-dB/Step
– Digital De-Emphasis
– Digital Filter Roll-Off: Sharp or Slow
– Soft Mute
– Zero Flag for Each Output
• Compatible With PCM1792A and PCM1796
(Pins and Mode Controls)
• Dual Supply Operation:
– 5-V Analog, 3.3-V Digital
• 5-V Tolerant Digital Inputs
• Small SSOP-28 Package
•
•
•
•
•
•
•
1
234567
A/V Receivers
SACD Players
DVD Players
HDTV Receivers
Car Audio Systems
Digital Multitrack Recorders
Other Applications Requiring 32-Bit Audio
DESCRIPTION
The PCM1795 is a monolithic CMOS integrated
circuit
that
includes
stereo
digital-to-analog
converters (DACs) and support circuitry in a small
SSOP-28 package. The data converters use TI’s
advanced segment DAC architecture to achieve
excellent dynamic performance and improved
tolerance to clock jitter. The PCM1795 provides
balanced current outputs, allowing the user to
optimize analog performance externally. The
PCM1795 accepts pulse code modulation (PCM) and
direct stream digital (DSD) audio data formats,
providing an easy interface to audio digital signal
processors (DSPs) and decoder chips. The PCM1795
also interfaces with external digital filter devices such
as the DF1704, DF1706, and the PMD200 from
Pacific Microsonics™. Sampling rates up to 200 kHz
are supported. A full set of user-programmable
functions is accessible through an SPI or I2C serial
control port that supports register write and readback
functions. The PCM1795 also supports the
time-division-multiplexed (TDM) command and audio
(TDMCA) data format.
1
2
3
4
5
6
7
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
System Two, Audio Precision are trademarks of Audio Precision, Inc.
SPI is a trademark of Motorola.
I2S, I2C are trademarks of NXP Semiconductors.
Pacific Microsonics is a trademark of Pacific Microsonics, Inc.
Super Audio CD is a trademark of Sony Corporation.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2009, Texas Instruments Incorporated
PCM1795
SLES248 – MAY 2009 ........................................................................................................................................................................................................ www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
ORDERING INFORMATION (1)
(1)
PRODUCT
PACKAGELEAD
PACKAGE
DESIGNATOR
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
PCM1795
SSOP-28
DB
–25°C to +85°C
PCM1795
ORDERING
NUMBER
TRANSPORT MEDIA,
QUANTITY
PCM1795DB
Tube
PCM1795DBR
Tape and Reel
For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range, unless otherwise noted.
Supply voltage
VCC1, VCC2L, VCC2R
VDD
VALUE
UNIT
–0.3 to +6.5
V
–0.3 to +4
V
Supply voltage differences
VCC1, VCC2L, VCC2R
±0.1
V
Ground voltage differences
AGND1, AGND2, AGND3L, AGND3R, DGND
±0.1
V
–0.3 to +6.5
V
–0.3 to (VDD + 0.3) < 4
V
Digital input voltage
LRCK, DATA, BCK, SCK, MSEL, RST, MS
MDO (2), ZEROL (2), ZEROR (2)
ZEROL
(3)
(3)
(3)
, ZEROR , MDO , MS
(2)
, MDI, MC,
(3)
Analog input voltage
–0.3 to (VCC + 0.3) < 6.5
V
±10
mA
Ambient temperature under bias
–40 to +125
°C
Storage temperature
–55 to +150
°C
Junction temperature
+150
°C
Package temperature (IR reflow, peak)
+260
°C
Input current (any pins except supplies)
(1)
(2)
(3)
2
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Input mode or I2C mode.
Output mode except for I2C mode.
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ELECTRICAL CHARACTERISTICS
All specifications at TA = +25°C, VCC1 = VCC2L = VCC2R = 5 V, VDD = 3.3 V, fS = 48 kHz, system clock = 256 fS, and 32-bit
data, unless otherwise noted.
PCM1795 DB
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
RESOLUTION
Resolution
32
Bits
DATA FORMAT (PCM Mode)
Audio data interface format
Standard, I2S, left-justified
Audio data bit length
16-, 24-, 32-bit selectable
Audio data format
fS
MSB first, twos complement
Sampling frequency
10
System clock frequency
200
128, 192, 256, 384, 512, 768
kHz
fS
DATA FORMAT (DSD Mode)
Audio data interface format
DSD (direct stream digital)
Audio data bit length
fS
1
Sampling frequency
Bit
2.8224
System clock frequency
2.8224
MHz
11.2986
MHz
DIGITAL INPUT/OUTPUT
TTL
compatible
Logic family
VIH
VIL
IIH
IIL
VOH
VOL
2
Input logic level
Input logic current
DYNAMIC PERFORMANCE (PCM MODE)
THD+N at VOUT = 0 dB
VDC
VIN = VDD
10
µA
VIN = 0 V
–10
IOH = –2 mA
Output logic level
2.4
IOL = 2 mA
0.4
fS = 48 kHz
0.0005
fS = 96 kHz
0.001
fS = 192 kHz
(1)
(2)
%
%
%
dB
123
dB
123
dB
123
dB
EIAJ, A-weighted, fS = 96 kHz
123
dB
EIAJ, A-weighted, fS = 192 kHz
123
dB
EIAJ, A-weighted, fS = 96 kHz
fS = 48 kHz
Level linearity error
0.001
123
EIAJ, A-weighted, fS = 48 kHz
Channel separation
VDC
0.0015
120
EIAJ, A-weighted, fS = 192 kHz
Signal-to-noise ratio
µA
VDC
(1) (2)
EIAJ, A-weighted, fS = 48 kHz
Dynamic range
VDC
0.8
120
119
dB
fS = 96 kHz
116
118
dB
fS = 192 kHz
117
dB
VOUT = –120 dB
±1
dB
Filter condition:
THD+N: 20-Hz high-pass filter (HPF), 20-kHz AES17 low-pass filter (LPF)
Dynamic range: 20-Hz HPF, 20-kHz AES17 LPF, A-weighted
Signal-to-noise ratio: 20-Hz HPF, 20-kHz AES17 LPF, A-weighted
Channel separation: 20-Hz HPF, 20-kHz AES17 LPF
Analog performance specifications are measured using the System Two™ Cascade audio measurement system by Audio Precision™ in
the averaging mode.
Dynamic performance and dc accuracy are specified at the output of the post-amplifier as shown in Figure 52.
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ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, VCC1 = VCC2L = VCC2R = 5 V, VDD = 3.3 V, fS = 48 kHz, system clock = 256 fS, and 32-bit
data, unless otherwise noted.
PCM1795 DB
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DYNAMIC PERFORMANCE (MONO MODE) (3) (4) (5)
fS = 48 kHz
0.0005
%
fS = 96 kHz
0.001
%
fS = 192 kHz
0.0015
%
EIAJ, A-weighted, fS = 48 kHz
126
dB
THD+N at VOUT = 0 dB
Dynamic range
Signal-to-noise ratio
EIAJ, A-weighted, fS = 96 kHz
126
dB
EIAJ, A-weighted, fS = 192 kHz
126
dB
EIAJ, A-weighted, fS = 48 kHz
126
dB
EIAJ, A-weighted, fS = 96 kHz
126
dB
EIAJ, A-weighted, fS = 192 kHz
126
dB
0.0007
%
–60 dB, EIAJ, A-weighted
122
dB
EIAJ, A-weighted
122
dB
DSD MODE DYNAMIC PERFORMANCE (44.1 kHz, 64 fS) (3) (6)
THD+N at FS
2 V rms
Dynamic range
Signal-to-noise ratio
ANALOG OUTPUT
Gain error
–7
±2
7
% of FSR
Gain mismatch, channel-to-channel
–3
±0.5
3
% of FSR
–2
±0.5
2
% of FSR
Bipolar zero error
At BPZ
Output current
Full-scale (0 dB)
Center current
At BPZ
4
mAPP
–3.5
mA
DIGITAL FILTER PERFORMANCE
De-emphasis error
±0.1
dB
±0.0002 dB
0.454
fS
–3 dB
0.49
fS
±0.0002
dB
FILTER CHARACTERISTICS–1: SHARP ROLL-OFF
Passband
Stop band
0.546
fS
Passband ripple
Stop-band attenuation
Stop band = 0.546 fS
–98
Delay time
dB
38/fS
s
FILTER CHARACTERISTICS–2: SLOW ROLL-OFF
Passband
±0.001 dB
0.21
fS
–3 dB
0.448
fS
±0.001
dB
Stop band
0.79
fS
Passband ripple
Stop-band attenuation
Stop band = 0.732 fS
Delay time
(3)
(4)
(5)
(6)
4
–80
dB
38/fS
s
Filter condition:
THD+N: 20-Hz high-pass filter (HPF), 20-kHz AES17 low-pass filter (LPF)
Dynamic range: 20-Hz HPF, 20-kHz AES17 LPF, A-weighted
Signal-to-noise ratio: 20-Hz HPF, 20-kHz AES17 LPF, A-weighted
Channel separation: 20-Hz HPF, 20-kHz AES17 LPF
Analog performance specifications are measured using the System Two™ Cascade audio measurement system by Audio Precision™ in
the averaging mode.
Dynamic performance and dc accuracy are specified at the output of the post-amplifier as shown in Figure 52.
Dynamic performance and dc accuracy are specified at the output of the measurement circuit as shown in Figure 54.
Dynamic performance and dc accuracy are specified at the output of the post-amplifier as shown in Figure 53.
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ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, VCC1 = VCC2L = VCC2R = 5 V, VDD = 3.3 V, fS = 48 kHz, system clock = 256 fS, and 32-bit
data, unless otherwise noted.
PCM1795 DB
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
3
3.3
3.6
VDC
4.75
5
5.25
VDC
fS = 48 kHz
6
8
mA
fS = 96 kHz
11
mA
fS = 192 kHz
21
mA
fS = 44.1 kHz
18
fS = 96 kHz
19
fS = 192 kHz
20
fS = 48 kHz
110
fS = 96 kHz
131
mW
fS = 192 kHz
166
mW
POWER-SUPPLY REQUIREMENTS
VDD
VCC1
VCC2L
Voltage range
VCC2R
IDD
Supply current (7)
ICC
Power dissipation (7)
23
mA
mA
mA
141
mW
TEMPERATURE RANGE
Operating temperature
θJA
(7)
Thermal resistance
–25
SSOP-28
+85
+100
°C
°C/W
Input is bipolar zero (BPZ) data.
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FUNCTIONAL BLOCK DIAGRAM
IOUTLLRCK
Current
Segment
DAC
BCK
DATA
Audio
Data Input
I/F
VOUTL
IOUTL+
I/V and Filter
RST
x8
Oversampling
Digital Filter
and
Function Control
MDO
VCOML
Advanced
Segment
DAC
Modulator
IREF
Bias
and VREF
VCOMR
MDI
MC
MS
IOUTR-
Function
Control I/F
Current
Segment
DAC
VOUTR
IOUTR+
MSEL
I/V and Filter
System
Clock
Manager
6
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VCC2L
VCC2R
VCC1
AGND3R
AGND3L
AGND2
AGND1
Power Supply
VDD
SCK
ZEROR
Zero
Detect
DGND
ZEROL
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PIN CONFIGURATION
DB PACKAGE
SSOP-28
(TOP VIEW)
ZEROL
1
28
VCC2L
ZEROR
2
27
AGND3L
MSEL
3
26
IOUTL-
LRCK
4
25
IOUTL+
DATA
5
24
AGND2
BCK
6
23
VCC1
SCL
7
22
VCOML
DGND
8
21
VCOMR
VDD
9
20
IREF
MS
10
19
AGND1
MDI
11
18
IOUTR-
MC
12
17
IOUTR+
MDO
13
16
AGND3R
RST
14
15
VCC2R
Table 1. TERMINAL FUNCTIONS
TERMINAL
NAME
NO.
I/O
AGND1
19
—
Analog ground (internal bias)
AGND2
24
—
Analog ground (internal bias)
AGND3L
27
—
Analog ground (left channel DACFF)
AGND3R
16
—
Analog ground (right channel DACFF)
BCK
6
I
Bit clock input (1)
DATA
5
I
Serial audio data input (2)
DGND
8
—
Digital ground
IOUTL+
25
O
Left channel analog current output+
IOUTL–
26
O
Left channel analog current output–
IOUTR+
17
O
Right channel analog current output+
IOUTR–
18
O
Right channel analog current output–
IREF
20
—
Output current reference bias pin
LRCK
4
I
Left and right clock (fS) input (2)
MC
12
I
Mode control clock input (2)
MDI
11
I
Mode control data input (2)
MDO
13
I/O
Mode control readback data output (3)
MS
10
I/OI
Mode control chip-select input (4); active low
MSEL
3
I
I2C/SPI select (2); active low SPI select
RST
14
I
Reset (2); active low
(1)
(2)
(3)
(4)
DESCRIPTION
Schmitt-trigger input, 5-V tolerant.
Schmitt-trigger input, 5-V tolerant.
Schmitt-trigger input and output. 5-V tolerant input. In I2C mode, this pin becomes an open-drain 3-state output; otherwise, this pin is a
CMOS output.
Schmitt-trigger input and output. 5-V tolerant input and CMOS output.
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Table 1. TERMINAL FUNCTIONS (continued)
TERMINAL
NAME
NO.
I/O
SCK
7
I
VCC1
23
—
Analog power supply, 5 V
VCC2L
28
—
Analog power supply (left channel DACFF), 5 V
VCC2R
15
—
Analog power supply (right channel DACFF), 5 V
VCOML
22
—
Left channel internal bias decoupling pin
VCOMR
21
—
Right channel internal bias decoupling pin
VDD
9
—
Digital power supply, 3.3 V
ZEROL
1
I/O
Zero flag for left channel (4)
ZEROR
2
I/O
Zero flag for right channel (4)
8
DESCRIPTION
System clock input (2)
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TIMING CHARACTERISTICS
Repeated Start
Start
Stop
t(SDA-F)
t(D-HD)
t(BUF)
t(D-SU)
t(SDA-R)
t(P-SU)
SDA
t(SCL-R)
t(RS-HD)
t(SP)
t(LOW)
SCL
t(SCL-F)
t(HI)
t(RS-SU)
t(S-HD)
Figure 1. Timing Definition on the I2C Bus
TIMING REQUIREMENTS
PARAMETER
f(SCL)
t(BUF)
t(LOW)
CONDITIONS
SCL clock frequency
Fast
Bus free time between stop and start conditions
Low period of the SCL clock
High period of the SCL clock
t(RS-SU)
Setup time for (repeated) start condition
t(RS-HD)
t(D-SU)
t(D-HD)
400
kHz
µs
1.3
µs
Standard
4.7
µs
Fast
1.3
µs
4
µs
600
ns
Standard
4.7
µs
Fast
600
ns
4
µs
Fast
600
ns
Standard
250
ns
Fast
100
Standard
Data hold time
kHz
Fast
Standard
Data setup time
UNIT
100
4.7
Fast
Hold time for (repeated) start condition
MAX
Standard
Standard
t(HI)
t(S-HD)
MIN
Standard
Fast
0
ns
900
ns
0
900
ns
Standard
20 + 0.1 CB
1000
ns
Fast
20 + 0.1 CB
300
ns
t(SCL-R)
Rise time of SCL signal
t(SCL-R1)
Rise time of SCL signal after a repeated start condition Standard
and after an acknowledge bit
Fast
20 + 0.1 CB
1000
ns
20 + 0.1 CB
300
ns
Standard
20 + 0.1 CB
1000
ns
Fast
20 + 0.1 CB
300
ns
Standard
20 + 0.1 CB
1000
ns
Fast
20 + 0.1 CB
300
ns
Standard
20 + 0.1 CB
1000
ns
Fast
20 + 0.1 CB
300
t(SCL-F)
t(SDA-R)
t(SDA-F)
Fall time of SCL signal
Rise time of SDA signal
Fall time of SDA signal
Standard
t(P-SU)
Setup time for stop condition
C(B)
Capacitive load for SDA and SCL line
t(SP)
Pulse duration of suppressed spike
VNH
Noise margin at high level for each connected device
(including hysteresis)
Fast
µs
600
ns
Fast
400
pF
50
ns
0.2 VDD
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4
V
9
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TYPICAL CHARACTERISTICS: DIGITAL FILTER
Digital Filter Response
AMPLITUDE vs FREQUENCY
0
AMPLITUDE vs FREQUENCY
0.0005
Frequency Response
Sharp Roll-Off
-20
0.0003
Amplitude (dB)
-40
Amplitude (dB)
Passband Ripple
Sharp Roll-Off
0.0004
-60
-80
-100
0.0002
0.0001
0
-0.0001
-0.0002
-120
-0.0003
-140
-0.0004
-160
0
1
2
3
4
-0.0005
0
0.1
0.2
Frequency (´ fS)
Figure 2.
AMPLITUDE vs FREQUENCY
-2
-4
Amplitude (dB)
Amplitude (dB)
-40
-60
-80
-100
-6
-8
-10
-12
-14
-120
-16
-140
Transition Characteristics
Slow Roll-Off
-18
-160
0
1
2
3
4
-20
0
Frequency (´ fS)
0.1
0.2
0.3
0.4
0.5
0.6
Frequency (´ fS)
Figure 4.
10
0.5
0
Frequency Response
Slow Roll-Off
-20
0.4
Figure 3.
AMPLITUDE vs FREQUENCY
0
0.3
Frequency (´ fS)
Figure 5.
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TYPICAL CHARACTERISTICS: DIGITAL FILTER
De-Emphasis Filter
DE-EMPHASIS LEVEL vs FREQUENCY
0
fS = 32 kHz
-1
fS = 32 kHz
0.4
-2
De-Emphasis Error (dB)
De-Emphasis Level (dB)
DE-EMPHASIS ERROR vs FREQUENCY
0.5
-3
-4
-5
-6
-7
-8
-9
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-10
0
2
4
6
12
10
8
-0.5
14
0
6
10
8
Figure 6.
Figure 7.
DE-EMPHASIS LEVEL vs FREQUENCY
12
14
DE-EMPHASIS ERROR vs FREQUENCY
0.5
fS = 44.1 kHz
-1
fS = 44.1 kHz
0.4
-2
De-Emphasis Error (dB)
De-Emphasis Level (dB)
4
Frequency (kHz)
0
-3
-4
-5
-6
-7
-8
-9
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-10
0
2
4
6
10
8
12
14
16
18
-0.5
20
0
2
4
6
10
8
12
Frequency (kHz)
Frequency (kHz)
Figure 8.
Figure 9.
DE-EMPHASIS LEVEL vs FREQUENCY
0
14
16
18
20
DE-EMPHASIS ERROR vs FREQUENCY
0.5
fS = 48 kHz
-1
fS = 48 kHz
0.4
-2
De-Emphasis Error (dB)
De-Emphasis Level (dB)
2
Frequency (kHz)
-3
-4
-5
-6
-7
-8
-9
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-10
0
2
4
6
8
10
12
14
16
18
20
22
-0.5
0
2
4
6
8
10
12
14
Frequency (kHz)
Frequency (kHz)
Figure 10.
Figure 11.
16
18
20
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TYPICAL CHARACTERISTICS: ANALOG DYNAMIC PERFORMANCE
Supply Voltage Characteristics
PCM mode, TA = +25°C, and VDD = 3.3 V; measured with circuit shown in Figure 52, unless otherwise noted.
THD+N vs SUPPLY VOLTAGE
DYNAMIC RANGE vs SUPPLY VOLTAGE
126
fS = 192 kHz
fS = 192 kHz
fS = 96 kHz
0.001
fS = 48 kHz
0.0001
4.50
4.75
122
fS = 48 kHz
120
118
5.00
116
4.50
5.50
5.25
4.75
Supply Voltage (V)
SNR vs SUPPLY VOLTAGE
5.50
CHANNEL SEPARATION vs SUPPLY VOLTAGE
122
124
122
fS = 192 kHz
120
118
4.75
5.00
fS = 96 kHz
fS = 96 kHz
5.25
5.50
Channel Separation (dB)
fS = 48 kHz
Signal-to-Noise Ratio (dB)
5.25
Figure 13.
126
116
4.50
5.00
Supply Voltage (V)
Figure 12.
12
fS = 96 kHz
124
Dynamic Range (dB)
Total Harmonic Distortion + Noise (%)
0.01
120
118
fS = 48 kHz
fS = 192 kHz
116
114
112
4.50
4.75
5.00
Supply Voltage (V)
Supply Voltage (V)
Figure 14.
Figure 15.
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5.50
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TYPICAL CHARACTERISTICS: ANALOG DYNAMIC PERFORMANCE
Temperature Characteristics
PCM mode, VDD = 3.3 V, and VCC = 5 V; measured with circuit shown in Figure 52, unless otherwise noted.
THD+N vs FREE-AIR TEMPERATURE
DYNAMIC RANGE vs FREE-AIR TEMPERATURE
126
fS = 96 kHz
124
Dynamic Range (dB)
Total Harmonic Distortion + Noise (%)
0.01
fS = 192 kHz
0.001
fS = 48 kHz
fS = 96 kHz
122
120
118
0.0001
116
-50
0
-25
50
25
75
100
-50
0
-25
Free-Air Temperature (°C)
75
100
Figure 17.
SNR vs FREE-AIR TEMPERATURE
CHANNEL SEPARATION vs FREE-AIR TEMPERATURE
126
122
fS = 96 kHz
fS = 96 kHz
124
Channel Separation (dB)
Signal-to-Noise Ratio (dB)
50
25
Free-Air Temperature (°C)
Figure 16.
122
fS = 48 kHz
fS = 192 kHz
120
118
116
fS = 48 kHz
120
fS = 192 kHz
118
116
114
112
0
-25
50
25
75
100
-50
-25
0
50
25
75
Free-Air Temperature (°C)
Free-Air Temperature (°C)
Figure 18.
Figure 19.
AMPLITUDE vs FREQUENCY
(Measurement Circuit: Figure 52)
AMPLITUDE vs FREQUENCY
(Measurement Circuit: Figure 52)
0
-60-dB Output Spectrum
BW = 20 kHz
PCM Mode
fS = 48 kHz
32768 Point 8 Average
TA = +25°C
VDD = 3.3 V
VCC = 5 V
-20
-40
-60
-80
-100
0
-40
-60
-80
-100
-120
-120
-140
-140
-160
100
-60-dB Output Spectrum
BW = 100 kHz
PCM Mode
fS = 96 kHz
32768 Point 8 Average
TA = +25°C
VDD = 3.3 V
VCC = 5 V
-20
Amplitude (dB)
-50
Amplitude (dB)
fS = 192 kHz
fS = 48 kHz
-160
0
2
4
6
8
10
12
14
16
18
20
0
Frequency (kHz)
10
20
30
40
50
60
70
80
90
100
Frequency (kHz)
Figure 20.
Figure 21.
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TYPICAL CHARACTERISTICS: ANALOG DYNAMIC PERFORMANCE (continued)
PCM mode, VDD = 3.3 V, and VCC = 5 V; measured with circuit shown in Figure 52, unless otherwise noted.
AMPLITUDE vs FREQUENCY
(Measurement Circuit: Figure 52)
-120
-120
-144-dB Output Spectrum
BW = 20 kHz
PCM Mode
fS = 48 kHz
32768 Point 8 Average
TA = +25°C
VDD = 3.3 V
VCC = 5 V
-128
-132
-136
-140
-144
-128
-132
-136
-140
-144
-148
-148
-152
-152
-156
-156
-160
100
-160
10 k
1k
-150-dB Output Spectrum
BW = 20 kHz
PCM Mode
fS = 48 kHz
32768 Point 8 Average
TA = +25°C
VDD = 3.3 V
VCC = 5 V
-124
Amplitude (dB)
-124
Amplitude (dB)
AMPLITUDE vs FREQUENCY
(Measurement Circuit: Figure 52)
100
Frequency (Hz)
Figure 22.
Figure 23.
THD+N vs INPUT LEVEL
(Measurement Circuit: Figure 52)
AMPLITUDE vs FREQUENCY
(Measurement Circuit: Figure 53)
PCM Mode
fS = 48 kHz
TA = +25°C
VDD = 3.3 V
VCC = 5 V
1
0.1
0.01
0
-60-dB Output Spectrum
DSD Mode (FIR-2)
32768 Point 8 Average
TA = +25°C
VDD = 3.3 V
VCC = 5 V
-20
-40
Amplitude (dB)
Total Harmonic Distortion + Noise (%)
10
-60
-80
-100
-120
0.001
-140
-160
0.0001
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
0
2
4
6
8
10
12
14
16
18
20
Frequency (kHz)
Input Level (dBFS)
Figure 24.
14
10 k
1k
Frequency (Hz)
Figure 25.
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TYPICAL CHARACTERISTICS: ANALOG FIR FILTER PERFORMANCE IN DSD MODE
All specifications at DBCK = 2.8224 MHz (44.1 kHz × 64 fS), and 50% modulation DSD data input, unless otherwise noted.
GAIN vs FREQUENCY (1)
GAIN vs FREQUENCY
0
0
DSD Filter-1
Low Bandwidth
-1
-10
-20
Gain (dB)
-2
Gain (dB)
DSD Filter-1
High Bandwidth
fC = 185 kHz
Gain = -6.6 dB
-3
-30
-4
-40
-5
-50
-6
-60
0
50
100
150
200
0
Figure 26.
Figure 27.
GAIN vs FREQUENCY
GAIN vs FREQUENCY
0
DSD Filter-2
Low Bandwidth
-1
-20
Gain (dB)
Gain (dB)
DSD Filter-2
High Bandwidth
fC = 90 kHz
Gain = 0.3 dB
-10
-2
-3
-30
-4
-40
-5
-50
-6
-60
0
50
100
150
200
0
500 k
Frequency (Hz)
Figure 28.
Figure 29.
GAIN vs FREQUENCY
GAIN vs FREQUENCY
0
DSD Filter-3
Low Bandwidth
-1
1.5 M
1M
Frequency (kHz)
0
DSD Filter-3
High Bandwidth
fC = 85 kHz
Gain = -1.5 dB
-10
-20
Gain (dB)
-2
Gain (dB)
1.5 M
1M
Frequency (Hz)
0
-3
-30
-4
-40
-5
-50
-6
-60
0
(1)
500 k
Frequency (kHz)
50
100
150
200
0
500 k
1M
Frequency (kHz)
Frequency (Hz)
Figure 30.
Figure 31.
1.5 M
This gain is in comparison to PCM 0 dB, when the DSD input signal efficiency is 50%.
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TYPICAL CHARACTERISTICS: ANALOG FIR FILTER PERFORMANCE IN DSD MODE (continued)
All specifications at DBCK = 2.8224 MHz (44.1 kHz × 64 fS), and 50% modulation DSD data input, unless otherwise noted.
GAIN vs FREQUENCY
0
GAIN vs FREQUENCY
0
DSD Filter-4
Low Bandwidth
-1
-20
Gain (dB)
Gain (dB)
-2
-3
-30
-4
-40
-5
-50
-6
-60
0
16
DSD Filter-4
High Bandwidth
fC = 94 kHz
Gain = -3.3 dB
-10
50
100
150
200
0
500 k
1M
Frequency (kHz)
Frequency (Hz)
Figure 32.
Figure 33.
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1.5 M
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GENERAL DESCRIPTION
SYSTEM CLOCK AND RESET FUNCTIONS
System Clock Input
The PCM1795 requires a system clock to operate the digital interpolation filters and advanced segment DAC
modulators. The system clock is applied at the SCK input (pin 7). The PCM1795 has a system clock detection
circuit that automatically senses the frequency at which the system clock is operating. Table 2 shows examples
of system clock frequencies for common audio sampling rates. If the oversampling rate of the delta-sigma (ΔΣ)
modulator is selected as 128 fS, the system clock frequency is required to be greater than 256 fS.
Figure 34 and Table 3 show the timing requirements for the system clock input. For optimal performance, it is
important to use a clock source with low phase jitter and noise. The Texas Instruments PLL1700 family of
multiclock generators is an excellent choice to provide the PCM1795 system clock.
Table 2. System Clock Rates for Common Audio Sampling Frequencies
SYSTEM CLOCK FREQUENCY (fSCK) (MHz)
SAMPLING FREQUENCY
(kHz)
128 fS
192 fS
256 fS
384 fS
512 fS
768 fS
32
4.096 (1)
6.144 (1)
8.192
12.288
16.384
24.576
44.1
5.6488 (1)
8.4672
11.2896
16.9344
22.5792
33.8688
48
6.144 (1)
9.216
12.288
18.432
24.576
36.864
96
12.288
192
(1)
(2)
18.432
24.576
36.864
24.576
49.152
(1)
36.864
73.728
(1)
49.152
X
(1)
73.728 (1)
(2)
X (2)
This system clock rate is not supported in I2C fast mode.
This system clock rate is not supported for the given sampling frequency.
t(SCKH)
High
2V
System Clock
(SCK)
0.8 V
Low
t(SCKL)
t(SCY)
Figure 34. System Clock Input Timing
Table 3. Timing Characteristics for Figure 34
PARAMETER
MIN
MAX
UNIT
t(SCY)
System clock pulse cycle time
13
ns
t(SCKH)
System clock pulse duration, high
0.4t(SCY)
ns
t(SCKL)
System clock pulse duration, low
0.4t(SCY)
ns
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Power-On and External Reset Functions
The PCM1795 includes a power-on reset function, as shown in Figure 35. With VDD > 2 V, the power-on reset
function is enabled. The initialization sequence requires 1024 system clocks from the time VDD > 2 V. After the
initialization period, the PCM1795 is set to its default reset state, as described in the Mode Control Registers
section.
The PCM1795 also includes an external reset capability using the RST input (pin 14). This feature allows an
external controller or master reset circuit to force the PCM1795 to initialize to the default reset state.
Figure 36 and Table 4 show the external reset operation and timing. The RST pin is set to logic 0 for a minimum
of 20 ns. The RST pin is then set to a logic 1 state, thus starting the initialization sequence that requires 1024
system clock periods. The external reset is especially useful in applications where there is a delay between the
PCM1795 power-up and system clock activation.
VDD
2.4 V (Max)
2 V (Typ)
1.6 V (Min)
Reset
Reset Removal
Internal Reset
1024 System Clocks
System Clock
Figure 35. Power-On Reset Timing
RST (Pin 14)
1.4 V
t(RST)
Reset
Reset Removal
Internal Reset
1024 System Clocks
System Clock
Figure 36. External Reset Timing
Table 4. Timing Characteristics for Figure 36
PARAMETER
t(RST)
18
MIN
Reset pulse duration, low
20
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MAX
UNIT
ns
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AUDIO DATA INTERFACE
Audio Serial Interface
The audio interface port is a three-wire serial port. It includes LRCK (pin 4), BCK (pin 6), and DATA (pin 5). BCK
is the serial audio bit clock, and it is used to clock the serial data present on DATA into the serial shift register of
the audio interface. Serial data are clocked into the PCM1795 on the rising edge of BCK. LRCK is the serial
audio left/right word clock.
The PCM1795 requires the synchronization of LRCK and the system clock, but does not need a specific phase
relation between LRCK and the system clock.
If the relationship between LRCK and the system clock changes more than ±6 BCK, internal operation is
initialized within 1/fS and analog outputs are forced to the bipolar zero level until resynchronization between
LRCK and the system clock is completed.
PCM Audio Data Formats and Timing
The PCM1795 supports industry-standard audio data formats, including standard right-justified, I2S, and
left-justified. The data formats are illustrated in Figure 38 to Figure 40. Data formats are selected using the
format bits, FMT[2:0], in control register 18. The default data format is 32-bit I2S. All formats require binary twos
complement, MSB-first audio data. Figure 37 and Table 5 show a detailed timing diagram for the serial audio
interface.
1.4 V
LRCK
t(BCH)
t(BCL)
t(LB)
1.4 V
BCK
t(BCY)
t(BL)
1.4 V
DATA
t(DS)
t(DH)
Figure 37. Audio Interface Timing
Table 5. Timing Characteristics for Figure 37
PARAMETER
MIN
MAX
UNIT
t(BCY)
BCK pulse cycle time
70
ns
t(BCL)
BCK pulse duration, low
30
ns
t(BCH)
BCK pulse duration, high
30
ns
t(BL)
BCK rising edge to LRCK edge
10
ns
t(LB)
LRCK edge to BCK rising edge
10
ns
t(DS)
DATA setup time
10
ns
t(DH)
DATA hold time
10
—
LRCK clock data
ns
50% ± 2 bit clocks
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1/fS
LRCK
Right Channel
Left Channel
BCK
Audio Data Word = 16-Bit, BCK ³ 32 fS
DATA
14 15 16
1
15 16
2
MSB
1
15 16
2
LSB
Audio Data Word = 24-Bit, BCK ³ 48 fS
DATA
22 23 24
1
2
23 24
MSB
1
2
23 24
LSB
Audio Data Word = 32-Bit, BCK ³ 64 fS
DATA
30 31 32
1
31 32
2
MSB
1
2
31 32
LSB
Figure 38. Audio Data Input Format: Standard Data Format (Right-Justified), Left Channel = High, Right
Channel = Low
1/fS
LRCK
Right Channel
Left Channel
BCK
Audio Data Word = 24-Bit, BCK ³ 48 fS
DATA
1
2
23 24
MSB
1
2
23 24
1
2
LSB
Figure 39. Audio Data Input Format: Left-Justified Data Format, Left Channel = High, Right Channel =
Low
1/fS
LRCK
Left Channel
Right Channel
BCK
Audio Data Word = 24-Bit, BCK ³ 48 fS
DATA
1
2
MSB
23 24
1
2
1
2
23 24
1
2
1
2
LSB
Audio Data Word = 32-Bit, BCK ³ 64 fS
DATA
1
2
MSB
31 32
31 32
LSB
Figure 40. Audio Data Input Format: I2S Data Format, Left Channel = Low, Right Channel = High
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External Digital Filter Interface and Timing
The PCM1795 supports an external digital filter interface that consists of a three- or four-wire synchronous serial
port that allows the use of an external digital filter. External filters include the Texas Instruments’ DF1704 and
DF1706, the Pacific Microsonics PMD200, or a programmable digital signal processor.
In the external DF mode, LRCK (pin 4), BCK (pin 6) and DATA (pin 5) are defined as: WDCK, the word clock;
BCK, the bit clock; and DATA, the monaural data. The external digital filter interface is selected by using the
DFTH bit of control register 20, which functions to bypass the internal digital filter of the PCM1795.
When the DFMS bit of control register 19 is set, the PCM1795 can process stereo data. In this case, ZEROL (pin
1) and ZEROR (pin 2) are defined as left-channel data and right-channel data input, respectively.
Detailed information for the external digital filter interface mode is provided in the Application For External Digital
Filter Interface section.
Direct Stream Digital (DSD) Format Interface and Timing
The PCM1795 supports the DSD format interface operation, which includes out-of-band noise filtering using an
internal analog FIR filter. For DSD operation, SCK (pin 7) is redefined as BCK, DATA (pin 5) as DATAL (left
channel audio data), and LRCK (pin 4) as DATAR (right channel audio data). BCK (pin 6) must be forced low in
the DSD mode. The DSD format interface is activated by setting the DSD bit of control register 20.
Detailed information for the DSD mode is provided in the Application For DSD Format (DSD Mode) Interface
section.
TDMCA Interface
The PCM1795 supports the time-division-multiplexed command and audio (TDMCA) data format to enable
control of and communication with a number of external devices over a single serial interface.
Detailed information for the TDMCA format is provided in the TDMCA Interface Format section.
FUNCTION DESCRIPTIONS
Zero Detect
The PCM1795 has a zero-detect function. When the PCM1795 detects the zero conditions as shown in Table 6,
the PCM1795 sets ZEROL (pin 1) and ZEROR (pin 2) high.
Table 6. Zero Conditions
MODE
DSD
DETECTING CONDITION AND TIME
PCM
DATA is continuously low for 1024 LRCKs.
External DF mode
DATA is continuously low for 1024 WDCKs.
DZ0
There are an equal number of 1s and 0s in every 8 bits of DSD input data for 23
ms.
DZ1
The input data are continuously 1001 0110 for 23 ms.
SERIAL CONTROL INTERFACE
The PCM1795 supports both SPI and I2C interfaces that set the mode control registers; see Table 9. The serial
control interface is selected by MSEL (pin 3); SPI is activated when MSEL is set low, and I2C is activated when
MSEL is set high.
SPI Interface
The SPI interface is a four-wire synchronous serial port that operates asynchronously to the serial audio interface
and the system clock (SCK). The serial control interface is used to program and read the on-chip mode registers.
The control interface includes MDO (pin 13), MDI (pin 11), MC (pin 12), and MS (pin 10). MDO is the serial data
output, used to read back the values of the mode registers; MDI is the serial data input, used to program the
mode registers; MC is the serial bit clock, used to shift data in and out of the control port; and MS is the mode
control enable, used to enable the internal mode register access.
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Register Read/Write Operation
All read/write operations for the serial control port use 16-bit data words. Figure 41 shows the control data word
format. The most significant bit (MSB) is the read/write (R/W) bit. For write operations, the R/W bit must be set to
'0'. For read operations, the R/W bit must be set to '1'. There are seven bits, labeled IDX[6:0], that hold the
register index (or address) for the read and write operations. The least significant eight bits, D[7:0], contain the
data to be written to, or the data that was read from, and the register specified by IDX[6:0].
Figure 42 shows the functional timing diagram for writing or reading the serial control port. MS is held at a logic 1
state until a register must be written to or read from. To start the register write or read cycle, MS is set to logic 0.
Sixteen clocks are then provided on MC, corresponding to the 16 bits of the control data word on MDI and
readback data on MDO. After the eighth clock cycle has completed, the data from the indexed-mode control
register appears on MDO during the read operation. After the 16th clock cycle has completed, the data are
latched into the indexed-mode control register during the write operation. To write or read subsequent data, MS
must be set to '1' once.
LSB
MSB
R/W
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
D7
D6
D5
D4
D3
D2
D1
D0
Register Data
Register Index (or Address)
Figure 41. Control Data Word Format for MDI
MS
MC
MDI
MDO
R/W
A6
A5
A4
A3
High Impedance
A2
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
When Read Mode is Instructed
NOTE: Bit 15 is used for selection of write or read. Setting R/W = 0 indicates a write, while R/W = 1 indicates a read. Bits 14–8 are used for
the register address. Bits 7–0 are used for register data.
Figure 42. Serial Control Format
22
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t(MHH)
1.4 V
MS
t(MSS)
t(MCH)
t(MCL)
t(MSH)
MC
1.4 V
t(MCY)
LSB
MDI
t(MDS)
1.4 V
t(MOS)
t(MDH)
50% of VDD
MDO
Figure 43. Control Interface Timing
Timing Characteristics for Figure 43
PARAMETER
MIN
MAX
UNIT
t(MCY)
MC pulse cycle time
100
ns
t(MCL)
MC low-level time
40
ns
t(MCH)
MC high-level time
40
ns
t(MHH)
MS high-level time
80
ns
t(MSS)
MS falling edge to MC rising edge
15
ns
t(MSH)
MS hold time (1)
15
ns
t(MDH)
MDI hold time
15
ns
t(MDS)
MDI setup time
15
t(MOS)
MC falling edge to MDO stable
(1)
ns
30
ns
MC rising edge for LSB to MS rising edge.
I2C INTERFACE
The PCM1795 supports the I2C serial bus and the data transmission protocol for standard and fast mode as a
slave device. This protocol is explained in the I2C specification 2.0.
In I2C mode, the control terminals are changed as described in Table 7.
Table 7. Control Terminals
TERMINAL NAME
TDMCA NAME
PROPERTY
DESCRIPTION
MS
ADR0
Input
I2C address 0
MDI
ADR1
Input
I2C address 1
MC
SCL
Input
I2C clock
MDO
SDA
Input/output
I2C data
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Slave Address
The PCM1795 has seven bits for its own slave address, as shown in Figure 44. The first five bits (MSBs) of the
slave address are factory preset to 10011. The next two bits of the address byte are the device select bits that
can be user-defined by the ADR1 and ADR0 terminals. A maximum of four PCM1795s can be connected on the
same bus at one time. Each PCM1795 responds when it receives its own slave address.
MSB
LSB
0
1
0
1
1
ADR0
ADR1
R/W
Figure 44. Slave Address
Packet Protocol
A master device must control packet protocol that consists of a start condition, slave address, read/write bit, data
if write or acknowledge if read, and stop condition. The PCM1795 supports only slave receivers and slave
transmitters.
SDA
SCL
17
St
Slave Address
8
9
18
9
18
9
9
R/W
ACK
DATA
ACK
DATA
ACK
ACK
R/W: Read Operation if 1; Otherwise, Write Operation
ACK: Acknowledgment of a Byte if 0
NACK: Not Acknowledged if 1
DATA: 8 Bits (Byte)
Start
Condition
Sp
Stop
Condition
Write Operation
Transmitter
M
M
M
S
M
S
M
S
S
M
Data Type
St
Slave Address
W
ACK
DATA
ACK
DATA
ACK
ACK
Sp
Transmitter
M
M
M
S
S
M
S
M
M
M
Data Type
St
Slave Address
R
ACK
DATA
ACK
DATA
ACK
NACK
Sp
Read Operation
M: Master Device
S: Slave Device
St: Start Condition
Sp: Stop Condition
R: Read
W: Write
ACK: Acknowledge
NACK: Not Acknowledged
Figure 45. Basic I2C Framework
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Write Register
A master can write to any PCM1795 registers using single or multiple accesses. The master sends a PCM1795
slave address with a write bit, a register address, and the data. If multiple access is required, the address is that
of the starting register, followed by the data to be transferred. When the data are received properly, the index
register is incremented by '1' automatically. When the index register reaches 0x7F, the next value is 0x00. When
undefined registers are accessed, the PCM1795 does not send an acknowledgment. Figure 46 shows a diagram
of the write operation.
Transmitter
Data Type
M
St
M
Slave Address
M
W
M: Master Device
S: Slave Device
S
S
M
ACK
Register Address
ACK
St: Start Condition
Sp: Stop Condition
M
S
ACK
Write Data 1
M
Write Data 2
S
ACK
S
M
NACK
Sp
W: Write
ACK: Acknowledge
NACK: Not Acknowledged
Figure 46. Write Operation
Read Register
A master can read the PCM1795 register. The value of the register address is stored in an indirect index register
in advance. The master sends a PCM1795 slave address with a read bit after storing the register address. Then
the PCM1795 transfers the data that the index register points to. When the data are transferred during a multiple
access, the index register is incremented by '1' automatically. (When first going into read mode immediately
following a write, the index register is not incremented. The master can read the register that was previously
written.) When the index register reaches 0x7F, the next value is 0x00. The PCM1795 outputs some data when
the index register is 0x10 to 0x1F, even if it is not defined in Table 9. Figure 47 shows a diagram of the read
operation.
Transmitter
M
M
M
S
M
S
M
M
M
S
S
M
M
M
Data Type
St
Slave Address
W
ACK
Register Address
ACK
Sr
Slave Address
R
ACK
Data
ACK
NACK
Sp
M: Master Device
S: Slave Device
St: Start Condition
Sr: Repeated Start Condition
Sp: Stop Condition
R: Read
W: Write
ACK: Acknowledge
NACK: Not Acknowledged
Figure 47. Read Operation
Noise Suppression
The PCM1795 incorporates noise suppression using the system clock (SCK). However, there must be no more
than two noise spikes in 600 ns. The noise suppression works for SCK frequencies between 8 MHz and 40 MHz
in fast mode. However, it works incorrectly under the following conditions:
Case 1:
1. t(SCK) > 120 ns (t(SCK): period of SCK)
2. t(HI) + t(D–HD) < t(SCK) × 5
3. Spike noise exists on the first half of the SCL high pulse.
4. Spike noise exists on the SDA high pulse just before SDA goes low.
SCL
Noise
SDA
Figure 48. Case 1
When these conditions occur at the same time, the data are recognized as low.
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Case 2:
1. t(SCK) > 120 ns
2. t(S–HD) or t(RS–HD) < t(SCK) × 5
3. Spike noise exists on both SCL and SDA during the hold time.
SCL
Noise
SDA
Figure 49. Case 2
When these conditions occur at the same time, the PCM1795 fails to detect a start condition.
Case 3:
1. t(SCK) < 50 ns
2. t(SP) > t(SCK)
3. Spike noise exists on SCL just after SCL goes low.
4. Spike noise exists on SDA just before SCL goes low.
SCL
SDA
Noise
Figure 50. Case 3
When these conditions occur at the same time, the PCM1795 erroneously detects a start or stop condition.
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MODE CONTROL REGISTERS
User-Programmable Mode Controls
The PCM1795 includes a number of user-programmable functions that are accessed via mode control registers.
The registers are programmed using the serial control interface, as previously discussed in the SPI Interface and
I2C Interface sections. Table 8 lists the available mode-control functions, along with the default reset conditions
and associated register index.
Table 8. User-Programmable Function Controls
FUNCTION
Digital attenuation control
DEFAULT
REGISTER
BIT
PCM
DSD
DF
BYPASS
Yes
No
No
Register 16
ATL[7:0] (for left channel)
Register 17
ATR[7:0] (for right channel)
Attenuation disabled
Register 18
ATLD
Yes
No
No
24-bit I2S format
Register 18
FMT[2:0]
Yes
No
Yes
De-emphasis disabled
Register 18
DMF[1:0]
Yes
Yes (1)
No
De-emphasis disabled
Register 18
DME
Yes
No
No
Mute disabled
Register 18
MUTE
Yes
No
No
Normal
Register 19
REV
Yes
Yes
Yes
×1 fS
Register 19
ATS[1:0]
Yes
No
No
DAC operation enabled
Register 19
OPE
Yes
Yes
Yes
Monaural
Register 19
DFMS
Yes
No
Yes
Sharp roll-off
Register 19
FLT
Yes
No
No
Disabled
Register 19
INZD
Yes
No
Yes
Normal operation
Register 20
SRST
Yes
Yes
Yes
Disabled
Register 20
DSD
Yes
Yes
No
DF enabled
Register 20
DFTH
Yes
No
Yes
Stereo
Register 20
MONO
Yes
Yes
Yes
Left channel
Register 20
CHSL
Yes
Yes
Yes
×64 fS
Register 20
OS[1:0]
Yes
Yes (2)
Yes
PCM zero output enable
Enabled
Register 21
PCMZ
Yes
No
Yes
DSD zero output enable
Disabled
Register 21
DZ[1:0]
Yes
Yes
No
0 dB to –120 dB and mute, 0.5-dB step
Attenuation load control
Disabled, enabled
0 dB
Input audio data format selection
16-, 20-, 32-bit standard (right-justified)
format
24-bit MSB-first left-justified format
16-/32-bit I2S format
Sampling rate selection for de-emphasis
Disabled, 44.1 kHz, 48 kHz, 32 kHz
De-emphasis control
Disabled, enabled
Soft mute control
Soft mute disabled, enabled
Output phase reversal
Normal, reverse
Attenuation speed selection
×1fS, ×(1/2)fS, ×(1/4)fS, ×(1/8)fS
DAC operation control
Enabled, disabled
Stereo DF bypass mode select
Monaural, stereo
Digital filter roll-off selection
Sharp roll-off, slow roll-off
Infinite zero mute control
Disabled, enabled
System reset control
Reset operation, normal operation
DSD interface mode control
DSD enabled, disabled
Digital-filter bypass control
DF enabled, DF bypass
Monaural mode selection
Stereo, monaural
Channel selection for monaural mode data
Left channel, Right channel
ΔΣ oversampling rate selection
×64 fS, ×128 fS, ×32 fS
(1)
(2)
When in DSD mode, DMF[1:0] is defined as DSD filter (analog FIR) performance selection.
When in DSD mode, OS[1:0] is defined as DSD filter (analog FIR) operating rate selection.
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Table 8. User-Programmable Function Controls (continued)
FUNCTION
DEFAULT
REGISTER
BIT
PCM
DSD
DF
BYPASS
Yes
Yes
Yes
Yes
No
No
FUNCTION AVAILABLE ONLY FOR READ
Zero detection flag
Not zero = 0
Not zero, zero detected
Device ID (at TDMCA)
ZFGL (for left channel)
Register 22
Zero detected = 1
—
ZFGR (for right channel)
Register 23
ID[4:0]
Register Map
The mode control register map is shown in Table 9. Registers 16 to 21 include an R/W bit that determines
whether a register read (R/W = 1) or write (R/W = 0) operation is performed. Registers 22 and 23 are read-only.
Table 9. Mode Control Register Map
REGISTER
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
Register 16
R/W
0
0
1
0
0
0
0
ATL7
ATL6
ATL5
ATL4
ATL3
ATL2
ATL1
ATL0
Register 17
R/W
0
0
1
0
0
0
1
ATR7
ATR6
ATR5
ATR4
ATR3
ATR2
ATR1
ATR0
Register 18
R/W
0
0
1
0
0
1
0
ATLD
FMT2
FMT1
FMT0
DMF1
DMF0
DME
MUTE
Register 19
R/W
0
0
1
0
0
1
1
REV
ATS1
ATS0
OPE
RSV
DFMS
FLT
INZD
Register 20
R/W
0
0
1
0
1
0
0
RSV
SRST
DSD
DFTH
MONO
CHSL
OS1
OS0
Register 21
R/W
0
0
1
0
1
0
1
RSV
RSV
RSV
RSV
RSV
DZ1
DZ0
PCMZ
Register 22
R
0
0
1
0
1
1
0
RSV
RSV
RSV
RSV
RSV
RSV
ZFGR
ZFGL
Register 23
R
0
0
1
0
1
1
1
RSV
RSV
RSV
ID4
ID3
ID2
ID1
ID0
Register Definitions
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
Register 16
R/W
0
0
1
0
0
0
0
ATL7
ATL6
ATL5
ATL4
ATL3
ATL2
ATL1
ATL0
Register 17
R/W
0
0
1
0
0
0
1
ATR7
ATR6
ATR5
ATR4
ATR3
ATR2
ATR1
ATR0
R/W: Read/Write Mode Select
When R/W = 0, a write operation is performed.
When R/W = 1, a read operation is performed.
Default value: 0
ATx[7:0]: Digital Attenuation Level Setting
These bits are available for read and write.
Default value: 1111 1111b
Each DAC output has a digital attenuator associated with it. The attenuator can be set from 0 dB to –120 dB, in
0.5-dB steps. Alternatively, the attenuator can be set to infinite attenuation (or mute). The attenuation data for
each channel can be set individually. However, the data load control (the ATLD bit of control register 18) is
common to both attenuators. ATLD must be set to '1' in order to change an attenuator setting. The attenuation
level can be set using Equation 1:
Attenuation level (dB) = 0.5 dB × (ATx[7:0]DEC – 255)
Where,
ATx[7:0]DEC = 0 through 255
For ATx[7:0]DEC = 0 through 14, the attenuator is set to infinite attenuation. Table 10 lists the attenuation levels
for various settings.
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Table 10. Attenuation Levels
Register 18
ATx[7:0]
DECIMAL VALUE
ATTENUATION LEVEL SETTING
1111 1111b
255
0 dB, no attenuation (default)
1111 1110b
254
–0.5 dB
1111 1101b
253
–1.0 dB
—
—
—
0001 0000b
16
–119.5 dB
0000 1111b
15
–120.0 dB
0000 1110b
14
Mute
—
—
—
0000 0000b
0
Mute
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
R/W
0
0
1
0
0
1
0
ATLD
FMT2
FMT1
FMT0
DMF1
DMF0
DME
MUTE
R/W: Read/Write Mode Select
When R/W = 0, a write operation is performed.
When R/W = 1, a read operation is performed.
Default value: 0
ATLD: Attenuation Load Control
This bit is available for read and write.
Default value: 0
ATLD
Attenuation Control Setting
ATLD = 0
Attenuation control disabled (default)
ATLD = 1
Attenuation control enabled
The ATLD bit is used to enable loading of the attenuation data contained in registers 16 and 17. When ATLD =
0, the attenuation settings remain at the previously programmed levels, ignoring new data loaded from registers
16 and 17. When ATLD = 1, attenuation data written to registers 16 and 17 is loaded normally.
FMT[2:0]: Audio Interface Data Format
These bits are available for read and write.
Default value: 101
FMT[2:0]
Audio Data Format Selection
000
16-bit standard format, right-justified data, BCK ≥ x32 fS
001
32-bit standard format, right-justified data, BCK ≥ x64 fS
010
24-bit standard format, right-justified data, BCK ≥ x48 fS
011
24-bit MSB-first, left-justified format data, BCK ≥ x48 fS
100
32-bit I2S format data, BCK ≥ x64 fS
101
24-bit I2S format data (default), BCK ≥ x48 fS
110
Reserved
111
Reserved
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The FMT[2:0] bits are used to select the data format for the serial audio interface.
For the external digital filter interface mode (DFTH mode), this register is operated as shown in the Application
for External Digital Filter Interface section.
DMF[1:0]: Sampling Frequency Selection for the De-Emphasis Function
These bits are available for read and write.
Default value: 00
DMF[1:0]
De-Emphasis Sampling Frequency Selection
00
Disabled (default)
01
48 kHz
10
44.1 kHz
11
32 kHz
The DMF[1:0] bits are used to select the sampling frequency used by the digital de-emphasis function when it is
enabled by setting the DME bit. The de-emphasis curves are shown in the Typical Characteristics section.
For the DSD mode, analog FIR filter performance can be selected using this register. A register map and filter
response plots are shown in the Application For DSD Format (DSD Mode) Interface section.
DME: Digital De-Emphasis Control
This bit is available for read and write.
Default value: 0
DME
De-Emphasis Setting
DME = 0
De-emphasis disabled (default)
DME = 1
De-emphasis enabled
The DME bit is used to enable or disable the de-emphasis function for both channels.
MUTE: Soft Mute Control
This bit is available for read and write.
Default value: 0
MUTE
Soft Mute Setting
MUTE = 0
Soft mute disabled (default)
MUTE = 1
Soft mute enabled
The MUTE bit is used to enable or disable the soft mute function for both channels.
Soft mute is operated as a 256-step attenuator. The speed for each step to –∞ dB (mute) is determined by the
attenuation rate selected in the ATS register.
Register 19
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
R/W
0
0
1
0
0
1
1
REV
ATS1
ATS0
OPE
RSV
DMFS
FLT
INZD
R/W: Read/Write Mode Select
When R/W = 0, a write operation is performed.
When R/W = 1, a read operation is performed.
Default value: 0
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REV: Output Phase Reversal
This bit is available for read and write.
Default value: 0
REV
Output Setting
REV = 0
Normal output (default)
REV = 1
Inverted output
The REV bit is used to invert the output phase for both channels.
ATS[1:0]: Attenuation Rate Select
These bits are available for read and write.
Default value: 00
ATS[1:0]
Attenuation Rate Selection
00
Every LRCK (default)
01
LRCK/2
10
LRCK/4
11
LRCK/8
The ATS[1:0] bits are used to select the rate at which the attenuator is decremented/incremented during level
transitions.
OPE: DAC Operation Control
This bit is available for read and write.
Default value: 0
OPE
DAC Operation Control
OPE = 0
DAC operation enabled (default)
OPE = 1
DAC operation disabled
The OPE bit is used to enable or disable the analog output for both channels. Disabling the analog outputs
forces them to the bipolar zero level (BPZ) even if audio data are present on the input.
DFMS: Stereo DF Bypass Mode Select
This bit is available for read and write.
Default value: 0
DFMS
Mode Selection
DFMS = 0
Monaural (default)
DFMS = 1
Stereo input enabled
The DFMS bit is used to enable stereo operation in DF bypass mode. In the DF bypass mode, when DFMS is
set to '0', the pin for the input data are DATA (pin 5) only; therefore, the PCM1795 operates as a monaural DAC.
When DFMS is set to '1', the PCM1795 can operate as a stereo DAC with inputs of the left channel and right
channel data on ZEROL (pin 1) and ZEROR (pin 2), respectively.
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FLT: Digital Filter Roll-Off Control
This bit is available for read and write.
Default value: 0
FLT
Roll-Off Control
FLT = 0
Sharp roll-off (default)
FLT = 1
Slow roll-off
The FLT bit is used to select the digital filter roll-off characteristic. The filter responses for these selections are
shown in the Typical Characteristics section.
INZD: Infinite Zero Detect Mute Control
This bit is available for read and write.
Default value: 0
INZD
Infinite Zero Detect Mute Setting
INZD = 0
Infinite zero detect mute disabled (default)
INZD = 1
Infinite zero detect mute enabled
The INZD bit is used to enable or disable the zero detect mute function. Setting INZD to '1' forces muted analog
outputs to hold a bipolar zero level when the PCM1795 detects a zero condition in both channels. The infinite
zero detect mute function is not available in the DSD mode.
Register 20
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
R/W
0
0
1
0
1
0
0
RSV
SRST
DSD
DFTH
MONO
CHSL
OS1
OS0
R/W: Read/Write Mode Select
When R/W = 0, a write operation is performed.
When R/W = 1, a read operation is performed.
Default value: 0
SRST: System Reset Control
This bit is available for write only.
Default value: 0
SRST
System Reset Control
SRST = 0
Normal operation (default)
SRST = 1
System reset operation (generate one reset pulse)
The SRST bit is used to reset the PCM1795 to the initial system condition.
DSD: DSD Interface Mode Control
This bit is available for read and write.
Default value: 0
DSD
DSD Interface Mode Control
DSD = 0
DSD interface mode disabled (default)
DSD = 1
DSD interface mode enabled
The DSD bit is used to enable or disable the DSD interface mode.
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DFTH: Digital Filter Bypass (or Through Mode) Control
This bit is available for read and write.
Default value: 0
DFTH
Digital Filter Control
DFTH = 0
Digital filter enabled (default)
DFTH = 1
Digital filter bypassed for external digital filter
The DFTH bit is used to enable or disable the external digital filter interface mode.
MONO: Monaural Mode Selection
This bit is available for read and write.
Default value: 0
MONO
Mode Selection
MONO = 0
Stereo mode (default)
MONO = 1
Monaural mode
The MONO function is used to change operation mode from the normal stereo mode to the monaural mode.
When the monaural mode is selected, both DACs operate in a balanced mode for one channel of audio input
data. Channel selection is available for left-channel or right-channel data, determined by the CHSL bit.
CHSL: Channel Selection for Monaural Mode
This bit is available for read and write.
Default value: 0
CHSL
Channel Selection
CHSL = 0
Left channel selected (default)
CHSL = 1
Right channel selected
This bit is available when MONO = 1.
The CHSL bit selects left-channel or right-channel data to be used in monaural mode.
OS[1:0]: ΔΣ Oversampling Rate Selection
These bits are available for read and write.
Default value: 00
OS[1:0]
Operating Speed Selection
00
64 times fS (default)
01
32 times fS
10
128 times fS
11
Reserved
The OS bits are used to change the oversampling rate of ΔΣ modulation. Use of this function enables the
designer to stabilize the conditions at the post low-pass filter for different sampling rates. As an application
example, programming to set 128 times in 44.1-kHz operation, 64 times in 96-kHz operation, or 32 times in
192-kHz operation allows the use of only a single type (cut-off frequency) of post low-pass filter. The 128-fS
oversampling rate is not available at sampling rates above 100 kHz. If the 128-fS oversampling rate is selected, a
system clock of more than 256 fS is required.
In DSD mode, these bits are used to select the speed of the bit clock for DSD data coming into the analog FIR
filter.
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Register 21
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
R/W
0
0
1
0
1
0
1
RSV
RSV
RSV
RSV
RSV
DZ1
DZ0
PCMZ
R/W: Read/Write Mode Select
When R/W = 0, a write operation is performed.
When R/W = 1, a read operation is performed.
Default value: 0
DZ[1:0]: DSD Zero Output Enable
These bits are available for read and write.
Default value: 00
DZ[1:0]
Zero Output Enable
00
Disabled (default)
01
Even pattern detect 1 × 96h pattern detect
The DZ bits are used to enable or disable the output zero flags and to select the zero pattern in DSD mode.
PCMZ: PCM Zero Output Enable
These bits are available for read and write.
Default value: 1
PCMZ
PCM Zero Output Setting
PCMZ = 0
PCM zero output disabled
PCMZ = 1
PCM zero output enabled (default)
The PCMZ bit is used to enable or disable the output zero flags in PCM mode and the external DF mode.
Register 22
B15
B14
B13
B12
B11
B10
B9
B8
R
0
0
1
0
1
1
0
B7
B6
B5
B4
B3
RSV
RSV
RSV
RSV
RSV
B2
RSV
B1
B0
ZFGR
ZFGL
R: Read Mode Select
Value is always '1', specifying the readback mode.
ZFGx: Zero-Detection Flag
Where x = L or R, corresponding to the DAC output channel. These bits are available only for readback.
Default value: 00
ZFGx
Zero Detection
ZFGx = 0
Not zero
ZFGx = 1
Zero detected
These bits show zero conditions. The status is the same as that of the zero flags at ZEROL (pin 1) and ZEROR
(pin 2). See Zero Detect in the Function Descriptions section.
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Register 23
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
R
0
0
1
0
1
1
1
RSV
RSV
RSV
ID4
ID3
ID2
ID1
ID0
Read Mode Select
Value is always '1', specifying the readback mode.
ID[4:0]: Device ID
The ID[4:0] bits hold a device ID in the TDMCA mode.
APPLICATION INFORMATION
TYPICAL CONNECTION DIAGRAM IN PCM MODE
Figure 51 shows a typical application circuit for PCM mode operation.
CF
5V
RF
0.1 mF
1
ZEROL
VCC2L
28
2
ZEROR
AGND3L
27
3
MSEL
IOUTL–
26
4
LRCK
IOUTL+
25
5
DATA
AGND2
24
6
BCK
VCC1
23
7
SCK
VCOML
22
VCOMR
21
+
10 mF
–
+
CF
RF
5V
PCM
Audio
Data
Source
–
DGND
9
VDD
IREF
20
10
MS
AGND1
19
11
MDI
IOUTR–
18
12
MC
IOUTR+
17
13
MDO
AGND3R
16
14
RST
VCC2R
15
+
+
8
VOUT
Left Channel
Differentialto-Single
Converter
With
Low-Pass
Filter
VOUT
Right Channel
+
47 mF
PCM1796
0.1 mF
Differentialto-Single
Converter
With
Low-Pass
Filter
CF
10 mF
RF
10 kW
–
+
Controller
CF
RF
0.1 mF
–
+
10 mF
5V
+
10 mF
+
3.3 V
Figure 51. Typical Application Circuit for Standard PCM Audio Operation
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APPLICATION CIRCUIT
The design of the application circuit is very important in order to actually realize the high S/N ratio of which the
PCM1795 is capable, because noise and distortion that are generated in an application circuit are not negligible.
In the third-order, low-pass filter (LPF) circuit of Figure 52, the output level of 2.1 V RMS and 123-dB
signal-to-noise ratio is achieved.
Figure 53 shows a circuit for the DSD mode, which is a fourth-order LPF in order to reduce the out-of-band
noise.
I/V Section
The current of the PCM1795 on each of the output pins (IOUTL+, IOUTL–, IOUTR+, IOUTR–) is 4 mAPP at 0 dB
(full-scale). The voltage output level of the current-to-voltage (I/V) converter, VI, is given by Equation 2:
VI = 4 mAPP × RF
Where:
RF = feedback resistance of the I/V converter
An NE5534 operational amplifier is recommended for the I/V circuit to obtain the specified performance. Dynamic
performance such as the gain bandwidth, settling time, and slew rate of the operational amplifier affects the
audio dynamic performance of the I/V section.
Differential Section
The PCM1795 voltage outputs are followed by differential amplifier stages that sum the differential signals for
each channel, creating a single-ended I/V op-amp output. In addition, the differential amplifiers provide a
low-pass filter function.
The operational amplifier recommended for the differential circuit is the low-noise type.
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C1
2700 pF
R1
820 W
VCC
VCC
C11
0.1 mF
7
IOUT-
5
2
R5
200 W
C17
22 pF
R3
220 W
8
–
6
3
+
4
R7
180 W
C5
27000 pF
U1
NE5534
C12
0.1 mF
C15
0.1 mF
C3
8200 pF
C19
22 pF
7
2
5
–
6
3
+
4
R4
220 W
VEE
R6
200 W
R8
180 W
C4
8200 pF
8
R9
100 W
U3
NE5534
C16
0.1 mF
VEE
C2
2700 pF
R2
820 W
VCC
C13
0.1 mF
C18
22 pF
7
IOUT+
2
5
–
8
6
3
+
4
U2
NE5534
C14
0.1 mF
VEE
Figure 52. Measurement Circuit for PCM
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C1
2200 pF
R1
820 W
VCC
VCC
C11
0.1 mF
7
IOUT-
5
2
8
–
6
3
R5
150 W
C17
22 pF
+
R3
91 W
C3
22000 pF
U1
NE5534
4
C12
0.1 mF
VEE
R8
75 W
C15
0.1 mF
C5
8200 pF
R10
120 W
C19
22 pF
7
2
5
–
6
C4
27000 pF
3
+
4
R4
91 W
R9
75 W
R6
150 W
8
R11
120 W
C6
8200 pF
R7
100W
U3
NE5534
C16
0.1 mF
VEE
C2
2200 pF
R2
820 W
VCC
C13
0.1 mF
C18
22 pF
7
IOUT+
2
5
–
8
6
3
+
4
U2
NE5534
C14
0.1 mF
VEE
Figure 53. Measurement Circuit for DSD
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IOUT-
IOUTL- (Pin 26)
Circuit
OUT+
(1)
IOUT+
IOUTL+ (Pin 25)
3
1
2
IOUT-
IOUTR- (Pin 18)
Circuit
OUT-
(1)
Balanced Out
IOUT+
IOUTR+ (Pin 17)
(1) Circuit corresponds to Figure 52.
Figure 54. Measurement Circuit for Monaural Mode
APPLICATION FOR EXTERNAL DIGITAL FILTER INTERFACE
Figure 55 shows the connection diagram for an external digital filter.
DFMS = 0
External Filter Device
PCM1796
1
ZEROL
2
ZEROR
3
MSEL
WDCK (Word Clock)
4
LRCK
DATA
5
DATA
BCK
6
BCK
SCK
7
SCK
DFMS = 1
External Filter Device
PCM1796
DATA_L
1
ZEROL
DATA_R
2
ZEROR
3
MSEL
4
LRCK
5
DATA
BCK
6
BCK
SCK
7
SCK
WDCK (Word Clock)
Figure 55. Connection Diagram for External Digital Filter (Internal DF Bypass Mode) Application
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Application for Interfacing With an External Digital Filter
For some applications, it may be desirable to use an external digital filter to perform the interpolation function, as
it can provide improved stop-band attenuation when compared to the internal digital filter of the PCM1795.
The PCM1795 supports several external digital filters, including:
• Texas Instruments DF1704 and DF1706
• Pacific Microsonics PMD200 HDCD filter/decoder IC
• Programmable digital signal processors (DSPs)
The external digital filter application mode is accessed by programming the following bits in the corresponding
control register:
• DFTH = 1 (register 20)
The pins used to provide the serial interface for the external digital filter are illustrated in Figure 55. The word
clock (WDCK) signal must be operated at 8 times or 4 times the desired sampling frequency, fS.
Pin Assignment When Using the External Digital Filter Interface
• LRCK (pin 4): WDCK as word clock input
• BCK (pin 6): Bit clock for audio data
• DATA (pin 5): Monaural audio data input when the DFMS bit is not set to '1'
• ZEROL (pin 1): DATAL as left channel audio data input when the DFMS bit is set to '1'
• ZEROR (pin 2): DATAR as right channel audio data input when the DFMS bit is set to '1'
Audio Format
The PCM1795 in the external digital filter interface mode supports right-justified audio formats including 16-bit,
24-bit, and 32-bit audio data, as shown in Figure 56. The audio format is selected by the FMT[2:0] bits of control
register 18.
1/4 fS or 1/8 fS
WDCK
BCK
Audio Data Word = 16-Bit
DATA, DATAL, DATAR
15 16
1
2
3
MSB
4
5
6
7
8
9 10 11 12 13 14 15 16
LSB
Audio Data Word = 32-Bit
DATA, DATAL, DATAR
31 32 1
2
3
4
5
19 20 21 22 23 24 25 26 27 28 29 30 31 32
MSB
LSB
Audio Data Word = 24-Bit
DATA, DATAL, DATAR
23 24
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
MSB
LSB
Figure 56. Audio Data Input Format for External Digital Filter (Internal DF Bypass Mode) Application
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System Clock (SCK) and Interface Timing
The PCM1795 in an application using an external digital filter requires the synchronization of WDCK and the
system clock. The system clock is phase-free with respect to WDCK. Interface timing among WDCK, BCK,
DATA, DATAL, and DATAR is shown in Figure 57 and Table 11.
WDCK
1.4 V
t(BCH)
t(BCL)
t(LB)
BCK
1.4 V
t(BCY)
t(BL)
DATA
DATAL
DATAR
1.4 V
t(DS)
t(DH)
Figure 57. Audio Interface Timing for External Digital Filter (Internal DF Bypass Mode) Application
Table 11. Timing Characteristics for Figure 57
PARAMETER
t(BCY)
BCK pulse cycle time
t(BCL)
t(BCH)
MIN
MAX
UNIT
20
ns
BCK pulse duration, low
7
ns
BCK pulse duration, high
7
ns
t(BL)
BCK rising edge to WDCK falling edge
5
ns
t(LB)
WDCK falling edge to BCK rising edge
5
ns
t(DS)
DATA, DATAL, DATAR setup time
5
ns
t(DH)
DATA, DATAL, DATAR hold time
5
ns
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FUNCTIONS AVAILABLE IN THE EXTERNAL DIGITAL FILTER MODE
The external digital filter mode is selected by setting DSD = 0 (register 20, B5) and DFTH = 1 (register 20, B4).
The external digital filter mode allows access to the majority of the PCM1795 mode control functions.
Table 12 shows the register mapping available when the external digital filter mode is selected, along with
descriptions of functions that are modified when using this mode selection.
Table 12. External Digital Filter Register Map
REGISTER
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
Register 16
R/W
0
0
1
0
0
0
0
X (1)
X
X
X
X
X
X
X
Register 17
R/W
0
0
1
0
0
0
1
X
X
X
X
X
X
X
X
Register 18
R/W
0
0
1
0
0
1
0
X
FMT2
FMT1
FMT0
X
X
X
X
Register 19
R/W
0
0
1
0
0
1
1
REV
X
X
OPE
X
DFMS
X
INZD
Register 20
R/W
0
0
1
0
1
0
0
X
SRST
0
1
MONO
CHSL
OS1
OS0
Register 21
R/W
0
0
1
0
1
0
1
X
X
X
X
X
X
X
PCMZ
Register 22
R
0
0
1
0
1
1
0
X
X
X
X
X
X
ZFGR
ZFGL
(1)
Function is disabled. No operation even if data bit is set.
FMT[2:0]: Audio Data Format Selection
Default value: 000
FMT[2:0]
Audio Data Format Selection
000
16-bit right-justified format
001
32-bit right-justified format
010
24-bit right-justified format (default)
Other
N/A
OS[1:0]: ΔΣ Modulator Oversampling Rate Selection
Default value: 00
OS[1:0]
Operation Speed Selection
00
8 times WDCK (default)
01
4 times WDCK
10
16 times WDCK
11
Reserved
The effective oversampling rate is determined by the oversampling performed by both the external digital filter
and the ΔΣ modulator. For example, if the external digital filter is 8× oversampling, and OS[1:0] = 00 is selected,
then the ΔΣ modulator oversamples by 8×, resulting in an effective oversampling rate of 64×. The 16× WDCK
oversampling rate is not available above a 100-kHz sampling rate. If the oversampling rate selected is 16×
WDCK, the system clock frequency must be over 256 fS.
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APPLICATION FOR DSD FORMAT (DSD MODE) INTERFACE
Figure 58 shows a connection diagram for DSD mode.
DSD Decoder
PCM1796
1
ZEROL
2
ZEROR
3
MSEL
DATA_R
4
LRCK
DATA_L
5
DATA
6
BCK
7
SCK
Bit Clock
Figure 58. Connection Diagram in DSD Mode
Feature
This mode is used for interfacing directly to a DSD decoder, which is found in Super Audio CD™ (SACD)
applications.
The DSD mode is accessed by programming the following bit in the corresponding control register.
• DSD = 1 (register 20)
The DSD mode provides a low-pass filtering function. The filtering is provided using an analog FIR filter structure.
Four FIR responses are available and are selected by the DMF[1:0] bits of control register 18.
The DSD bit must be set before inputting DSD data; otherwise, the PCM1795 erroneously detects the TDMCA
mode and commands are not accepted through the serial control interface.
Pin Assignment When Using DSD Format Interface
Several pins are redefined for DSD mode operation. These include:
• DATA (pin 5): DSDL as left-channel DSD data input
• LRCK (pin 4): DSDR as right-channel DSD data input
• SCK (pin 7): DBCK as bit clock for DSD data
• BCK (pin 6): Set low (N/A)
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Requirements for System Clock
For operation in DSD mode, the bit clock (DBCK) is required on pin 7 of the PCM1795. The frequency of the bit
clock can be N times the sampling frequency. Generally, N is 64 in DSD applications.
The interface timing between the bit clock and DSDL and DSDR is required to meet the setup and hold time
specifications shown in Figure 60 and Table 13.
t = 1/(64 ´ 44.1 kHz)
DBCK
DSDL,
DSDR
D0
D3
D2
D1
D4
Figure 59. Normal Data Output Form From DSD Decoder
t(BCH)
t(BCL)
DBCK
1.4 V
t(BCY)
DSDL,
DSDR
1.4 V
t(DS)
t(DH)
Figure 60. Timing for DSD Audio Interface
Table 13. Timing Characteristics for Figure 60
PARAMETER
MIN
MAX
UNIT
85 (1)
ns
DBCK high-level time
30
ns
t(BCL)
DBCK low-level time
30
ns
t(DS)
DSDL, DSDR setup time
10
ns
t(DH)
DSDL, DSDR hold time
10
ns
t(BCY)
DBCK pulse cycle time
t(BCH)
(1)
2.8224 MHz × 4. (2.8224 MHz = 64 × 44.1 kHz. This value is specified as a sampling rate of DSD.
DSD MODE CONFIGURATION AND FUNCTION CONTROLS
Configuration for the DSD Interface Mode
The DSD interface mode is selected by setting DSD = 1 (register 20, B5).
Table 14. DSD Mode Register Map
REGISTER
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
Register 16
R/W
0
0
1
0
0
0
0
X (1)
X
X
X
X
X
X
X
Register 17
R/W
0
0
1
0
0
0
1
X
X
X
X
X
X
X
X
Register 18
R/W
0
0
1
0
0
1
0
X
X
X
X
DMF1
DMF0
X
X
Register 19
R/W
0
0
1
0
0
1
1
REV
X
X
OPE
X
X
X
X
Register 20
R/W
0
0
1
0
1
0
0
X
SRST
1
X
MONO
CHSL
OS1
OS0
Register 21
R
0
0
1
0
1
0
1
X
X
X
X
X
DZ1
DZ0
X
Register 22
R
0
0
1
0
1
1
0
X
X
X
X
X
X
ZFGR
ZFGL
(1)
44
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DMF[1:0]: Analog-FIR Performance Selection
Default value: 00
DMF[1:0]
Analog-FIR Performance Selection
00
FIR-1 (default)
01
FIR-2
10
FIR-3
11
FIR-4
Plots for the four analog finite impulse response (FIR) filter responses are shown in the Analog FIR Filter
Performance in DSD Mode section of the Typical Characteristics.
OS[1:0]: Analog-FIR Operation-Speed Selection
Default value: 00
OS[1:0]
Operating Speed Selection
00
fDBCK (default)
01
fDBCK/2
10
Reserved
11
fDBCK/4
The OS bit in the DSD mode is used to select the operating rate of the analog FIR. The OS bits must be set
before setting the DSD bit to '1'.
TDMCA INTERFACE FORMAT
The PCM1795 supports the time-division-multiplexed command and audio (TDMCA) data format to simplify the
host control serial interface. TDMCA format is designed not only for the multichannel buffered serial port
description (McBSP) of TI DSPs but also for any programmable devices. TDMCA format can transfer not only
audio data but also command data, so that it can be used together with any kind of device that supports TDMCA
format. The TDMCA frame consists of a command field, extended command field, and some audio data fields.
Those audio data are transported to IN devices (such as a DAC) and/or from OUT devices (such as an ADC).
The PCM1795 is an IN device. LRCK and BCK are used with both IN and OUT devices so that the sample
frequency of all devices in a system must be the same. The TDMCA mode supports a maximum of 30 device
IDs. The maximum number of audio channels depends on the BCK frequency.
TDMCA Mode Determination
The PCM1795 recognizes the TDMCA mode automatically when it receives an LRCK signal with a pulse
duration of two BCK clocks. If the TDMCA mode operation is not needed, the duty cycle of LRCK must be 50%.
Figure 61 shows the LRCK and BCK timing that determines the TDMCA mode. The PCM1795 enters TDMCA
mode after two continuous TDMCA frames. Any TDMCA commands can be issued during the next TDMCA
frame after entering TDMCA mode.
Pre-TDMCA Frame
TDMCA Frame
Command
Accept
LRCK
2 BCKs
BCK
Figure 61. LRCK and BCK Timing for Determination of TDMCA Mode
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TDMCA Terminals
TDMCA requires six signals: four signals are for the command and audio data interface, and one pair for
daisy-chaining. These signals can be shared as shown in Table 15. The DO signal has a 3-state output so that it
can be connected directly to other devices.
Table 15. TDMCA Terminals
TERMINAL NAME
TDMCA NAME
PROPERTY
LRCK
LRCK
Input
TDMCA frame start signal; it must be the same as the sampling
frequency
BCK
BCK
Input
TDMCA clock; its frequency must be high enough to communicate a
TDMCA frame within an LRCK cycle
TDMCA command and audio data input signal
DATA
DI
Input
MDO
DO
Output
MC
DCI
Input
MS
DCO
Output
DESCRIPTION
TDMCA command data 3-state output signal
TDMCA daisy-chain input signal
TDMCA daisy-chain output signal
Device ID Determination
TDMCA mode also supports a multichip implementation in one system. This capability means that a host
controller (DSP) can simultaneously support several TDMCA devices, which can be of the same type or different
types, including PCM devices. The PCM devices are categorized as either IN devices, OUT devices, IN/OUT
devices, and NO devices. The IN device has an input port to receive audio data; the OUT device has an output
port to supply audio data; the IN/OUT device has both input and output ports for audio data; and the NO device
has no port for audio data, but requires command data from the host. A DAC is an IN device; an ADC is an OUT
device; a codec is an IN/OUT device; and a PLL is a NO device. The PCM1795 is an IN device. For the host
controller to distinguish the devices, each device is assigned its own device ID by the daisy-chain. The devices
obtain their own device IDs automatically by connecting the DCI to the DCO of the preceding device and the
DCO to the DCI of the following device in the daisy-chain. The daisy-chains are categorized as the IN chain and
the OUT chain, which are completely independent and equivalent. Figure 62 shows an example daisy-chain
connection. If a system must chain the PCM1795 and a NO device in the same IN or OUT chain, the NO device
must be chained at the back end of the chain because it does not require any audio data. Figure 63 shows an
example TDMCA system including an IN chain and an OUT chain with a TI DSP. For a device to get its own
device ID, the DID signal must be set to '1' (see the Command Field section for details), and LRCK and BCK
must be driven in the TDMCA mode for all PCM devices that are chained. The device at the top of the chain
knows its device ID is '1' because its DCI is fixed high. Other devices count the BCK pulses and observe the
respective DCI signal to determine ID and position in the chain. Figure 64 shows the initialization of each device
ID.
DCI
DCOo
DCO
DCI
NO Device
NO Device
OUT
DCIo
DCO
NO Device
NO Device
¼
DCO
¼
¼
DCI
IN/OUT
Device
DCO
IN/OUT
Device
DCI
DCOi
DCIi
IN
OUT
DCIo
DCO
OUT Device
¼
DCI
DCO
OUT Device
DCOi
DCIi
IN Device
IN
DCOo
¼
IN Device
DCI
DCO
DCI
DCO
DCI
IN Chain
OUT Chain
Figure 62. Daisy-Chain Connection Example
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DCII
LRCK
DCOI
BCK
DI
IN/OUT
Device
(DIX1700)
DCIO
DO
DCOO
Device ID = 1
LRCK
BCK
DCI
IN Device
(PCM1795)
DCO
DI
DO
Device ID = 2
LRCK
DCI
NO Device
BCK
DCO
DI
DO
Device ID = 3
¼
FSX
FSR
CLKX
CLKR
DX
DR
LRCK
OUT Device
DCI
BCK
DI
DCO
DO
Device ID = 2
TI DSP
LRCK
DCI
OUT Device
BCK
DCO
DI
DO
Device ID = 3
¼
Figure 63. IN Daisy-Chain and OUT Daisy-Chain Connection Example for a Multichip System
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LRCK
BCK
DID
DI
Device ID = 1
DCO1
Device ID = 2
DCO1,
DCI2
Device ID = 3
DCO2,
DCI3
Command Field
58 BCKs
Device ID = 30
DCO29,
DCI30
Figure 64. Device ID Determination Sequence
TDMCA Frame
In general, the TDMCA frame consists of the command field, extended command (EMD) field, and audio data
fields. All fields are 32 bits in length, but the lowest byte has no meaning. The MSB is transferred first for each
field. The command field is always transferred as the first packet of the frame. The EMD field is transferred if the
EMD flag of the command field is high. If any EMD packets are transferred, no audio data follow the EMD
packets. This frame is for quick system initialization. All devices of a daisy-chain should respond to the command
field and extended command field. The PCM1795 has two audio channels that can be selected by OPE (register
19). If the OPE bit is not set to high, those audio channels are transferred. Figure 65 shows the general TDMCA
frame. If some DACs are enabled, but corresponding audio data packets are not transferred, the analog outputs
are unpredictable.
1/fS
LRCK
BCK
[For Initialization]
DI
CMD
EMD
EMD
EMD
EMD
EMD
Don’t
Care
CMD
Don’t
Care
CMD
32 Bits
DO
CMD
CMD
CMD
CMD
CMD
CMD
[For Operation]
DI
DO
CMD
CMD
Ch 1
Ch 2
Ch 3
Ch 4
Ch (n)
Ch 1
Ch 2
Ch 3
Ch 4
Ch (m)
Figure 65. General TDMCA Frame
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1/fS (256 BCK Clocks)
7 Packets ´ 32 Bits
LRCK
BCK
DI
Ch 1
CMD
Ch 2
Ch 3
Ch 4
Ch 5
Don’t
Care
Ch 6
CMD
IN and OUT Channel Orders are Completely Independent
DO
Ch 1
CMD
Ch 2
Figure 66. TDMCA Frame Example of Six-Channel DAC and Two-Channel ADC With Command Read
Command Field
The normal command field is defined as shown in Figure 67. When the DID bit (MSB) is '1', this frame is used
only for device ID determination, and all remaining bits in the field are ignored.
Command
31
30
29
DID
EMD
DCS
28
24
Device ID
23
R/W
22
16 15
Register ID
8
7
Data
0
Not Used
Figure 67. Normal Command Field
Bit 31: Device ID enable flag
The PCM1795 operates to get its own device ID for TDMCA initialization if this bit is high.
Bit 30: Extended command enable flag
The EMD packet is transferred if this bit is high; otherwise, it is skipped. Once this bit is high, this frame does not
contain any audio data. This is for system initialization.
Bit 29: Daisy-chain selection flag
A high setting designates OUT-chain devices, low designates IN-chain devices. The PCM1795 is an IN device,
so the DCS bit must be set low.
Bits[28:24]: Device ID
The device ID is five bits in length and it can be defined. These bits identify the order of a device in the IN or
OUT daisy-chain. The top of the daisy-chain defines device ID 1 and successive devices are numbered 2, 3, 4,
etc. All devices for which the DCI is fixed high are also defined as ID 1. The maximum device ID is 30 each in
the IN and OUT chains. If a device ID of 0x1F is used, all devices are selected as broadcast when in the write
mode. If a device ID of 0x00 is used, no device is selected.
Bit 23: Command Read/Write flag
If this bit is high, the command is a read operation.
Bits[22:16]: Register ID
The register ID is seven bits in length.
Bits[15:8]: Command data
The command data are eight bits in length. Any valid data can be chosen for each register.
Bits[7:0]: Not used
These bits are never transported when a read operation is performed.
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Extended Command Field
The extended command field is the same as the command field, except that it does not have a DID flag.
Figure 68 defines the extended command field.
Extended Command
31
30
29
RSVD
EMD
DCS
28
24
Device ID
23
22
R/W
16 15
8
7
Data
Register ID
0
Not Used
Figure 68. Extended Command Field
Audio Fields
The audio field is 32 bits in length and the audio data are transferred MSB first, so the other fields must be filled
with 0s as shown in Figure 69.
Audio Data
31
16
MSB
24 Bits
12
8
7
LSB
4 3
0
All 0s
Figure 69. Audio Field Example
TDMCA Register Requirements
The TDMCA mode requires device ID and audio channel information, as previously described. The OPE bit in
register 19 indicates audio channel availability and register 23 indicates the device ID. Register 23 is used only in
the TDMCA mode; see the mode control register map of Table 9.
Register Write/Read Operation
The command supports register write and read operations. If the command requests to read one register, the
read data are transferred on DO during the data phase of the timing cycle. The DI signal can be retrieved at the
positive edge of BCK, and the DO signal is driven at the negative edge of BCK. DO is activated one BCK cycle
early to compensate for the output delay caused by high impedance. Figure 70 shows the TDMCA write and
read timing.
Register ID Phase
Data Phase
BCK
DI
Read Mode and Proper Register ID
Write Data Retrieved, if Write Mode
Read Data Driven, if Read Mode
DO
1 BCK Early
DOEN
(Internal)
Figure 70. TDMCA Write and Read Operation Timing
50
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TDMCA Mode Operation
DCO specifies the owner of the next audio channel in TDMCA mode operation. When a device retrieves its own
audio channel data, DCO goes high during the last audio channel period. Figure 71 shows the DCO output
timing in TDMCA mode operation. The host controller ignores the behavior of DCI and DCO. DCO indicates the
last audio channel of each device. Therefore, DCI means the next audio channel is allocated.
If some devices are skipped because of no active audio channel, the skipped devices must notify the next device
that the DCO will be passed through the next DCI. Figure 72 and Figure 73 show DCO timing with skip
operation. Figure 74 and Table 16 show the ac timing of the daisy-chain signals.
1/fS (384 BCK Clocks)
9 Packets ´ 32 Bits
LRCK
BCK
IN Daisy Chain
CMD
DI
Ch 1
Ch 2
Ch 3
Ch 4
Ch 5
Ch 6
Ch 7
Ch 8
Don’t Care
CMD
DCI1
DID = 1
DCO1
DCI2
DID = 2
DCO2
DCI3
DID = 3
DID = 4
DCO3
DCI4
DCO4
Figure 71. DCO Output Timing of TDMCA Mode Operation
1/fS (256 BCK Clocks)
5 Packets ´ 32 Bits
LRCK
BCK
DI
CMD
Ch 1
Ch 2
Ch 15
Ch 16
Don’t Care
CMD
DCI
DID = 1
DCO
DCI
2 BCK Delay
DID = 2
DCO
¼
¼
14 BCK Delay
DCI
DID = 8
DCO
Figure 72. DCO Output Timing with Skip Operation
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Command Packet
LRCK
BCK
DI
DID EMD
DCO1
DCO2
¼
Figure 73. DCO Output Timing with Skip Operation (for Command Packet 1)
LRCK
t(LB)
t(BL)
BCK
t(BCY)
t(DS)
t(DH)
DI
t(DOE)
DO
t(DS)
t(DH)
DCI
t(COE)
DCO
Figure 74. AC Timing of Daisy-Chain Signals
Table 16. Timing Characteristics for Figure 74
PARAMETER
t(BCY)
BCK pulse cycle time
t(LB)
t(BL)
MIN
MAX
UNIT
20
ns
LRCK setup time
0
ns
LRCK hold time
3
ns
t(DS)
DI setup time
0
ns
t(DH)
DI hold time
3
ns
t(DS)
DCI setup time
0
ns
t(DH)
DCI hold time
3
t(DOE)
DO output delay (1)
t(COE)
(1)
52
DCO output delay
(1)
ns
8
ns
6
ns
Load capacitance is 10 pF.
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ANALOG OUTPUT
Table 17 and Figure 75 show the relationship between the digital input code and analog output.
Table 17. Analog Output Current and Voltage (1)
(1)
PARAMETER
800000 (–FS)
000000 (BPZ)
7FFFFF (+FS)
IOUTN (mA)
–1.5
–3.5
–5.5
IOUTP (mA)
–5.5
3.5
–1.5
VOUTN (V)
–1.23
–2.87
–4.51
VOUTP (V)
–4.51
–2.87
–1.23
VOUT (V)
–2.91
0
2.91
VOUTN is the output of U1, VOUTP is the output of U2, and VOUT is the output of U3 in the measurement circuit of Figure 52.
OUTPUT CURRENT vs INPUT CODE
0
Output Current (mA)
-1
IOUTN
-2
-3
-4
-5
IOUTP
-6
80000000 (-FS)
000000 (BPZ)
7FFFFFFF (+FS)
Input Code (Hex)
Figure 75. Relationship Between Digital Input and Analog Output
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PACKAGE OPTION ADDENDUM
www.ti.com
18-May-2009
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
PCM1795DB
ACTIVE
SSOP
DB
28
PCM1795DBR
ACTIVE
SSOP
DB
28
50
Lead/Ball Finish
MSL Peak Temp (3)
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-1-260C-UNLIM
2000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-1-260C-UNLIM
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
13-Jul-2009
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
PCM1795DBR
Package Package Pins
Type Drawing
SSOP
DB
28
SPQ
Reel
Reel
Diameter Width
(mm) W1 (mm)
2000
330.0
16.4
Pack Materials-Page 1
A0 (mm)
B0 (mm)
K0 (mm)
P1
(mm)
W
Pin1
(mm) Quadrant
8.2
10.5
2.5
12.0
16.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
13-Jul-2009
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
PCM1795DBR
SSOP
DB
28
2000
346.0
346.0
33.0
Pack Materials-Page 2
MECHANICAL DATA
MSSO002E – JANUARY 1995 – REVISED DECEMBER 2001
DB (R-PDSO-G**)
PLASTIC SMALL-OUTLINE
28 PINS SHOWN
0,38
0,22
0,65
28
0,15 M
15
0,25
0,09
8,20
7,40
5,60
5,00
Gage Plane
1
14
0,25
A
0°–ā8°
0,95
0,55
Seating Plane
2,00 MAX
0,10
0,05 MIN
PINS **
14
16
20
24
28
30
38
A MAX
6,50
6,50
7,50
8,50
10,50
10,50
12,90
A MIN
5,90
5,90
6,90
7,90
9,90
9,90
12,30
DIM
4040065 /E 12/01
NOTES: A.
B.
C.
D.
All linear dimensions are in millimeters.
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion not to exceed 0,15.
Falls within JEDEC MO-150
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
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