PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
24-Bit, 192-kHz Sampling, Enhanced Multilevel, Delta-Sigma,
Audio Digital-to-Analog Converter
FEATURES
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
24-Bit Resolution
Analog Performance (VCC = 5 V):
– Dynamic Range:
• 106 dB, Typical (PCM1742KE)
• 100 dB, Typical (PCM1742E)
– SNR:
• 106 dB, Typical (PCM1742KE)
• 100 dB, Typical (PCM1742E)
– THD+N:
• 0.002%, Typical (PCM1742KE)
• 0.003%, Typical (PCM1742E)
– Full-Scale Output: 3.1 Vp-p, Typical
4x/8x Oversampling Digital Filter:
Stop-Band Attenuation: –55 dB
Pass-Band Ripple: ±0.03 dB
Sampling Frequency: 5 kHz to 200 kHz
System Clock: 128 fS, 192 fS, 256 fS, 384 fS,
512 fS, 768 fS With Autodetect
Accepts 16-, 18-, 20-, and 24-Bit Audio Data
Data Formats: Standard, I2S, and
Left-Justified
User-Programmable Mode Controls:
Digital Attenuation: 0 dB to –63 dB, 0.5
dB/Step
Digital De-Emphasis
Digital Filter Rolloff: Sharp or Slow
Soft Mute
Zero Flags for Each Output
Dual-Supply Operation: 5-V Analog, 3.3-V
Digital
5-V Tolerant Digital Inputs
Small SSOP-16 Package
AV Receivers
DVD Movie Players
DVD Add-On Cards for High-End PCs
DVD Audio Players
HDTV Receivers
Car Audio Systems
Other Applications Requiring 24-Bit Audio
DESCRIPTION
The PCM1742 is a CMOS, monolithic, integrated
circuit which includes stereo digital-to-analog converters (DACs) and support circuitry in a small
SSOP-16 package. The data converters use Texas
Instruments' enhanced multilevel delta-sigma architecture that employs fourth-order noise shaping and
8-level amplitude quantization to achieve excellent
dynamic performance and improved tolerance to
clock jitter. The PCM1742 accepts industry-standard
audio data formats with 16- to 24-bit data, providing
easy interfacing to audio DSP and decoder chips.
Sampling rates up to 200 kHz are supported. A full
set of user-programmable functions is accessible
through a 3-wire serial control port that supports
register write functions.
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.
FilterPro is a trademark of Texas Instruments.
System Two, Audio Precision are trademarks of Audio Precision, Inc.
All 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 © 2000–2005, Texas Instruments Incorporated
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
Power supply voltage, VDD
–0.3 V to 4 V
Power supply voltage, VCC
–0.3 V to 6.5 V
Supply voltage difference, VCC, VDD
VCC – VDD < 3 V
Ground voltage differences
±0.1 V
Digital input voltage
–0.3 V to 6.5 V
Input current (except power supply pins)
±10 mA
Ambient temperature under bias
–40°C to 125°C
Storage temperature, Tstg
–55°C to 150°C
Junction temperature, TJ
150°C
Lead temperature (soldering)
260°C, 5 s
Package temperature (IR reflow, peak)
(1)
235°C
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.
RECOMMENDED OPERATING CONDITIONS
over operating free-air temperature range
Digital supply voltage, VDD
Analog supply voltage, VCC
MIN
NOM
MAX
3
3.3
3.6
V
4.5
5
5.5
V
Digital input logic family
Digital input clock frequency
UNIT
TTL
System clock
Sampling clock
Analog output load resistance
8.192
36.864
MHz
32
192
kHz
5
kΩ
Analog output load capacitance
50
pF
Digital output load capacitance
20
pF
85
°C
Operating free-air temperature, TA
–25
ELECTRICAL CHARACTERISTICS
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, fS = 44.1 kHz, system clock = 384 fS, and 24-bit data (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
Resolution
TYP
MAX
24
UNIT
Bits
DATA FORMAT
Audio data interface formats
Audio data bit length
Audio data format
fS
Sampling frequency
System clock frequency
Standard, I2S, left-justified
16-, 18-, 20-, 24-bit selectable
MSB-first, binary 2s complement
5
200
kHz
128, 192, 256, 384, 512, 768 fS
DIGITAL INPUT/OUTPUT
Logic family
TTL compatible
Input Logic Level
VIH
High-level input votlage
VIL
Low-level input voltage
2
2
Vdc
0.8
Vdc
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, fS = 44.1 kHz, system clock = 384 fS, and 24-bit data (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Input Logic Current
IIH
High-level input current (1)
VIN = VDD
10
µA
IIL
Low-level input current (1)
VIN = 0 V
–10
µA
IIH
High-level input
current (2)
VIN = VDD
100
µA
IIL
Low-level input current (2)
VIN = 0 V
–10
µA
65
Output Logic Level
VOH
High-level output voltage (3)
IOH = –2 mA
VOL
Low-level output voltage (3)
IOL = 2 mA
2.4
Vdc
1
Vdc
DYNAMIC PERFORMANCE (4) (5)
PCM1742E
THD+N
Total harmonic distortion + noise
VOUT = 0 dB, fS = 44.1 kHz
0.003%
VOUT = 0 dB, fS = 96 kHz
0.004%
VOUT = 0 dB, fS = 192 kHz
0.005%
VOUT = –60 dB, fS = 44.1 kHz
1.2%
VOUT = –60 dB, fS = 96 kHz
1.6%
VOUT = –60 dB, fS = 192 kHz
1.8%
EIAJ, A-weighted, fS = 44.1 kHz
Dynamic range
Signal-to-noise ratio
98
A-weighted, fS = 192 kHz
96
Level linearity error
(1)
(2)
(3)
(4)
(5)
94
98
A-weighted, fS = 192 kHz
96
91
dB
98
fS = 96 kHz
96
fS = 192 kHz
94
VOUT = –90 dB
dB
100
A-weighted, fS = 96 kHz
fS = 44.1 kHz
Channel separation
100
A-weighted, fS = 96 kHz
EIAJ, A-weighted, fS = 44.1 kHz
SNR
94
0.008%
±0.5
dB
dB
Pins 1, 2, 3, 16 (SCK, BCK, LRCK, DATA).
Pins 13–15 (MD, MC, ML).
Pins 11, 12 (ZEROR, ZEROL).
Analog performance specifications are tested with a Shibasoku #725 THD meter with 400-Hz HPF on, 30-kHz LPF on, and an average
mode with 20-kHz bandwidth limiting. The load connected to the analog output is 5 kΩ or larger, via capacitive coupling.
Conditions in 192-kHz operation are: system clock = 128 fS and oversampling rate = 64 fS (under register control).
3
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, fS = 44.1 kHz, system clock = 384 fS, and 24-bit data (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
VOUT = 0 dB, fS = 44.1 kHz
0.002%
0.006%
VOUT = 0 dB, fS = 96 kHz
0.003%
VOUT = 0 dB, fS = 192 kHz
0.004%
UNIT
PCM1742KE
THD+N
Total harmonic distortion + noise
VOUT = –60 dB, fS = 44.1 kHz
0.65%
VOUT = –60 dB, fS = 96 kHz
0.8%
VOUT = –60 dB, fS = 192 kHz
EIAJ, A-weighted, fS = 44.1 kHz
Dynamic range
Signal-to-noise ratio
104
A-weighted, fS = 192 kHz
102
Level linearity error
100
104
A-weighted, fS = 192 kHz
102
97
dB
106
A-weighted, fS = 96 kHz
fS = 44.1 kHz
Channel separation
106
A-weighted, fS = 96 kHz
EIAJ, A-weighted, fS = 44.1 kHz
SNR
0.95%
100
dB
103
fS = 96 kHz
101
fS = 192 kHz
100
VOUT = –90 dB
±0.5
dB
dB
DC ACCURACY
Gain error
±1
±6
% of FSR
Gain mismatch, channel-to-channel
±1
±3
% of FSR
±30
±60
mV
Bipolar zero error
VOUT = 0.5 VCC at bipolar zero
ANALOG OUTPUT
Output voltage
Full scale (0 dB)
Center voltage
Load Impedance
AC load
0.62 VCC
Vp-p
0.5 VCC
Vdc
5
kΩ
DIGITAL FILTER PERFORMANCE
Filter Characteristics, Sharp Rolloff
Pass band
±0.03 dB
Pass band
–3 dB
Stop band
0.454 fS
0.487 fS
0.546 fS
Pass-band ripple
Stop-band attenuation
±0.03
Stop band = 0.546 fS
–50
Stop band = 0.567 fS
–55
dB
dB
Filter Characteristics, Slow Rolloff
Pass band
±0.5 dB
Pass band
–3 dB
Stop band
0.198 fS
0.39 fS
0.884 fS
Pass-band ripple
Stop-band attenuation
±0.5
Stop band = 0.884 fS
–40
dB
dB
Delay time
20/fS
s
De-emphasis error
±0.1
dB
ANALOG FILTER PERFORMANCE
Frequency response
4
f = 20 kHz
–0.03
f = 44 kHz
–0.20
dB
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
ELECTRICAL CHARACTERISTICS (continued)
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, fS = 44.1 kHz, system clock = 384 fS, and 24-bit data (unless
otherwise noted)
PARAMETER
TEST CONDITIONS
POWER SUPPLY REQUIREMENTS
VDD
VCC
MIN
TYP
MAX
3
3.3
3.6
4.5
5
5.5
Voltage range
6
10
fS = 44.1 kHz
IDD
ICC
UNIT
(6)
Supply current
Supply current
Power dissipation
fS = 96 kHz
13
fS = 192 kHz
16
fS = 44.1 kHz
8.5
fS = 96 kHz
9
fS = 192 kHz
9
fS = 44.1 kHz
62
fS = 96 kHz
88
fS = 192 kHz
98
Vdc
mA
13
mA
98
mW
TEMPERATURE RANGE
TA
Operation temperature
θJA
Thermal resistance
(6)
–25
85
115
°C
°C/W
Conditions in 192-kHz operation are: system clock = 128 fS and oversampling rate = 64 fS (under register control).
Functional Block Diagram
BCK
LRCK
Audio
Serial
Port
DAC
VOUTL
Low−Pass F ilter
4x/8x
Oversampling
Digital Filter
with
Function
Controller
DATA
ML
MC
Output Amp and
Enhanced
Multilevel
Delta−Sigma
Modulator
Serial
Control
Port
VCOM
DAC
Output Amp and
VOUTR
Low−Pass F ilter
MD
System Clock
VCC
AGND
ZEROR
VDD
Power Supply
Zero Detect
DGND
System Clock
M anager
ZEROL
SCK
5
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
PIN ASSIGNMENTS
PCM1742DBQ PACKAGE
(TOP VIEW)
BCK
1
16 SCK
DATA
2
15 ML
LRCK
3
14 MC
DGND
4
13 MD
PCM1742
VDD
5
12 ZEROL/NA
VCC
6
11 ZEROR/ZEROA
VOUTL
7
10 VCOM
VOUTR
8
9
AGND
TERMINAL FUNCTIONS
TERMINAL
I/O
DESCRIPTION
9
–
Analog ground
1
I
Audio data bit clock input
DATA
2
I
Audio data digital input
DGND
4
–
Digital ground
LRCK
3
I
L-channel and R-channel audio-data latch-enable input
MC
14
I
Mode control clock input
MD
13
I
Mode control data input
(2)
ML
15
I
Mode control latch input
(2)
NAME
NO.
AGND
BCK
(1)
(1)
(1)
(2)
(1)
SCK
16
I
System clock input
VCC
6
–
Analog power supply, 5 V
VCOM
10
–
Common voltage decoupling
VDD
5
–
Digital power supply, 3.3 V
VOUTL
7
O
Analog output for L-channel
VOUTR
8
O
Analog output for R-channel
ZEROL/NA
12
O
Zero-flag output for L-channel/No assign
ZEROR/ZEROA
11
O
Zero-flag output for R-channel/Zero-flag output for L-/R-channel
(1)
(2)
6
Schmitt-trigger input, 5-V tolerant.
Schmitt-trigger input with internal pulldown, 5-V tolerant.
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
TYPICAL PERFORMANCE CURVES
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, fS = 44.1 kHz, system clock = 384 fS, and 24-bit input data, unless
otherwise noted
Digital Filter (De-Emphasis Off)
FREQUENCY RESPONSE (SHARP ROLLOFF)
PASS-BAND FREQUENCY RESPONSE (SHARP ROLLOFF)
0.05
0
0.04
−20
0.03
0.02
Amplitude (dB)
Amplitude (dB)
−40
−60
−80
−100
0.01
0
−0.01
−0.02
−0.03
−120
−0.04
−0.05
−140
0
1
2
3
0
4
0.1
0.2
0.3
0.4
0.5
Frequency (x fS)
Frequency (x fS )
Figure 1.
Figure 2.
FREQUENCY RESPONSE (SLOW ROLLOFF)
TRANSITION CHARACTERISTICS (SLOW ROLLOFF)
0
5
4
−20
3
2
Amplitude (dB)
Amplitude (dB)
−40
−60
−80
−100
1
0
−1
−2
−3
−120
−4
−5
−140
0
1
2
Frequency (x fS )
Figure 3.
3
4
0
0.1
0.2
0.3
0.4
0.5
Frequency (x fS )
Figure 4.
7
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
TYPICAL PERFORMANCE CURVES (continued)
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, fS = 44.1 kHz, system clock = 384 fS, and 24-bit input data, unless
otherwise noted
Digital Filter (De-Emphasis)
DE-EMPHASIS ERROR (fS = 32 kHz)
0.5
−1.0
0.4
−2.0
0.3
−3.0
0.2
−4.0
0.1
Error (dB)
Level (dB)
DE-EMPHASIS (fS = 32 kHz)
0.0
−5.0
−6.0
0.0
−0.1
−7.0
−0.2
−8.0
−0.3
−9.0
−0.4
−10.0
−0.5
0
2
4
6
8
10
12
14
0
2
4
Frequency (kHz)
Figure 5.
0.5
−1.0
0.4
−2.0
0.3
−3.0
0.2
−4.0
0.1
Error (dB)
Level (dB)
10
12
14
DE-EMPHASIS ERROR (fS = 44.1 kHz)
0.0
−5.0
−6.0
0.0
−0.1
−7.0
−0.2
−8.0
−0.3
−9.0
−0.4
−10.0
−0.5
0
2
4
6
8
10
12
14
16
18
20
0
2
4
6
8
10
12
Frequency (kHz)
Frequency (kHz)
Figure 7.
Figure 8.
DE-EMPHASIS (fS = 48 kHz)
14
16
18
20
18
22
DE-EMPHASIS ERROR (fS = 48 kHz)
0.0
0.5
−1.0
0.4
−2.0
0.3
−3.0
0.2
−4.0
0.1
Error (dB)
Level (dB)
8
Figure 6.
DE-EMPHASIS (fS = 44.1 kHz)
−5.0
−6.0
0.0
−0.1
−7.0
−0.2
−8.0
−0.3
−9.0
−0.4
−10.0
−0.5
0
8
6
Frequency (kHz)
2
4
6
8
10
12
14
16
18
22
0
2
4
6
8
10
12
Frequency (kHz)
Frequency (kHz)
Figure 9.
Figure 10.
14
16
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
TYPICAL PERFORMANCE CURVES (continued)
ANALOG DYNAMIC PERFORMANCE
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, and 24-bit input data, unless otherwise specified. Conditions in
192-kHz operation are system clock = 128 fS and oversampling rate = 64 fS (under register control).
Supply Voltage Characteristics
TOTAL HARMONIC DISTORTION + NOISE
vs
VCC (VDD = 3.3 V)
DYNAMIC RANGE
vs
VCC (VDD = 3.3 V)
110
10
− 60dB/192kHz, 384f S
− 60dB/96kHz, 384fS
108
44.1kHz, 384fS
Dynamic Range (dB)
THD+N (%)
1
− 60dB/44.1kHz, 384f S
0.1
0dB/192kHz, 384fS
0.01
0dB/96kHz, 384fS
0.001
106
96kHz, 384fS
104
192kHz, 384fS
102
100
98
0dB/44.1kHz, 384fS
96
0.0001
4
4.5
5.5
5
4
6
4.5
5.5
Figure 11.
Figure 12.
SIGNAL-TO-NOISE RATIO
vs
VCC (VDD = 3.3 V)
CHANNEL SEPARATION
vs
VCC (VDD = 3.3 V)
110
6
110
108
108
Channel Separation (dB)
44.1kHz, 384fS
106
SNR (dB)
5
VCC (V)
VCC (V)
96kHz, 384fS
104
192kHz, 384fS
102
100
98
106
44.1kHz, 384fS
104
102
96kHz, 384fS
100
192kHz, 384fS
98
96
96
4
4.5
5
VCC (V)
Figure 13.
5.5
6
4
4.5
5
5.5
6
VCC (V)
Figure 14.
9
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
TYPICAL PERFORMANCE CURVES (continued)
ANALOG DYNAMIC PERFORMANCE (continued)
All specifications at TA = 25°C, VCC = 5 V, VDD = 3.3 V, and 24-bit input data, unless otherwise specified. Conditions in
192-kHz operation are system clock = 128 fS and oversampling rate = 64 fS (under register control).
Temperature Characteristics
TOTAL HARMONIC DISTORTION + NOISE
vs
TEMPERATURE (TA)
DYNAMIC RANGE
vs
TEMPERATURE (TA)
110
10
−60dB/192kHz, 384f S
−60dB/96kHz, 384f S
108
Dynamic Range (dB)
THD+N (%)
1
−60dB/44.1kHz, 384fS
0.1
0dB/192kHz, 384fS
0.01
0.001
0dB/96kHz, 384fS
0dB/44.1kHz, 384f S
44.1kHz, 384fS
106
96kHz, 384fS
104
192kHz, 384fS
102
100
98
96
0.0001
−50
−25
0
25
50
75
−50
100
−25
0
Figure 16.
SIGNAL-TO-NOISE RATIO
vs
TEMPERATURE (TA)
CHANNEL SEPARATION
vs
TEMPERATURE (TA)
75
100
75
100
110
108
108
Channel Separation (dB)
44.1kHz, 384fS
106
96kHz, 384fS
SNR (dB)
50
Figure 15.
110
104
192kHz, 384fS
102
100
98
106
44.1kHz, 384fS
104
96kHz, 384fS
102
100
192kHz, 384fS
98
96
96
−50
−25
0
25
50
Temperature (°C)
Figure 17.
10
25
Temperature (°C)
Temperature (°C)
75
100
−50
−25
0
25
50
Temperature (°C)
Figure 18.
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
SYSTEM CLOCK AND RESET FUNCTIONS
SYSTEM CLOCK INPUT
The PCM1742 requires a system clock for operating the digital interpolation filters and multilevel delta-sigma
modulators. The system clock is applied at the SCK input (pin 16). Table 1 shows examples of system clock
frequencies for common audio sampling rates.
Figure 19 shows 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 PLL1700 multiclock generator from Texas Instruments is
an excellent choice for providing the PCM1742 system clock.
Table 1. System Clock Rates for Common Audio Sampling Frequencies
SAMPLING FREQUENCY
192 fS
256 fS
384 fS
512 fS
8 kHz
(1)
(1)
2.048
3.072
4.096
6.144
16 kHz
(1)
(1)
4.096
6.144
8.192
12.288
768 fS
32 kHz
(1)
(1)
8.192
12.288
16.384
24.576
44.1 kHz
(1)
(1)
11.2896
16.9344
22.5792
33.8688
48 kHz
(1)
(1)
12.288
18.432
24.576
36.864
88.2 kHz
(1)
(1)
22.5792
33.8688
45.1584
(1)
96 kHz
(1)
(1)
24.576
36.864
49.152
(1)
36.864
(1)
(1)
(1)
(1)
192 kHz
(1)
SYSTEM CLOCK FREQUENCY (fSCLK) (MHz)
128 fS
24.576
This system clock is not supported for the given sampling frequency.
t SCKH
H
2V
L
0.8 V
System Clock
t SCKL
SYMBOL
t SCKY
DESCRIPTION
MIN
MAX
UNIT
tSCKY
System clock cycle time (1)
20
ns
tSCKH
System clock pulse duration, HIGH
7
ns
tSCKL
System clock pulse duration, LOW
7
ns
(1)
1/128 fS, 1/192 fS, 1/256 fS, 1/384 fS, 1/512 fS, or 1/768 fS
Figure 19. System Clock Input Timing
11
PCM1742
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SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
POWER-ON RESET FUNCTIONS
The PCM1742 includes a power-on-reset function, as shown in Figure 20. With the system clock active and VDD
> 2 V (typical, 1.6 V to 2.4 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 PCM1742 is set to its reset default
state, as described in the Mode Control Registers section of this data sheet.
During the reset period (1024 system clocks), the analog outputs are forced to the bipolar zero level, or VCC/2.
After the reset period, all the mode control registers are initialized in the next 1/fS period and, if SCK, BCK, and
LRCK are provided continuously, the PCM1742 provides proper analog output with group delay corresponding to
the input data.
VDD
2.4V
2.0V
1.6V
0V
Reset
Reset Removal
Internal Reset
Don’t Care
1024 System Clocks
System Clock
Figure 20. Power-On-Reset Timing
AUDIO SERIAL INTERFACE
The audio serial interface for the PCM1742 comprises a 3-wire synchronous serial port. It includes LRCK (pin 3),
BCK (pin 1), and DATA (pin 2). BCK is the serial audio bit clock, which is used to clock the serial data present on
DATA into the audio interface serial shift register. Serial data is clocked into the PCM1742 on the rising edge of
BCK. LRCK is the serial audio left/right word clock used to latch serial data into the serial audio interface internal
registers.
Both LRCK and BCK must be synchronous to the system clock. Ideally, it is recommended that LRCK and BCK
be derived from the system clock input, SCK. LRCK is operated at the sampling frequency, fS. BCK can be
operated at 32 (16-bit, right-justified only), 48, or 64 times the sampling frequency. Internal operation of the
PCM1742 is synchronized with LRCK. Accordingly, internal operation of the device is suspended when the
sampling rate clock of LRCK is changed or SCK and/or BCK is interrupted at least for three bit-clock cycles. If
SCK, BCK, and LRCK are provided continuously after this suspended state, the internal operation is
resynchronized automatically within a period of less than 3/fS. During this resynchronization period and for a 3/fS
time thereafter, the analog output is forced to the bipolar zero level, or VCC/2. External resetting is not required.
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AUDIO DATA FORMATS AND TIMING
The PCM1742 supports industry-standard audio data formats, including standard, I2S, and left-justified, as shown
in Figure 21. Data formats are selected using the format bits, FMT[2:0], in control register 20. The default data
format is 24-bit, left-justified. All formats require binary 2s complement, MSB-first audio data. See Figure 22 for a
detailed timing diagram of the serial audio interface.
(1) Sta nd ard D ata Fo rm at: L −C h an n el = H IG H , R−C ha nn el = L O W
1/fS
LRCK
R−Channel
L−Channel
BCK
(= 32, 48 or 64fS )
16−Bit Right−Justified, BCK = 48fS or 64f S
DATA
14
15
16
1
14
15
3
14
15
14
15
MSB
16−Bit Right−Justified, BCK = 32fS
DATA
2
16
1
2
3
16
1
LSB
MSB
2
3
14
15
14
15
MSB
16
1
LSB
2
3
16
LSB
MSB
16
LSB
18−Bit Right−Justified
DATA
16
17
18
1
2
3
16
17
MSB
18
1
LSB
2
17
MSB
18
LSB
20−Bit Right−Justified
DATA
18
19
20
1
2
3
18
19
MSB
20
1
LSB
2
3
18
19
MSB
20
LSB
24−Bit Right−Justified
DATA
22
23
24
1
2
3
22
MSB
23
24
1
LSB
2
3
22
23
MSB
24
LSB
2
(2) I S D ata Fo rm at: L −C h an n el = L O W , R −Ch an nel = H IG H
1/fS
LRCK
L−Channel
R−Channel
BCK
(= 48 or 64fS )
DATA
1
2
3
N−2 N−1
MSB
N
1
LSB
2
3
N−2 N−1
MSB
N
1
2
1
2
LSB
(3) L eft−Ju stified D ata Fo rm at: L−C han nel = H IG H , R −C h ann el = L O W
1/fS
L−Channel
LRCK
R−Channel
BCK
(= 48 or 64fS )
DATA
1
MSB
2
3
N−2 N−1
N
LSB
1
2
3
MSB
N−2 N−1
N
LSB
Figure 21. Audio Data Input Formats
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LRCK
50% of VDD
tBCH
tBCL
t LB
BCK
50% of VDD
tBCY
tBL
50% of VDD
DATA
tDS
SYMBOL
t DH
DESCRIPTION
MIN
MAX
UNIT
1/(64 fS)(1)
tBCY
BCK pulse cycle time
tBCH
BCK high-level time
35
ns
tBCL
BCK low-level time
35
ns
tBL
BCK rising edge to LRCK edge
10
ns
tLB
LRCK falling edge to BCK rising edge
10
ns
tDS
DATA setup time
10
ns
tDH
DATA hold time
10
ns
(1)
fS is the sampling frequency (e.g., 44.1 kHz, 48 kHz, 96 kHz, etc.).
Figure 22. Audio Interface Timing
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SERIAL CONTROL INTERFACE
The serial control interface is a 3-wire serial port that operates asynchronously to the serial audio interface. The
serial control interface is used to program the on-chip mode registers. The serial control interface includes
MD (pin 13), MC (pin 14), and ML (pin 15). MD is the serial data input, used to program the mode registers; MC
is the serial bit clock, used to shift data into the control port; and ML is the control-port latch clock.
REGISTER WRITE OPERATION
All write operations for the serial control port use 16-bit data words. Figure 23 shows the control data word
format. The most significant bit must be a 0. Seven bits, labeled IDX[6:0], set the register index (or address) for
the write operation. The least significant eight bits, D[7:0], contain the data to be written to the register specified
by IDX[6:0].
MSB
0
LSB
IDX 6
IDX 5
IDX 4
IDX3
IDX 2
IDX 1
IDX0
D7
D6
Register Index (or Address)
D5
D4
D3
D2
D1
D0
Register Data
Figure 23. Control Data Word Format for MD
Figure 24 shows the functional timing diagram for writing to the serial control port. ML is held at a logic-1 state
until a register needs to be written. To start the register write cycle, ML is set to logic-0. Sixteen clocks are then
provided on MC, corresponding to the 16 bits of the control data word on MD. After the sixteenth clock cycle has
completed, ML is set to logic-1 to latch the data into the indexed mode control register.
ML
MC
MD
X
0
IDX6 IDX 5 IDX 4
IDX3
IDX 2 IDX1
IDX0
D7
D6
D5
D4
D3
D2
D1
D0
X
X
0
IDX 6
Figure 24. Register Write Operation
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CONTROL INTERFACE TIMING REQUIREMENTS
See Figure 25 for a detailed timing diagram of the serial control interface. These timing parameters are critical for
proper control port operation.
tMHH
50% of V D D
ML
tM L S
tMCH
tMCL
tMLH
50% of V D D
MC
tMCY
LSB
MD
50% of V D D
tMDS
SYMBOL
PARAMETER
t MDH
MIN
TYP
MAX
UNIT
tMCY
MC pulse cycle time
100
ns
tMCL
MC low-level time
50
ns
tMCH
MC high-level time
50
ns
tMHH
ML high-level time
3/(256 × fS) (2)
ns
tMLS
ML falling edge to MC rising edge
20
ns
tMLH
ML hold time(1)
20
ns
tMDH
MD hold time
15
ns
tMDS
MD setup time
20
ns
(1)
MC rising edge for LSB to ML rising edge
(2)
fS = sampling rate
Figure 25. Control Interface Timing
MODE CONTROL REGISTERS
User-Programmable Mode Controls
The PCM1742 includes a number of user-programmable functions that are accessed via control registers. The
registers are programmed using the serial control interface that is discussed in a preceding section of this data
sheet. Table 2 lists the available mode control functions, along with their reset default conditions and associated
register index.
Table 2. User-Programmable Mode Controls
FUNCTION
Digital attenuation control, 0 dB to –63 dB in 0.5-dB steps
Soft mute control
RESET DEFAULT
CONTROL
REGISTER
INDEX IDX[6:0]
0 dB, no attenuation
16 and 17
AT1[7:0], AT2[7:0]
MUT[2:0]
Mute disabled
18
64-fS oversampling
18
OVER
DAC1 and DAC2 enabled
19
DAC[2:1]
De-emphasis disabled
19
DM12
44.1 kHz
19
DMF[1:0]
Audio data format control
24-bit, left-justified
20
FMT[2:0]
Digital filter rolloff control
Sharp rolloff
20
FLT
Zero-flag function select
L-/R-channels independent
22
AZRO
Normal phase
22
DREV
High
22
ZREV
Oversampling rate control (64 fS or 128 fS)
DAC operation control
De-emphasis function control
De-emphasis sample rate selection
Output phase select
Zero-flag polarity select
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Register Map
The mode control register map is shown in Table 3. Each register includes an index (or address) indicated by the
IDX[6:0] bits.
Table 3. Mode Control Register Map
IDX
(B14–B8)
REGISTER
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
10h
16
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
AT17
AT16
AT15
AT14
AT13
AT12
AT11
AT10
11h
17
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
AT27
AT26
AT25
AT24
AT23
AT22
AT21
AT20
12h
18
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
RSV (1)
OVER
RSV (1)
RSV (1)
RSV (1)
RSV (1)
MUT2
MUT1
13h
19
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
RSV (1)
DMF1
DMF0
DM12
RSV (1)
RSV (1)
DAC2
DAC1
RSV (1)
FLT
RSV (1)
RSV (1)
FMT2
FMT1
FMT0
(1)
14h
20
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
RSV (1)
15h
21
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
RSV (1)
RSV (1)
RSV (1)
RSV (1)
RSV (1)
RSV (1)
RSV (1)
RSV (1)
16h
22
0
IDX6
IDX5
IDX4
IDX3
IDX2
IDX1
IDX0
RSV (1)
RSV (1)
RSV (1)
RSV (1)
RSV (1)
AZRO
ZREV
DREV
RSV: Reserved for test operation. It should be set to 0 during normal operation.
REGISTER DEFINITIONS
B7
B6
B5
B4
B3
B2
B1
B0
REGISTER 16
B15
0
IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0
B14
B13
B12
B11
B10
B9
B8
AT17
AT16
AT15
AT14
AT13
AT12
AT11
AT10
REGISTER 17
0
IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0
AT27
AT26
AT25
AT24
AT23
AT22
AT21
AT20
ATx[7:0] – Digital Attenuation Level Setting
where x = 1 or 2, corresponding to the DAC output VOUTL (x = 1) and VOUTR (x = 2).
Default value: 1111 1111b
Each DAC channel (VOUTL and VOUTR) includes a digital attenuator function. The attenuation level can be set
from 0 dB to –63 dB, in 0.5-dB steps. Changes in attenuation levels are made by incrementing or decrementing,
by one step (0.5 dB), for every 8/fS time interval until the programmed attenuator setting is reached. Alternatively,
the attenuation level can be set to infinite attenuation, or mute. The attenuation data for each channel can be set
individually.
The attenuation level is calculated using the following formula:
Attenuation level (dB) = 0.5 (ATx[7:0]DEC – 255)
where: ATx[7:0]DEC = 0 through 255
for: ATx[7:0]DEC = 0 through 128, the attenuator is set to infinite attenuation.
The following table shows attenuator levels for various settings.
ATx[7:0]
DECIMAL VALUE
ATTENUATOR LEVEL SETTING
1111 1111b
255
0 dB, no attenuation (default)
1111 1110b
254
–0.5 dB
1111 1101b
253
–1 dB
:
:
:
1000 0011b
131
–62 dB
1000 0010b
130
–62.5 dB
1000 0001b
129
–63 dB
1000 0000b
128
Mute
:
:
:
0000 0000b
0
Mute
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B15
REGISTER 18
0
B14
B13
B12
B11
B10
B9
B8
IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0
B7
B6
B5
B4
B3
B2
B1
B0
RSV
OVER
RSV
RSV
RSV
RSV
MUT2
MUT1
MUTx – Soft Mute Control
where x = 1 or 2, corresponding to the DAC output VOUTL (x = 1) and VOUTR (x = 2).
Default value: 0
MUTx = 0
Mute disabled (default)
MUTx = 1
Mute enabled
The mute bits, MUT1 and MUT2, are used to enable or disable the soft mute function for the corresponding DAC
outputs, VOUTL and VOUTR. The soft mute function is incorporated into the digital attenuators. When mute is
disabled (MUTx = 0), the attenuator and DAC operate normally. When mute is enabled by setting MUTx = 1, the
digital attenuator for the corresponding output is decreased from the current setting to the infinite attenuation
setting by one attenuator step (0.5 dB) at a time for every 8/fS period. This provides a pop-free muting of the
DAC output.
By setting MUTx = 0, the attenuator is increased by one step for every 8/fS period to the previously programmed
attenuation level.
OVER – Oversampling Rate Control
Default value: 0
System clock rate = 256 fS, 384 fS, 512 fS, or 768 fS
OVER = 0
64× oversampling (default)
OVER = 1
128× oversampling
System clock rate = 128 fS or 192 fS
OVER = 0
32× oversampling (default)
OVER = 1
64× oversampling
The OVER bit is used to control the oversampling rate of the delta-sigma DACs. The OVER = 1 setting is
recommended when the oversampling rate is 192 kHz (system clock is 128 fS or 192 fS).
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B15
REGISTER 19
0
B14
B13
B12
B11
B10
B9
B8
IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0
B7
B6
B5
B4
B3
B2
B1
B0
RSV
DMF1
DMF0
DM12
RSV
RSV
DAC2
DAC1
DACx – DAC Operation Control
where x = 1 or 2, corresponding to the DAC output VOUTL (x = 1) or VOUTR (x = 2).
Default value: 0
DACx = 0
DAC operation enabled (default)
DACx = 1
DAC operation disabled
The DAC operation controls are used to enable and disable the DAC outputs, VOUTL and VOUTR. When DACx =
0, the corresponding output generates the audio waveform dictated by the data present on the DATA pin. When
DACx = 1, the corresponding output is set to the bipolar zero level, or VCC/2.
DM12 – Digital De-Emphasis Function Control
Default value: 0
DM12 = 0
De-emphasis disabled (default)
DM12 = 1
De-emphasis enabled
The DM12 bit is used to enable or disable the digital de-emphasis function. Refer to the Typical Performance
Curves section of this data sheet for more information.
DMF[1:0] – Sampling Frequency Selection for the De-Emphasis Function
Default value: 00
DMF[1:0]
De-Emphasis Sample Rate Selection
00
44.1 kHz (default)
01
48 kHz
10
32 kHz
11
Reserved
The DMF[1:0] bits select the sampling frequency used for the digital de-emphasis function when it is enabled.
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B15
REGISTER 20
0
B14
B13
B12
B11
B10
B9
B8
IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0
B7
B6
B5
B4
B3
B2
B1
B0
RSV
RSV
FLT
RSV
RSV
FMT2
FMT1
FMT0
FMT[2:0] – Audio Interface Data Format
Default value: 101
The FMT[2:0] bits are used to select the data format for the serial audio interface. The following table shows the
available format options.
FMT[2:0]
Audio Data Format Selection
000
24-bit standard format, right-justified data
001
20-bit standard format, right-justified data
010
18-bit standard format, right-justified data
011
16-bit standard format, right-justified data
100
I2S format, 16- to 24-bit
101
Left-justified format, 16- to 24-bit (default)
110
Reserved
111
Reserved
FLT – Digital Filter Rolloff Control
Default value: 0
FLT = 0
Sharp rolloff (default)
FLT = 1
Slow rolloff
The FLT bit allows the user to select the digital filter rolloff that is best suited to their application. Two filter rolloff
selections are available: sharp or slow. The filter responses for these selections are shown in the Typical
Performance Curves section of this data sheet.
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B15
REGISTER 22
0
B14
B13
B12
B11
B10
B9
B8
IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0
B7
B6
B5
B4
B3
B2
B1
B0
RSV
RSV
RSV
RSV
RSV
AZRO
ZREV
DREV
DREV – Output Phase Select
Default value: 0
DREV = 0
Normal output (default)
DREV = 1
Inverted output
The DREV bit is used to set the output phase of VOUTL and VOUTR.
ZREV – Zero-Flag Polarity Select
Default value: 0
ZREV = 0
Zero-flag pins HIGH at a zero detect (default)
ZREV = 1
Zero-flag pins LOW at a zero detect
The ZREV bit allows the user to select the active polarity of zero-flag pins.
AZRO – Zero-Flag Function Select
Default value: 0
AZRO = 0
L-/R-channel independent zero flags (default)
Pin 11: ZEROR; zero-flag output for R-channel
Pin 12: ZEROL; zero flag output for L-channel
AZRO = 1
L-/R-channel common zero flag
Pin 11: ZEROA; zero flag output for L-/R-channel
Pin 12: NA; not assigned
The AZRO bit allows the user to select the function of the zero-flag pins
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ANALOG OUTPUTS
The PCM1742 includes two independent output channels: VOUTL and VOUTR. These are unbalanced outputs,
each capable of driving 3.1 Vp-p typical into a 5-kΩ ac-coupled load. The internal output amplifiers for VOUTL and
VOUTR are biased to the dc common-mode (or bipolar zero) voltage, equal to VCC/2.
The output amplifiers include an RC continuous-time filter that helps to reduce the out-of-band noise energy
present at the DAC outputs, due to the noise shaping characteristics of the PCM1742 delta-sigma DACs. The
frequency response of this filter is shown in Figure 26. By itself, this filter is not enough to attenuate the
out-of-band noise to an acceptable level for many applications; therefore, an external low-pass filter is required to
provide sufficient out-of-band noise rejection. Further discussion of DAC post-filter circuits is provided in the
Applications Information section of this data sheet.
0
Response (dB)
−10
−20
−30
−40
−50
−60
0.1
1
10
100
1K
10K
Frequency (kHz)
Figure 26. Output Filter Frequency Response
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VCOM OUTPUT
One unbuffered common-mode voltage output pin, VCOM (pin 10), is brought out for decoupling purposes. This
pin is nominally biased to a dc voltage level equal to VCC/2. This pin can be used to bias external circuits. An
example of using the VCOM pin for external biasing applications is shown in Figure 27.
P C M 17 4 2
VOUTx
R2
10µF
R1
AV = −1, where AV = −
C1
R3
VCC
R2
R1
2
+
1/2
C2
3
OP A2353
1
Filtered
Output
VCOM
+
x = L or R
10µF
(a) Using VCOM to Bias a Single−Supply Filter Stage
VCC
P C M 1 74 2
Buffered
VCOM
OPA337
VCOM
+
10µ F
(b) Using a Voltage Follower to Buffer VCOM When Biasing Multiple Nodes
V+
VCC
25kΩ
49.9kΩ
1%
P C M 17 4 2
−IN
VOUTx
SENSE
25kΩ
OUT
25kΩ
+IN
VCOM
+
10µF
25kΩ
To Low−Pass
Filter Stage
REF
INA134
x = L or R
V−
(c) Using an INA134 for DC−Coupled Output
Figure 27. Biasing External Circuits Using the VCOM Pin
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www.ti.com
ZERO FLAGS
Zero-Detect Condition
Zero detection for each output channel is independent from the other. If the data for a given channel remains at a
0 level for 1024 sample periods (or LRCK clock periods), a zero-detect condition exists for that channel.
Zero Output Flags
Given that a zero-detect condition exists for one or more channels, the zero-flag pins for those channels are set
to a logic-1 state. The zero-flag pins for each channel are ZEROL (pin 12) and ZEROR (pin 11). These pins can
be used to operate external mute circuits, or used as status indicators for a microcontroller, audio signal
processor, or other digitally controlled function.
The active polarity of the zero-flag output can be inverted by setting the ZREV bit of control register 22 to 1. The
reset default is active-high output, or ZREV = 0.
The L-channel and R-channel common zero flag can be selected by setting the AZRO bit of control register 22
to 1. The reset default is L-channel and R-channel independent zero flag, or AZRO = 0.
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APPLICATION INFORMATION
Connection Diagram
A basic connection diagram is shown in Figure 28, with the necessary power-supply bypassing and decoupling
components. Texas Instruments recommends using the component values shown in Figure 28 for all designs.
+
+3.3V
Regulator
+
1
BCK
2
DATA
ML 15
3
LRCK
MC 14
4
DGND
MD 13
5
VDD
ZEROL/NA 12
6
VCC
ZEROR/ZEROA 11
7
VOUTL
8
VOUTR
10µF
10µF
System Clock
SCK 16
Mode
Control
Zero Mute
Control
VCOM 10
+
PCM
Audio Data
Input
10µF
AGND
9
+5V VCC
Post LPF
Post LPF
L−Chan OUT
R−Chan OUT
Figure 28. Basic Connection Diagram
The use of series resistors (22 Ω to 100 Ω) is recommended for the SCK, LRCK, BCK, and DATA inputs. The
series resistor combines with stray PCB and device input capacitance to form a low-pass filter that reduces
high-frequency noise emissions and helps to dampen glitches and ringing present on clock and data lines.
Power Supplies and Grounding
The PCM1742 requires a 5-V analog supply (VCC) and a 3.3-V digital supply (VDD). The 5-V supply is used to
power the DAC analog and output-filter circuitry, while the 3.3-V supply is used to power the digital filter and
serial interface circuitry. For best performance, the 3.3-V supply should be derived from the 5-V supply using a
linear regulator, as shown in Figure 28. The REG1117-3.3 from Texas Instruments is an ideal choice for this
application.
Proper power-supply bypassing is shown in Figure 28. The 10-µF capacitors should be tantalum or aluminum
electrolytic.
DAC Output Filter Circuits
Delta-sigma DACs use noise-shaping techniques to improve in-band signal-to-noise ratio (SNR) performance at
the expense of generating increased out-of-band noise above the Nyquist frequency, or fS/2. The out-of-band
noise must be low-pass filtered in order to provide the optimal converter performance. This is accomplished by a
combination of on-chip and external low-pass filtering.
Figure 27(a) and Figure 29 show the recommended external low-pass active filter circuits for single- and
dual-supply applications. These circuits are second-order Butterworth filters using a multiple feedback (MFB)
circuit arrangement that reduces sensitivity to passive component variations over frequency and temperature. For
more information regarding MFB active filter design, see FilterPro™ MFB and Sallen-Key Low-Pass Filter Design
Program (SBFA001), available from the TI Web site at http://www.ti.com.
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APPLICATION INFORMATION (continued)
AV ≈ −
R2
R1
C1
R3
VIN
2
3
R1
R4
1
C2
R2
VOUT
OP A2 134
Figure 29. Dual-Supply Filter Circuit
Because the overall system performance is defined by the quality of the DACs and their associated analog
output circuitry, high-quality audio operational amplifiers are recommended for the active filters. The OPA2353
and OPA2134 dual operational amplifiers from Texas Instruments are recommended for use with the PCM1742;
see Figure 27(a) and Figure 29.
PCB LAYOUT GUIDELINES
A typical PCB floor plan for the PCM1742 is shown in Figure 30. A ground plane is recommended, with the
analog and digital sections being isolated from one another using a split or cut in the circuit board. The PCM1742
should be oriented with the digital I/O pins facing the ground plane split/cut to allow for short, direct connections
to the digital audio interface and control signals originating from the digital section of the board.
Separate power supplies are recommended for the digital and analog sections of the board. This prevents the
switching noise present on the digital supply from contaminating the analog power supply and degrading the
dynamic performance of the PCM1742. In cases where a common 5-V supply must be used for the analog and
digital sections, an inductance (RF choke, ferrite bead) should be placed between the analog and digital 5-V
supply connections to avoid coupling of the digital switching noise into the analog circuitry. Figure 31 shows the
recommended approach for single-supply applications.
Digital Power
+VD
Analog Power
DGND
AGND +5VA
+VS −VS
REG
VCC
VDD
Digital Logic
and
Audio
Processor
DGND
PCM1742
Output
Circuits
Digital
Ground
AGND
DIGITAL SECTION
ANALOG SECTION
Return Path for Digital Signals
Figure 30. Recommended PCB Layout
26
Analog
Ground
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
APPLICATION INFORMATION (continued)
Power Supplies
RF Choke or Ferrite Bead
+5V
AGND
+VS
−VS
REG
VCC
VDD
VDD
Digital Logic
and
Audio
Processor
Output
Circuits
DGND
PCM1742
AGND
Common
Ground
DIGITAL SECTION
ANALOG SECTION
Figure 31. Single-Supply PCB Layout
THEORY OF OPERATION
The delta-sigma section of the PCM1742 is based on an 8-level amplitude quantizer and a fourth-order noise
shaper. This section converts the oversampled input data to 8-level delta-sigma format. A block diagram of the
8-level delta-sigma modulator is shown in Figure 32. This 8-level delta-sigma modulator has the advantage of
stability and clock jitter sensitivity over the typical one-bit (2-level) delta-sigma modulator. The combined
oversampling rate of the delta-sigma modulator and the interpolation filter is 64 fS.
The theoretical quantization noise performance of the 8-level delta-sigma modulator is shown in Figure 33. The
enhanced multilevel delta-sigma architecture also has advantages for input clock-jitter sensitivity due to the
multilevel quantizer, with the simulated jitter sensitivity, as shown in Figure 34.
−
+
8fS
+
Z−1
+
Z−1
Z−1
+
+
Z−1
+
8−Level Quantizer
64fS
Figure 32. 8-Level Delta-Sigma Modulator
27
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
THEORY OF OPERATION (continued)
QUANTIZATION NOISE SPECTRUM
(128x Oversampling)
0
0
− 20
− 20
− 40
− 40
Amplitude (dB)
Amplitude (dB)
QUANTIZATION NOISE SPECTRUM
(64x Oversampling)
− 60
− 80
− 100
− 120
− 60
− 80
− 100
− 120
− 140
− 140
− 160
− 160
− 180
− 180
0
1
2
3
4
5
6
7
8
0
1
2
3
Frequency (fS)
Figure 33. Quantization Noise Spectrum
JITTER DEPENDENCE (64x Oversampling)
125
Dynamic Range (dB)
120
115
110
105
100
95
90
0
100
200
300
400
Jitter (ps)
Figure 34. Jitter Sensitivity
28
4
5
Frequency (f S)
500
600
6
7
8
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
KEY PERFORMANCE PARAMETERS AND MEASUREMENT
This section provides information on how to measure key dynamic performance parameters for the PCM1742. In
all cases, a System Two™ Cascade audio measurement system by Audio Precision™ or equivalent audio
measurement system is used to perform the testing.
Total Harmonic Distortion + Noise
Total harmonic distortion + noise (THD+N) is a significant figure of merit for audio DACs, because it takes into
account both harmonic distortion and all noise sources within a specified measurement bandwidth. The true rms
value of the distortion and noise is referred to as THD+N. Figure 35 shows the test setup for THD+N
measurements.
For the PCM1742, THD+N is measured with a full-scale, 1-kHz digital sine wave as the test stimulus at the input
of the DAC. The digital generator is set to a 24-bit audio word length and a sampling frequency of 44.1 kHz or 96
kHz. The digital generator output is taken from the unbalanced S/PDIF connector of the measurement system.
The S/PDIF data is transmitted via a coaxial cable to the digital audio receiver on the DEM-DAI1742
demonstration board. The receiver is then configured to output 24-bit data in either I2S or left-justified data
format. The DAC audio interface format is programmed to match the receiver output format. The analog output is
then taken from the DAC post filter and connected to the analog analyzer input of the measurement system. The
analog input is band-limited using filters resident in the analyzer. The resulting THD+N is measured by the
analyzer and displayed by the measurement system.
Evaluation Board
DEM−DAI1742
S/PDIF
Receiver
2nd−Order
Low−Pass
Filter
PCM1742
f− 3dB = 54kHz or 108kHz
S/PDIF
Output
Digital
Generator
Analyzer
and
Display
0dBFS,
1kHz Sine Wave
rms Mode
20kHz
Apogee
Filter
Band Limit
HPF = 22Hz
LPF = 30kHz
Notch Filter
f C = 1kHz
Figure 35. Test Setup for THD+N Measurements
Dynamic Range
Dynamic range is specified as A-weighted, THD+N measured with a –60-dBFS, 1-kHz digital sine wave stimulus
at the input of the DAC. This measurement is designed to give a good indicator of the DAC performance given a
low-level input signal.
The measurement setup for the dynamic range measurement is shown in Figure 36 and is similar to the THD+N
test setup discussed previously. The differences include the band limit filter selection, the additional A-weighting
filter, and the –60-dBFS input level.
29
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
KEY PERFORMANCE PARAMETERS AND MEASUREMENT (continued)
Evaluation Board
DEM−DAI1742
S/PDIF
Receiver
PCM1742(1)
2nd−Order
Low−Pass
Filter
f− 3dB = 54kHz or 108kHz
S/PDIF
Output
Digital
Generator
0% Full−Scale,
Dither Off (SNR)
− 60dBFS,
1kHz Sine Wave
(Dynamic Range)
Analyzer
and
Display
A−Weight
Filter(2)
rms Mode
(1)
Infinite-zero-detect mute disabled
(2)
Results without A-weighting are approximately 3 dB worse.
Band Limit
HPF = 22Hz
LPF = 22kHz
Notch Filter
fC = 1kHz
Figure 36. Test Setup Dynamic Range and SNR Measurements
Idle-Channel Signal-to-Noise Ratio
The SNR test provides a measure of the noise floor of the DAC. The input to the DAC is all-0s data, and the
DAC infinite-zero-detect mute function must be disabled (default condition at power up for the PCM1742). This
ensures that the delta-sigma modulator output is connected to the output amplifier circuit so that idle tones (if
present) can be observed and affect the SNR measurement. The dither function of the digital generator must
also be disabled to ensure an all-0s data stream at the input of the DAC. The measurement setup for SNR is
identical to that used for dynamic range, with the exception of the input signal level (see the notes provided in
Figure 36).
30
PCM1742
www.ti.com
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
REVISION HISTORY
DATE
REV
PAGE
Apr 2005
A
–
Global
Changed to new format
2
Absolute Maximum Ratings
Changed values for power supply voltage, digital input voltage, lead
temperature, and package temperature. Added supply voltage
difference, VCC – VDD < 3 V.
2
Electrical Characteristics
Corrected maximum sampling frequency from 100 kHz to 200 kHz.
Added new values of 128 fS and 192 fS for system clock frequency.
2
Package/Ordering Information
Table removed from page 2, reformatted, and appended at end of
data sheet.
2
Recommended Operating Conditions
New table added to data sheet.
6
Pin Assignments and Terminal
Functions
Moved from page 4
Typical Performance Curves
In Figure 11, corrected Y-axis scale and X-axis scale.
9, 10
SECTION
DESCRIPTION
In Figure 15, corrected frequency from 96 kHz to 192 kHz on graph
label.
11
System Clock Input
In Figure 19, added 1/128 fS and 1/192 fS to note for clock cycle
time.
Audio Data Formats and Timing
In Figure 21, Audio Data Input Formats, removed 32-fS availability
from left-justified format. In Figure 22, Audio Interface Timing,
corrected specification for BCK pulse cycle time.
17
Register Map
For Table 3, Mode Control Register Map, added note to explain the
RSV table entry.
18
Register Definitions
For MUTx – Soft Mute Control, added description about incrementing/decrementing attenuation level by one step for every
8/fS period.
25
Connection Diagram
In Figure 28, corrected capacitor polarity for VDD decoupling
capacitor.
PCB Layout Guidelines
In Figure 30 and Figure 31, deleted extraneous signal lines. In
Figure 31, changed leftmost block to Digital Logic and Audio
Processor.
Dynamic Range
Corrected parameters in test setup diagram, Figure 36.
13, 14
26, 27
30
31
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
PCM1742E
ACTIVE
SSOP
DBQ
16
75
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-25 to 85
PCM
1742E
PCM1742E/2K
ACTIVE
SSOP
DBQ
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-25 to 85
PCM
1742E
PCM1742KE
ACTIVE
SSOP
DBQ
16
75
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-25 to 85
PCM
1742KE
PCM1742KE/2K
ACTIVE
SSOP
DBQ
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-25 to 85
PCM
1742KE
PCM1742KE/2KG4
ACTIVE
SSOP
DBQ
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-25 to 85
PCM
1742KE
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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