TAS5508B
8-Channel Digital Audio PWM Processor
Data Manual
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.
Literature Number: SLES162C
December 2005 – Revised July 2009
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Contents
1
Introduction......................................................................................................................... 9
1.1
1.2
1.3
1.4
2
Description ........................................................................................................................ 14
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
3
Physical Characteristics ...................................................................................................
2.1.1
Terminal Assignments ..........................................................................................
2.1.2
Ordering Information ............................................................................................
2.1.3
Terminal Descriptions ...........................................................................................
TAS5508B Functional Description .......................................................................................
2.2.1
Power Supply ....................................................................................................
2.2.2
Clock, PLL, and Serial Data Interface ........................................................................
2.2.2.1 Serial Audio Interface ................................................................................
2.2.3
I 2C Serial-Control Interface ....................................................................................
2.2.4
Device Control ...................................................................................................
2.2.5
Digital Audio Processor (DAP) .................................................................................
2.2.5.1 TAS5508B Audio-Processing Configurations .....................................................
2.2.5.2 TAS5508B Audio Signal-Processing Functions ..................................................
TAS5508B DAP Architecture .............................................................................................
2.3.1
TAS5508B DAP Architecture Diagrams ......................................................................
2.3.2
I 2C Coefficient Number Formats ..............................................................................
2.3.2.1 28-Bit 5.23 Number Format .........................................................................
2.3.2.2 48-Bit 25.23 Number Format ........................................................................
2.3.2.3 TAS5508B Audio Processing .......................................................................
Input Crossbar Mixer .......................................................................................................
Biquad Filters ...............................................................................................................
Bass and Treble Controls .................................................................................................
Volume, Automute, and Mute .............................................................................................
Automute and Mute Channel Controls ..................................................................................
Loudness Compensation ..................................................................................................
2.9.1
Loudness Example ..............................................................................................
Dynamic Range Control (DRC)...........................................................................................
2.10.1 DRC Implementation ............................................................................................
2.10.2 Compression/Expansion Coefficient Computation Engine Parameters .................................
2.10.2.1 Threshold Parameter Computation ...............................................................
2.10.2.2 Offset Parameter Computation ....................................................................
2.10.2.3 Slope Parameter Computation ....................................................................
Output Mixer ................................................................................................................
PWM .........................................................................................................................
2.12.1 DC Blocking (High-Pass Filter Enable/Disable) .............................................................
2.12.2 De-Emphasis Filter ..............................................................................................
2.12.3 Power-Supply Volume Control (PSVC) .......................................................................
2.12.4 AM Interference Avoidance ....................................................................................
14
14
14
15
17
17
17
17
18
18
18
18
19
20
20
23
23
25
26
27
27
28
29
30
30
31
32
35
35
36
36
37
37
38
39
39
39
40
TAS5508B Controls and Status ............................................................................................ 42
3.1
3.2
2
Features ....................................................................................................................... 9
Overview..................................................................................................................... 10
Changes From the TAS5508A to the TAS5508B ...................................................................... 12
TAS5508B System Diagrams............................................................................................. 12
I2C Status Registers .......................................................................................................
3.1.1
General Status Register (0x01)................................................................................
3.1.2
Error Status Register (0x02) ...................................................................................
TAS5508B Pin Controls ...................................................................................................
3.2.1
Reset (RESET) ..................................................................................................
Contents
42
42
42
42
42
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Power Down (PDN) .............................................................................................
Back-End Error (BKND_ERR) .................................................................................
3.2.3.1 BKND_ERR and VALID..............................................................................
3.2.4
Speaker/Headphone Selector (HP_SEL).....................................................................
3.2.5
Mute (MUTE) .....................................................................................................
Device Configuration Controls ............................................................................................
3.3.1
Channel Configuration Registers ..............................................................................
3.3.2
Headphone Configuration Registers ..........................................................................
3.3.3
Audio System Configurations ..................................................................................
3.3.3.1 Using Line Outputs in 6-Channel Configurations .................................................
3.3.4
Recovery from Clock Error .....................................................................................
3.3.5
Power-Supply Volume-Control Enable .......................................................................
3.3.6
Volume and Mute Update Rate ................................................................................
3.3.7
Modulation Index Limit ..........................................................................................
Master Clock and Serial Data Rate Controls ...........................................................................
3.4.1
PLL Operation....................................................................................................
Bank Controls ...............................................................................................................
3.5.1
Manual Bank Selection .........................................................................................
3.5.2
Automatic Bank Selection ......................................................................................
3.5.2.1 Coefficient Write Operations While Automatic Bank Switch Is Enabled.......................
3.5.3
Bank Set ..........................................................................................................
3.5.4
Bank-Switch Timeline ...........................................................................................
3.5.5
Bank-Switching Example 1 .....................................................................................
3.5.6
Bank-Switching Example 2 .....................................................................................
3.2.2
3.2.3
3.3
3.4
3.5
4
Electrical Specifications ...................................................................................................... 52
4.1
5
44
44
45
45
45
46
46
47
47
48
48
48
48
48
49
49
49
50
50
50
50
51
51
51
Absolute Maximum Ratings ...............................................................................................
4.2
Dissipation Rating Table (High-k Board, 105 °C Junction) .................................................
4.3
Dynamic Performance at Recommended Operating Conditions at 25°C ................................
4.4
Recommended Operating Conditions ........................................................................
4.5
Electrical Characteristics .......................................................................................
4.6
PWM Operation ..................................................................................................
4.7
Switching Characteristics .......................................................................................
4.7.1
Clock Signals.....................................................................................................
4.7.2
Serial Audio Port.................................................................................................
4.7.3
TAS5508B Pin-Related Characteristics of the SDA and SCL I/O Stages for F/S-Mode I 2C-Bus
Devices ...........................................................................................................
4.7.4
TAS5508B Bus-Related Characteristics of the SDA and SCL I/O Stages for F/S-Mode I 2C-Bus
Devices ...........................................................................................................
4.7.4.1 Recommended I2C Pullup Resistors ...............................................................
4.7.5
Reset Timing (RESET) .........................................................................................
4.7.6
Power-Down (PDN) Timing ....................................................................................
4.7.7
Back-End Error (BKND_ERR) .................................................................................
4.7.8
Mute Timing (MUTE) ............................................................................................
4.7.9
Headphone Select (HP_SEL) ..................................................................................
4.7.10 Volume Control ..................................................................................................
4.8
Serial Audio Interface Control and Timing ...................................................................
4.8.1
I 2S Timing ........................................................................................................
4.8.2
Left-Justified Timing .............................................................................................
4.8.3
Right-Justified Timing ...........................................................................................
52
52
52
52
53
53
53
53
54
54
55
56
57
57
58
58
59
59
60
60
61
62
I2C Serial-Control Interface (Slave Addresses 0x36 and 0x37) .................................................. 63
5.1
5.2
5.3
General I2C Operation ..................................................................................................... 63
Single- and Multiple-Byte Transfers ..................................................................................... 64
Single-Byte Write ........................................................................................................... 64
Contents
3
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
5.4
5.5
5.6
5.7
6
7
www.ti.com
Multiple-Byte Write .........................................................................................................
Incremental Multiple-Byte Write ..........................................................................................
Single-Byte Read ...........................................................................................................
Multiple-Byte Read .........................................................................................................
65
65
66
66
Serial-Control I2C Register Summary .................................................................................... 67
Serial-Control Interface Register Definitions .......................................................................... 71
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
7.20
7.21
7.22
7.23
7.24
7.25
7.26
7.27
7.28
7.29
7.30
7.31
7.32
7.33
7.34
7.35
Clock Control Register (0x00) ............................................................................................
General Status Register 0 (0x01) ........................................................................................
System Control Register 1 (0x03) ........................................................................................
System Control Register 2 (0x04) ........................................................................................
Channel Configuration Control Registers (0x05–0x0C) ...............................................................
Headphone Configuration Control Register (0x0D) ....................................................................
Serial Data Interface Control Register (0x0E) ..........................................................................
Soft Mute Register (0x0F) .................................................................................................
Automute Control Register (0x14) .......................................................................................
Output Automute PWM Threshold and Back-End Reset Period Register (0x15)..................................
Modulation Index Limit Register (0x16) .................................................................................
Bank-Switching Command Register (0x40).............................................................................
Input Mixer Registers, Channels 1–8 (0x41–0x48) ....................................................................
Bass Management Registers (0x49–0x50) .............................................................................
Biquad Filter Register (0x51–0x88) ......................................................................................
Bass and Treble Bypass Register, Channels 1–8 (0x89–0x90) .....................................................
Loudness Registers (0x91–0x95) ........................................................................................
DRC1 Control Registers, Channels 1–7 (0x96) ........................................................................
DRC2 Control Register, Channel 8 (0x97) ..............................................................................
DRC1 Data Registers (0x98–0x9C) .....................................................................................
DRC2 Data Registers (0x9D–0xA1) .....................................................................................
DRC Bypass Registers (0xA2–0xA9) ....................................................................................
8×2 Output Mixer Registers (0xAA–0xAF) ..............................................................................
8×3 Output Mixer Registers (0xB0–0xB1) ..............................................................................
PSVC Volume Biquad Register (0xCF) .................................................................................
Volume, Treble, and Bass Slew Rates Register (0xD0) ..............................................................
Volume Registers (0xD1–0xD9) ..........................................................................................
Bass Filter Set Register (0xDA) ..........................................................................................
Bass Filter Index Register (0xDB) .......................................................................................
Treble Filter Set Register (0xDC) ........................................................................................
Treble Filter Index (0xDD).................................................................................................
AM Mode Register (0xDE) ................................................................................................
PSVC Range Register (0xDF) ............................................................................................
General Control Register (0xE0) .........................................................................................
Incremental Multiple-Byte Write Append Register (0xFE) ............................................................
71
71
71
72
72
73
73
74
75
76
77
78
79
82
82
83
83
84
85
85
86
86
86
87
89
90
90
92
93
94
95
95
97
97
97
8
TAS5508B Example Application Schematic ........................................................................... 99
4
Contents
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
List of Figures
1-1
TAS5508B Functional Structure................................................................................................. 11
1-2
..............................................................................
Pass-Through Output Mixer TAS5508B Channel Configuration ............................................................
TAS5508B DAP Architecture With I2C Registers (fS ≤ 96 kHz) .............................................................
TAS5508B Architecture With I2C Registers (fS = 176.4 kHz or fS = 192 kHz) ............................................
TAS5508B Detailed Channel Processing ......................................................................................
5.23 Format ........................................................................................................................
Conversion Weighting Factors—5.23 Format to Floating Point .............................................................
Alignment of 5.23 Coefficient in 32-Bit I2C Word .............................................................................
25.23 Format ......................................................................................................................
Conversion Weighting Factors—25.23 Format to Floating Point ...........................................................
Alignment of 25.23 Coefficient in Two 32-Bit I2C Words .....................................................................
TAS5508B Digital Audio Processing ...........................................................................................
Input Crossbar Mixer .............................................................................................................
Biquad Filter Structure ............................................................................................................
Automute Threshold ..............................................................................................................
Loudness Compensation Functional Block Diagram .........................................................................
Loudness Example Plots .........................................................................................................
DRC Positioning in TAS5508B Processing Flow .............................................................................
Dynamic Range Compression (DRC) Transfer Function Structure ........................................................
Output Mixers ......................................................................................................................
De-Emphasis Filter Characteristics .............................................................................................
Power-Supply and Digital Gains (Linear Space) ..............................................................................
Power-Supply and Digital Gains (Log Space) .................................................................................
Block Diagrams of Typical Systems Requiring TAS5508B Automatic AM Interference-Avoidance Circuit ...........
Slave Mode Serial Data Interface Timing ......................................................................................
Start and Stop Conditions Timing Waveforms ................................................................................
I2C Pullup Circuit (With No Series Resistor) ...................................................................................
I2C Pullup Circuit (With Series Resistor) .......................................................................................
Reset Timing .......................................................................................................................
Power-Down Timing ..............................................................................................................
Error-Recovery Timing ...........................................................................................................
Mute Timing ........................................................................................................................
HP_SEL Timing ...................................................................................................................
I2S 64-fS Format ...................................................................................................................
Left-Justified 64-fS Format .......................................................................................................
Right-Justified 64-fS Format .....................................................................................................
Typical I2C Sequence.............................................................................................................
Single-Byte Write Transfer .......................................................................................................
1-3
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
2-14
2-15
2-16
2-17
2-18
2-19
2-20
2-21
2-22
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
5-1
5-2
Typical TAS5508B Application (DVD Receiver)
List of Figures
13
13
21
22
23
24
24
24
25
25
26
27
27
28
30
31
32
33
34
38
39
40
40
41
54
55
56
56
57
57
58
58
59
60
61
62
63
64
5
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
5-3
Multiple-Byte Write Transfer ..................................................................................................... 65
5-4
Single-Byte Read Transfer ....................................................................................................... 66
5-5
Multiple-Byte Read Transfer ..................................................................................................... 66
6
List of Figures
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
List of Tables
1-1
I2C Register 0xD0 Bit 30 Usage................................................................................................. 12
2-1
Serial Data Formats
2-2
2-3
2-4
2-5
2-6
2-7
2-8
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
7-1
7-2
7-3
7-4
7-5
7-6
7-7
7-8
7-9
7-10
7-11
7-12
7-13
7-14
7-15
7-16
7-17
7-18
7-19
7-20
7-21
7-22
..............................................................................................................
TAS5508B Audio-Processing Feature Sets ...................................................................................
Contents of One 20-Byte Biquad Filter Register (Default = All-Pass) ......................................................
Bass and Treble Filter Selections ...............................................................................................
Linear Gain Step Size ............................................................................................................
Default Loudness Compensation Parameters.................................................................................
Example Loudness Function Parameters ......................................................................................
DRC Recommended Changes From TAS5508B Defaults ..................................................................
Device Outputs During Reset ...................................................................................................
Values Set During Reset .........................................................................................................
Device Outputs During Power Down ...........................................................................................
Device Outputs During Back-End Error ........................................................................................
Description of the Channel Configuration Registers (0x05 to 0x0C) .......................................................
Recommended TAS5508B Configurations for Texas Instruments Power Stages........................................
Audio System Configuration (General Control Register 0xE0)..............................................................
Volume Ramp Periods in ms ....................................................................................................
Clock Control Register Format ..................................................................................................
General Status Register Format ................................................................................................
System Control Register-1 Format .............................................................................................
System Control Register-2 Format .............................................................................................
Channel Configuration Control Register Format ..............................................................................
Headphone Configuration Control Register Format ..........................................................................
Serial Data Interface Control Register Format ................................................................................
Soft Mute Register Format .......................................................................................................
Automute Control Register Format .............................................................................................
Automute PWM Threshold and Back-End Reset Period Register Format ................................................
Modulation Index Limit Register Format .......................................................................................
Bank-Switching Command Register Format...................................................................................
Channel 1–8 Input Mixer Register Format .....................................................................................
Bass Management Register Format ............................................................................................
Biquad Filter Register Format ...................................................................................................
Contents of One 20-Byte Biquad Filter Register (Default = All-Pass) ......................................................
Channel 1–8 Bass and Treble Bypass Register Format .....................................................................
Loudness Register Format .......................................................................................................
Channel 1–7 DCR1 Control Register Format .................................................................................
Channel-8 DRC2 Control Register Format ....................................................................................
DRC1 Data Register Format.....................................................................................................
DRC2 Data Register Format.....................................................................................................
List of Tables
18
20
28
29
29
31
32
33
42
43
44
45
46
47
47
48
71
71
71
72
72
73
73
74
75
76
77
78
79
82
82
83
83
83
84
85
85
86
7
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
7-23
DRC Bypass Register Format ................................................................................................... 86
7-24
Output Mixer Register Format (Upper 4 Bytes) ............................................................................... 87
7-25
Output Mixer Register Format (Lower 4 Bytes) ............................................................................... 87
7-26
Output Mixer Register Format (Upper 4 Bytes) ............................................................................... 88
7-27
Output Mixer Register Format (Middle 4 Bytes)
7-28
7-29
7-30
7-31
7-32
7-33
7-34
..............................................................................
Output Mixer Register Format (Lower 4 Bytes) ...............................................................................
Volume Biquad Register Format (Default = All-Pass) ........................................................................
Volume Gain Update Rate (Slew Rate) ........................................................................................
Treble and Bass Gain Step Size (Slew Rate) .................................................................................
Volume Register Format .........................................................................................................
Master and Individual Volume Controls ........................................................................................
Channel 8 (Subwoofer) ...........................................................................................................
88
88
89
90
90
90
91
92
7-35
Channels 6 and 5 (Right and Left Lineout in 6-Channel Configuration; Right and Left Surround in 8-Channel
Configuration) ...................................................................................................................... 92
7-36
Channels 4 and 3 (Right and Left Rear) ....................................................................................... 92
7-37
Channels 7, 2, and 1 (Center, Right Front, and Left Front) ................................................................. 93
7-38
Bass Filter Index Register Format .............................................................................................. 93
7-39
Bass Filter Indexes................................................................................................................ 93
7-40
Channel 8 (Subwoofer) ........................................................................................................... 94
7-41
Channels 6 and 5 (Right and Left Lineout in 6-Channel Configuration; Right and Left Surround in 8-Channel
Configuration) ...................................................................................................................... 94
7-42
Channels 4 and 3 (Right and Left Rear) ....................................................................................... 94
7-43
Channels 7, 2, and 1 (Center, Right Front, and Left Front) ................................................................. 95
7-44
Treble Filter Index Register Format............................................................................................. 95
7-45
Treble Filter Indexes .............................................................................................................. 95
7-46
AM Mode Register Format ....................................................................................................... 96
7-47
AM Tuned Frequency Register in BCD Mode (Lower 2 Bytes of 0xDE)
7-48
7-49
7-50
8
..................................................
AM Tuned Frequency Register in Binary Mode (Lower 2 Bytes of 0xDE) ................................................
PSVC Range Register Format ..................................................................................................
General Control Register Format ...............................................................................................
List of Tables
96
96
97
97
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
1
Introduction
1.1
Features
•
•
•
General Features
– Automated Operation With an Easy-to-Use
Control Interface
– I2C Serial-Control Slave Interface
– Integrated AM Interference-Avoidance
Circuitry
– Single, 3.3-V Power Supply
– 64-Pin TQFP Package
– 5-V Tolerant Inputs
Audio Input/Output
– Automatic Master-Clock-Rate and
Data-Sample-Rate Detection
– Eight Serial Audio Input Channels
– Eight PWM Audio Output Channels
Configurable as Six Channels With Stereo
Lineout or Eight Channels
– Line Output Is a PWM Output to Drive an
External Differential-Input Operational
Amplifier
– Headphone PWM Output to Drive an
External Differential Amplifier Like the
TPA112
– PWM Outputs Support Single-Ended and
Bridge-Tied Loads
– 32-, 38-, 44.1-, 48-, 88.2-, 96-, 176.4-, and
192-kHz Sampling Rates
– Data Formats: 16-, 20-, or 24-Bit
Left-Justified, I2S, or Right-Justified Input
Data
– 64-fS Bit-Clock Rate
– 128-, 192-, 256-, 384-, 512-, and 768-fS
Master Clock Rates (Up to a Maximum of
50 MHz)
Audio Processing
– 48-Bit Processing Architecture With 76 Bits
of Precision for Most Audio-Processing
Features
– Volume Control Range 36 dB to –109 dB
• Master Volume Control Range of 18 dB
to –109 dB
• Eight Individual Channel Volume Control
Ranges of 18 dB to –109 dB
– Programmable Soft Volume and Mute
Update Rates
– Four Bass and Treble Tone Controls With
±18-dB Range, Selectable Corner
Frequencies, and Second-Order Slopes
SLES162C – DECEMBER 2005 – REVISED JULY 2009
•
• L, R, and C
• LS, RS
• LR, RR
• Sub
– Configurable Loudness Compensation
– Two Dynamic Range Compressors With
Two Thresholds, Two Offsets, and Three
Slopes
– Seven Biquads Per Channel
– Full 8×8 Input Crossbar Mixer. Each
Signal-Processing Channel Input Can Be
Any Ratio of the Eight Input Channels.
– 8×2 Output Mixer, Channels 1–6. Each
Output Is a Mix of Any Two
Signal-Processed Channels. It Is
Recommended to Use the Pass-Through
output Mixer Configuration.
– 8×3 Output Mixer, Channels 7 and 8. Each
Output Is a Mix of Any Three
Signal-Processed Channels. It Is
Recommended to Use the Pass-Through
Output Mixer Configuration.
– Three Coefficient Sets Stored on the Device
Can Be Selected Manually or Automatically
(Based on Specific Data Rates).
– DC Blocking Filters
– Able to Support a Variety of Bass
Management Algorithms
PWM Processing
– 32-Bit Processing PWM Architecture With
40 Bits of Precision
– 8× Oversampling With Fifth-Order Noise
Shaping at 32 kHz–48 kHz, 4×
Oversampling at 88.2 kHz and 96 kHz, and
2× Oversampling at 176.4 kHz and 192 kHz
– >102-dB Dynamic Range
– THD+N < 0.1%
– 20-Hz–20-kHz, Flat Noise Floor for 44.1-,
48-, 88.2-, 96-, 176.4-, and 192-kHz Data
Rates
– Digital De-Emphasis for 32-, 44.1-, and
48-kHz Data Rates
– Flexible Automute Logic With
Programmable Threshold and Duration for
Noise-Free Operation
– Intelligent AM Interference-Avoidance
System Provides Clear AM Reception
– Power-Supply Volume Control (PSVC)
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 document.
Matlab is a trademark of Math Works, Inc.
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 © 2005–2009, Texas Instruments Incorporated
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Support for Enhanced Dynamic Range in
High-Performance Applications
1.2
www.ti.com
– Adjustable Modulation Limit
Overview
The TAS5508B is an 8-channel digital pulse-width modulator (PWM) that provides both advanced
performance and a high level of system integration. The TAS5508B is designed to interface seamlessly
with most audio digital signal processors. The TAS5508B automatically adjusts control configurations in
response to clock and data rate changes and idle conditions. This enables the TAS5508B to provide an
easy-to-use control interface with relaxed timing requirements.
The TAS5508B can drive eight channels of H-bridge power stages. Texas Instruments power stage parts
TAS5111, TAS5112, or TAS5182 with FETs are designed to work seamlessly with the TAS5508B. The
TAS5508B supports either the single-ended or bridge-tied-load configuration. The TAS5508B also
provides a high-performance, differential output to drive an external, differential-input, analog headphone
amplifier (such as the TPA112).
The TAS5508B uses AD modulation operating at a 384-kHz switching rate for 48-, 96-, and 192-kHz data.
The 8× oversampling combined with the fifth-order noise shaper provides a broad, flat noise floor and
excellent dynamic range from 20 Hz to 20 kHz.
The TAS5508B is a clocked slave-only device. The TAS5508B receives MCLK, SCLK, and LRCLK from
other system components. The TAS5508B accepts master clock rates of 128, 192, 256, 384, 512, and
768 fS. The TAS5508B accepts a 64-fS bit clock.
The TAS5508B allows for extending the dynamic range by providing a power-supply, volume-control
(PSVC) output signal.
10
Introduction
Submit Documentation Feedback
Submit Documentation Feedback
Device
Control
8 × 8 Crossbar Mixer
8
9
DAP Control
4
Volume
Control
8
8
2
2
8
8
DC
De Interpolate SRC NS PWM
Block Emph
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
DC
De Interpolate SRC NS PWM
Block Emph
DC
De Interpolate SRC NS PWM
Block Emph
DC
De Interpolate SRC NS PWM
Block Emph
DC
De Interpolate SRC NS PWM
Block Emph
DC
De Interpolate SRC NS PWM
Block Emph
DC
De Interpolate SRC NS PWM
Block Emph
PWM Section
DC
De Interpolate SRC NS PWM
Block Emph
8 × 2 Crossbar Mixer
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
0
7
Soft Soft Loud DRC
Det Biquads Tone Vol Comp
0
7
Soft Soft Loud
Det Biquads Tone Vol Comp DRC
Digital Audio Processor
PSVC
PSVC
VALID
PWM AP and AM6 R Surround
PWM R Lineout
PWM AP and AM5 L Surround
PWM L Lineout
PWM AP and AM8
Subwoofer
PWM AP and AM7 Center
PWM AP and AM4 R Rear
PWM AP and AM3 L Rear
PWM AP and AM2 R Front
PWM AP and AM1 L Front
PWM_HPP and MR
PWM_HPP and ML
www.ti.com
MUTE
HP_SEL
BKND_ERR
RESET
PDN
SCL
I2 C
Serial
Control
I/F
Clock, PLL, and Serial Data I/F
SDA
SDIN1
SDIN2
SDIN3
SDIN4
PLL_FLTM
PLL_FLTP
OSC CAP
SCLK
LRCLK
MCLK
XTL_OUT
XTL_IN
AVSS
AVDD
DVSS
DVDD
VRD_PLL
VRA_PLL
VBGAP
AVDD_REF
AVSS_PLL
AVDD_PLL
VR_PLL
Power Supply
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Output Control
PWM Control
System Control
B0011-01
Figure 1-1. TAS5508B Functional Structure
Introduction
11
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
1.3
www.ti.com
Changes From the TAS5508A to the TAS5508B
•
•
High-pass filter is enabled by default (0x03 bit 7)
I2C register 0xD0 bit 30 is added in TAS5508B to support remapped output mixer configuration. It has
a default value of 0.
Table 1-1. I2C Register 0xD0 Bit 30 Usage
0xD0 Bit 30
Output Mixer Configuration
Mode
PWM (Speaker) Operation
Headphone operation
Pass-through
8-channel mode or
6-channel mode (2
channels become lineouts)
Normal operation
Normal operation
8-channel mode
Constraints are placed in
setting the combined volume
below –109 dB and in using
individual channel mute.
Normal Operation
1
0 (default)
Remapped
6-channel mode (2
channels become lineouts)
Following the assertion or
Constraints are placed in
de-assertion of headphone,
setting the combined volume
mute must be asserted and
below –109 dB and in using
de-asserted using the
individual channel mute.
MUTE pin.
The pass-through output mixer configuration means that each DAP channel is mapped to the same output
PWM channel. For example, DAP channel 1 is routed to PWM channel 1, etc.
The remapped output mixer configuration means that the PWM channel could be a mix or rerouting of the
DAP channels. For example, DAP channel 2 is routed to PWM channel 1. This remapping causes some
complications in operation (see Table 1-1).
The TAS55508 recommended initialization sequence to use the pass-through ouput mixer configuration
follows.
1. After TAS5508B reset, the default master volume is muted. It must be updated with a nonmute value
for the system to start.
2. I2C register 0xD0 bit 30 must be set to a value of 1.
Note that for best results, the pass-through ouput mixer configuration is recommended (0xD0 Bit
30 = 1).
When remapping or mixing DAP channels to different PWM output channels (remapped output mixer
configuration) consider the following limitations:
• Individual channel mute should not be used.
• The sum of the minimum channel volume and master volume should not be below –109 dB.
• 0xD0 bit 30 = 0
1.4
TAS5508B System Diagrams
Typical applications for the TAS5508B are 6- to 8-channel audio systems such as DVD or AV receivers.
Figure 1-2 shows the basic system diagram of the DVD receiver.
12
Introduction
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
AM
FM
Tuner
Power Supply
Texas Instruments
Digital Audio Amplifier
TAS5508B
DVD Loader
MPEG Decoder
Front-Panel Controls
B0012-03
Figure 1-2. Typical TAS5508B Application (DVD Receiver)
Figure 1-3 shows the pass-through output mixer channel configuration when using the TAS5508B.
TAS5121
TAS5121
TAS5121
PWM_P_1
PWM_HPML
PWM_HPPL
PWM_P_4
TAS5508B
PWM_M_1
TAS5121
PWM_HPMR PWM_M_2
TAS5121
PWM_HPPR PWM_P_2
LEFT
+
−
PWM_M_3
RIGHT
+
−
PWM_P_3
LEFT
SURROUND
+
−
PWM_M_4
RIGHT
SURROUND
+
−
PWM_M_7
PWM_M_8
TAS5121
PWM_P_8
PWM_P_5
PWM_M_5
TAS5121
PWM_P_5
PWM_M_6
PWM_P_6
PWM_P_6
PWM_M_6
TAS5121
CENTER
+
−
PWM_P_7
LEFT BACK
SURROUND SUBWOOFER
+
−
+
−
PWM_M_5
RIGHT BACK
SURROUND
+
−
Headphone
Out Left
Lineout Left
PWM to Analog
(Headphone Level)
Headphone
Out Right
HW Control
and Status
Clocks
SDIN 1, 2, 3, 4
(8-Channel PCM)
PWM to Analog
(Line Level)
I2C Control
and Status
Lineout Right
B0013-03
Figure 1-3. Pass-Through Output Mixer TAS5508B Channel Configuration
Submit Documentation Feedback
Introduction
13
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
2
Description
2.1
Physical Characteristics
2.1.1
www.ti.com
Terminal Assignments
RESEVED
MCLK
PWM_HPPR
PWM_HPMR
PWM_HPPL
PWM_HPML
PWM_P_6
PWM_M_6
PWM_P_5
PWM_M_5
DVDD_PWM
DVSS_PWM
PWM_P_8
PWM_M_8
PWM_P_7
PWM_M_7
PAG PACKAGE
(TOP VIEW)
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
VRA_PLL
PLL_FLT_RET
PLL_FLTM
PLL_FLTP
AVSS
AVSS
VRD_PLL
AVSS_PLL
AVDD_PLL
VBGAP
RESET
HP_SEL
PDN
MUTE
DVDD
DVSS
1
48
2
47
3
46
4
45
5
44
6
43
7
42
8
41
9
40
10
39
11
38
12
37
13
36
14
35
15
34
16
33
VR_PWM
PWM_P_4
PWM_M_4
PWM_P_3
PWM_M_3
PWM_P_2
PWM_M_2
PWM_P_1
PWM_M_1
VALID
DVSS
BKND_ERR
DVDD
DVSS
DVSS
VR_DIG
VR_DPLL
OSC_CAP
XTL_OUT
XTL_IN
RESERVED
RESERVED
RESERVED
SDA
SCL
LRCLK
SCLK
SDIN4
SDIN3
SDIN2
SDIN1
PSVC
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
P0010-01
2.1.2
14
Ordering Information
Description
TA
PLASTIC 64-PIN PQFP (P/N)
0°C to 70°C
TAS5508BPAG
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
2.1.3
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Terminal Descriptions
TERMINAL
NAME
AVDD_PLL
AVSS
NO.
TYPE (1)
5-V
TOLERANT
TERMINATION (2)
DESCRIPTION
9
P
3.3-V analog power supply for PLL. This terminal can be connected to the same
power source used to drive power terminal DVDD; but to achieve low PLL jitter,
this terminal should be bypassed to AVSS_PLL with a 0.1-µF low-ESR
capacitor.
5, 6
P
Analog ground
AVSS_PLL
8
P
Analog ground for PLL. This terminal should reference the same ground as
terminal DVSS; but to achieve low PLL jitter, ground noise at this terminal must
be minimized. The availability of the AVSS terminal allows a designer to use
optimizing techniques such as star ground connections, separate ground planes,
or other quiet ground-distribution techniques to achieve a quiet ground reference
at this terminal.
BKND_ERR
37
DI
15, 36
P
3.3-V digital power supply. It is recommended that decoupling capacitors of
0.1 µF and 10 µF be mounted close to this pin (see application schematics).
54
P
3.3-V digital power supply for PWM
16, 34,
35, 38
P
Digital ground
DVDD
DVDD_PWM
DVSS
Pullup
Active-low. A back-end error sequence is generated by applying logic low to this
terminal. The BKND_ERR results in no change to any system parameters, with
all H-bridge drive signals going to a hard-mute state (M-state).
DVSS_PWM
53
P
HP_SEL
12
DI
5V
LRCLK
26
DI
5V
MCLK
63
DI
5V
Pulldown
MCLK is a 3.3-V master clock input. The input frequency of this clock can range
from 4 MHz to 50 MHz.
MUTE
14
DI
5V
Pullup
Soft mute of outputs, active-low (muted signal = a logic low, normal operation =
a logic high). The mute control provides a noiseless volume ramp to silence.
Releasing mute provides a noiseless ramp to previous volume.
OSC_CAP
18
AO
PDN
13
DI
5V
Pullup
PLL_FLT_RET
2
AO
PLL external filter return
PLL_FLTM
3
AO
PLL negative input. Connected to PLL_FLT_RET via an RC network
PLL_FLTP
4
AI
PLL positive input. Connected to PLL_FLT_RET via an RC network
PSVC
32
O
Power-supply volume control PWM output
PWM_HPML
59
DO
PWM left-channel headphone (differential –)
PWM_HPMR
61
DO
PWM right-channel headphone (differential –)
PWM_HPPL
60
DO
PWM left-channel headphone (differential +)
PWM_HPPR
62
DO
PWM right-channel headphone (differential +)
PWM_M_1
40
DO
PWM 1 output (differential –)
PWM_M_2
42
DO
PWM 2 output (differential –)
PWM_M_3
44
DO
PWM 3 output (differential –)
PWM_M_4
46
DO
PWM 4 output (differential –)
PWM_M_5
55
DO
PWM 5 output (lineout L) (differential –)
PWM_M_6
57
DO
PWM 6 output (lineout R) (differential –)
PWM_M_7
49
DO
PWM 7 output (differential –)
PWM_M_8
51
DO
PWM 8 output (differential –)
PWM_P_1
41
DO
PWM 1 output (differential +)
PWM_P_2
43
DO
PWM 2 output (differential +)
PWM_P_3
45
DO
PWM 3 output (differential +)
(1)
(2)
Digital ground for PWM
Pullup
Headphone in/out selector. When a logic low is applied, the headphone is
selected (speakers are off). When a logic high is applied, speakers are selected
(headphone is off).
Serial-audio data left/right clock (sampling-rate clock)
Oscillator capacitor
Power down, active-low. PDN powers down all logic and stops all clocks
whenever a logic low is applied. The internal parameters are preserved through
a power-down cycle, as long as RESET is not active. The duration for system
recovery from power down is 100 ms.
Type: A = analog; D = 3.3-V digital; P = power/ground/decoupling; I = input; O = output
All pullups are 20-µA weak pullups and all pulldowns are 20-µA weak pulldowns. The pullups and pulldowns are included to ensure
proper input logic levels if the terminals are left unconnected (pullups → logic-1 input; pulldowns → logic-0 input). Devices that drive
inputs with pullups must be able to sink 20 µA while maintaining a logic-0 drive level. Devices that drive inputs with pulldowns must be
able to source 20 µA while maintaining a logic-1 drive level.
Submit Documentation Feedback
Description
15
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
TERMINAL
NAME
NO.
TYPE (1)
5-V
TOLERANT
www.ti.com
TERMINATION (2)
DESCRIPTION
PWM_P_4
47
DO
PWM 4 output (differential +)
PWM_P_5
56
DO
PWM 5 output (lineout L) (differential +)
PWM_P_6
58
DO
PWM 6 output (lineout R) (differential +)
PWM_P_7
50
DO
PWM 7 output (differential +)
PWM_P_8
52
DO
PWM 8 output (differential +)
RESERVED
21, 22,
23, 64
Connect to digital ground
RESET
11
DI
5V
SCL
25
DI
5V
I2C serial-control clock input/output
SCLK
27
DI
5V
Serial-audio data clock (shift clock) input
SDA
24
DIO
5V
SDIN1
31
DI
5V
Pulldown
Serial-audio data input 1 is one of the serial-data input ports. SDIN1 supports
four discrete (stereo) data formats and is capable of inputting data at 64 fS.
SDIN2
30
DI
5V
Pulldown
Serial-audio data input 2 is one of the serial-data input ports. SDIN2 supports
four discrete (stereo) data formats and is capable of inputting data at 64 fS.
SDIN3
29
DI
5V
Pulldown
Serial-audio data input 3 is one of the serial-data input ports. SDIN3 supports
four discrete (stereo) data formats and is capable of inputting data at 64 fS.
SDIN4
28
DI
5V
Pulldown
Serial-audio data input 4 is one of the serial-data input ports. SDIN4 supports
four discrete (stereo) data formats and is capable of inputting data at 64 fS.
VALID
39
DO
VBGAP
10
P
Band-gap voltage reference. A pinout of the internally regulated 1.2-V reference.
Typically has a 1-nF low-ESR capacitor between VBGAP and AVSS_PLL. This
terminal must not be used to power external devices.
VR_DIG
33
P
Voltage reference for 1.8-V digital core supply. A pinout of the internally
regulated 1.8-V power used by digital core logic. A 4.7-µF low-ESR capacitor (3)
should be connected between this terminal and DVSS. This terminal must not
be used to power external devices.
VR_DPLL
17
P
Voltage reference for 1.8-V digital PLL supply. A pinout of the internally
regulated 1.8-V power used by digital PLL logic. A 0.1-µF low-ESR capacitor (3)
should be connected between this terminal and DVSS_CORE. This terminal
must not be used to power external devices.
VR_PWM
48
P
Voltage reference for 1.8-V digital PWM core supply. A pinout of the internally
regulated 1.8-V power used by digital PWM core logic. A 0.1-µF low-ESR
capacitor (3) should be connected between this terminal and DVSS_PWM. This
terminal must not be used to power external devices.
VRA_PLL
1
P
Voltage reference for 1.8-V PLL analog supply. A pinout of the internally
regulated 1.8-V power used by PLL logic. A 0.1-µF low-ESR capacitor (3) should
be connected between this terminal and AVSS_PLL. This terminal must not be
used to power external devices.
VRD_PLL
7
P
Voltage reference for 1.8-V PLL digital supply. A pinout of the internally
regulated 1.8-V power used by PLL logic. A 0.1-µF low-ESR capacitor (3) should
be connected between this terminal and AVSS_PLL. This terminal must not be
used to power external devices.
XTL_IN
20
AI
XTL_OUT and XTL_IN are the only LVCMOS terminals on the device. They
provide a reference clock for the TAS5508B via use of an external
fundamental-mode crystal. XTL_IN is the 1.8-V input port for the oscillator
circuit. A 13.5-MHz crystal (HCM49) is recommended.
XTL_OUT
19
AO
XTL_OUT and XTL_IN are the only LVCMOS terminals on the device. They
provide a reference clock for the TAS5508B via use of an external
fundamental-mode crystal. XTL_OUT is the 1.8-V output drive to the crystal. A
13.5-MHz crystal (HCM49) is recommended.
(3)
16
Pullup
System reset input, active-low. A system reset is generated by applying a logic
low to this terminal. RESET is an asynchronous control signal that restores the
TAS5508B to its default conditions, sets the valid output low, and places the
PWM in the hard-mute state (M-state). Master volume is immediately set to full
attenuation. On the release of RESET, if PDN is high, the system performs a 4to 5-ms device initialization and sets the volume at mute.
I2C serial-control data-interface input/output
Output indicating validity of PWM outputs, active-high
If desired, low-ESR capacitance values can be implemented by paralleling two or more ceramic capacitors of equal value. Paralleling
capacitors of equal value provides an extended high-frequency supply decoupling. This approach avoids the potential of producing
parallel resonance circuits that have been observed when paralleling capacitors of different values.
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
2.2
SLES162C – DECEMBER 2005 – REVISED JULY 2009
TAS5508B Functional Description
Figure 1-1 shows the TAS5508B functional structure. The following sections describe the TAS5508B
functional blocks:
• Power supply
• Clock, PLL, and serial data interface
• I2C serial-control interface
• Device control
• Digital audio processor (DAP)
2.2.1
Power Supply
The power-supply section contains supply regulators that provide analog and digital regulated power for
various sections of the TAS5508B. The analog supply supports the analog PLL, whereas digital supplies
support the digital PLL, the digital audio processor (DAP), the pulse-width modulator (PWM), and the
output control.
2.2.2
Clock, PLL, and Serial Data Interface
The TAS5508B is a clocked slave-only device that requires the use of an external 13.5-MHz crystal. It
accepts MCLK, SCLK, and LRCLK as inputs only.
The TAS5508B uses the external crystal to provide a time base for:
• Continuous data and clock error detection and management
• Automatic data-rate detection and configuration
• Automatic MCLK-rate detection and configuration (automatic bank switching)
• Supporting I2C operation/communication while MCLK is absent
The TAS5508B automatically handles clock errors, data-rate changes, and master-clock frequency
changes without requiring intervention from an external system controller. This feature significantly
reduces system complexity and design.
2.2.2.1 Serial Audio Interface
The TAS5508B operates as a slave-only/receive-only serial data interface in all modes. The TAS5508B
has four PCM serial data interfaces to permit eight channels of digital data to be received through the
SDIN1, SDIN2, SDIN3, and SDIN4 inputs. The serial audio data is in MSB-first, 2s-complement format.
The serial data input interface of the TAS5508B can be configured in right-justified, I2S, or left-justified
modes. The serial data interface format is specified using the I2C data-interface control register. The
supported formats and word lengths are shown in Table 2-1.
Submit Documentation Feedback
Description
17
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Table 2-1. Serial Data Formats
RECEIVE SERIAL DATA FORMAT
WORD LENGTH
Right-justified
16
Right-justified
20
Right-justified
24
I2S
16
2
I S
20
I2S
24
Left-justified
16
Left-justified
20
Left-justified
24
Serial data is input on SDIN1, SDIN2, SDIN3, and SDIN4. The TAS5508B accepts 16-, 20-, or 24-bit serial
data at 32, 38, 44.1, 48, 88.2, 96, 176.4, or 192 kHz in left-justified, I2S, or right-justified format. Data is
input using a 64-fS SCLK clock and an MCLK rate of 128, 192, 256, 384, 512, or 768 fS, up to a maximum
of 50 MHz. The clock speed and serial data format are I2C configurable.
2.2.3
I 2C Serial-Control Interface
The TAS5508B has an I2C serial-control slave interface (write address = 0x36 and read address = 0x37)
to receive commands from a system controller. The serial-control interface supports both normal-speed
(100-kHz) and high-speed (400-kHz) operations without wait states. Because the TAS5508B has a crystal
time base, this interface operates even when MCLK is absent.
The serial control interface supports both single-byte and multiple-byte read/write operations for status
registers and the general control registers associated with the PWM. However, for the DAP
data-processing registers, the serial control interface also supports multiple-byte (4-byte) write operations.
The I2C supports a special mode which permits I2C write operations to be broken up into multiple
data-write operations that are multiples of 4 data bytes. These are 6-byte, 10-byte, 14-byte, 18-byte, etc.,
write operations that are composed of a device address, read/write bit, subaddress, and any multiple of 4
bytes of data. This permits the system to incrementally write large register values without blocking other
I2C transactions. In order to use this feature, the first block of data is written to the target I2C address, and
each subsequent block of data is written to a special append register (0xFE) until all the data is written
and a stop bit is sent. An incremental read operation is not supported.
2.2.4
Device Control
The TAS5508B control section provides the control and sequencing for the TAS5508B. The device control
provides both high- and low-level control for the serial control interface, clock and serial data interfaces,
digital audio processor, and pulse-width modulator sections.
2.2.5
Digital Audio Processor (DAP)
The DAP arithmetic unit is used to implement all audio-processing functions: soft volume, loudness
compensation, bass and treble processing, dynamic range control, channel filtering, and input and output
mixing. Figure 2-1 shows the TAS5508B DAP architecture.
The DAP accepts 24-bit data from the serial data interface and outputs 32-bit data to the PWM section.
The DAP supports two configurations, one for 32-kHz to 96-kHz data and one for 176.4-kHz to 192-kHz
data.
2.2.5.1 TAS5508B Audio-Processing Configurations
The 32-kHz to 96-kHz configuration supports eight channels of data processing that can be configured
either as eight channels, or as six channels with two channels for separate stereo line outputs.
The 176.4-kHz to 192-kHz configuration supports three channels of signal processing with five channels
passed through (or derived from the three processed channels).
18
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
To support efficiently the processing requirements of both multichannel 32-kHz to 96-kHz data and the
2-channel 176.4-kHz and 192-kHz data, the TAS5508B has separate audio-processing features for
32-kHz to 96-kHz data rates and for 176.4 kHz and 192 kHz. See Table 2-2 for a summary of TAS5508B
processing feature sets.
2.2.5.2 TAS5508B Audio Signal-Processing Functions
The DAP provides 10 primary signal-processing functions:
• The data-processing input has a full 8×8 input crossbar mixer. This enables each input to be any mix
of the eight input channels.
• Two I2C programmable threshold detectors in each channel support automute.
• Seven biquads per channel
• Four soft bass and treble tone controls with ±18-dB range, programmable corner frequencies, and
second-order slopes. In 8-channel mode, bass and treble controls are normally configured as follows:
– Bass and treble 1: Channel 1 (left), channel 2 (right), and channel 7 (center)
– Bass and treble 2: Channel 3 (left surround) and channel 4 (right surround)
– Bass and treble 3: Channel 5 (left back surround) and channel 6 (right back surround)
– Bass and treble 4: Channel 8 (subwoofer)
• Individual channel and master volume controls. Each control provides an adjustment range of 18 dB to
–109 dB plus mute. This permits a total volume device control range of 36 dB to –109 dB plus mute.
The master volume control can be configured to control six or eight channels. The DAP soft volume
and mute update interval is I2C programmable. The update is performed at a fixed rate regardless of
the sample rate.
• Programmable loudness compensation that is controlled via the combination of the master and
individual volume settings.
• Two dual-threshold, dual-rate, dynamic range compressors (DRCs). The volume gain values provided
are used as input parameters using the maximum RMS (master volume × individual channel volume).
• 8×2 output mixer (channels 1–6). Each output is a mix of any two signal-processed channels. It is
recommended to use the pass-through output mixer configuration.
• 8×3 output mixer (channels 7 and 8). Each output is a mix of any three signal-processed channels. It is
recommended to use the pass-through output mixer configuration.
• The DAP maintains three sets of coefficient banks that are used to maintain separate sets of
sample-rate-dependent parameters for the biquad, tone controls, loudness, and DRC in RAM. These
can be set to be automatically selected for one or more data sample rates or can be manually selected
under I2C program control. This feature enables coefficients for different sample rates to be stored in
the TAS5508B and then selected when needed.
Submit Documentation Feedback
Description
19
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Table 2-2. TAS5508B Audio-Processing Feature Sets
FEATURE
32 kHz–96 kHz
8-CHANNEL FEATURE SET
Signal-processing channels
8
Pass-through channels
Master volume
1 for 8 channels
3
1 for 6 channels
1 for 8 channels
5
Four bass and treble tone controls
with ±18-dB range, programmable
corner frequencies, and secondorder slopes
L, R, and C (Ch1, 2, and 7)
LS, RS (Ch3 and 4)
LBS, RBS (Ch5 and 6)
Sub (Ch8)
8
Four bass and treble tone controls
with ±18-dB range, programmable
corner frequencies, and secondorder slopes
L, R, and C (Ch1, 2, and 7)
LS, RS (Ch3 and 4)
Sub (Ch8)
Line L and R (Ch5 and 6)
Two bass and treble tone
controls with ±18-dB range,
programmable corner
frequencies, and second-order
slopes
L and R (Ch1 and 2)
Sub (Ch8)
56
Dynamic range
compressors
Input/output mapping/
mixing
DRC1 for seven satellites and
DRC2 for sub
Digital de-emphasis
(implemented in PWM
section)
Loudness
21
DRC1 for five satellites and DRC2
for sub (Ch5 and 6 uncompressed)
Each of the eight signal-processing channel inputs can be any mix of the
eight input channels.
Each of the eight outputs can be any mix of any two processed channels.
DC-blocking filters
(implemented in PWM
section)
DRC1 for two satellites and
DRC2 for sub
Each of the three signalprocessing channels or the five
pass-though channel inputs can
be any mix of the eight input
channels.
Each of the eight outputs can be
any mix of any of the three
processed channels or five
bypass channels.
Eight channels
Eight channels for 32 kHz,
44.1 kHz, and 48 kHz
Eight channels
Number of coefficient sets
stored
2.3.1
6+2
8
Biquads
2.3
176.4- and 192-kHz
FEATURE SET
N/A
Individual channel volume
controls
Bass and treble tone
controls
32 kHz–96 kHz
6 + 2 LINEOUT FEATURE SET
Six channels for 32 kHz, 44.1 kHz,
and 48 kHz
N/A
Six channels
Three channels
Three additional coefficient sets can be stored in memory.
TAS5508B DAP Architecture
TAS5508B DAP Architecture Diagrams
Figure 2-1 shows the TAS5508B DAP architecture for fS ≤ 96 kHz. Note the TAS5508B bass management
architecture shown in channels 1, 2, 7, and 8. Note that the I2C registers are shown to help the designer
configure the TAS5508B.
Figure 2-2 shows the TAS5508B architecture for fS = 176.4 kHz or fS = 192 kHz. Note that only channels
1, 2, and 8 contain all the features. Channels 3–7 are pass-through except for volume controls.
Figure 2-3 shows TAS5508B detailed channel processing. The output mixer is 8×2 for channels 1–6 and
8×3 for channels 7 and 8.
20
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Master Vol
(0xD9)
SDIN1-L (L) (1)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R) (1)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS) (1)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS) (1)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS) (1)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS) (1)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C) (1)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 1
(I2C 0x41)
8×8
Crossbar
Input Mixer
7 DAP 1
BQ
(0x51−
0x57)
Bass and
Treble 1
(0xDA−
0xDD)
DAP 1
Volume
(0xD1)
Master Vol
(0xD9)
IP Mixer 2
(I2C 0x42)
8×8
Crossbar
Input Mixer
7 DAP 2
BQ
(0x58−
0x5E)
Bass and
Treble 1
(0xDA−
0xDD)
DAP 2
Volume
(0xD2)
Master Vol
(0xD9)
IP Mixer 3
(I2C 0x43)
8×8
Crossbar
Input Mixer
7 DAP 3
BQ
(0x5F−
0x65)
Bass and
Treble 2
(0xDA−
0xDD)
DAP 3
Volume
(0xD3)
Master Vol
(0xD9)
IP Mixer 4
(I2C 0x44)
8×8
Crossbar
Input Mixer
7 DAP 4
BQ
(0x66−
0x6C)
Bass and
Treble 2
(0xDA−
0xDD)
DAP 4
Volume
(0xD4)
Master Vol
(0xD9)
IP Mixer 5
(I2C 0x45)
8×8
Crossbar
Input Mixer
7 DAP 5
BQ
(0x6D−
0x73)
Bass and
Treble 3
(0xDA−
0xDD)
DAP 5
Volume
(0xD5)
Master Vol
(0xD9)
IP Mixer 6
(I2C 0x46)
8×8
Crossbar
Input Mixer
7 DAP 6
BQ
(0x74−
0x7A)
Coeff = 0 (lin), (I2C 0x4E)
Bass and
Treble 3
(0xDA−
0xDD)
Master Vol
(0xD9)
Coeff = 0 (lin), (I2C 0x4B)
IP Mixer 7
(I2C 0x47)
8×8
Crossbar
Input Mixer
2 DAP 7
BQ
(0x7B−
0x7C)
Coeff = 1 (lin)
(I2C 0x4D)
DAP 6
Volume
(0xD6)
5 DAP 7
BQ
(0x7D−
0x81)
Bass and
Treble 1
(0xDA−
0xDD)
DAP 7
Volume
(0xD7)
Max Vol
Loudness
(0x91−
0x95)
DRC1
(0x96−
0x9C)
OP Mixer 1
(I2C 0xAA)
8 × 2 Output
Mixer
L to
PWM1
DRC1
(0x96−
0x9C)
OP Mixer 2
(I2C 0xAB)
8 × 2 Output
Mixer
R to
PWM2
DRC1
(0x96−
0x9C)
OP Mixer 3
(I2C 0xAC)
8 × 2 Output
Mixer
LS to
PWM3
DRC1
(0x96−
0x9C)
OP Mixer 4
(I2C 0xAD)
8 × 2 Output
Mixer
RS to
PWM4
DRC1
(0x96−
0x9C)
OP Mixer 5
(I2C 0xAE)
8 × 2 Output
Mixer
LBS to
PWM5
DRC1
(0x96−
0x9C)
OP Mixer 6
(I2C 0xAF)
8 × 2 Output
Mixer
RBS to
PWM6
DRC1
(0x96−
0x9C)
OP Mixer 7
(I2C 0xB0)
8 × 3 Output
Mixer
C to
PWM7
DRC2
(0x9D−
0xA1)
OP Mixer 8
(I2C 0xB1)
8 × 3 Output
Mixer
Sub to
PWM8
Max Vol
Loudness
(0x91−
0x95)
Max Vol
Loudness
(0x91−
0x95)
Max Vol
Loudness
(0x91−
0x95)
Max Vol
Loudness
(0x91−
0x95)
Max Vol
Loudness
(0x91−
0x95)
Max Vol
Loudness
(0x91−
0x95)
Coeff = 0 (lin), (I2C 0x4C)
Coeff = 0 (lin), (I2C 0x49)
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE) (1)
A
B
C
D
E
F
G
H
IP Mixer 8
(I2C 0x48)
8×8
Crossbar
Input Mixer
2 DAP 8
BQ
(0x82−
0x83)
Coeff = 1 (lin)
(I2C 0x50)
Master Vol
(0xD9)
Coeff = 0 (lin)
(I2C 0x4A)
5 DAP 8
BQ
(0x84−
0x88)
Bass and
Treble 4
(0xDA−
0xDD)
DAP 8
Volume
(0xD8)
Max Vol
Loudness
(0x91−
0x95)
Coeff = 0 (lin), (I2C 0x4F)
(1)
B0014-01
Default inputs
Figure 2-1. TAS5508B DAP Architecture With I2C Registers (fS ≤ 96 kHz)
Submit Documentation Feedback
Description
21
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Master Vol
(0xD9)
SDIN1-L (L) (1)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
SDIN1-L (L)
SDIN1-R (R) (1)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 2
(I2C 0x42)
8×8
Crossbar
Input Mixer
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS) (1)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 3
(I2C 0x43)
8×8
Crossbar
Input Mixer
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS) (1)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 4
(I2C 0x44)
8×8
Crossbar
Input Mixer
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS) (1)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 5
(I2C 0x45)
8×8
Crossbar
Input Mixer
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS) (1)
SDIN4-L (C)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 6
(I2C 0x46)
8×8
Crossbar
Input Mixer
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C) (1)
SDIN4-R (LFE)
A
B
C
D
E
F
G
H
IP Mixer 7
(I2C 0x47)
8×8
Crossbar
Input Mixer
SDIN1-L (L)
SDIN1-R (R)
SDIN2-L (LS)
SDIN2-R (RS)
SDIN3-L (LBS)
SDIN3-R (RBS)
SDIN4-L (C)
SDIN4-R (LFE) (1)
A
B
C
D
E
F
G
H
IP Mixer 1
(I2C 0x41)
8×8
Crossbar
Input Mixer
7 DAP 1
BQ
(0x51−
0x57)
Bass and
Treble 1
(0xDA−
0xDD)
DAP 1
Volume
(0xD1)
Master Vol
(0xD9)
7 DAP 2
BQ
(0x58−
0x5E)
Bass and
Treble 1
(0xDA−
0xDD)
DAP 2
Volume
(0xD2)
Max Vol
Loudness
(0x91−
0x95)
DRC1
(0x96−
0x9C)
OP Mixer 1
(I2C 0xAA)
8 × 2 Output
Mixer
L to
PWM1
DRC1
(0x96−
0x9C)
OP Mixer 2
(I2C 0xAB)
8 × 2 Output
Mixer
R to
PWM2
OP Mixer 3
(I2C 0xAC)
8 × 2 Output
Mixer
LS to
PWM3
OP Mixer 4
(I2C 0xAD)
8 × 2 Output
Mixer
RS to
PWM4
OP Mixer 5
(I2C 0xAE)
8 × 2 Output
Mixer
LBS to
PWM5
OP Mixer 6
(I2C 0xAF)
8 × 2 Output
Mixer
RBS to
PWM6
OP Mixer 7
(I2C 0xB0)
8 × 3 Output
Mixer
C to
PWM7
OP Mixer 8
(I2C 0xB1)
8 × 3 Output
Mixer
Sub to
PWM8
Max Vol
Loudness
(0x91−
0x95)
Master Vol
(0xD9)
DAP 3
Volume
(0xD3)
Master Vol
(0xD9)
DAP 4
Volume
(0xD4)
Master Vol
(0xD9)
DAP 5
Volume
(0xD5)
Master Vol
(0xD9)
DAP 6
Volume
(0xD6)
Master Vol
(0xD9)
DAP 7
Volume
(0xD7)
Master Vol
(0xD9)
IP Mixer 8
(I2C 0x48)
8×8
Crossbar
Input Mixer
2 DAP 8
BQ
(0x82−
0x83)
5 DAP 8
BQ
(0x84−
0x88)
Bass and
Treble 4
(0xDA−
0xDD)
DAP 8
Volume
(0xD8)
Max Vol
Loudness
(0x91−
0x95)
DRC2
(0x9D−
0xA1)
B0015-01
(1)
Default inputs
Figure 2-2. TAS5508B Architecture With I2C Registers (fS = 176.4 kHz or fS = 192 kHz)
22
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
A_to_ipmix
Left
Master
Volume
A
B
SDIN1
Right
B_to_ipmix
Channel Volume
C_to_ipmix
Left
C
D
SDIN2
Right
E_to_ipmix
E
SDIN3
7
Biquads
in
Series
Input
Mixer
F_to_ipmix
Output
Gain
Output Mixer Sums
Any Two Channels
Bass
and
Treble
F
Right
DRC
Bypass
Loudness
D_to_ipmix
Left
Max
Volume
Bass and Treble
Bypass
Bass
and
Treble
Inline
PrePostVolume Volume
DRC
32-Bit
Trunc
DRC
Inline
PWM
Proc
PWM
Output
1 Other
Channel Output
From 7 Available
G_to_ipmix
Left
G
SDIN4
H
Right
H_to_ipmix
B0016-01
Figure 2-3. TAS5508B Detailed Channel Processing
2.3.2
I 2C Coefficient Number Formats
The architecture of the TAS5508B is contained in ROM resources within the TAS5508B and cannot be
altered. However, mixer gain, level offset, and filter tap coefficients, which can be entered via the I2C bus
interface, provide a user with the flexibility to set the TAS5508B to a configuration that achieves
system-level goals.
The firmware is executed in a 48-bit, signed, fixed-point arithmetic machine. The most significant bit of the
48-bit data path is a sign bit, and the 47 lower bits are data bits. Mixer gain operations are implemented
by multiplying a 48-bit, signed data value by a 28-bit, signed gain coefficient. The 76-bit, signed output
product is then truncated to a signed, 48-bit number. Level offset operations are implemented by adding a
48-bit, signed offset coefficient to a 48-bit, signed data value. In most cases, if the addition results in
overflowing the 48-bit, signed number format, saturation logic is used. This means that if the summation
results in a positive number that is greater than 0x7FFF FFFF FFFF (the spaces are used to ease the
reading of the hexadecimal number), the number is set to 0x7FFF FFFF FFFF. If the summation results in
a negative number that is less than 0x8000 0000 0000, the number is set to 0x8000 0000 0000.
2.3.2.1 28-Bit 5.23 Number Format
All mixer gain coefficients are 28-bit coefficients using a 5.23 number format. Numbers formatted as 5.23
numbers have 5 bits to the left of the binary point and 23 bits to the right of the binary point. This is shown
in Figure 2-4.
Submit Documentation Feedback
Description
23
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
2−23 Bit
2−4 Bit
2−1 Bit
20 Bit
23 Bit
Sign Bit
S_xxxx.xxxx_xxxx_xxxx_xxxx_xxxx_xxx
M0007-01
Figure 2-4. 5.23 Format
The decimal value of a 5.23 format number can be found by following the weighting shown in Figure 2-5. If
the most significant bit is logic 0, the number is a positive number, and the weighting shown yields the
correct number. If the most significant bit is a logic 1, then the number is a negative number. In this case,
every bit must be inverted, a 1 added to the result, and then the weighting shown in Figure 2-5 applied to
obtain the magnitude of the negative number.
23 Bit
22 Bit
20 Bit
2−1 Bit
2−4 Bit
2−23 Bit
(1 or 0) y 23 + (1 or 0) y 22 + … + (1 or 0) y 20 + (1 or 0) y 2−1 + … + (1 or 0) y 2−4 + … + (1 or 0) y 2−23
M0008-01
Figure 2-5. Conversion Weighting Factors—5.23 Format to Floating Point
Gain coefficients, entered via the I2C bus, must be entered as 32-bit binary numbers. The format of the
32-bit number (4-byte or 8-digit hexadecimal number) is shown in Figure 2-6.
Fraction
Digit 6
Sign
Bit
Integer
Digit 1
u
u
u
u
Coefficient
Digit 8
S
x
x
x
Coefficient
Digit 7
Fraction
Digit 1
x. x
x
x
Coefficient
Digit 6
Fraction
Digit 2
x
x
x
x
Coefficient
Digit 5
Fraction
Digit 3
x
x
x
x
Coefficient
Digit 4
Fraction
Digit 4
x
x
x
x
Coefficient
Digit 3
Fraction
Digit 5
x
x
x
x
Coefficient
Digit 2
0
x
x
x
x
Coefficient
Digit 1
u = unused or don’t care bits
Digit = hexadecimal digit
M0009-01
Figure 2-6. Alignment of 5.23 Coefficient in 32-Bit I2C Word
As Figure 2-6 shows, the hexadecimal (hex) value of the integer part of the gain coefficient cannot be
24
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
concatenated with the hex value of the fractional part of the gain coefficient to form the 32-bit I2C
coefficient. The reason is that the 28-bit coefficient contains 5 bits of integer, and thus the integer part of
the coefficient occupies all of one hex digit and the most significant bit of the second hex digit. In the same
way, the fractional part occupies the lower three bits of the second hex digit, and then occupies the other
five hex digits (with the eighth digit being the zero-valued most significant hex digit).
2.3.2.2 48-Bit 25.23 Number Format
All level adjustment and threshold coefficients are 48-bit coefficients using a 25.23 number format.
Numbers formatted as 25.23 numbers have 25 bits to the left of the decimal point and 23 bits to the right
of the decimal point. This is shown in Figure 2-7.
2−23 Bit
2−10 Bit
2−1 Bit
20 Bit
216 Bit
222 Bit
223 Bit
Sign Bit
S_xxxx_xxxx_xxxx_xxxx_xxxx_xxxx.xxxx_xxxx_xxxx_xxxx_xxxx_xxx
M0007-02
Figure 2-7. 25.23 Format
Figure 2-8 shows the derivation of the decimal value of a 48-bit 25.23 format number.
223 Bit
222 Bit
20 Bit
2−1 Bit
2−23 Bit
(1 or 0) y 223 + (1 or 0) y 222 + … + (1 or 0) y 20 + (1 or 0) y 2−1 + … + (1 or 0) y 2−23
M0008-02
Figure 2-8. Conversion Weighting Factors—25.23 Format to Floating Point
Two 32-bit words must be sent over the I2C bus to download a level or threshold coefficient into the
TAS5508B. The alignment of the 48-bit, 25.23 formatted coefficient in the 8-byte (two 32-bit words) I2C
word is shown in Figure 2-9.
Submit Documentation Feedback
Description
25
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Integer
Digit 4
(Bits 211 − 29)
Sign
Bit
Integer
Digit 1
u
u
u
u
Coefficient
Digit 16
u
u
u
u
Coefficient
Digit 15
u
u
u
u
Coefficient
Digit 14
u
u
u
u
Coefficient
Digit 13
S
x
x
x
Coefficient
Digit 12
Integer
Digit 2
x
x
x
x
Coefficient
Digit 11
Integer
Digit 3
x
x
x
x
x
Coefficient
Digit 10
Word 1
(MostSignificant
Word)
x
Fraction
Digit 6
Integer
Digit 5
x
x
Coefficient
Digit 9
Integer
Digit 4
(Bit 28)
x
x
x
x
Coefficient
Digit 8
Integer
Digit 6
x
x
x
x
Coefficient
Digit 7
Fraction
Digit 1
x. x
x
x
Coefficient
Digit 6
Fraction
Digit 2
x
x
x
x
Coefficient
Digit 5
Fraction
Digit 3
x
x
x
x
Coefficient
Digit 4
Fraction
Digit 4
x
x
x
x
Coefficient
Digit 3
Fraction
Digit 5
x
x
x
x
Coefficient
Digit 2
0
x
x
x
x
Word 2
(LeastSignificant
Word)
Coefficient
Digit 1
u = unused or don’t care bits
Digit = hexadecimal digit
M0009-02
Figure 2-9. Alignment of 25.23 Coefficient in Two 32-Bit I2C Words
2.3.2.3 TAS5508B Audio Processing
The TAS5508B digital audio processing is designed so that noise produced by filter operations is
maintained below the smallest signal amplitude of interest, as shown in Figure 2-10. The TAS5508B
achieves this low noise level by increasing the precision of the signal representation substantially above
the number of bits that are absolutely necessary to represent the input signal.
Similarly, the TAS5508B carries additional precision in the form of overflow bits to permit the value of
intermediate calculations to exceed the input precision without clipping. The TAS5508B advanced digital
audio processor achieves both of these important performance capabilities by using a high-performance
digital audio-processing architecture with a 48-bit data path, 28-bit filter coefficients, and a 76-bit
accumulator.
26
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Ideal Input
Possible Outputs
Desired Output
Values Retained by
Overflow Bits
Overflow
Maximum Signal Amplitude
Filter
Operation
Signal
Bits
Input
Reduced
SNR
Signal
Output
Signal
Bits
Output
Noise Floor With No
Additional Precision
Noise Floor as a Result
of Additional Precision
M0010-01
Figure 2-10. TAS5508B Digital Audio Processing
2.4
Input Crossbar Mixer
The TAS5508B has a full 8×8 input crossbar mixer. This mixer permits each signal-processing channel
input to be any mix of any of the eight input channels, as shown in Figure 2-11. The control parameters for
the input crossbar mixer are programmable via the I2C interface. See the Input Mixer Registers, Channels
1–8 (0x41–0x48), Section 7.13, for more information.
Gain Coefficient
28
48
SDIN1-L
Gain Coefficient
48
28
48
48
SUM
SDIN1-R
w
w
w
Gain Coefficient
48
28
48
SDIN4-R
M0011-01
Figure 2-11. Input Crossbar Mixer
2.5
Biquad Filters
For 32-kHz to 96-kHz data, the TAS5508B provides 56 biquads across the eight channels (seven per
channel).
For 176.4-kHz and 192-kHz data, the TAS5508B has 21 biquads across the three channels (seven per
channel). All of the biquad filters are second-order direct form I structure.
Submit Documentation Feedback
Description
27
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
The direct form I structure provides a separate delay element and mixer (gain coefficient) for each node in
the biquad filter. Each mixer output is a signed 76-bit product of a signed 48-bit data sample (25.23 format
number) and a signed 28-bit coefficient (5.23 format number), as shown in Figure 2-12. The 76-bit ALU in
the TAS5508B allows the 76-bit resolution to be retained when summing the mixer outputs (filter
products).
The five 28-bit coefficients for the each of the 56 biquads are programmable via the I2C interface. See
Table 2-3.
b0
28
48
76
76
S
b1
z
–1
a1
28
48
76
b2
z
–1
48
a2
28
48
z
28
76
–1
48
Magnitude
Truncation
z
28
76
76
–1
48
M0012-01
Figure 2-12. Biquad Filter Structure
All five coefficients for one biquad filter structure are written to one I2C register containing 20 bytes (or five
32-bit words). The structure is the same for all biquads in the TAS5508B. Registers 0x51–0x88 show all
the biquads in the TAS5508B. Note that u[31:28] bits are unused and default to 0x0.
Table 2-3. Contents of One 20-Byte Biquad Filter Register (Default = All-Pass)
2.6
INITIALIZATION GAIN COEFFICIENT VALUE
DESCRIPTION
REGISTER FIELD CONTENTS
DECIMAL
HEX
b0 coefficient
u[31:28], b0[27:24], b0[23:16], b0[15:8], b0[7:0]
1.0
0x00, 0x80, 0x00, 0x00
b1 coefficient
u[31:28], b1[27:24], b1[23:16], b1[15:8], b1[7:0]
0.0
0x00, 0x00, 0x00, 0x00
b2 coefficient
u[31:28], b2[27:24], b2[23:16], b2[15:8], b2[7:0]
0.0
0x00, 0x00, 0x00, 0x00
a1 coefficient
u[31:28], a1[27:24], a1[23:16], a1[15:8], a1[7:0]
0.0
0x00, 0x00, 0x00, 0x00
a2 coefficient
u[31:28], a2[27:24], a2[23:16], a2[15:8], a2[7:0]
0.0
0x00, 0x00, 0x00, 0x00
Bass and Treble Controls
From 32-kHz to 96-kHz data, the TAS5508B has four bass and treble tone controls. Each control has a
±18-dB control range with selectable corner frequencies and second-order slopes. These controls operate
four channel groups:
• L, R, and C (channels 1, 2, and 7)
• LS, RS (channels 3 and 4)
• LBS, RBS (alternatively called L and R lineout) (channels 5 and 6)
• Sub (channel 8)
For 176.4-kHz and 192-kHz data, the TAS5508B has two bass and treble tone controls. Each control has
a ±18-dB I2C control range with selectable corner frequencies and second-order slopes. These controls
operate two channel groups:
28
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
•
•
SLES162C – DECEMBER 2005 – REVISED JULY 2009
L and R
Sub
The bass and treble filters use a soft update rate that does not produce artifacts during adjustment.
Table 2-4. Bass and Treble Filter Selections
3-dB CORNER FREQUENCIES, Hz
fS
(kHz)
FILTER SET 1
FILTER SET 2
FILTER SET 3
FILTER SET 4
FILTER SET 5
BASS
TREBLE
BASS
TREBLE
BASS
TREBLE
BASS
TREBLE
BASS
TREBLE
32
42
917
83
1833
125
3000
146
3667
167
4333
38
49
1088
99
2177
148
3562
173
4354
198
5146
44.1
57
1263
115
2527
172
4134
201
5053
230
5972
48
63
1375
125
2750
188
4500
219
5500
250
6500
88.2
115
2527
230
5053
345
8269
402
10106
459
11944
96
125
2750
250
5500
375
9000
438
11000
500
13000
176.4
230
5053
459
10106
689
16538
804
20213
919
23888
192
250
5500
500
11000
750
18000
875
22000
1000
26000
The I2C registers that control bass and treble are:
• Bass and treble bypass register (0x89–0x90, channels 1–8)
• Bass and treble slew rates (0xD0)
• Bass filter sets 1–5 (0xDA)
• Bass filter index (0xDB)
• Treble filter sets 1–5 (0xDC)
• Treble filter index (0xDD)
Note that the bass and treble bypass registers (0x89–0x90) are defaulted to the bypass mode. In
order to use the bass and treble, these registers must be in the inline (or enabled) mode for each
channel using bass and treble.
2.7
Volume, Automute, and Mute
The TAS5508B provides individual channel and master volume controls. Each control provides an
adjustment range of 18 dB to –109 dB in 0.25-dB increments. This permits a total volume device control
range of 36 dB to –109 dB plus mute. The master volume control can be configured to control six or eight
channels.
The TAS5508B has a master soft mute control that can be enabled by a terminal or I2C command. The
device also has individual channel soft mute controls that are enabled via I2C.
The soft volume and mute update rates are programmable. The soft adjustments are performed using a
soft-gain linear update with an I2C-programmable linear step size at a fixed temporal rate. The linear
soft-gain step size can be varied from 0.5 to 0.003906. Table 2-5 lists the linear gain step sizes.
Table 2-5. Linear Gain Step Size
0.5
0.25
0.125
0.0625
0.03125
0.015625
0.007813
0.003906
Time to go from 36 db to –109 dB in ms
STEP SIZE (GAIN)
10.67
21.33
42.67
85.34
170.67
340.35
682.70
1365.4
Time to go from 18 db to –109 dB in ms
1.33
2.67
5.33
10.67
21.33
42.67
85.33
170.67
Time to go from 0 db to –109 dB in ms
0.17
0.33
0.67
1.33
2.67
5.33
10.67
21.33
Submit Documentation Feedback
Description
29
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
2.8
www.ti.com
Automute and Mute Channel Controls
The TAS5508B has individual channel automute controls that are enabled via I2C register 0x04 bits D5
and D6 (the default setting is enabled). Two separate detectors can trigger the automute:
• Input automute (I2C register 0x14): All channels are muted when all 8 inputs to the TAS5508B are less
in magnitude than the input threshold value for a programmable amount of time.
• Output automute (I2C register 0x15): A single channel is muted when the output of the DAP section is
less in magnitude than the input threshold value for a programmable amount of time.
The detection period and thresholds for these two detectors are the same.
This time interval is selectable via I2C to be from 1 ms to 110 ms. The increments of time are 1, 2, 3, 4, 5,
10, 20, 30, 40, 50, 60, 70, 80, 90, 100, and 110 ms. This interval is independent of the sample rate. The
default value is mask programmable.
The input threshold value is an unsigned magnitude that is expressed as a bit position. This value is
adjustable via I2C. The range of the input threshold adjustment is from below the LSB (bit position 0) to
below bit position 12 in a 24-bit input-data word. This range provides an input threshold that can be
adjusted for 12 to 24 bits of data. The default value is mask programmable.
DVD Data Range
CD Data Range
24-Bit Input 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
32 Bits in DSPE
Representation 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
Threshold Range
M0013-01
Figure 2-13. Automute Threshold
The automute state is exited when the TAS5508B receives one sample that is greater than the output
threshold.
The output threshold can be one of two values:
• Equal to the input threshold
• 6 dB (one bit position) greater than the input threshold
The value for the output threshold is selectable via I2C. The default value is mask programmable.
The system latency enables the data value that is above the threshold to be preserved and output.
A mute command initiated by automute, master mute, individual I2C mute, the AM interference mute
sequence, or the bank-switch mute sequence overrides an unmute command or a volume command.
While a mute command is activated, the commanded channels transition to the mute state. When a
channel is unmuted, it goes to the last commanded volume setting that has been received for that
channel.
2.9
Loudness Compensation
The loudness compensation function compensates for the Fletcher-Munson loudness curves. The
30
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
TAS5508B loudness implementation tracks the volume control setting to provide spectral compensation
for weak low- or high-frequency response at low volume levels. For the volume tracking function, both
linear and logarithmic control laws can be implemented. Any biquad filter response can be used to provide
the desired loudness curve. The control parameters for the loudness control are programmable via the I2C
interface.
The TAS5508B has a single set of loudness controls for the eight channels. In 6-channel mode, loudness
is available to the six speaker outputs and also to the line outputs. The loudness control input uses the
maximum individual master volume (V) to control the loudness that is applied to all channels. In the
192-kHz and 176.4-kHz modes, the loudness function is active only for channels 1, 2, and 8.
V
Audio In
Audio Out
Loudness
Biquad
H(z)
Loudness Function = f(V)
V
B0017-01
Figure 2-14. Loudness Compensation Functional Block Diagram
Loudness function = f(V) = G × [2(Log V) × LG + LO] + O or alternatively,
Loudness function = f(V) = G × [VLG × 2LO] + O
For example, for the default values LG = –0.5, LO = 0, G = 1, and O = 0, then:
Loudness function = 1/SQRT(V), which is the recommended transfer function for loudness. So,
Audio out = (audio in) × V + H(Z) × SQRT(V). Other transfer functions are possible.
Table 2-6. Default Loudness Compensation Parameters
LOUDNESS
TERM
DESCRIPTION
USAGE
DATA
FORMAT
I2C
SUBADDRESS
DEFAULT
HEX
FLOAT
V
Max volume
Gains audio
5.23
NA
NA
NA
Log V
Log2 (max volume)
Loudness function
5.23
NA
0000 0000
0.0
H(Z)
Loudness biquad
Controls shape of
loudness curves
5.23
0x95
b0 = 0000 D513
b1 = 0000 0000
b2 = 0FFF 2AED
a1 = 00FE 5045
a2 = 0F81 AA27
b0 = 0.006503
b1 = 0
b2 = –0.006503
a1 = 1.986825
a2 = –0.986995
LG
Gain (log space)
Loudness function
5.23
0x91
FFC0 0000
–0.5
LO
Offset (log space)
Loudness function
25.23
0x92
0000 0000
0
G
Gain
Switch to enable
loudness (ON = 1, OFF = 0)
5.23
0x93
0000 0000
0
O
Offset
Provides offset
25.23
0x94
0000 0000
0
2.9.1
Loudness Example
Problem: Due to the Fletcher-Munson phenomena, compensation for low-frequency attenuation near 60
Hz is desirable. The TAS5508B provides a loudness transfer function with EQ gain = 6, EQ center
frequency = 60 Hz, and EQ bandwidth = 60 Hz.
Submit Documentation Feedback
Description
31
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Solution: Using Texas Instruments ALE TAS5508B DSP tool, Matlab™, or other signal-processing tool,
develop a loudness function with the parameters listed in Table 2-7.
Table 2-7. Example Loudness Function Parameters
DATA
FORMAT
I2C
SUBADDRESS
5.23
Loudness function
Loudness function
Gain
Switch to enable
loudness (ON = 1, OFF = 0)
Offset
Offset
LOUDNESS
TERM
DESCRIPTION
USAGE
H(Z)
Loudness biquad
Controls shape of
loudness curves
LG
Loudness gain
LO
Loudness offset
G
O
EXAMPLE
HEX
FLOAT
0x95
b0 = 0000 8ACE
b1 = 0000 0000
b2 = FFFF 7532
a1 = FF01 1951
a2 = 007E E914
b0 = 0.004236
b1 = 0
b2 = –0.004236
a1 = –1.991415
a2 = 0.991488
5.23
0x91
FFC0 0000
–0.5
25.23
0x92
0000 0000
0
5.23
0x93
0080 0000
1
25.23
0x94
0000 0000
0
See Figure 2-15 for the resulting loudness function at different gains.
20
Gain − dB
10
0
−10
−20
−30
−40
10
100
1k
10k
20k
f − Frequency − Hz
G001
Figure 2-15. Loudness Example Plots
2.10 Dynamic Range Control (DRC)
DRC provides both compression and expansion capabilities over three separate and definable regions of
audio signal levels. Programmable threshold levels set the boundaries of the three regions. Within each of
the three regions, a distinct compression or expansion transfer function can be established and the slope
of each transfer function is determined by programmable parameters. The offset (boost or cut) at the two
boundaries defining the three regions can also be set by programmable offset coefficients. The DRC
implements the composite transfer function by computing a 5.23-format gain coefficient from each sample
output from the rms estimator. This gain coefficient is then applied to a mixer element, whose other input
is the audio data stream. The mixer output is the DRC-adjusted audio data.
The TAS5508B has two distinct DRC blocks. DRC1 services channels 1–7 in the 8-channel mode and
channels 1–4 and 7 in the 6-channel mode. This DRC computes rms estimates of the audio data streams
on all channels that it controls. The estimates are then compared on a sample-by-sample basis and the
larger of the estimates is used to compute the compression/expansion gain coefficient. The gain
coefficient is then applied to the appropriate channel audio streams. DRC2 services only channel 8. This
DRC also computes an rms estimate of the signal level on channel 8 and this estimate is used to compute
the compression/expansion gain coefficient applied to the channel-8 audio stream.
32
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
All of the TAS5508B default values for DRC can be used except for the DRC1 decay and DRC2 decay.
Table 2-8 shows the recommended time constants and their hex values. If the user wants to implement
other DRC functions, Texas Instruments recommends using the automatic loudspeaker equalization (ALE)
tool available from Texas Instruments. The ALE tool allows the user to select the DRC transfer function
graphically. It then outputs the TAS5508B hex coefficients for download to the TAS5508B.
Table 2-8. DRC Recommended Changes From TAS5508B Defaults
2
I C
SUBADDRESS
REGISTER FIELDS
RECOMMENDED TIME
CONSTANT (ms)
DRC1 energy
5
0x98
RECOMMENDED
HEX VALUE
DRC1 (1 – energy)
0x9C
DRC1 attack
5
DRC1 (1 – attack)
DRC1 decay
2
DRC1 (1 – decay)
0x9D
DRC2 energy
0000 883F
007F 77C0
007F FF51
0000 883F
0000 883F
007F 77C0
007F 77C0
DRC2 (1 – attack)
DRC2 decay
0000 883F
007F 77C0
0000 00AE
5
2
DRC2 (1 – decay)
0000 883F
007F 77C0
0001 538F
5
DRC2 attack
0000 883F
007F 77C0
007E AC70
DRC2 (1 – energy)
0xA1
DEFAULT HEX
0000 883F
0000 883F
007F 77C0
007F 77C0
0001 538F
0000 0056
007E AC70
003F FFA8
Recommended DRC setup flow if the defaults are used:
• After power up, load the recommended hex value for DRC1 and DRC2 decay and (1 – decay). See
Table 2-8.
• Enable either the pre-volume or post-volume DRC using I2C registers 0x96 and 0x97. Note that to
avoid a potential timing problem, there should be a 10-ms delay between a write to 0x96 and a write to
0x97.
Recommended DRC setup flow if the DRC design uses values different from the defaults:
• After power up, load all DRC coefficients per the DRC design.
• Enable either the pre-volume or post-volume DRC. Note that to avoid a potential timing problem, there
should be a 10-ms delay between a write to 0x96 and a write to 0x97.
Figure 2-16 shows the positioning of the DRC block in the TAS5508B processing flow. As seen, the DRC
input can come either before or after soft volume control and loudness processing.
Master
Volume
Channel Volume
Max
Volume
Bass and Treble
Bypass
DRC
Bypass
Loudness
7
Biquads
in
Series
From Input Mixer
Bass
and
Treble
To Output Mixer
Bass
and
Treble
Inline
PrePostVolume Volume
DRC
Inline
DRC
B0016-02
Figure 2-16. DRC Positioning in TAS5508B Processing Flow
Submit Documentation Feedback
Description
33
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Figure 2-17 illustrates a typical DRC transfer function.
DRC − Compensated Output
Region
0
Region
1
Region
2
k2
k1
1:1 Transfer Function
Implemented Transfer Function
k0
O2
O1
T1
T2
DRC Input Level
M0014-01
Figure 2-17. Dynamic Range Compression (DRC) Transfer Function Structure
The three regions shown in Figure 2-17 are defined by three sets of programmable coefficients:
• Thresholds T1 and T2 define region boundaries.
• Offsets O1 and O2 define the DRC gain coefficient settings at thresholds T1 and T2, respectively.
• Slopes k0, k1, and k2 define whether compression or expansion is to be performed within a given
region. The magnitudes of the slopes define the degree of compression or expansion to be performed.
The three sets of parameters are all defined in logarithmic space and adhere to the following rules:
• The maximum input sample into the DRC is referenced at 0 dB. All values below this maximum value
then have negative values in logarithmic (dB) space.
• The samples input into the DRC are 32-bit words and consist of the upper 32 bits of the 48-bit word
format used by the digital audio processor (DAP). The 48-bit DAP word is derived from the 32-bit serial
data received at the serial-audio receive port by adding 8 bits of headroom above the 32-bit word and
8 bits of computational precision below the 32-bit word. If the audio-processing steps between the SAP
input and the DRC input result in no accumulative boost or cut, the DRC operates on the 8 bits of
headroom and the 24 MSBs of the audio sample. Under these conditions, a 0-dB (maximum value)
audio sample (0x7FFF FFFF) is seen at the DRC input as a –48-dB sample (8 bits × –6 dB/bit = –48
dB).
• Thresholds T1 and T2 define, in dB, the boundaries of the three regions of the DRC, as referenced to
the rms value of the data into the DRC. Zero-valued threshold settings reference the maximum-valued
rms input into the DRC and negative-valued thresholds reference all other rms input levels.
Positive-valued thresholds have no physical meaning and are not allowed. In addition, zero-valued
threshold settings are not allowed.
Although the DRC input is limited to 32-bit words, the DRC itself operates using the 48-bit word format of
the DAP. The 32-bit samples input into the DRC are placed in the upper 32 bits of this 48-bit word space.
This means that the threshold settings must be programmed as 48-bit (25.23 format) numbers.
CAUTION
Zero-valued and positive-valued threshold settings are not allowed and cause
unpredictable behavior if used.
•
34
Offsets O1 and O2 define, in dB, the attenuation (cut) or gain (boost) applied by the DRC-derived gain
coefficient at the threshold points T1 and T2, respectively. Positive offsets are defined as cuts, and
thus boost or gain selections are negative numbers. Offsets must be programmed as 48-bit (25.23
format) numbers.
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
•
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Slopes k0, k1, and k2 define whether compression or expansion is to be performed within a given
region, and the degree of compression or expansion to be applied. Slopes are programmed as 28-bit
(5.23 format) numbers.
2.10.1 DRC Implementation
The three elements comprising the DRC include: (1) an rms estimator, (2) a compression/expansion
coefficient computation engine, and (3) an attack/decay controller.
• RMS estimator—This DRC element derives an estimate of the rms value of the audio data stream into
the DRC. For the DRC block shared by Ch1 and Ch2, two estimates are computed—an estimate of the
Ch1 audio data stream into the DRC, and an estimate of the Ch2 audio data stream into the DRC. The
outputs of the two estimators are then compared, sample-by-sample, and the larger-valued sample is
forwarded to the compression/expansion coefficient computation engine.
Two programmable parameters, ae and (1 – ae), set the effective time window over which the rms
estimate is made. For the DRC block shared by Ch1 and Ch2, the programmable parameters apply to
both rms estimators. The time window over which the rms estimation is computed can be determined
by:
*1
t window +
f S ȏn(1 * ae)
•
•
Compression/expansion coefficient computation—This DRC element converts the output of the rms
estimator to a logarithmic number, determines the region where the input resides, and then computes
and outputs the appropriate coefficient to the attack/decay element. Seven programmable parameters,
T1, T2, O1, O2, k0, k1, and k2, define the three compression/expansion regions implemented by this
element.
Attack/decay control—This DRC element controls the transition time of changes in the coefficient
computed in the compression/expansion coefficient computation element. Four programmable
parameters define the operation of this element. Parameters ad and (1 – ad) set the decay or release
time constant to be used for volume boost (expansion). Parameters aa and (1 – aa) set the attack time
constant to be used for volume cuts. The transition time constants can be determined by:
*1
*1
ta +
td +
f S ȏn(1 * aa)
f S ȏn(1 * ad)
2.10.2 Compression/Expansion Coefficient Computation Engine Parameters
Seven programmable parameters are assigned to each DRC block: two threshold parameters—T1 and
T2, two offset parameters—O1 and O2, and three slope parameters—k0, k1, and k2. The threshold
parameters establish the three regions of the DRC transfer curve, the offsets anchor the transfer curve by
establishing known gain settings at the threshold levels, and the slope parameters define whether a given
region is a compression or an expansion region.
The audio input stream into the DRC must pass through DRC-dedicated programmable input mixers.
These mixers are provided to scale the 32-bit input into the DRC to account for the positioning of the
audio data in the 48-bit DAP word and the net gain or attenuation in signal level between the SAP input
and the DRC. The selection of threshold values must take the gain (attenuation) of these mixers into
account. The DRC implementation examples that follow illustrate the effect these mixers have on
establishing the threshold settings.
T2 establishes the boundary between the high-volume region and the mid-volume region. T1 establishes
the boundary between the mid-volume region and the low-volume region. Both thresholds are set in
logarithmic space, and which region is active for any given rms estimator output sample is determined by
the logarithmic value of the sample.
Submit Documentation Feedback
Description
35
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Threshold T2 serves as the fulcrum or pivot point in the DRC transfer function. O2 defines the boost
(> 0 dB) or cut (< 0 dB) implemented by the DRC-derived gain coefficient for an rms input level of T2. If
O2 = 0 dB, the value of the derived gain coefficient is 1 (0x0080 0000 in 5.23 format). k2 is the slope of
the DRC transfer function for rms input levels above T2, and k1 is the slope of the DRC transfer function
for rms input levels below T2 (and above T1). The labeling of T2 as the fulcrum stems from the fact that
there cannot be a discontinuity in the transfer function at T2. The user can, however, set the DRC
parameters to realize a discontinuity in the transfer function at the boundary defined by T1. If no
discontinuity is desired at T1, the value for the offset term O1 must obey the following equation.
O1
+ |T1 * T2|
k1 ) O2 For ( |T1| w |T2| )
No Discontinuity
T1 and T2 are the threshold settings in dB, k1 is the slope for region 1, and O2 is the offset in dB at T2. If
the user chooses to select a value of O1 that does not obey the above equation, a discontinuity at T1 is
realized.
Decreasing in volume from T2, the slope k1 remains in effect until the input level T1 is reached. If, at this
input level, the offset of the transfer function curve from the 1 : 1 transfer curve does not equal O1, there
is a discontinuity at this input level as the transfer function is snapped to the offset called for by O1. If no
discontinuity is wanted, O1 and/or k1 must be adjusted so that the value of the transfer curve at input level
T1 is offset from the 1 : 1 transfer curve by the value O1. The examples that follow illustrate both
continuous and discontinuous transfer curves at T1.
Decreasing in volume from T1, starting at offset level O1, slope k0 defines the compression/expansion
activity in the lower region of the DRC transfer curve.
2.10.2.1 Threshold Parameter Computation
For thresholds,
TdB
= –6.0206TINPUT = –6.0206TSUB_ADDRESS_ENTRY
If, for example, it is desired to set T1 = –64 dB, then the subaddress entry required to set T1 to –64 dB is:
T1
+ *64 + 10.63
SUB_ADDRESS_ENTRY
*6.0206
T1 is entered as a 48-bit number in 25.23 format. Therefore:
T1 = 10.63
= 0 1010.1010 0001 0100 0111 1010 111
= 0x0000 0550 A3D7 in 25.23 format
2.10.2.2 Offset Parameter Computation
The offsets set the boost or cut applied by the DRC-derived gain coefficient at the threshold point. An
equivalent statement is that offsets represent the departure of the actual transfer function from a 1 : 1
transfer at the threshold point. Offsets are 25.23-formatted, 48-bit logarithmic numbers. They are
computed by the following equation.
O
) 24.0824 dB
O
+ DESIRED
INPUT
6.0206
Gains or boosts are represented as negative numbers; cuts or attenuations are represented as positive
numbers. For example, to achieve a boost of 21 dB at threshold T1, the I2C coefficient value entered for
O1 must be:
O1
+ –21 dB ) 24.0824 dB + 0.51197555
INPUT
6.0206
+ 0.1000_0011_0001_1101_0100
+ 0x00000041886A in 25.23 format
36
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
2.10.2.3 Slope Parameter Computation
In developing the equations used to determine the subaddress of the input value required to realize a
given compression or expansion within a given region of the DRC, the following convention is adopted.
DRC transfer = Input increase : Output increase
If the DRC realizes an output increase of n dB for every dB increase in the rms value of the audio into the
DRC, a 1 : n expansion is being performed. If the DRC realizes a 1-dB increase in output level for every
n-dB increase in the rms value of the audio into the DRC, an n : 1 compression is being performed.
k=n–1
For n : 1 compression, the slope k can be found by:
k+1
n*1
In both expansion (1 : n) and compression (n : 1), n is implied to be greater than 1. Thus, for expansion:
k = n – 1 means k > 0 for n > 1. Likewise, for compression,
appears that k must always lie in the range k > –1.
k+1
n*1
means –1 < k < 0 for n > 1. Thus, it
The DRC imposes no such restriction and k can be programmed to values as negative as –15.999. To
determine what results when such values of k are entered, it is first helpful to note that the compression
and expansion equations for k are actually the same equation. For example, a 1 : 2 expansion is also a
0.5 : 1 compression.
0.5 : 1 compression å k + 1 * 1 + 1
0.5
1 : 2 expansion å k + 2 * 1 + 1
As can be seen, the same value for k is obtained either way. The ability to choose values of k less than –1
allows the DRC to implement negative-slope transfer curves within a given region. Negative-slope transfer
curves are usually not associated with compression and expansion operations, but the definition of these
operations can be expanded to include negative-slope transfer functions. For example, if k = –4
1
Compression equation: k + *4 + 1
n *1 å n + * 3 å *0.3333 : 1 compression
Expansion equation: k + *4 + n * 1 å n + *3 å 1 : *3 expansion
With k = –4, the output decreases 3 dB for every 1 dB increase in the rms value of the audio into the
DRC. As the input increases in volume, the output decreases in volume.
2.11 Output Mixer
The TAS5508B provides an 8×2 output mixer for channels 1, 2, 3, 4, 5, and 6. For channels 7 and 8, the
TAS5508B provides an 8×3 output mixer. These mixers allow each output to be any mix of any two (or
three) signal-processed channels. The control parameters for the output crossbar mixer are programmable
via the I2C interface. All of the TAS5508B features are available when the 8×2 and 8×3 output mixers are
configured in the pass-through output mixer configuration, where the audio data from each DAP channel
maps directly to the corresponding PWM channel (i.e., DAP channel 1 to PWM channel 1, etc).
When mixing or remapping DAP channels to different PWM output channels there are limitations to
consider:
•
•
Individual channel mute should not be used.
The sum of the minimum channel volume and master volume should not be below –109 dB.
Submit Documentation Feedback
Description
37
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
Gain Coefficient
28
Select
Output
N
48
Gain Coefficient
48
28
Select
Output
N
48
48
Output
1, 2, 3, 4, 5, or 6
Output
7 or 8
Gain Coefficient
28
Select
Output
N
48
Gain Coefficient
48
28
Select
Output
N
48
48
Gain Coefficient
48
28
Select
Output
N
48
M0011-02
Figure 2-18. Output Mixers
2.12 PWM
The TAS5508B has eight channels of high-performance digital PWM modulators that are designed to drive
switching output stages (back ends) in both single-ended (SE) and H-bridge (bridge-tied-load)
configurations. The TAS5508B device uses noise-shaping and sophisticated, error-correction algorithms to
achieve high power efficiency and high-performance digital audio reproduction. The TAS5508B uses an
AD1 PWM modulation scheme combined with a fifth-order noise shaper to provide a 102-dB SNR from
20 Hz to 20 kHz.
The PWM section accepts 32-bit PCM data from the DAP and outputs eight PWM audio output channels
configurable as either:
• Six channels to drive power stages and two channels to drive a differential-input active filter to provide
a separately controllable stereo lineout
• Eight channels to drive power stages
The TAS5508B PWM section output supports both single-ended and bridge-tied loads.
The PWM section provides a headphone PWM output to drive an external differential amplifier like the
TPA112. The headphone circuit uses the PWM modulator for channels 1 and 2. The headphone does not
operate while the six or eight back-end drive channels are operating. The headphone is enabled via a
headphone-select terminal.
The PWM section has individual-channel dc-blocking filters that can be enabled and disabled. The filter
cutoff frequency is less than 1 Hz.
The PWM section has individual-channel de-emphasis filters for 32, 44.1, and 48 kHz that can be enabled
and disabled.
38
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
The PWM section also contains the power-supply volume control (PSVC) PWM.
The interpolator, noise shaper, and PWM sections provide a PWM output with the following features:
• Up to 8× oversampling
– 8× at fS = 44.1 kHz, 48 kHz, 32 kHz, 38 kHz
– 4× at fS = 88.2 kHz, 96 kHz
– 2× at fS = 176.4 kHz, 192 kHz
• Fifth-order noise shaping
• 100-dB dynamic range 0–20 kHz (TAS5508B + TAS5111 system measured at speaker terminals)
• THD < 0.01%
• Adjustable maximum modulation limit of 93.8% to 99.2%
• 3.3-V digital signal
2.12.1 DC Blocking (High-Pass Filter Enable/Disable)
Each input channel incorporates a first-order, digital, high-pass filter to block potential dc components. The
filter –3-dB point is approximately 0.89-Hz at the 44.1-kHz sampling rate. The high-pass filter can be
enabled and disabled via the I2C system control register 1 (0x03 bit D7). The default setting is 1
(high-pass filter enabled).
2.12.2 De-Emphasis Filter
Response – dB
For audio sources that have been pre-emphasized, a precision 50-µs/15-µs de-emphasis filter is provided
to support the sampling rates of 32 kHz, 44.1 kHz, and 48 kHz. Figure 2-19 shows a graph of the
de-emphasis filtering characteristics. De-emphasis is set using two bits in the system control register.
0
De-emphasis
−10
3.18 (50 µs)
10.6 (15 µs)
f – Frequency – kHz
M0015-01
Figure 2-19. De-Emphasis Filter Characteristics
2.12.3 Power-Supply Volume Control (PSVC)
The TAS5508B supports volume control both by conventional digital gain/attenuation and by a
combination of digital and analog gain/attenuation. Varying the H-bridge power-supply voltage performs
the analog volume control function. The benefits of using power-supply volume control (PSVC) are
reduced idle channel noise, improved signal resolution at low volumes, increased dynamic range, and
reduced radio frequency emissions at reduced power levels. The PSVC is enabled via I2C. When enabled,
the PSVC provides a PWM output that is filtered to provide a reference voltage for the power supply. The
power-supply adjustment range can be set for –12, –18, or –24 dB, to accommodate a range of variable
power-supply designs.
Figure 2-20 and Figure 2-21 show how power-supply and digital gains can be used together.
The volume biquad (0xCF) can be used to implement a low-pass filter in the digital volume control to
match the PSVC volume transfer function. Note that if the PVSC function is not used, the volume biquad
should be all-pass (default).
Submit Documentation Feedback
Description
39
TAS5508B
8-Channel Digital Audio PWM Processor
Power-Supply and Digital Gains − dB
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
30
20
10
Digital Gain
0
−10
−20
−30
Power-Supply Gain
−40
−50
−60
−80
−70
−60
−50
−40
−30
−20
−10
0
10
20
30
Desired Gain − dB
G002
Power-Supply and Digital Gains − dB
Figure 2-20. Power-Supply and Digital Gains (Linear Space)
100
10
Digital Gain
1
0.1
Power-Supply Gain
0.01
0.001
0.0001
0.00001
0.0001
0.001
0.01
0.1
1
10
100
Desired Gain − Linear
G003
Figure 2-21. Power-Supply and Digital Gains (Log Space)
2.12.4 AM Interference Avoidance
Digital amplifiers can degrade AM reception as a result of their RF emissions. Texas Instruments' patented
AM interference-avoidance circuit provides a flexible system solution for a wide variety of digital audio
architectures. During AM reception, the TAS5508B adjusts the radiated emissions to provide an
emission-clear zone for the tuned AM frequency. The inputs to the TAS5508B for this operation are the
tuned AM frequency, the IF frequency, and the sample rate. The sample rate is automatically detected.
40
Description
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Analog
Receiver
ADC
PCM1802
Audio
DSP
TAS5508B
TAS5111
TAS5111
TAS5111
TAS5111
TAS5111
Audio DSP Provides the
Master and Bit Clocks
TAS5111
TAS5111
TAS5111
Digital
Receiver
Audio
DSP
TAS5508B
TAS5111
TAS5111
TAS5111
TAS5111
TAS5111
The Digital Receiver or the Audio DSP
Provides the Master and Bit Clocks
TAS5111
TAS5111
TAS5111
B0018-03
Figure 2-22. Block Diagrams of Typical Systems Requiring TAS5508B Automatic AM
Interference-Avoidance Circuit
Submit Documentation Feedback
Description
41
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
3
www.ti.com
TAS5508B Controls and Status
The TAS5508B provides control and status information from both the I2C registers and device pins.
This section describes some of these controls and status functions. The I2C summary and detailed
register descriptions are contained in Section 6 and Section 7.
3.1
I2C Status Registers
The TAS5508B has two status registers that provide general device information. These are the general
status register 0 (0x01) and the error status register (0x02).
3.1.1
General Status Register (0x01)
•
•
3.1.2
Error Status Register (0x02)
•
•
•
3.2
Device identification code
Clip indicator – The TAS5508B has a clipping indicator. Writing to the register clears the indicator.
No internal errors (the valid signal is high)
A clock error has occurred – These are sticky bits that are cleared by writing to the register.
– LRCLK error – when the number of MCLKs per LRCLK is incorrect
– SCLK error – when the number of SCLKS per LRCLK is incorrect
– Frame slip – when the number of MCLKs per LRCLK changes by more than 10 MCLK cycles
– PLL phase-lock error
This error status register is normally used for system development only.
TAS5508B Pin Controls
The TAS5508B provide a number of terminal controls to manage the device operation. These controls are:
• RESET
• PDN
• BKND_ERR
• HP_SEL
• MUTE
3.2.1
Reset (RESET)
The TAS5508B is placed in the reset mode either by the power-up reset circuitry when power is applied,
or by setting the RESET terminal low.
RESET is an asynchronous control signal that restores the TAS5508B to the hard-mute state (M-state).
Master volume is immediately set to full attenuation (there is no ramp down). Reset initiates the device
reset without an MCLK input. As long as the RESET terminal is held low, the device is in the reset state.
During reset, all I2C and serial data bus operations are ignored.
Table 3-1 shows the device output signals while RESET is active.
Table 3-1. Device Outputs During Reset
42
SIGNAL
SIGNAL STATE
Valid
Low
PWM P-outputs
Low (M-state)
PWM M-outputs
Low (M-state)
SDA
Signal input (not driven)
TAS5508B Controls and Status
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Because RESET is an asynchronous signal, clicks and pops produced during the application (the leading
edge) of RESET cannot be avoided. However, the transition from the hard-mute state (M-state) to the
operational state is performed using a quiet start-up sequence to minimize noise. This control uses the
PWM reset and unmute sequence to shut down and start up the PWM. A detailed description of these
sequences is contained in the PWM section. If a completely quiet reset or power-down sequence is
desired, MUTE should be applied before applying RESET.
The rising edge of the reset pulse begins device initialization before the transition to the operational mode.
During device initialization, all controls are reset to their initial states. Table 3-2 shows the default control
settings following a reset.
Table 3-2. Values Set During Reset
CONTROL
SETTING
Output mixer configuration
0xD0 bit 30 = 0 (remapped output mixer configuration)
High pass
Enabled
Unmute from clock error
Hard unmute
Input automute
Enabled
Output automute
Enabled
De-emphasis
Disabled
Serial data interface format
I2S, 24-bit
Individual channel mute
No channels are muted
Automute delay
5 ms
Automute threshold 1
< 8 bits
Automute threshold 2
Same as automute threshold 1
Modulation limit
97.7% (Note: Some power stages require a lower
modulation index)
Six- or eight-channel configuration
Eight channels
Volume and mute update rate
Volume ramp 88.2 ms
Treble and bass slew rate
Update every 1.31 ms
Bank switching
Manual bank selection is enabled
Biquad coefficients
Set to all pass
Input mixer coefficients
Input N → Channel N, no attenuation
Output mixer coefficients
Channel N → Output N, no attenuation
Subwoofer sum into Ch1 and Ch2
Gain of 0
Ch1 and Ch2 sum in subwoofer
Gain of 0
Bass and treble bypass/inline
Bypass
DRC bypass/inline
Bypass
DRC
Default values
Master volume
Mute
Individual channel volumes
0 dB
All bass and treble indexes
0x12 neutral
Treble filter sets
Filter set 3
Bass filter sets
Filter set 3
Loudness
Loudness disabled, default values
AM interference mode enable
Disabled
AM interference mode IF
455 kHz
AM interference mode select sequence
1
AM interference mode tuned frequency and
input mode
0000, BCD
Submit Documentation Feedback
TAS5508B Controls and Status
43
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
After the initialization time, the TAS5508B starts the transition to the operational state with the master
volume set at mute.
Because the TAS5508B has an external crystal time base, following the release of reset, the TAS5508B
sets the MCLK and data rates and performs the initialization sequences. The PWM outputs are held at a
mute state until the master volume is set to a value other than mute via I2C.
3.2.2
Power Down (PDN)
The TAS5508B can be placed into the power-down mode by holding the PDN terminal low. When the
power-down mode is entered, both the PLL and the oscillator are shut down. Volume is immediately set to
full attenuation (there is no ramp down). This control uses the PWM mute sequence that provides a low
click and pop transition to the hard-mute state (M-state).
Power down is an asynchronous operation that does not require MCLK to go into the power-down state.
To initiate the power-up sequence requires MCLK to be operational and the TAS5508B to receive five
MCLKs prior to the release of PDN.
As long as the PDN terminal is held low, the device is in the power-down state with the PWM outputs in a
hard-mute state (M-state). During power down, all I2C and serial data bus operations are ignored.
Table 3-3 shows the device output signals while PDN is active.
Table 3-3. Device Outputs During Power Down
SIGNAL
SIGNAL STATE
VALID
Low
PWM P-outputs
M-state = low
PWM M-outputs
M-state = low
SDA
Signal input
PSVC
M-state = low
Following the application of PDN, the TAS5508B does not perform a quiet shutdown to prevent clicks and
pops produced during the application (the leading edge) of this command. The application of PDN
immediately performs a PWM stop. A quiet stop sequence can be performed by first applying MUTE
before PDN.
When PDN is released, the system goes to the end state specified by the MUTE and BKND_ERR pins
and the I2C register settings.
The crystal time base allows the TAS5508B to determine the CLK rates. Once these rates are determined,
the TAS5508B unmutes the audio.
3.2.3
Back-End Error (BKND_ERR)
Back-end error is used to provide error management for back-end error conditions. Back-end error is a
level-sensitive signal. Back-end error can be initiated by bringing the BKND_ERR terminal low for a
minimum of five MCLK cycles. When BKND_ERR is brought low, the PWM sets either six or eight
channels into the PWM back-end error state. This state is described in Section 2.12. Once the back-end
error sequence is initiated, a delay of 5 ms is performed before the system starts the output re-initialization
sequence. After the initialization time, the TAS5508B begins normal operation. Back-end error does not
affect other PWM modulator operations.
44
TAS5508B Controls and Status
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Table 3-4. Device Outputs During Back-End Error
SIGNAL
SIGNAL STATE
Valid
Low
PWM P-outputs
M-state = low
PWM M-outputs
M-state = low
PWM_HP P-outputs
M-state = low
PWM_HP M-outputs
M-state = low
SDA
Signal input (not driven)
3.2.3.1 BKND_ERR and VALID
The number of channels that are affected by the BKND_ERR signal depends on the setting of bit D1 of
I2C register 0xE0. If the I2C setting is 0 (8-channel mode), the TAS5508B places all eight PWM outputs in
the PWM back-end error state. If the I2C setting is 1, the TAS5508B is in 6-channel mode. For proper
operation in 6-channel mode, the lineout configuration registers (0x09 and 0x0A) must be 0x00 instead of
the default of 0xE0. In this case, VALID is pulled LOW, and the TAS5508B brings PWM outputs 1, 2, 3, 4,
7, and 8 to a back-end error state, while not affecting lineout channels 5 and 6. Table 3-4 shows the
device output signal states during back-end error.
3.2.4
Speaker/Headphone Selector (HP_SEL)
The HP_SEL terminal enables the headphone output or the speaker outputs. The headphone output
receives the processed data output from DAP and PWM channels 1 and 2.
In 6-channel configuration, this feature does not affect the two lineout channels.
When low, the headphone output is enabled. In this mode, the speaker outputs are disabled. When high,
the speaker outputs are enabled and the headphone is disabled.
Changes in the pin logic level result in a state change sequence using soft mute to the hard-mute state
(M-state) for both speaker and headphone followed by a soft unmute.
When HP_SEL is low, the configuration of channels 1 and 2 is defined by the headphone configuration
register. When HP_SEL is high, the channel-1 and -2 configuration registers define the configuration of
channels 1 and 2.
If using the remapped-output mixer configuration (0xD0 bit 30 = 0) in the 6-channel mode, the headphone
operation is modified. That is, following the assertion or de-assertion of headphone, mute must be
asserted and de-asserted using the MUTE pin.
3.2.5
Mute (MUTE)
The mute control provides a noiseless volume ramp to silence. Releasing mute provides a noiseless ramp
to previous volume. The TAS5508B has both master and individual channel mute commands. A terminal
is also provided for the master mute. The active-low master mute I2C register and the MUTE terminal are
logically ORed together. If either is set to low, a mute on all channels is performed. The master mute
command operates on all channels regardless of whether the system is in the 6- or 8-channel
configuration.
When mute is invoked, the PWM output stops switching and then goes to an idle state.
The master mute terminal is used to support a variety of other operations in the TAS5508B, such as
setting the the biquad coefficients, the serial interface format, and the clock rates. A mute command by the
master mute terminal, individual I2C mute, the AM interference mute sequence, the bank-switch mute
sequence, or automute overrides an unmute command or a volume command. While a mute is active, the
commanded channels are placed in a mute state. When a channel is unmuted, it goes to the last
commanded volume setting that has been received for that channel.
Submit Documentation Feedback
TAS5508B Controls and Status
45
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
3.3
www.ti.com
Device Configuration Controls
The TAS5508B provides a number of system configuration controls that are set at initialization and
following a reset.
• Channel configuration
• Headphone configuration
• Audio system configurations
• Recovery from clock error
• Power-supply volume-control enable
• Volume and mute update rate
• Modulation index limit
• Master-clock and data-rate controls
• Bank controls
3.3.1
Channel Configuration Registers
For the TAS5508B to have full control of the power stages, registers 0x05 to 0x0C must be programmed
to reflect the proper power stage and how each one should be controlled. There are eight channel
configuration registers, one for each channel. For information on using BKND_ERR and VALID, see
Section 3.2.3.1
The primary reason for using these registers is that different power stages require different handling
during start-up, mute/unmute, shutdown, and error recovery. The TAS5508B must select the sequence
that gives the best click and pop performance and ensures that the bootstrap capacitor is charged
correctly during start-up. This sequence depends on which power stage is present at the TAS5508B
output.
Table 3-5. Description of the Channel Configuration Registers (0x05 to 0x0C)
BIT
DESCRIPTION
D7
Enable/disable error recovery sequence. In case the BKND_ERR pin is pulled low, this register determines if this channel is to
follow the error recovery sequence or to continue with no interruption.
D6
Determines if the power stage needs the TAS5508B VALID pin to go low to reset the power stage. Some power stages can be
reset by a combination of PWM signals. For these devices, it is recommended to set this bit low, because the VALID pin is
shared for power stages. This provides better control of each power stage.
D5
Determines if the power stage needs the TAS5508B VALID pin to go low to mute the power stage. Some power stages can be
muted by a combination of PWM signals. For these devices, it is recommended to set this bit low, because the VALID pin is
shared for power stages. This provides better control of each power stage.
D4
Inverts the PWM output. Inverting the PWM output can be an advantage if the power stage input pin is opposite the TAS5508B
PWM pinout. This makes routing on the PCB easier. To keep the phase of the output, the speaker terminals must also be
inverted.
D3
When using the TAS5182 power stage this bit must be set.
D2
Can be used to handle click and pop for some applications.
D1
This bit is normally used together with D2. For some power stages, both PWM signals must be high to get the desired operation
of both speaker outputs to be low. This bit sets the PWM outputs high-high during mute.
D0
Not used
Table 3-6 lists the optimal setting for each output-stage configuration. Note that the default value is
applicable in all configurations except the TAS5182 SE/BTL configuration.
46
TAS5508B Controls and Status
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Table 3-6. Recommended TAS5508B Configurations for Texas Instruments Power Stages
DEVICE
ERROR RECOVERY
CONFIGURATION
D7
D6
D5
D4
D3
D2
D1
D0
BTL
1
1
1
0
0
0
0
0
RES
TAS5111
(default)
AUT
RES
TAS5112
AUT
TAS5182
RES
SE
1
1
1
0
0
0
0
0
BTL
0
1
1
0
0
0
0
0
SE
0
1
1
0
0
0
0
0
BTL
1
1
0
0
0
0
0
0
SE
1
1
0
0
0
0
0
0
BTL
0
1
0
0
0
0
0
0
SE
0
1
0
0
0
0
0
0
BTL
1
1
1
0
1
0
0
0
SE
1
1
1
0
1
0
0
0
RES: To recover from a shutdown, the output stage requires VALID to go low.
AUT: The power stage can auto-recover from a shutdown.
BTL: Bridge-tied load configuration
SE: Single-ended configuration
3.3.2
Headphone Configuration Registers
The headphone configuration controls are identical to the speaker configuration controls. The headphone
configuration control settings are used in place of the speaker configuration control settings for channels 1
and 2 when the headphones are selected. However, only one configuration setting for headphones is
used, and that is the default setting.
3.3.3
Audio System Configurations
The TAS5508B can be configured to comply with various audio systems: 5.1-channel system, 6-channel
system, 7.1-channel system, and 8-channel system.
The audio system configuration is set in the general control register (0xE0). Bits D31–D4 must be zero
and D0 is don't care.
D3
Must always be 0 (default). Note that subwoofer cannot be used as lineout when PSVC is
enabled. (D3 is a write-only bit)
D2
Enables/disables power-supply volume control
D1
Sets number of speakers in the system, including possible line outputs
D3–D1 must be configured for the audio system in the application, as shown in Table 3-7.
Table 3-7. Audio System Configuration (General Control Register 0xE0)
D31–D4
D3
D2
D1
D0
6 channels or 5.1 not using PSVC
Audio System
0
0
0
1
X
6 channels using PSVC
0
0
1
1
X
5.1 system using PSVC
0
0
1
1
X
8 channels or 7.1 not using PSVC (default)
0
0
0
0
X
8 channels using PSVC
0
0
1
0
X
7.1 system using PSVC
0
0
1
0
X
Submit Documentation Feedback
TAS5508B Controls and Status
47
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
3.3.3.1 Using Line Outputs in 6-Channel Configurations
The audio system can be configured for a 6-channel configuration (with 2 lineouts) by writing a 1 to bit D1
of register 0xE0 (general control register). In this configuration, channel-5 and -6 processing are exactly
the same as the other channels, except that the master volume and the loudness function have no effect
on the signal.
Note that in 6-channel configuration, channels 5 and 6 are unaffected by back-end error (BKND_ERR
goes low).
To use channels 5 and 6 as unprocessed lineouts, the following setup is recommended:
• Channel-5 volume and channel-6 volume should be set for a constant output, such as 0 dB.
• Bass and treble for channels 5 and 6 can be used if desired.
• DRC1 should be bypassed for channels 5 and 6.
• If a down mix is desired on channels 5 and 6 as lineout, the down mixing can be performed using the
channel-5 and channel-6 input mixers.
• The operation of the channel-5 and -6 biquads is unaffected by the 6-/8-channel configuration setting.
3.3.4
Recovery from Clock Error
The TAS5508B can be set either to perform a volume ramp up during the recovery sequence of a clock
error or simply to come up in the last state (or desired state if a volume or tone update was in progress).
This feature is enabled via I2C system control register 0x03.
3.3.5
Power-Supply Volume-Control Enable
The power-supply volume control (PSVC) can be enabled and disabled via I2C register 0xE0. The
subwoofer PWM output is always controlled by the PSVC. When using PSVC the subwoofer cannot be
used as lineout.
3.3.6
Volume and Mute Update Rate
The TAS5508B has fixed soft volume and mute ramp durations. The ramps are linear. The soft volume
and mute ramp rates are adjustable by programming the I2C register 0xD0 for the appropriate number of
steps to be 512, 1024, or 2048. The update is performed at a fixed rate regardless of the sample rate.
• In normal speed, the update rate is 1 step every 4/fS seconds.
• In double speed, the update is 1 step every 8/fS seconds.
• In quad speed, the update is 1 step every 16/fS seconds.
Because of processor loading, the update rate can increase for some increments by one step every 1/fS to
3/fS. However, the variance of the total time to go from 18 dB to mute is less than 25%.
Table 3-8. Volume Ramp Periods in ms
NUMBER OF STEPS
512
3.3.7
SAMPLE RATE (kHz)
44.1, 88.2, 176.4
32, 48, 96, 192
46.44
42.67
1024
92.88
85.33
2048
185.76
170.67
Modulation Index Limit
PWM modulation is a linear function of the audio signal. When the audio signal is 0, the PWM modulation
is 50%. When the audio signal increases toward full scale, the PWM modulation increases toward 100%.
For negative signals, the PWM modulations fall below 50% toward 0%.
However, the maximum possible modulation does have a limit. During the offtime period, the power stage
48
TAS5508B Controls and Status
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
SLES162C – DECEMBER 2005 – REVISED JULY 2009
connected to the TAS5508B output needs to get ready for the next on-time period. The maximum possible
modulation is then set by the power stage requirements. The default modulation index limit setting is
97.7%; however, some power stages may require a lower modulation limit. See the applicable power
stage data sheet for details on setting the modulation index limit. The default setting of 97.7% can be
changed in the modulation index register (0x16).
3.4
Master Clock and Serial Data Rate Controls
The TAS5508B functions only as a receiver of the MCLK (master clock), SCLK (shift clock), and LRCLK
(left/right clock) signals that control the flow of data on the four serial data interfaces. The 13.5-MHz
external crystal allows the TAS5508B to detect MCLK and the data rate automatically.
The MCLK frequency can be 64 fS, 128 fS, 196 fS, 256 fS, 384 fS, 512 fS, or 768 fS.
The TAS5508B operates with the serial data interface signals LRCLK and SCLK synchronized to MCLK.
However, the phase relationship of these signals has no constraint. The TAS5508B accepts a 64 fS SCLK
rate and a 1 fS LRCLK.
If the phase of SCLK or LRCLK drifts more than ±10 MCLK cycles since the last reset, the TAS5508B
senses a clock error and resynchronizes the clock timing.
The clock and serial data interface have several control parameters:
• MCLK ratio (64 fS, 128 fS, 196 fS, 256 fS, 384 fS, 512 fS, or 768 fS) – I2C parameter
• Data rate (32, 38, 44.1, 48, 88.2, 96, 176.4, 192 kHz) – I2C parameter
• AM mode enable/disable – I2C parameter
During AM interference avoidance, the clock control circuitry uses three other configuration inputs:
• Tuned AM frequency (for AM interference avoidance) (550 kHz to 1750 kHz) – I2C parameter
• Frequency set select (1–4) – I2C parameter
• Sample rate – I2C parameter or auto-detected
3.4.1
PLL Operation
The TAS5508B uses two internal clocks generated by two internal phase-locked loops (PLLs), the digital
PLL (DPLL) and the analog PLL (APLL). The APLL provides the reference clock for the PWM. The DPLL
provides the reference clock for the digital audio processor and the control logic.
The master clock MCLK input provides the input reference clock for the APLL. The external 13.5-MHz
crystal provides the input reference clock for the DPLL. The crystal provides a time base to support a
number of operations, including the detection of the MCLK ratio, the data rate, and clock error conditions.
The crystal time base provides a constant rate for all controls and signal timing.
Even if MCLK is not present, the TAS5508B can receive and store I2C commands and provide status.
3.5
Bank Controls
The TAS5508B permits the user to specify and assign sample-rate-dependent parameters for biquad,
loudness, DRC, and tone in one of three banks that can be manually selected or selected automatically
based on the data sampling rate. Each bank can be enabled for one or more specific sample rates via I2C
bank control register 0x40. Each bank set holds the following values:
• Coefficients for seven biquads (7 × 5 = 35 coefficients) for each of the eight channels (registers
0x51–0x88)
• Coefficients for one loudness biquad (register 0x95)
• DRC1 energy and (1 – energy) values (register 0x98)
• DRC1 attack, (1 – attack), decay, (1 – decay) values (register 0x9C)
• DRC2 energy and (1 – energy) values (register 0x9D)
• DRC2 attack, (1 – attack), decay, (1 – decay) values (register 0xA1)
Submit Documentation Feedback
TAS5508B Controls and Status
49
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
•
•
www.ti.com
Five bass filter-set selections (register 0xDA)
Five treble filter-set selections (register 0xDC)
The default selection for bank control is manual bank with bank 1 selected. Note that if bank switching is
used, bank 2 and bank 3 must be programmed on power up, because the default values are all zeroes. If
bank switching is used and bank 2 and bank 3 are not programmed correctly, then the output of the
TAS5508B could be muted when switching to those banks.
3.5.1
Manual Bank Selection
The three bank-selection bits of the bank control register allow the appropriate bank to be manually
selected (000 = bank 1, 001 = bank 2, 010 = bank 3). In the manual mode, when a write occurs to the
biquad, DRC, or loudness coefficients, the currently selected bank is updated. If audio data is streaming to
the TAS5508B during a manual bank selection, the TAS5508B first performs a mute sequence, then
performs the bank switch, and finally restores the volume using an unmute sequence.
A mute command initiated by the bank-switch mute sequence overrides an unmute command or a volume
command. While a mute is active, the commanded channels are muted. When a channel is unmuted, the
volume level goes to the last commanded volume setting that has been received for that channel.
If MCLK or SCLK is stopped, the TAS5508B performs a bank-switch operation. If the clocks start up once
the manual bank-switch command has been received, the bank-switch operation is performed during the
5-ms, silent-start sequence.
3.5.2
Automatic Bank Selection
To enable automatic bank selection, a value of 3 is written into the bank-selection bits of the bank control
register. Banks are associated with one or more sample rates by writing values into the bank 1 or bank 2
data-rate selection registers. The automatic bank selection is performed when a frequency change is
detected according to the following scheme:
1. The system scans bank-1 data-rate associations to see if bank 1 is assigned for that data rate.
2. If bank 1 is assigned, then the bank-1 coefficients are loaded.
3. If bank 1 is not assigned, the system scans bank 2 to see if bank 2 is assigned for that data rate.
4. If bank 2 is assigned, the bank-2 coefficients are loaded.
5. If bank 2 is not assigned, the system loads the bank-3 coefficients.
The default is that all frequencies are enabled for bank 1. This default is expressed as a value of all 1s in
the bank-1 auto-selection byte and all 0s in the bank-2 auto-selection byte.
3.5.2.1 Coefficient Write Operations While Automatic Bank Switch Is Enabled
In automatic mode, if a write occurs to the tone, EQ, DRC, or loudness coefficients, the bank that is
written to is the current bank.
3.5.3
Bank Set
Bank set is used to provide a secure way to update the bank coefficients in both the manual and
automatic switching modes without causing a bank switch to occur. Bank-set mode does not alter the
current bank register mapping. It simply enables any bank coefficients to be updated while inhibiting any
bank switches from taking place. In manual mode, this enables the coefficients to be set without switching
banks. In automatic mode, this prevents a clock error or data-rate change from corrupting a bank
coefficient write.
To update the coefficients of a bank, a value of 4, 5, or 6 is written into in the bank-selection bits of the
bank control register. This enables the tone, EQ, DRC, and loudness coefficient values of bank 1, 2, or 3,
respectively, to be updated.
Once the coefficients of the bank have been updated, the bank-selection bits are then returned to the
desired manual or automatic bank-selection mode.
50
TAS5508B Controls and Status
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
3.5.4
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Bank-Switch Timeline
After a bank switch is initiated (manual or automatic), no I2C writes to the TAS5508B should occur before
a minimum of 186 ms. This value is determined by the volume ramp rates for a particular sample rate.
3.5.5
Bank-Switching Example 1
Problem: The audio unit containing a TAS5508B needs to handle different audio formats with different
sample rates. Format #1 requires fS = 32 kHz, format #2 requires fS = 44.1 kHz, and format #3 requires fS
= 48 kHz. The sample-rate-dependent parameters in the TAS5508B require different coefficients and data
depending on the sample rate.
Strategy: Use the TAS5508B bank-switching feature to allow for managing and switching three banks
associated with the three sample rates, 32 kHz (bank 1), 44.1 kHz (bank 2), and 48 kHz (bank 3).
One possible algorithm is to generate, load, and automatically manage bank switching for this problem:
1. Generate bank-related coefficients for sample rates of 32 kHz, 44.1 kHz, and 48 kHz, and include the
same in the microprocessor-based TAS5508B I2C firmware.
2. On TAS5508B power up or reset, the microprocessor runs the following TAS5508B initialization code:
a. Update bank 1 (write 0x0004 8040 to register 0x40).
b. Write bank-related I2C registers with appropriate values for bank 1.
c. Write bank 2 (write 0x0005 8040 to register 0x40).
d. Load bank-related I2C registers with appropriate values for bank 2.
e. Write bank 3 (write 0x0006 8040 to register 0x40).
f. Load bank-related I2C registers with appropriate values for bank 3.
g. Select automatic bank switching (write 0x0003 8040 to register 0x40).
3. When the audio media changes, the TAS5508B automatically detects the incoming sample rate and
automatically switches to the appropriate bank.
In this example, any sample rates other than 32 kHz and 44.1 kHz use bank 3. If other sample rates are
used, then the banks must be set up differently.
3.5.6
Bank-Switching Example 2
Problem: The audio system uses all of the sample rates supported by the TAS5508B. How can the
automatic bank switching be set up to handle this situation?
Strategy: Use the TAS5508B bank-switching feature to allow for managing and switching three banks
associated with sample rates as follows:
• Bank 1: Coefficients for 32 kHz, 38 kHz, 44.1 kHz, and 48 kHz
• Bank 2: Coefficients for 88.2 kHz and 96 kHz
• Bank 3: Coefficients for 176.4 kHz and 192 kHz
One possible algorithm is to generate, load, and automatically manage bank switching for this problem:
1. Generate bank-related coefficients for sample rates 48 kHz (bank 1), 96 kHz (bank 2), and 192 kHz
(bank 3) and include the same in the microprocessor-based TAS5508B I2C firmware.
2. On TAS5508B power up or reset, the microprocessor runs the following TAS5508B initialization code:
a. Update bank 1 (write 0x0004 F00C to register 0x40).
b. Write bank-related I2C registers with appropriate values for bank 1.
c. Write bank 2 (write 0x0005 F00C to register 0x40).
d. Load bank-related I2C registers with appropriate values for bank 2.
e. Write bank 3 (write 0x0006 F00C to register 0x40).
f. Load bank-related I2C registers with appropriate values for bank 3.
g. Select automatic bank switching (write 0x0003 F00C to register 0x40).
3. When the audio media changes, the TAS5508B automatically detects the incoming sample rate and
automatically switches to the appropriate bank.
Submit Documentation Feedback
TAS5508B Controls and Status
51
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
4
Electrical Specifications
4.1
Absolute Maximum Ratings (1)
www.ti.com
Supply voltage, DVDD and DVD_PWM
–0.3 V to 3.6 V
Supply voltage, AVDD_PLL
–0.3 V to 3.6 V
3.3-V digital input
Input voltage
–0.5 V to DVDD + 0.5 V
5-V tolerant (2) digital input
1.8-V LVCMOS
–0.5 V to 6 V
(3)
–0.5 V to VREF (4) + 0.5 V
IIK
Input clamp current (VI < 0 or VI > 1.8 V
±20 µA
IOK
Output clamp current (VO < 0 or VO > 1.8 V)
±20 µA
TA
Operating free-air temperature
Tstg
Storage temperature range
(1)
(2)
(3)
(4)
4.2
4.3
0°C to 70°C
–65°C to 150°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.
5-V tolerant inputs are RESET, PDN, MUTE, HP_SEL, SCLK, LRCLK, MCLK, SDIN1, SDIN2, SDIN3, SDIN4, SDA, and SCL.
VRA_PLL, VRD_PLL, VR_DPLL, VR_DIG, VR_PWM
VREF is a 1.8-V supply derived from regulators internal to the TAS5508B chip. VREF is on terminals VRA_PLL, VRD_PLL, VR_DPLL,
VR_DIG, and VR_PWM. These terminals are provided to permit use of external filter capacitors, but should not be used to source power
to external devices.
Dissipation Rating Table (High-k Board, 105 °C Junction)
PACKAGE
TA ≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
PAG
1869 mW
23.36 mW/°C
818 mW
Dynamic Performance at Recommended Operating Conditions at 25 °C
PARAMETER
TEST CONDITIONS
Dynamic range
TAS5508B + TAS5111 A-weighted (fS = 48 kHz)
Total harmonic distortion
Frequency response
4.4
NOM
0.1%
TAS5508B output
0.01%
32-kHz to 96-kHz sample rates
±0.1
176.4, 192-kHz sample rates
±0.2
TJ
52
dB
MIN
NOM
MAX
3
3.3
3.6
V
Analog supply voltage, AVDD_PLL
3
3.3
3.6
V
High-level input voltage
Low-level input voltage
5-V tolerant (1)
5-V tolerant
UNIT
2
2
V
1.26
0.8
(1)
0.8
1.8-V (XTL_IN)
(1)
dB
Digital supply voltage, DVDD and DVDD_PWM
3.3 V
TA
UNIT
Recommended Operating Conditions
1.8-V LVCMOS (XTL_IN)
VIL
MAX
102
TAS5111 at 1 W
3.3 V
VIH
MIN
V
0.54
Operating ambient-air temperature range
0
Operating junction temperature range
0
25
70
°C
105
°C
5-V tolerant inputs are RESET, PDN, MUTE, HP_SEL, SCLK, LRCLK, MCLK, SDIN1, SDIN2, SDIN3, SDIN4, SDA, and SCL.
Electrical Specifications
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
4.5
SLES162C – DECEMBER 2005 – REVISED JULY 2009
Electrical Characteristics
Over recommended operating conditions (unless otherwise noted)
PARAMETER
VOH
High-level output voltage
VOL
Low-level output voltage
IOZ
High-impedance output current
IIL
Low-level input current
IIH
High-level input current
TEST CONDITIONS
MAX
1.8-V LVCMOS (XTL_OUT)
IOH = –0.55 mA
3.3-V TTL and 5-V (1) tolerant
IOL = 4 mA
0.5
1.8-V LVCMOS (XTL_OUT)
IOL = 0.75 mA
0.5
UNIT
2.4
V
1.44
V
±20
3.3-V TTL
3.3-V TTL
VI = VIL
±1
1.8-V LVCMOS (XTL_IN)
VI = VIL
±1
5-V tolerant (2)
VI = 0 V, DVDD = 3 V
±1
3.3-V TTL
VI = VIH
±1
1.8-V LVCMOS (XTL_IN)
VI = VIH
5-V tolerant (2)
VI = 5.5 V, DVDD = 3 V
Input supply current
Analog supply voltage, AVDD
(1)
(2)
TYP
IOH = –4 mA
Digital supply voltage, DVDD
IDD
MIN
3.3-V TTL and 5-V (1) tolerant
µA
µA
±1
µA
±20
fS = 48 kHz
140
fS = 96 kHz
150
fS = 192 kHz
155
Power down
8
Normal
mA
20
Power down
2
5-V tolerant outputs are SCL and SDA.
5-V tolerant inputs are RESET, PDN, MUTE, HP_SEL, SCLK, LRCLK, MCLK, SDIN1, SDIN2, SDIN3, SDIN4, SDA, and SCL.
4.6
PWM Operation
Over recommended operating conditions
PARAMETER
Output sample rate 1×–8× oversampled
TEST CONDITIONS
MODE
VALUE
UNIT
384
kHz
8×, 4×, or 2× sample rate
352.8
kHz
8×, 4×, or 2× sample rate
384
kHz
32-kHz data rate ±2%
12× sample rate
44.1-, 88.2-, 176.4-kHz data rate ±2%
48-, 96-, 192-kHz data rate ±1%
4.7
Switching Characteristics
4.7.1
Clock Signals
PLL input parameters and external filter components over recommended operating conditions (unless otherwise noted) (1)
PARAMETER
fXTALI
Frequency, XTAL IN
fMCLKI
Frequency, MCLK (1/tcyc2)
TEST CONDITIONS
TYP
MAX
UNIT
13.5
2
MCLK duty cycle
40%
MHz
50
50%
MHz
60%
MCLK minimum high time
≥2-V MCLK = 49.152 MHz, within the min
and max duty cycle constraints
5
ns
MCLK minimum low time
≤0.8-V MCLK = 49.152 MHz, within the min
and max duty cycle constraints
5
ns
LRCLK allowable drift before LRCLK reset
(1)
MIN
Only use 13.5-MHz crystal ≤1000 ppm
–10
10
MCLKs
External PLL filter capacitors C11 and C12
SMD 0603 Y5V
100
nF
External PLL filter capacitors C10 and C13
SMD 0603 Y5V
10
nF
External PLL filter resistors R10 and R11
SMD 0603, metal film
200
Ω
External VRA_PLL decoupling C14
SMD, Y5V
100
nF
See the TAS5508B Example Application Schematic, Section 8.
Submit Documentation Feedback
Electrical Specifications
53
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
4.7.2
www.ti.com
Serial Audio Port
Serial audio port slave mode over recommended operating conditions (unless otherwise noted)
PARAMETER
fSCLKIN SCLK input frequency
TEST CONDITIONS
MIN
CL = 30 pF, SCLK = 64 fS
2.048
TYP
MAX
UNIT
12.288
MHz
tsu1
Setup time, LRCLK to SCLK rising edge
10
ns
th1
Hold time, LRCLK from SCLK rising edge
10
ns
tsu2
Setup time, SDIN to SCLK rising edge
10
ns
th2
Hold time, SDIN from SCLK rising edge
10
LRCLK frequency
32
48
192
SCLK duty cycle
40%
50%
60%
LRCLK duty cycle
40%
50%
60%
64
64
SCLK
edges
–1/4
1/4
SCLK
period
SCLK rising edges between LRCLK rising edges
LRCLK clock edge with respect to the falling edge of
SCLK
ns
kHz
SCLK
(Input)
th1
tsu1
LRCLK
(Input)
th2
tsu2
SDIN1
SDIN2
SDIN3
T0026-01
Figure 4-1. Slave Mode Serial Data Interface Timing
4.7.3
TAS5508B Pin-Related Characteristics of the SDA and SCL I/O Stages for F/S-Mode
I 2C-Bus Devices
PARAMETER
TEST CONDITIONS
STANDARD MODE
MIN
FAST MODE
MAX
MIN
LOW-level input voltage
–0.5
VIH
HIGH-level input voltage
0.7 VDD
Vhys
Hysteresis of Schmitt-trigger inputs
VOL1
LOW-level output voltage (open drain or
open collector)
3-mA sink current
tof
Output fall time from VIHmin to VILmax
Bus capacitance from 10 pF
to 400 pF
tSP
Pulse duration of spikes suppressed (2)
N/A
N/A
0
30
ns
Ii
Input current, each I/O pin
–30
30
–30 (3)
30 (3)
µA
Ci
Capacitance, each I/O pin
10
pF
(1)
(2)
(3)
54
–0.5
N/A
250
V
0.7 VDD
V
0.05 VDD
V
0
0.4
V
7 + 0.1 Cb
250
ns
(1)
10
0.3 VDD
UNIT
VIL
N/A
0.3 VDD
MAX
2
Cb = capacitance of one bus line in pF. The output fall time is faster than the standard I C specification.
SCL and SDA have a 30-ns glitch filter.
The I/O pins of fast-mode devices must not obstruct the SDA and SDL lines if VDD is switched off.
Electrical Specifications
Submit Documentation Feedback
TAS5508B
8-Channel Digital Audio PWM Processor
www.ti.com
4.7.4
SLES162C – DECEMBER 2005 – REVISED JULY 2009
TAS5508B Bus-Related Characteristics of the SDA and SCL I/O Stages for F/S-Mode
I 2C-Bus Devices
All values are referred to VIHmin and VILmax (see Section 4.7.3).
A
PARAMETER
TEST CONDITIONS
STANDARD MODE
MIN
MAX
FAST MODE
MIN
UNIT
MAX
fSCL
SCL clock frequency
0
100
0
400
kHz
tHD-STA
Hold time (repeated) START condition.
After this period, the first clock pulse is
generated.
4
0.6
µs
tLOW
LOW period of the SCL clock
4.7
1.3
µs
tHIGH
HIGH period of the SCL clock
4
0.6
µs
tSU-STA
Setup time for repeated START
4.7
0.6
µs
tSU-DAT
Data setup time
250
100
µs
tHD-DAT
Data hold time
0
0.9
µs
tr
Rise time of both SDA and SCL
1000 20 + 0.1 Cb (3)
500 (4)
ns
tf
Fall time of both SDA and SCL
300 20 + 0.1 Cb (3)
300
ns
tSU-STO
Setup time for STOP condition
tBUF
Bus free time between a STOP and
START condition
Cb
Capacitive loads for each bus line
VnL
Noise margin at the LOW level for each
connected device (including hysteresis)
0.1 VDD
0.1 VDD
V
VnH
Noise margin at the HIGH level for each
connected device (including hysteresis)
0.2 VDD
0.2 VDD
V
(1)
(2)
(3)
(4)
(1) (2)
0
3.45
4
0.6
µs
4.7
1.3
µs
400
400
pF
Note that SDA does not have the standard I2C specification 300-ns hold time and that SDA must be valid by the rising and falling edges
of SCL. TI recommends that a 3.3-kΩ pullup resistor be used to avoid potential timing issues.
A fast-mode I2C-bus device can be used in a standard-mode I2C-bus system, but the requirement tSU-DAT ≥ 250 ns must then be met.
This is automatically the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW
period of the SCL signal, it must output the next data bit to the SDA line tr-max + tSU-DAT = 1000 + 250 = 1250 ns (according to the
standard-mode I2C bus specification) before the SCL line is released.
Cb = total capacitance of one bus line in pF.
Rise time varies with pullup resistor.
SDA
tf
tSU-DAT
tHD-STA
tLOW
tr
tr
tSP
tBUF
tf
SCL
tHD-DAT
tSU-STA
tHD-STA
tSU-STO
tHIGH
S
Sr
P
S
T0114-01
Figure 4-2. Start and Stop Conditions Timing Waveforms
Submit Documentation Feedback
Electrical Specifications
55
TAS5508B
8-Channel Digital Audio PWM Processor
SLES162C – DECEMBER 2005 – REVISED JULY 2009
www.ti.com
4.7.4.1 Recommended I2C Pullup Resistors
It is recommended that the I2C pullup resistors RP be 3.3 kΩ (see Figure 4-3). If a series resistor is in the circuit
(see Figure 4-4), then the series resistor RS should be less than or equal to 300 Ω.
5V
TAS5508B
External
Microcontroller
IP
RP
SDA
SCL
IP
RP
VI(SDA)
VI(SCL)
B0099-01
Figure 4-3. I2C Pullup Circuit (With No Series Resistor)
5V
TAS5508B
External
Microcontroller
RP
SDA
or
SCL
VI
RS
(2)
VS
IP
RS
(2)
(1)
B0100-01
(1)
VS = 5 × RS/(RS = RP). When driven low, VS
工商网监
湘ICP备2023018690号
