SLASE12A July   2014  – October 2014 PCM5242

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified System Diagram
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
    1. 6.1 Control Mode Effect On Pin Assignments
    2. 6.2 Pin Assignments
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Handling Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Timing Requirements: SCK Input
    8. 7.8 Timing Requirements: PCM Audio Data
    9. 7.9 Timing Requirements: XSMT
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Terminology
    4. 8.4 Audio Data Interface
      1. 8.4.1 Audio Serial Interface
      2. 8.4.2 PCM Audio Data Formats
      3. 8.4.3 Zero Data Detect
    5. 8.5 XSMT Pin (Soft Mute / Soft Un-Mute)
    6. 8.6 Audio Processing
      1. 8.6.1 PCM5242 Audio Processing Options
        1. 8.6.1.1 Overview
        2. 8.6.1.2 miniDSP Instruction Register
        3. 8.6.1.3 Digital Output
        4. 8.6.1.4 Software
      2. 8.6.2 Interpolation Filter
      3. 8.6.3 Fixed Audio Processing Flow (Program 5)
        1. 8.6.3.1 Processing Blocks - Detailed Descriptions
        2. 8.6.3.2 Biquad Section
        3. 8.6.3.3 Dynamic Range Compression
        4. 8.6.3.4 Stereo Mixer
        5. 8.6.3.5 Stereo Multiplexer
        6. 8.6.3.6 Mono Mixer
        7. 8.6.3.7 Master Volume Control
        8. 8.6.3.8 Miscellaneous Coefficients
    7. 8.7 DAC and Differential Analog Outputs
      1. 8.7.1 Analog Outputs
      2. 8.7.2 Choosing Between VREF and VCOM Modes
        1. 8.7.2.1 Voltage Reference and Output Levels
        2. 8.7.2.2 Mode Switching Sequence, From VREF Mode to VCOM Mode
      3. 8.7.3 Digital Volume Control
        1. 8.7.3.1 Emergency Ramp Down
      4. 8.7.4 Analog Gain Control
    8. 8.8 Reset and System Clock Functions
      1. 8.8.1 Clocking Overview
      2. 8.8.2 Clock Slave Mode With Master Clock (SCK) Input (4 Wire I2S)
      3. 8.8.3 Clock Slave Mode with BCK PLL to Generate Internal Clocks (3-Wire PCM)
      4. 8.8.4 Clock Generation Using The PLL
      5. 8.8.5 PLL Calculation
        1. 8.8.5.1 Examples:
          1. 8.8.5.1.1 Recommended PLL settings
      6. 8.8.6 Clock Master Mode from Audio Rate Master Clock
      7. 8.8.7 Clock Master from a Non-Audio Rate Master Clock
    9. 8.9 Device Functional Modes
      1. 8.9.1 Choosing A Control Mode
        1. 8.9.1.1 Software Control
          1. 8.9.1.1.1 SPI Interface
            1. 8.9.1.1.1.1 Register Read/Write Operation
          2. 8.9.1.1.2 I2C Interface
            1. 8.9.1.1.2.1 Slave Address
            2. 8.9.1.1.2.2 Register Address Auto-Increment Mode
            3. 8.9.1.1.2.3 Packet Protocol
            4. 8.9.1.1.2.4 Write Register
            5. 8.9.1.1.2.5 Read Register
            6. 8.9.1.1.2.6 Timing Characteristics
      2. 8.9.2 Choosing Between VREF and VCOM Modes
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 High Fidelity Smartphone Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Initialization Script
        3. 9.2.1.3 Application Performance Plot
  10. 10Power Supply Recommendations
    1. 10.1 Power Supply Distribution and Requirements
    2. 10.2 Recommended Powerdown Sequence
      1. 10.2.1 Planned Shutdown
      2. 10.2.2 Unplanned Shutdown
    3. 10.3 External Power Sense Undervoltage Protection mode (supported only when DVDD = 3.3V)
    4. 10.4 PCM5242 Power Modes
      1. 10.4.1 Setting Digital Power Supplies and I/O Voltage Rails
      2. 10.4.2 Power Save Modes
      3. 10.4.3 Power Save Parameter Programming
  11. 11Layout
    1. 11.1 Layout Guidelines
  12. 12Programming and Registers Reference
    1. 12.1 Coefficient Data Formats
    2. 12.2 PCM5242 Register Map
      1. 12.2.1 Detailed Register Descriptions
        1. 12.2.1.1 Register Map Summary
          1. 12.2.1.1.1 Register Map Summary
        2. 12.2.1.2 Page 0 Registers
          1. 12.2.1.2.1  Page 0 / Register 1
          2. 12.2.1.2.2  Page 0 / Register 2
          3. 12.2.1.2.3  Page 0 / Register 3
          4. 12.2.1.2.4  Page 0 / Register 4
          5. 12.2.1.2.5  Page 0 / Register 6
          6. 12.2.1.2.6  Page 0 / Register 7
          7. 12.2.1.2.7  Page 0 / Register 8
          8. 12.2.1.2.8  Page 0 / Register 9
          9. 12.2.1.2.9  Page 0 / Register 10
          10. 12.2.1.2.10 Page 0 / Register 12
          11. 12.2.1.2.11 Page 0 / Register 13
          12. 12.2.1.2.12 Page 0 / Register 14
          13. 12.2.1.2.13 Page 0 / Register 18
          14. 12.2.1.2.14 Page 0 / Register 19
          15. 12.2.1.2.15 Page 0 / Register 20
          16. 12.2.1.2.16 Page 0 / Register 21
          17. 12.2.1.2.17 Page 0 / Register 22
          18. 12.2.1.2.18 Page 0 / Register 23
          19. 12.2.1.2.19 Page 0 / Register 24
          20. 12.2.1.2.20 Page 0 / Register 27
          21. 12.2.1.2.21 Page 0 / Register 28
          22. 12.2.1.2.22 Page 0 / Register 29
          23. 12.2.1.2.23 Page 0 / Register 30
          24. 12.2.1.2.24 Page 0 / Register 32
          25. 12.2.1.2.25 Page 0 / Register 33
          26. 12.2.1.2.26 Page 0 / Register 34
          27. 12.2.1.2.27 Page 0 / Register 35
          28. 12.2.1.2.28 Page 0 / Register 36
          29. 12.2.1.2.29 Page 0 / Register 37
          30. 12.2.1.2.30 Page 0 / Register 40
          31. 12.2.1.2.31 Page 0 / Register 41
          32. 12.2.1.2.32 Page 0 / Register 42
          33. 12.2.1.2.33 Page 0 / Register 43
          34. 12.2.1.2.34 Page 0 / Register 44
          35. 12.2.1.2.35 Page 0 / Register 59
          36. 12.2.1.2.36 Page 0 / Register 60
          37. 12.2.1.2.37 Page 0 / Register 61
          38. 12.2.1.2.38 Page 0 / Register 62
          39. 12.2.1.2.39 Page 0 / Register 63
          40. 12.2.1.2.40 Page 0 / Register 64
          41. 12.2.1.2.41 Page 0 / Register 65
          42. 12.2.1.2.42 Page 0 / Register 80
          43. 12.2.1.2.43 Page 0 / Register 81
          44. 12.2.1.2.44 Page 0 / Register 82
          45. 12.2.1.2.45 Page 0 / Register 83
          46. 12.2.1.2.46 Page 0 / Register 84
          47. 12.2.1.2.47 Page 0 / Register 85
          48. 12.2.1.2.48 Page 0 / Register 86
          49. 12.2.1.2.49 Page 0 / Register 87
          50. 12.2.1.2.50 Page 0 / Register 90
          51. 12.2.1.2.51 Page 0 / Register 91
          52. 12.2.1.2.52 Page 0 / Register 92
          53. 12.2.1.2.53 Page 0 / Register 93
          54. 12.2.1.2.54 Page 0 / Register 94
          55. 12.2.1.2.55 Page 0 / Register 95
          56. 12.2.1.2.56 Page 0 / Register 108
          57. 12.2.1.2.57 Page 0 / Register 109
          58. 12.2.1.2.58 Page 0 / Register 114
          59. 12.2.1.2.59 Page 0 / Register 115
          60. 12.2.1.2.60 Page 0 / Register 118
          61. 12.2.1.2.61 Page 0 / Register 119
          62. 12.2.1.2.62 Page 0 / Register 120
          63. 12.2.1.2.63 Page 0 / Register 121
          64. 12.2.1.2.64 Page 0 / Register 122
          65. 12.2.1.2.65 Page 0 / Register 123
          66. 12.2.1.2.66 Page 0 / Register 124
          67. 12.2.1.2.67 Page 0 / Register 125
        3. 12.2.1.3 Page 1 Registers
          1. 12.2.1.3.1 Page 1 / Register 1
          2. 12.2.1.3.2 Page 1 / Register 2
          3. 12.2.1.3.3 Page 1 / Register 5
          4. 12.2.1.3.4 Page 1 / Register 6
          5. 12.2.1.3.5 Page 1 / Register 7
          6. 12.2.1.3.6 Page 1 / Register 8
          7. 12.2.1.3.7 Page 1 / Register 9
        4. 12.2.1.4 Page 44 Registers
          1. 12.2.1.4.1 Page 44 / Register 1
        5. 12.2.1.5 Page 253 Registers
          1. 12.2.1.5.1 Page 253 / Register 63
          2. 12.2.1.5.2 Page 253 / Register 64
      2. 12.2.2 PLL Tables for Software Controlled Devices
  13. 13Device and Documentation Support
    1. 13.1 Community Resources
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8 Detailed Description

8.1 Overview

The integrated PLL on the device provided adds the flexibility to remove the system clock (commonly known as master clock), allowing a 3-wire I2S connection and reducing system EMI. In addition, the PLL is completely programmable, allowing the device to become the I2S clock master and drive a DSP serial port as a slave. The PLL also accepts a non-standard clock (up to 50MHz) as a source to generate the audio related clock (for example 24.576MHz).

Powersense undervoltage protection utilizes a two-level mute system. Upon clock error or system power failure, the device digitally attenuates the data (or last known good data), then mutes the analog circuit.

Compared with existing DAC technology, the PCM5242 offers up to 20dB lower out-of-band noise, reducing EMI and aliasing in downstream amplifiers/ADCs. (from traditional 100kHz OBN measurements all the way to 3MHz).

The PCM5242 accepts industry-standard audio data formats with 16- to 32-bit data. Sample rates up to 384kHz are supported.

8.2 Functional Block Diagram

fbd_pcm524x.gif

8.3 Terminology

Control registers in this datasheet are given by REGISTER BIT/BYTE NAME (Page.x HEX ADDRESS). SE refers to "Single Ended" analog inputs, DIFF refers to "Differential" analog inputs. SCK (System Clock) and MCLK (Master Clock) are used interchangeably. Sampling frequency is symbolized by "fS". Full scale is symbolized by "FS". Sample time as a unit is symbolized by "tS".

8.4 Audio Data Interface

8.4.1 Audio Serial Interface

The audio interface port is a 3-wire serial port with the signals LRCK, BCK, and DIN. BCK is the serial audio bit clock, used to clock the serial data present on DIN into the serial shift register of the audio interface. Serial data is clocked into the PCM5242 on the rising edge of BCK. LRCK is the serial audio left/right word clock. LRCK polarity for Left/Right is given by the format selected.

Table 4. PCM5242 Audio Data Formats, Bit Depths and Clock Rates

CONTROL MODE FORMAT DATA BITS MAX LRCK FREQUENCY [fS] SCK RATE [x fS] BCK RATE [x fS]
Software Control
(SPI or I2S) 		I2S/LJ 32, 24, 20, 16 Up to 192kHz 128 – 3072 64, 48, 32
384kHz 64, 128 64, 48, 32
TDM/DSP 32, 24, 20, 16 Up to 48kHz 128 – 3072 125, 256
96kHz 128 – 512 125, 256
192kHz 128, 192, 256 128
Hardware Control I2S/LJ 32, 24, 20, 16 Up to 192kHz 128 – 3072 64, 48, 32
384kHz 64, 128 64, 48, 32

The PCM5242 requires the synchronization of LRCK and system clock, but does not need a specific phase relation between LRCK and system clock.

If the relationship between LRCK and system clock changes more than ±5 SCK, internal operation is initialized within one sample period and analog outputs are forced to the bipolar zero level until resynchronization between LRCK and system clock is completed.

If the relationship between LRCK and BCK are invalid more than 4 LRCK periods, internal operation is initialized within one sample period and analog outputs are forced to the bipolar zero level until resynchronization between LRCK and BCK is completed.

8.4.2 PCM Audio Data Formats

The PCM5242 supports industry-standard audio data formats, including standard I2S and left-justified. Data formats are selected via Register (Pg0Reg40). All formats require binary 2s-complement, MSB-first audio data; up to 32-bit audio data is accepted.

The PCM5242 also supports right-justified and TDM/DSP in software control mode. I2S, LJ, RJ, and TDM/DSP are selected using Register (Pg0Reg40). All formats require binary 2s complement, MSB-first audio data. Up to 32 bits are accepted. Default setting is I2S and 24 bit word length.

f_pcm51xx_aud_data_format_lj.gifFigure 18. Left Justified Audio Data Format
f_pcm51xx_aud_data_format_i2s.gif
I2S Data Format; L-channel = LOW, R-channel = HIGH
Figure 19. I2S Audio Data Format

The following data formats are only available in software mode.

f_pcm51xx_aud_data_format_rj.gif
Right Justified Data Format; L-channel = HIGH, R-channel = LOW
Figure 20. Right Justified Audio Data Format
f_pcm51xx_aud_data_format_tdm1.gif
TDM/DSP Data Format; L-channel = FIRST, R-channel = LAST with OFFSET = 0
Figure 21. TDM/DSP 1 Audio Data Format

NOTE

In TDM Modes, Duty Cycle of LRCK should be 1x BCK at minimum. Rising edge is considered frame start.
f_pcm51xx_aud_data_format_tdm2.gif
TDM/DSP Data Format; L-channel = FIRST, R-channel = LAST with OFFSET = 1
Figure 22. TDM/DSP 2 Audio Data Format
f_pcm51xx_aud_data_format_tdm3.gif
TDM/DSP Data Format; L-channel = FIRST, R-channel = LAST with OFFSET = N
Figure 23. TDM/DSP 3 Audio Data Format

8.4.3 Zero Data Detect

The PCM5242 has a zero-detect function. When the device detects the continuous zero data for both left and right channels, or separate channels, Analog mutes are set to both OUTL and OUTR, or separate OUTL and OUTR. These are controlled by Page0, Register 65, D(2:1) as shown in Table 5.

Continuous Zero data cycles are counted by LRCK, and the threshold of decision for analog mute can be set by Page 0, Register 59, D(6:4) for L-ch, and D(2:0) for Rch as shown in Table 6. Default values are 0 for both channels.

In Hardware mode, the device uses default values.

Table 5. Zero Data Detection Mode

ATMUTECTL Value Function
Bit : 2 0 Independently L-ch or R-ch are zero data for zero data detection
1 (Default) Both L-ch and R-ch have to be zero data for zero data detection
Bit : 1 0 Zero detection and analog mute are disabled for R-ch
1 (Default) Zero detection analog mute are enabled for R-ch
Bit : 0 0 Zero detection analog mute are disabled for L-ch
1 (Default) Zero detection analog mute are enabled for L-ch

Table 6. Zero Data Detection Time

ATMUTETIML / ATMUTETIMR Number of LRCKs Time @ 48kHz
0 0 0 1024 21 ms
0 0 1 5120 106 ms
0 1 0 10240 213 ms
0 1 1 25600 533 ms
1 0 0 51200 1.066 sec
1 0 1 102400 2.133 sec
1 1 0 256000 5.333 sec
1 1 1 512000 10.66 sec

8.5 XSMT Pin (Soft Mute / Soft Un-Mute)

An external digital host controls the PCM5242 soft mute function by driving the XSMT pin with a specific minimum rise time (tr) and fall time (tf) for soft mute and soft un-mute. The PCM5242 requires tr and tf times of less than 20ns. In the majority of applications, this is no problem, however, traces with high capacitance may have issues.

When the XSMT pin is shifted from high to low (3.3V to 0V), a soft digital attenuation ramp begins. -1dB attenuation is then applied every sample time from 0dBFS to - ∞. The soft attenuation ramp takes 104 samples.

When the XSMT pin is shifted from low to high (0V to 3.3V), a soft digital “un-mute” is started. 1dB gain steps are applied every sample time from - ∞ to 0dBFS. The un-mute takes 104 samples.

In systems where XSMT is not required, it can be directly connected to AVDD.

8.6 Audio Processing

8.6.1 PCM5242 Audio Processing Options

8.6.1.1 Overview

The PCM5242 features a fully-programmable miniDSP core. The algorithms for the miniDSP must be loaded into the device after power up. The miniDSP has direct access to the digital stereo audio stream, offering the possibility for advanced DSP algorithms with very low group delay. The miniDSP can run up to 1024 instructions on every audio sample at a 48kHz sample rate.

The PCM5242 features a programmable miniDSP core that offers Hybrid-Flows which are a RAM/ROM combination of code. Common functions are embedded in ROM, and custom RAM flows, created by TI can be run on the miniDSP core. The algorithms for the miniDSP must be loaded into the device after power up. The miniDSP can run up to 1024 instructions on every audio sample at a 48kHz sample rate. Development is done using Purepath Console software.

NOTE

At higher sampling frequencies, fewer instruction cycles are available. (For example, 512 instructions can be done in a 96kHz frame.)

The PCM5242 supports two different code sources. ROM based process flow (See the next section for how to select) and RAM based process flow. In program 31 (RAM based), different algorithms can be called from ROM - such as EQ, DRC and Zero Crossing volume control. Please see the PurePath Studio Development Environment for more details.

8.6.1.2 miniDSP Instruction Register

Registers on Page 152-169 are 25-bit instructions for the miniDSP engine. For details see Table 49. 7 bits of Instr(32:25) in Base register +0 are reserved bits. 1 bit of Instr(24) - (LSB) in Base register +0 is MSB bit of 25 bit instruction. These instructions control miniDSP operation. When the fully programmable miniDSP mode is enabled and the DAC channel is powered up, the read and write access to these registers is disabled.

8.6.1.3 Digital Output

The PCM5242 supports an SDOUT output. This can be selected within the process flow, and driven out of a GPIO pin selected in the register map (e.g. Page 0 / Register 80). Users should note that the I2S output will be attenuated by 0.5dB. A full scale (FS) output will actually be FS-0.5dB. This can be compensated for within the process flow using PurePath Studio. The I2S output can be a separate audio stream to the analog DAC output, allowing 2.1 and 2.2 systems to be implimented. By default, the SDOUT is not linked to the volume control registers on Page 0 / Register 60, 61, 62. However, it is possible to configure the SDOUT component in Purepath studio to mirror that register.

8.6.1.4 Software

Software development for the PCM5242 is supported through TI's comprehensive PurePath Console; a powerful, easy-to-use tool designed specifically to simplify software development on the PCM5242 miniDSP audio platform. The Graphical Development Environment consists of number of Hybrid Flows that can be downloaded to the device and run on the miniDSP.

Please visit the PCM5242 product folder on www.ti.com to learn more about PurePath Console and the latest status on available, ready-to-use DSP algorithms.

8.6.2 Interpolation Filter

The PCM5242 provides 4 types of interpolation filters, selectable by writing to Page 0, Register 43, D(4:0).

Additional RAM based Hybrid Flows can be implemented by selecting Program 31, and downloading instructions and coefficients to the device.

Table 7. ROM Preset Programs

Program number D(4:0) Description Minimum Cycles
0 0 0000 Reserved
1 0 0001 Normal x8/x4/x2/x1 Interpolation Filter(1) 256
2 0 0010 Low Latency x8/x4/x2/x1 Interpolation Filter(1) 256
3 0 0011 High Attenuation x8/x4/x2 Interpolation Filter(1) 512
4 0 0100 Reserved
5 0 0101 Preset Process Flow n/a
6 0 0110 Reserved
7 0 0111 Asymmetric FIR Interpolation Filter(1) 512
: : Reserved
31 1 1111 RAM program / Hybrid Flows
(1) fS 44.1kHz De-emphasis filter is supported.

The PCM5242supports four sampling modes (single rate, dual rate, quad rate, and octal rate) which produce different oversampling rates (OSR) in the interpolation digital filter operation. These are shown in Table 8.

Table 8. Sampling Modes and Oversampling Rates

Sampling Mode Sampling Frequency (fS) kHz Oversampling Rate (OSR)
Single Rate 8 8 or 16
16
32
44.1
48
Dual Rate 88.2 4
96
Quad Rate 176.4 2
192
Octal Rate 384 1 (Bypass)

Table 9. Normal x8 Interpolation Filter, Single Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.01 dB
Filter Gain Stop Band 0.55fS ….. 7.455fS –60 dB
Filter Group Delay 20tS S
G012_gphpcm51xx_frequency_response_x8_normal.gifFigure 24. Normal x8 Interpolation Filter Frequency Response
G034_gphpcm51xx_pass_band_ripple_x8_normal.gifFigure 26. Normal x8 Interpolation Filter Passband Ripple
G023_gphpcm51xx_impulse_response_x8_normal.gifFigure 25. Normal x8 Interpolation Filter Impulse Response

Table 10. Normal x4 Interpolation Filter, Dual Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.01 dB
Filter Gain Stop Band 0.55fS ….. 3.455fS –60 dB
Filter Group Delay 20tS S
G009_gphpcm51xx_frequency_response_x4_slase12.gifFigure 27. Normal x4 Interpolation Filter Frequency Response
G031_gphpcm51xx_pass_band_ripple_x4_normal_slase12.gifFigure 29. Normal x4 Interpolation Filter Passband Ripple
G020_gphpcm51xx_impulse_response_x4_normal.gifFigure 28. Normal x4 Interpolation Filter Impulse Response

Table 11. Normal x2 Interpolation Filter, Quad Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.01 dB
Filter Gain Stop Band 0.55fS ….. 1.455fS –60 dB
Filter Group Delay 20tS S
G006_gphpcm51xx_frequency_response_x4_slase12.gifFigure 30. Normal x2 Interpolation Filter Frequency Response
G028_gphpcm51xx_pass_band_ripple_x2_normal_slase12.gifFigure 32. Normal x2 Interpolation Filter Passband Ripple
G017_gphpcm51xx_impulse_response_x2_normal.gifFigure 31. Normal x2 Interpolation Filter Impulse Response

Table 12. Low latency x8 Interpolation Filter, Single Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.001 dB
Filter Gain Stop Band 0.55fS ….. 7.455fS –52 dB
Filter Group Delay 3.5tS S
G011_gphpcm51xx_frequency_response_x8_lowlt.gifFigure 33. Low latency x8 Interpolation Filter Frequency Response
G033_gphpcm51xx_pass_band_ripple_x8_lowlt.gifFigure 35. Low latency x8 Interpolation Filter Passband Ripple
G022_gphpcm51xx_impulse_response_x8_lowlt.gifFigure 34. Low latency x8 Interpolation Filter Impulse Response

Table 13. Low latency x4 Interpolation Filter, Dual Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.001 dB
Filter Gain Stop Band 0.55fS ….. 3.455fS –52 dB
Filter Group Delay 3.5tS S
G008_gphpcm51xx_frequency_response_x4_slase12.gifFigure 36. Low latency x4 Interpolation Filter Frequency Response
G030_gphpcm51xx_pass_band_ripple_x4_lowlt_slase12.gifFigure 38. Low latency x4 Interpolation Filter Passband Ripple
G019_gphpcm51xx_impulse_response_x4_lowlt.gifFigure 37. Low latency x4 Interpolation Filter Impulse Response

Table 14. Low latency ×2 Interpolation Filter, Quad Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.001 dB
Filter Gain Stop Band 0.55fS ….. 1.455fS –52 dB
Filter Group Delay 3.5tS S
G005_gphpcm51xx_frequency_response_x4_slase12.gifFigure 39. Low latency x2 Interpolation Filter Frequency Response
G030_gphpcm51xx_pass_band_ripple_x4_lowlt_slase12.gifFigure 41. Low latency x2 Interpolation Filter Passband Ripple
G016_gphpcm51xx_impulse_response_x2_lowlt.gifFigure 40. Low latency x2 Interpolation Filter Impulse Response

Table 15. Asymmetric FIR x8 Interpolation Filter, Single Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.40fS ±0.05 dB
Filter Gain Stop Band 0.72fS ….. 7.28fS –50 dB
Filter Group Delay 1.2tS S
gphpcm51xx_frequency_response_x8_asymFIR.pngFigure 42. Asymmetric FIR x8 Interpolation Filter Frequency Response, Single Rate
gphpcm51xx_pass_band_ripple_x8_asymFIR.pngFigure 44. Asymmetric FIR x8 Interpolation Filter Passband Ripple, Single Rate
gphpcm51xx_impulse_response_x8_asymFIR.pngFigure 43. Asymmetric FIR x8 Interpolation Filter Impulse Response, Single Rate

Table 16. Asymmetric FIR x4 Interpolation Filter, Dual Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.40fS ±0.05 dB
Filter Gain Stop Band 0.72fS ….. 3.28fS –50 dB
Filter Group Delay 1.2tS S
G002_gphpcm51xx_frequency_response_x4_asymFIR_slase12.gifFigure 45. Asymmetric FIR x4 Interpolation Filter Frequency Response, Dual Rate
gphpcm51xx_pass_band_ripple_x4_asymFIR.pngFigure 47. Asymmetric x4 Interpolation Filter Passband Ripple, Dual Rate
gphpcm51xx_impulse_response_x4_asymFIR.pngFigure 46. Asymmetric FIR x4 Interpolation Filter Impulse Response, Dual Rate

Table 17. Asymmetric FIR x2 Interpolation Filter, Quad Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.40fS ±0.05 dB
Filter Gain Stop Band 0.72fS ….. 1.28fS –50 dB
Filter Group Delay 1.2tS S
G001_gphpcm51xx_frequency_response_x2_asymFIR_slase12.gifFigure 48. Asymmetric FIR x2 Interpolation Filter Frequency Response, Quad Rate
G100_gphpcm51xx_pass_band_ripple_x2_asymFIR_slase12.gifFigure 50. Asymmetric x2 Interpolation Filter Passband Ripple, Quad Rate
gphpcm51xx_impulse_response_x2_asymFIR.pngFigure 49. Asymmetric FIR x2 Interpolation Filter Impulse Response, Quad Rate

Table 18. High-Attentuation x8 Interpolation Filter, Single Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.0005 dB
Filter Gain Stop Band 0.55fS ….. 7.455fS –100 dB
Filter Group Delay 33.7tS S
gphpcm51xx_frequency_response_x8_high_ATT.pngFigure 51. High-Attentuation x8 Interpolation Filter Frequency Response, Single Rate
gphpcm51xx_pass_band_ripple_x8_high_ATT.pngFigure 53. High-Attentuation x8 Interpolation Filter Passband Ripple, Single Rate
gphpcm51xx_impulse_response_x8_high_ATT.pngFigure 52. High-Attentuation x8 Interpolation Filter Impulse Response, Single Rate

Table 19. High-Attentuation x4 Interpolation Filter, Dual Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.0005 dB
Filter Gain Stop Band 0.55fS ….. 3.455fS –100 dB
Filter Group Delay 33.7tS S
G004_gphpcm51xx_frequency_response_x4_high_ATT_slase12.gifFigure 54. High-Attentuation x4 Interpolation Filter Frequency Response, Dual Rate
G101_gphpcm51xx_pass_band_ripple_x4_high_ATT_slase12.gifFigure 56. High-Attentuation x4 Interpolation Filter Passband Ripple, Dual Rate
gphpcm51xx_impulse_response_x4_high_ATT.pngFigure 55. High-Attentuation x4 Interpolation Filter Impulse Response, Dual Rate

Table 20. High-Attentuation x2 Interpolation Filter, Quad Rate

Parameter Condition Value (Typical) Value (Max) Units
Filter Gain Pass Band 0 ……. 0.45fS ±0.0005 dB
Filter Gain Stop Band 0.55fS ….. 1.455fS –100 dB
Filter Group Delay 33.7tS S
G003_gphpcm51xx_frequency_response_x2_high_ATT_slase12.gifFigure 57. High-Attentuation x2 Interpolation Filter Frequency Response, Quad Rate
G102_gphpcm51xx_pass_band_ripple_x2_high_ATT_slase12.gifFigure 59. High-Attentuation x2 Interpolation Filter Passband Ripple, Quad Rate
gphpcm51xx_impulse_response_x2_high_ATT.pngFigure 58. High-Attentuation x2 Interpolation Filter Impulse Response, Quad Rate

8.6.3 Fixed Audio Processing Flow (Program 5)

The PCM5242 implements signal processing capabilities and interpolation filtering via processing blocks. These fixed processing blocks give users the choice of how much and what type of signal processing they may use and which interpolation filter is applied.

The signal processing blocks available are:

  • Biquad filters
  • Multiband DRC
  • Mono mixer
  • Stereo mixer
  • Master volume

The addresses of the coefficients are fixed when selecting the fixed processing flow, however, if these components are used in the RAM source mode (Program 31) the registers for coefficients will change. Users can find more details in Purepath Studio.

NOTE

This process flow requires 1024 instruction cycles. Therefore, it will only function at sampling frequencies up to 48kHz.

8.6.3.1 Processing Blocks – Detailed Descriptions

Figure 60 shows the fixed processing flow.

pcm512x4x_aud_fixed_proc_flow.gifFigure 60. Preset Process Flow

Figure 61 shows a screen capture of PurePath Studio.

pcm514x_purepath_screenshot_whitebg.pngFigure 61. PurePath Studio Screen Capture

8.6.3.2 Biquad Section

The transfer function of each of the biquad filters is given by

Equation 1. q1_xfr_func_las759.gif
pcm512x4x_biquad_block.gifFigure 62. Biquad Block

Table 21. Biquad Filter Coefficients

Filter Channel Coefficient Register
BIQUAD (1) - 1 BIQUAD (2) - 1 Lch,
Rch		 N0 C10 (Pg 44, Reg 48,49,50,51)
N1 C11 (Pg 44, Reg 52,53,54,55)
N2 C12 (Pg 44, Reg 56,57,58,59)
D1 C13 (Pg 44, Reg 60,61,62,63)
D2 C14 (Pg 44, Reg 64,65,66,67)
BIQUAD (1) - 2 BIQUAD (2) - 2 Lch,
Rch		 N0 C15 (Pg 44, Reg 68,69,70,71)
N1 C16 (Pg 44, Reg 72,73,74,75)
N2 C17 (Pg 44, Reg 76,77,78,79)
D1 C18 (Pg 44, Reg 80,81,82,83)
D2 C19 (Pg 44, Reg 84,85,86,87)
BIQUAD (1) - 3 BIQUAD (2) - 3 Lch,
Rch		 N0 C20 (Pg 44, Reg 88,89,90,91)
N1 C21 (Pg 44, Reg 92,93,94,95)
N2 C22 (Pg 44, Reg 96,97,98,99)
D1 C23 (Pg 44, Reg 100,101, 102, 103)
D2 C24 (Pg 44, Reg 104, 105, 106, 107)
BIQUAD (1) - 4 BIQUAD (2) - 4 Lch,
Rch		 N0 C25 (Pg 44, Reg 108, 109, 110, 111)
N1 C26 (Pg 44, Reg 112, 113, 114, 115)
N2 C27 (Pg 44, Reg 116, 117, 118, 119)
D1 C28 (Pg 44, Reg 120, 121, 122, 123)
D2 C29 (Pg 44, Reg 124, 125, 126, 127)
BIQUAD (1) - 5 BIQUAD (2) - 5 Lch,
Rch		 N0 C30 (Pg 45, Reg 8, 9, 10, 11)
N1 C31 (Pg 45, Reg 12, 13, 14, 15)
N2 C32 (Pg 45, Reg 16, 17, 18, 19)
D1 C33 (Pg 45, Reg 20, 21, 22, 23)
D2 C34 (Pg 45, Reg 24, 25, 26, 27)
BIQUAD (1) - 6 BIQUAD (2) - 6 Lch,
Rch		 N0 C35 (Pg 45, Reg 28, 29, 30, 31)
N1 C36 (Pg 45, Reg 32, 33, 34, 35)
N2 C37 (Pg 45, Reg 36, 37, 38, 39)
D1 C38 (Pg 45, Reg 40, 41, 42, 43)
D2 C39 (Pg 45, Reg 44, 45, 46, 47)
BIQUAD (3) - 1 BIQUAD (4) - 1 Lch,
Rch		 N0 C40 (Pg 45, Reg 48, 49, 50, 51)
N1 C41 (Pg 45, Reg 52, 53, 54, 55)
N2 C42 (Pg 45, Reg 56, 57, 58, 59)
D1 C43 (Pg 45, Reg 60, 61, 62, 63)
D2 C44 (Pg 45, Reg 64, 65, 66, 67)
BIQUAD (3) - 2 BIQUAD (4) - 2 Lch,
Rch		 N0 C45 (Pg 45, Reg 68, 69, 70, 71)
N1 C46 (Pg 45, Reg 72, 73, 74, 75)
N2 C47 (Pg 45, Reg 76, 77, 78, 79)
D1 C48 (Pg 45, Reg 80, 81, 82, 83)
D2 C49 (Pg 45, Reg 84, 85, 86, 87)
BIQUAD (5) - 1 BIQUAD (6) - 1 Lch,
Rch		 N0 C50 (Pg 45, Reg 88, 89, 90, 91)
N1 C51 (Pg 45, Reg 92, 93, 94, 95)
N2 C52 (Pg 45, Reg 96, 97, 98, 99)
D1 C53 (Pg 45, Reg 100, 101, 102, 103)
D2 C54 (Pg 45, Reg 104, 105, 106, 107)
BIQUAD (5) - 2 BIQUAD (6) - 2 Lch,
Rch		 N0 C55 (Pg 45, Reg 108, 109, 110, 111)
N1 C56 (Pg 45, Reg 112, 113, 114, 115)
N2 C57 (Pg 45, Reg 116, 117, 118, 119)
D1 C58 (Pg 45, Reg 120, 121, 122, 123)
D2 C59 (Pg 45, Reg 124, 125, 126, 127)
BIQUAD (7) - 1 BIQUAD (8) - 1 Lch,
Rch		 N0 C60 (Pg 46, Reg 8, 9, 10, 11)
N1 C61 (Pg 46, Reg 12, 13, 14, 15)
N2 C62 (Pg 46, Reg 16, 17, 18, 19)
D1 C63 (Pg 46, Reg 20, 21, 22, 23)
D2 C64 (Pg 46, Reg 24, 25, 26, 27)
BIQUAD (7) - 2 BIQUAD (8) - 2 Lch,
Rch		 N0 C65 (Pg 46, Reg 28, 29, 30, 31)
N1 C66 (Pg 46, Reg 32, 33, 34, 35)
N2 C67 (Pg 46, Reg 36, 37, 38, 39)
D1 C68 (Pg 46, Reg 40, 41, 42, 43)
D2 C69 (Pg 46, Reg 44, 45, 46, 47)

8.6.3.3 Dynamic Range Compression

Dynamic range compression (DRC) improves the overall listening experience. Typical music signals are characterized by crest factors (the ratio of peak signal power to average signal power) of 12dB or more. To avoid audible distortion due to clipping of peak signals, the gain of the DAC channel must be adjusted so as not to cause hard clipping. As a result, the low applied gain during nominal periods causes the perception that the signal is not loud enough. To overcome this problem, the DRC in the PCM5242 continuously monitors the output of the DAC Digital Volume control to detect its power level with respect to 0dB full-scale. When the power level is low, the DRC increases the input signal gain to make it sound louder, and reduces the gain during peaks to avoid hard clipping. The DRC enables louder audio during nominal periods with a clearer, more pleasant listening experience.

The 3-band DRC function applies DRC to 3 different mono/stereo signals with 3 different time constants. The same DRC curve is applied on all the signals, enabling a multi-band DRC solution. The underlying DRC algorithm is the same as that available with the DRC component in PurePath Studio. In this instance, the DRC gain acts on each signal in time-multiplexed order, for example, 1-2-3, 1-2-3, 1-2-3.

Table 22. DRC Coefficients

Coefficient Register Description
DRC_MB_1_DRC_1_DRCAE C70 (Pg 46, Reg 48, 49, 50, 51)
DRC_MB_1_DRC_1_DRC1AE C71 (Pg 46, Reg 52, 53, 54, 55)
DRC_MB_1_DRC_1_DRCAA C72 (Pg 46, Reg 56, 57, 58, 59)
DRC_MB_1_DRC_1_DRC1AA C73 (Pg 46, Reg 60, 61, 62, 63)
DRC_MB_1_DRC_1_DRCAD C74 (Pg 46, Reg 64, 65, 66, 67)
DRC_MB_1_DRC_1_DRC1AD C75 (Pg 46, Reg 68, 69, 70, 71)
DRC_MB_1_DRC_2_DRCAE C76 (Pg 46, Reg 72, 73, 74, 75)
DRC_MB_1_DRC_2_DRC1AE C77 (Pg 46, Reg 76, 77, 78, 79)
DRC_MB_1_DRC_2_DRCAA C78 (Pg 46, Reg 80, 81, 82, 83)
DRC_MB_1_DRC_2_DRC1AA C79 (Pg 46, Reg 84, 85, 86, 87)
DRC_MB_1_DRC_2_DRCAD C80 (Pg 46, Reg 88, 89, 90, 91)
DRC_MB_1_DRC_2_DRC1AD C81 (Pg 46, Reg 92, 93, 94, 95)
DRC_MB_1_DRC_3_DRCAE C82 (Pg 46, Reg 96, 97, 98, 99)
DRC_MB_1_DRC_3_DRC1AE C83 (Pg 46, Reg 100, 101, 102, 103)
DRC_MB_1_DRC_3_DRCAA C84 (Pg 46, Reg 104, 105, 106, 107)
DRC_MB_1_DRC_3_DRC1AA C85 (Pg 46, Reg 108, 109, 119, 111)
DRC_MB_1_DRC_3_DRCAD C86 (Pg 46, Reg 112, 113, 114, 115)
DRC_MB_1_DRC_3_DRC1AD C87 (Pg 46, Reg 116, 117, 118, 119)
DRC_MB_1_DRC_DRCK0 C88 (Pg 46, Reg 120, 121, 122, 123)
DRC_MB_1_DRC_DRCK1 C89 (Pg 46, Reg 124, 125, 126, 127)
DRC_MB_1_DRC_DRCK2 C90 (Pg 47, Reg 8, 9, 10, 11)
DRC_MB_1_DRC_DRCMT1 C91 (Pg 47, Reg 12, 13, 14, 15)
DRC_MB_1_DRC_DRCMT2 C92 (Pg 47, Reg 16, 17, 18, 19)
DRC_MB_1_DRC_DRCOFF1 C93 (Pg 47, Reg 20, 21, 22, 23)
DRC_MB_1_DRC_DRCOFF2 C94 (Pg 47, Reg 24, 25, 26, 27)
DRC_MB_1_MinusOne_Q22 C95 (Pg 47, Reg 28, 29, 30, 31)
DRC_MB_1_MinusTwo_Q22 C96 (Pg 47, Reg 32, 33, 34, 35)
DRC_MB_1_One_M2 C97 (Pg 47, Reg 36, 37, 38, 39)
DRC_MB_1_Zero C98 (Pg 47, Reg 40, 41, 42, 43)
DRC_MB_1_En_dB C99 (Pg 47, Reg 44, 45, 46, 47)
DRC_MB_1_Minus__Zero_dB C100 (Pg 47, Reg 48, 49, 50, 51)
DRC_MB_1_60_dB C101 (Pg 47, Reg 52, 53, 54, 55)
DRC_MB_1_Minus_60_dB C102 (Pg 47, Reg 56, 57, 58, 59)
DRC_MB_1_12_dB C103 (Pg 47, Reg 60, 61, 62, 63)
DRC_MB_1_Offset C104 (Pg 47, Reg 64, 65, 66, 67)
DRC_MB_1_K C105 (Pg 47, Reg 68, 69, 70, 71)
DRC_MB_1_x / DRC_MB_1_DRC C106 (Pg 47, Reg 72, 73, 74, 75)
DRC_MB_1_48_dB C107 (Pg 47, Reg 76, 77, 78, 79)
DRC_MB_1_Minus_48_dB C108 (Pg 47, Reg 80, 81, 82, 83)
DRC_MB_1_c1_3 C109 (Pg 47, Reg 84, 85, 86, 87)
DRC_MB_1_c1_2 C110 (Pg 47, Reg 88, 89, 90, 91)
DRC_MB_1_c1_1 C111 (Pg 47, Reg 92, 93, 94, 95)
DRC_MB_1_c1_0 C112 (Pg 47, Reg 96, 97, 98, 99)
DRC_MB_1_O1_1 C113 (Pg 47, Reg 100, 101, 102, 103)
DRC_MB_1_S1_1 C114 (Pg 47, Reg 104, 105, 106, 107)
DRC_MB_1_O1_2 C115 (Pg 47, Reg 108, 109, 119, 111)
DRC_MB_1_S1_2 C116 (Pg 47, Reg 112, 113, 114, 115)
DRC_MB_1_O1_3 C117 (Pg 47, Reg 116, 117, 118, 119)
DRC_MB_1_S1_3 C118 (Pg 47, Reg 120, 121, 122, 123)
DRC_MB_1_One_1_Q17 C119 (Pg 47, Reg 124, 125, 126, 127)
DRC_MB_1_Scale1 C120 (Pg 48, Reg 8, 9, 10, 11)
DRC_MB_1_x1Coeff C121 (Pg 48, Reg 12, 13, 14, 15)
DRC_MB_1_c2_3 C122 (Pg 48, Reg 16, 17, 18, 19)
DRC_MB_1_c2_2 C123 (Pg 48, Reg 20, 21, 22, 23)
DRC_MB_1_c2_1 C124 (Pg 48, Reg 24, 25, 26, 27)
DRC_MB_1_c2_0 C125 (Pg 48, Reg 28, 29, 30, 31)
DRC_MB_1_O2_1 C126 (Pg 48, Reg 32, 33, 34, 35)
DRC_MB_1_S2_1 C127 (Pg 48, Reg 36, 37, 38, 39)
DRC_MB_1_O2_2 C128 (Pg 48, Reg 40, 41, 42, 43)
DRC_MB_1_S2_2 C129 (Pg 48, Reg 44, 45, 46, 47)
DRC_MB_1_O2_3 C130 (Pg 48, Reg 48, 49, 50, 51)
DRC_MB_1_S2_3 C131 (Pg 48, Reg 52, 53, 54, 55)
DRC_MB_1_One_2_Q17 C132 (Pg 48, Reg 56, 57, 58, 59)
DRC_MB_1_Scale2 C133 (Pg 48, Reg 60, 61, 62, 63)
DRC_MB_1_x2Coeff C134 (Pg 48, Reg 64, 65, 66, 67)
DRC_MB_1_R1_1 C135 (Pg 48, Reg 68, 69, 70, 71)
DRC_MB_1_R1_2 C136 (Pg 48, Reg 72, 73, 74, 75)
DRC_MB_1_R2_1 C137 (Pg 48, Reg 76, 77, 78, 79)
DRC_MB_1_R2_2 C138 (Pg 48, Reg 80, 81, 82, 83)
DRC_MB_1_Band1_GainC C139 (Pg 48, Reg 84, 85, 86, 87)
DRC_MB_1_Band2_GainC C140 (Pg 48, Reg 88, 89, 90, 91)
DRC_MB_1_Band3_GainC C141 (Pg 48, Reg 92, 93, 94, 95)
DRC_MB_1_MinusOne_M1 C142 (Pg 48, Reg 96, 97, 98, 99)
DRC_MB_1_One_M1 C143 (Pg 48, Reg 100, 101, 102, 103)
DRC_MB_1_Band1_GainE C144 (Pg 48, Reg 104, 105, 106, 107)
DRC_MB_1_Band2_GainE C145 (Pg 48, Reg 108, 109, 110, 111)
DRC_MB_1_Band3_GainE C146 (Pg 48, Reg 112, 113, 114, 115)
DRC_MB_1_minus_One_M2 C147 (Pg 48, Reg 116, 117, 118, 119)

8.6.3.4 Stereo Mixer

Three stereo inputs are mixed into one stereo output with input signal gain given by Equation 2.

Equation 2. q2_stereo_mix_signal_gain_pcm512x4x.gif

where

  • i=1:2,3

Figure 63 and Table 23 show the strereo mixer operation.

pcm512x4x_stereo_mixer_block.gifFigure 63. Stereo Mixer Block

Table 23. Stereo Mixer Coefficients

Coefficient Register Description
Stereo_Mixer_1_MixGain1 C148 (Pg 48, Reg 120, 121, 122, 123)
Stereo_Mixer_1_MixGain2 C149 (Pg 48, Reg 124, 125, 126, 127)
Stereo_Mixer_1_MixGain3 C150 (Pg 49, Reg 8, 9, 10, 11)

8.6.3.5 Stereo Multiplexer

The Stereo Multiplexer selects one or 2 from 4 stereo input channels.

pcm512x4x_stereo_mux_block.gifFigure 64. Stereo Multiplexer Block

Table 24. Stereo Multiplexer Select Coefficient

Coefficient Register Description
Stereo_Mux_1_MuxSelect C152 (Pg 49, Reg 16, 17, 18, 19)

Table 25. Stereo Multiplexer Input Coefficient

Coefficient Register Description
C_to_D_1_Coefval
C_to_D_2_Coefval 		C153 (Pg 49, Reg 20, 21, 22, 23)

8.6.3.6 Mono Mixer

The Mono Mixer computes a weighted sum of 2 input channels and produces an output.

pcm512x4x_mono_mixer_block.gifFigure 65. Mono Mixer Block

Table 26. Mono Mixer Coefficients

Coefficient Register Description
Mono_Mixer_1_MixGain1 C154 (Pg 49, Reg 24, 25, 26, 27)
Mono_Mixer_1_MixGain2 C155 (Pg 49, Reg 28, 29, 30, 31)

8.6.3.7 Master Volume Control

The Master Volume controls the volume using a linear ramp and zero crossing detection for transitions.

Table 27. Mono Mixer Coefficients

Coefficient Register Description
Volume_ZeroX_1_volcmd C158 (Pg 49, Reg 40, 41, 42, 43)
Volume_ZeroX_1_volout C159 (Pg 49, Reg 44, 45, 46, 47)
Volume_ZeroX_1_volout_loudness C160 (Pg 49, Reg 48, 49, 50, 51)
Volume_ZeroX_1_MinusOne_M2 C161 (Pg 49, Reg 52, 53, 54, 55)
Volume_ZeroX_1_workingval_1_pre_CRAM C162 (Pg 49, Reg 56, 57, 58, 59)
Volume_ZeroX_1_volout_pre1 C163 (Pg 49, Reg 60, 61, 62, 63)
Volume_ZeroX_1_workingval_2_pre_CRAM C164 (Pg 49, Reg 64, 65, 66, 67)
Volume_ZeroX_1_volout_pre2 C165 (Pg 49, Reg 68, 69, 70, 71)
Volume_ZeroX_1_workingval_3_pre_CRAM C166 (Pg 49, Reg 72, 73, 74, 75)
Volume_ZeroX_1_volout_pre3 C167 (Pg 49, Reg 76, 77, 78, 79)
Volume_ZeroX_1_One_M2 C168 (Pg 49, Reg 80, 81, 82, 83)
Volume_ZeroX_1_Zero C169 (Pg 49, Reg 84, 85, 86, 87)
MinusOne_Int C170 (Pg 49, Reg 88, 89, 90, 91)
MinusOne_M1 C171 (Pg 49, Reg 92, 93, 94, 95)
One_M2 C172 (Pg 49, Reg 96, 97, 98, 99)
One_M1 C173 (Pg 49, Reg 100, 101, 102, 103)
Zero C174 (Pg 49, Reg 104, 105, 106, 107)

8.6.3.8 Miscellaneous Coefficients

Table 28. Miscellaneous Coefficients

Coefficient Register Description
DRC_MB_1_DataBlock C175 (Pg 49, Reg 108, 109, 110, 111)
DRC_MB_1_CoeffBlock C176 (Pg 49, Reg 112, 113, 114, 115)
Volume_ZeroX_1_DataBlock C177 (Pg 49, Reg 116, 117, 118, 119)
Volume_ZeroX_1_CoeffBlock C178 (Pg 49, Reg 120, 121, 122, 123)
plus_one C179 (Pg 49, Reg 124, 125, 126, 127)
ADD_OF_filter_in_L C180 (Pg 50, Reg 8, 9, 10, 11)
ADD_OF_filter_in_R C181 (Pg 50, Reg 12, 13, 14, 15)

8.7 DAC and Differential Analog Outputs

8.7.1 Analog Outputs

The PCM5242 devices include a two-channel DAC, with differential outputs. Each pin has a full-scale output voltage is 2.1Vrms with ground center output. This equates to a 4.2Vrms differential output. A dc-coupled load is supported in addition to an ac-coupled load, if the load resistance conforms to the specification. The PCM5242 DAC outputs on the OUTLP, OUTLN, OUTRP, and OUTRN terminals have market-leading low out-of-band noise, which offer up to 20dB lower out-of-band noise compared with existing DAC technology.

Many applications require an external low-pass RC filter (470Ω + 1.2nF) to provide sufficient out-of-band noise rejection. This RC filter provides the added advantage of improved protection against ESD damage.

The PCM5242 can also support single ended outputs, using OUTLP and OUTRP respectively. A single 470Ω and 2.2nF capacitor can be used on each pin in single ended mode.

The choice between VREF and VCOM modes affects the maximum output level. This is explained in Voltage Reference and Output Levels.

pcm52xx_diff_out_rc_filter.gifFigure 66. Optional Low Pass Filters

8.7.2 Choosing Between VREF and VCOM Modes

VREF mode is the default configuration. This mode allows full 2.1Vrms signal output. As shown in Recommended Operating Conditions, the minimum AVDD to avoid clipping is 3.2V.

VCOM mode allows setting a custom common-mode voltage when required by the application. This somewhat limits the output signal swing before clipping.

8.7.2.1 Voltage Reference and Output Levels

The PCM5242 has an internal, fixed band-gap reference voltage, with default operation in VREF mode. No external decoupling capacitor is required for this mode.

The PCM5242 can be operated with a common-mode voltage output (VCOM mode) at the VCOM pin by setting Page 1, Register 1, D(0) to 1. In this mode, an external decoupling capacitor is required.

When using this DAC in VREF mode, the output-signal voltage is independent of the power-supply voltage: The D/A conversion gain in VREF mode yields a 2.1Vrms output voltage with a digital full-scale input. However, in VREF mode, an output waveform may clip due to the limitations that may be present in the analog power supply voltage. On the other hand, the full-scale output voltage in VCOM mode is proportional to the analog power supply AVDD. Example, (2.1 × AVDD / 3.3) Vrms.

8.7.2.2 Mode Switching Sequence, From VREF Mode to VCOM Mode

Following register setting sequence is recommended for changing VREF mode to VCOM mode.

1. Page 0 / Register 2 RQST = 1: Standby mode
2. Page 1 / Register 8 RCMF = 1: Fast ramp up → on
3. Page 1 / Register 9　 VCPD = 0: VCOM is power on
4. Wait 3ms with external capacitor = 1µF
5. Page 1 / Register 8 RCMF = 0: Fast ramp up → off
6. Page 1 / Register 1 OSEL = 1: VCOM mode
7. Page 0 / Register 2 RQST = 0: Normal mode

8.7.3 Digital Volume Control

A basic digital volume control with range from 24 dB to -103 dB and mute is available on each channels by Page 0, Resister 61, D(7:0) for L-ch and Register 62, D(7:0) for R-ch. These volume controls all have 0.5 dB step programmability over most gain and attenuation ranges. Table 29 lists the detailed gain versus programmed setting for this basic volume control. Volume can be changed for both L-ch and R-ch at the same time or independently by Page 0, Register 60, D(1:0). When D(1:0) set 00 (default), independent control is selected. When D(1:0) set 01, R-ch accords with L-ch volume. When D(1:0) set 10, L-ch accords with R-ch volume. To set D(1:0) to 11 is prohibited.

NOTE

This volume control is done externally to the miniDSP and only influences the analog DAC output. Any changes to the SDOUT data should be done in the miniDSP process flow

Table 29. Digital Volume Control Settings

Gain Setting Binary Data Gain (dB) Comments
0 0000-0000 24.0 Positive maximum
1 0000-0001 23.5
: : :
46 0010-1110 1.0
47 0010-1111 0.5
48 0011-0000 0.0 No attenuation (default)
49 0011-0001 - 0.5
50 0011-0010 - 1.0
51 0011-0011 - 1.5
: : :
253 1111-1101 - 102.5
254 1111-1110 - 103 Negative maximum
255 1111-1111 - ∞ Negative infinite (Mute)

Ramp-up frequency and ramp-down frequency can be controlled by Page 0, Register 63, D(7:6) and D(3:2) as shown in Table 30. Also Ramp-up step and ramp-down step can be controlled by Page 0, Register 63 D(5:4) and D(1:0) as shown in Table 31.

Table 30. Ramp Up or Down Frequency

Ramp up speed Every N fS Comments Ramp down frequency Every N fS Comments
00 1 Default 00 1 Default
01 2 01 2
10 4 10 4
11 Direct change 11 Direct change

Table 31. Ramp Up or Down Step

Ramp up step Step dB Comments Ramp down step Step dB Comments
00 4.0 00 -4.0
01 2.0 01 -2.0
10 1.0 Default 10 -1.0 Default
11 0.5 11 -0.5

8.7.3.1 Emergency Ramp Down

Digital volume emergency ramp down by is provided for situations such as I2S clock error and power supply failure. Ramp-down speed is controlled by Page 0, Register 64, D(7:6). Ramp-down step can be controlled by Page 0 Register 64, D(5:4). Default is ramp-down by every fS cycle with -4dB step.

8.7.4 Analog Gain Control

Analog gain control can be selected between 2Vrms FS (0dB) or 1Vrms FS (-6dB). Gain is controlled via hardware by the AGNS pin, and via software (SPI/I2C), Page 1, Register 2, D4(L-ch) / D0(R-ch).

8.8 Reset and System Clock Functions

8.8.1 Clocking Overview

The PCM5242 devices have flexible systems for clocking. Internally, the device requires a number of clocks, mostly at related clock rates to function correctly. All of these clocks can be derived from the Serial Audio Interface in one form or another.

f_pcm51xx_clk_bd.gifFigure 67. Audio flow with respective clocks

As shown in Figure 67 the basic data flow at basic sample rate (fS). Once the data is brought into the serial audio interface, it gets processed, interpolated and modulated all the way to 128 × fS before arriving at the current segments for the final digital to analog conversion.

The clock tree is shown in Figure 68.

f_pcm51xx_clk_tree_PLL.gifFigure 68. PCM5242 Clock Distribution Tree

The Serial Audio Interface typically has 4 connections SCK (System Master Clock), BCK (Bit Clock), LRCK (Left Right Word Clock) and Data. The device has an internal PLL that is used to take either SCK or BCK and create the higher rate clocks required by the miniDSP and the DAC clock.

In situations where the highest audio performance is required, it’s suggested that the SCK is brought to the device, along with BCK and LRCK. The device should be configured so that the PLL is only providing a clock source to the miniDSP. By ensuring that the DACCK (DAC Clock) is being driven by the external SCK source, jitter evident in the PLL (in all PLL's) is kept out of the DAC, Charge Pump and Oversampling system.

Everything else should be a division of the incoming SCK. This is done by setting DAC CLK Source Mux (SDAC in the diagram above) to use SCK as a source, rather than the output of the SCK/PLL Mux. Code Examples for this are available in SLAC622

When the Auto Clock Configuration bit is set (Page0/ Register 0x25), no additional clocks configuration is required. However, when setting custom PLL values etc, the target output rates should match those shown in the recommended PLL values of Table 50.

8.8.2 Clock Slave Mode With Master Clock (SCK) Input (4 Wire I2S)

The PCM5242 requires a system clock to operate the digital interpolation filters and advanced segment DAC modulators. The system clock is applied at the SCK input and supports up to 50MHz. The PCM5242 system-clock detection circuit automatically senses the system-clock frequency. Common audio sampling frequencies in the bands of 8kHz, 16kHz, (32kHz - 44.1kHz - 48kHz), (88.2kHz - 96kHz), (176.4kHz -192kHz), and 384kHz with ±4% tolerance are supported. Values in the parenthises are "grouped" when detected, e.g. 88.2kHZ and 96kHz are detected as "double rate", 32kHz, 44.1kHz and 48kHz will be detected as "single rate".

In the presence of a valid bit SCK, BCK and LRCK in software mode, the device will autoconfigure the clock tree and PLL to drive the miniDSP as required.

The sampling frequency detector sets the clock for the digital filter, Delta Sigma Modulator (DSM) and the Negative Charge Pump (NCP) automatically. Table 32 shows examples of system clock frequencies for common audio sampling rates.

SCK rates that are not common to standard audio clocks, between 1MHz and 50MHz, are only supported in software mode by configuring various PLL and clock-divider registers. This programmability allows the device to become a clock master and drive the host serial port with LRCK and BCK, from a non-audio related clock (for example, using 12MHz to generate 44.1kHz (LRCK) and 2.8224MHz (BCK) ).

Table 32. System Master Clock Inputs for Audio Related Clocks

Sampling Frequency System Clock Frequency (fSCK) (MHz)
64 fS 128 fS 192 fS 256 fS 384 fS 512 fS 768 fS 1024 fS 1152 fS 1536 fS 2048 fS 3072 fS
8 kHz –(1) 1.0240(2) 1.5360(2) 2.0480 3.0720 4.0960 6.1440 8.1920 9.2160 12.2880 16.3840 24.5760
16 kHz –(1) 2.0480(2) 3.0720(2) 4.0960 6.1440 8.1920 12.2880 16.3840 18.4320 24.5760 36.8640 49.1520
32 kHz –(1) 4.0960(2) 6.1440(2) 8.1920 12.2880 16.3840 24.5760 32.7680 36.8640 49.1520 –(1) –(1)
44.1 kHz –(1) 5.6488(2) 8.4672(2) 11.2896 16.9344 22.5792 33.8688 45.1584 –(1) –(1) –(1) –(1)
48 kHz –(1) 6.1440(2) 9.2160(2) 12.2880 18.4320 24.5760 36.8640 49.1520 –(1) –(1) –(1) –(1)
88.2 kHz –(1) 11.2896(2) 16.9344 22.5792 33.8688 45.1584 –(1) –(1) –(1) –(1) –(1) –(1)
96 kHz –(1) 12.2880(2) 18.4320 24.5760 36.8640 49.1520 –(1) –(1) –(1) –(1) –(1) –(1)
176.4 kHz –(1) 22.5792 33.8688 45.1584 –(1) –(1) –(1) –(1) –(1) –(1) –(1) –(1)
192 kHz –(1) 24.5760 36.8640 49.1520 –(1) –(1) –(1) –(1) –(1) –(1) –(1) –(1)
384 kHz 24.5760 49.1520 –(1) –(1) –(1) –(1) –(1) –(1) –(1) –(1) –(1) –(1)
(1) This system clock rate is not supported for the given sampling frequency.
(2) This system clock rate is supported by PLL mode.

See Timing Requirements: PCM Audio Data for clock timing requirements.

8.8.3 Clock Slave Mode with BCK PLL to Generate Internal Clocks (3-Wire PCM)

The system clock PLL mode allows designers to use a simple 3-wire I2S audio source. The 3-wire source reduces the need for a high frequency SCK, making PCB layout easier, and reduces high frequency electromagnetic interference.

In hardwired mode, the internal PLL is disabled as soon as an external SCK is supplied.

In hardwired mode, the device starts up expecting an external SCK input, but if BCK and LRCK start correctly while SCK remains at ground level for 16 successive LRCK periods, then the internal PLL starts, automatically generating an internal SCK from the BCK reference. Specific BCK rates are required to generate an appropriate master clock.Table 33 describes the minimum and maximum BCK per LRCK for the integrated PLL to automatically generate an internal SCK.

In software mode, the user must set all the PLL registers and clock divider registers for referencing BCK. See Clock Generation Using The PLL for more information. Recommended values can be found in Table 50.

Table 33. BCK Rates (MHz) by LRCK Sample Rate for PCM5242 PLL Operation

  BCK (fS)
Sample f (kHz)  32 64
8 - -
16 - 1.024
32 1.024 2.048
44.1 1.4112 2.8224
48 1.536 3.072
96 3.072 6.144
192 6.144 12.288
384 12.288 24.576

8.8.4 Clock Generation Using The PLL

The PCM5242 supports a wide range of options to generate the required clocks for the DAC section as well as interface and other control blocks as shown in Figure 68.

The clocks for the PLL require a source reference clock. This clock is sourced as the incoming BCK or SCK. In software mode, a GPIO can also be used.

The source reference clock for the PLL reference clock is selected by programming the SRCREF value on Page 0, Register 13, D(6:4). The PCM5242 provides several programmable clock dividers to achieve a variety of sampling rates for the DAC and clocks for the NCP, OSR, and the miniDSP. OSRCK for OSR must be set at 16fS frequency by DOSR on Page0, Register 30, D(6:0). See Figure 68.

If PLL functionality is not required, set the PLLEN value on Page 0, Register 4, D(0) to 0. In this situation, an external SCK is required.

Table 34. PLL Configuration Registers

Clock multiplexer Function Bits
SREF PLL Reference Page 0, Register 13, D(6:4)
Divider Function Bits
DDSP miniDSP clock divider Page 0, Register 27, D(6:0)
DACCK DAC clock divider Page 0, Register 28, D(6:0)
CPCK NCP clock divider Page 0, Register 29, D(6:0)
OSRCK OSR clock divider Page 0, Register 30, D(6:0)
DBCK External BCK Div Page 0, Register 32, D(6:0)
DLRK External LRCK Div Page 0, Register 33, D(7:0)

8.8.5 PLL Calculation

The PCM5242 has an on-chip PLL with fractional multiplication to generate the clock frequency needed by the audio DAC, Negative Charge Pump, Modulator and Digital Signal Processing blocks. The programmability of the PLL allows operation from a wide variety of clocks that may be available in the system. The PLL input (PLLCKIN) supports clock frequencies from 1MHz to 50MHz and is register programmable to enable generation of required sampling rates with fine precision.

The PLL is enabled by default. The PLL can be turned on by writing to Page 0, Register 4, D(0). When the PLL is enabled, the PLL output clock PLLCK is given by Equation 3:

Equation 3. f_pcm51xx_eq_pll_rate_clac.gif

R = 1, 2, 3,4, ... , 15, 16

J = 4,5,6, . . . 63, and D = 0000, 0001, 0002, . . . 9999

K = [J value].[D value]

P = 1, 2, 3, ... 15

R, J, D, and P are programmable. J is the integer portion of K (the numbers to the left of the decimal point), while D is the fractional portion of K (the numbers to the right of the decimal point, assuming four digits of precision).

8.8.5.1 Examples:

  • If K = 8.5, then J = 8, D = 5000
  • If K = 7.12, then J = 7, D = 1200
  • If K = 14.03, then J = 14, D = 0300
  • If K = 6.0004, then J = 6, D = 0004

When the PLL is enabled and D = 0000, the following conditions must be satisfied:

  • 1MHz ≤ ( PLLCKIN / P ) ≤ 20MHz
  • 64MHz ≤ (PLLCKIN x K x R / P ) ≤ 100MHz (in VREF mode)
  • 72MHz ≤ (PLLCKIN x K x R / P ) ≤ 86MHz (in VCOM mode)
  • 1 ≤ J ≤ 63

When the PLL is enabled and D ≠ 0000, the following conditions must be satisfied:

  • 6.667MHz ≤ PLLCLKIN / P ≤ 20MHz
  • 64MHz ≤ (PLLCKIN x K x R / P ) ≤ 100MHz (in VREF mode)
  • 72MHz ≤ (PLLCK IN x K x R / P ) ≤ 86MHz (in VCOM mode)
  • 4 ≤ J ≤ 11
  • R = 1

When the PLL is enabled,

  • fS = (PLLCLKIN × K × R) / (2048 × P)
  • The value of N is selected so that fS × N = PLLCLKIN x K x R / P is in the allowable range.

Example: MCLK = 12MHz and fS = 44.1kHz, (N=2048)

Select P = 1, R = 1, K = 7.5264, which results in J = 7, D = 5264

Example: MCLK = 12MHz and fS = 48.0kHz, (N=2048)

Select P = 1, R = 1, K = 8.192, which results in J = 8, D = 1920

Values are written to the registers in Table 35.

8.8.5.1.1 Recommended PLL settings

Recommended values for the PLL can be found after the register descriptions in this datasheet. Different values are defined based on the device configuration for VREF or VCOM mode.

Other configurations are possible, at your own risk.

Below are details of the register locations, as well as the nomenclature for the table of registers found at the end of this document.

Table 35. PLL Registers

Divider Function Bits
PLLE PLL enable Page 0, Register 4, D(0)
PPDV PLL P Page 0, Register 20, D(3:0)
PJDV PLL J Page 0, Register 21, D(5:0)
PDDV PLL D Page 0, Register 22, D(5:0)
Page 0, Register 23, D(7:0)
PRDV PLL R Page 0, Register 24, D(3:0)

Table 36. PLL Configuration Recommendations

Column Description
fS (kHz) Sampling frequency
RSCK Ratio between sampling frequency and SCK frequency (SCK frequency = RSCK x sampling frequency)
SCK (MHz) System master clock frequency at SCK input (pin 20)
PLL VCO (MHz) PLL VCO frequency as PLLCK in Figure 68
P One of the PLL coefficients in Equation 3
PLL REF (MHz) Internal reference clock frequency which is produced by SCK / P
M = K * R The final PLL multiplication factor computed from K and R as described in Equation 3
K = J.D One of the PLL coefficients in Equation 3
R One of the PLL coefficients in Equation 3
PLL fS Ratio between fS and PLL VCO frequency (PLL VCO / fS)
DSP fS Ratio between miniDSP operating clock rate and fS (PLL fS / NMAC)
NMAC The miniDSP clock divider value in Table 34
DSP CLK (MHz) The miniDSP operating frequency as DSPCK in Figure 68
MOD fS Ratio between DAC operating clock frequency and fS (PLL fS / NDAC)
MOD f (kHz) DAC operating frequency as DACCK in
NDAC DAC clock divider value in Table 34
DOSR OSR clock divider value in Table 34 for generating OSRCK in Figure 68. DOSR must be chosen so that MOD fS / DOSR = 16 for correct operation.
NCP NCP (negative charge pump) clock divider value in Table 34
CP f Negative charge pump clock frequency (fS * MOD fS / NCP)
% Error Percentage of error between PLL VCO / PLL fS and fS (mismatch error).
  • This number is typically zero but can be non-zero especially when K is not an integer (D is not zero).
  • This number may be non-zero only when the PCM5242 acts as a master.

8.8.6 Clock Master Mode from Audio Rate Master Clock

In Master Mode, the device generates bit clock (BCK) and left-right clock (LRCK) and outputs them on the appropriate pins. To configure the device in this mode, first put the device into reset, then use registers BCKO and LRKO (Pg 0, Reg 9 0x09). Then reset the LRCK and BCK divider counters using bits RBCK and RLRK (Pg 0, Reg 12 0x0C). Finally exit reset.

An example of this is given in Register Programming Examples SLAC622.

Figure 69 shows a simplified serial port clock tree for the device in master mode.

f_pcm51xx_serialport_clk_tree.gifFigure 69. Simplified clock tree for SCK sourced master mode

In master mode, SCK is an input and BCK/LRCK are outputs. BCK and LRCK are integer divisions of SCK. Master mode with a non-audio rate master clock source will require external GPIO’s to use the PLL in standalone mode.

The PLL will also need to be configured to ensure that the onchip miniDSP processor can be driven at its maximum clock rate.

Register changes that need to be done include switching the device into master mode, and setting the divider ratio.

Here is an example of using 24.576MCLK as a master clock source and driving the BCK and LRCK with integer dividers to create 48kHz.

In this mode, the DAC section of the device is also running from the PLL output. While the PLL inside the PCM5242 is one that has been spec’d well enough to achieve the stated performance, using the SCK CMOS Oscillator source will have less jitter.

To switch the DAC clocks (SDAC in the Figure 68) the following registers should be modified

  • Clock Tree Flex Mode ( Page 253, Registers 0x3F and 0x40)
  • DAC & OSR Source Clock Register (Page 0, Reg 14) – set to 0x30 (SCK input, and OSR is set to whatever the DAC source is)
  • The DAC clock divider should be 16FS.
    • 16*48kHz = 768kHz
    • 24.576MHz (SCK in) / 768kHz = 32
    • Therefor, divide ratio for register DDAC (Page 0, Reg 28 0x1C) should be set to 32. The may the register is mapped gives 0x00 = 1, so 32 must be converter to 0x1F (31dec).

An example configuration can be found in SLAC622

8.8.7 Clock Master from a Non-Audio Rate Master Clock

The classic example here is running 12MHz Master clock for a 48kHz sampling system. Given the clock tree for the device (shown in Figure 68), a non-audio clock rate cannot be brought into the SCK to the PLL in master mode. Therefore, the PLL source must be configured to be a GPIO pin, and the output brought back into another GPIO pin.

f_pcm51xx_non-aud_mstr_clk.gifFigure 70. Application diagram for using non-audio clock sources to generate audio clocks

The clock flow through the system is shown above. The newly generated SCK must be brought out of the device on a GPIO pin, then brought into the SCK pin for integer division to create BCK and LRCK outputs.

NOTE

Pull up resistors should be used on BCK and LRCK in this mode to ensure the device doesn't go into sleep mode.

A code example for configuring this mode is provided in SLAC622

8.9 Device Functional Modes

8.9.1 Choosing A Control Mode

SPI Mode is selected by connecting MODE1 to DVDD. SPI mode uses four signal lines and allows higher-speed full-duplex communication between the host and the PCM5242.

I2C Mode is selected by connecting MODE1 to DGND and Mode2 to DVDD. I2C uses two signal lines for half-duplex communication, and is widely used in a variety of devices.

Hardware Control Mode is selected by connecting both MODE1 and MODE2 pins to DGND. Hardware control is useful in applications that do not require on-the-fly device-reconfiguration changes in operating features such as gain or filter latency selection.

See Pin Assignments for a comparison of pin assignments for the 32-terminal QFN.

8.9.1.1 Software Control

8.9.1.1.1 SPI Interface

The SPI interface is a 4-wire synchronous serial port which operates asynchronously to the serial audio interface and the system clock (SCK). The serial control interface is used to program and read the on-chip mode registers.

The control interface includes MISO (pin 24), MOSI (pin 11), MC (pin 12), and MS (pin 18). MISO (Master In Slave Out) is the serial data output, used to read back the values of the mode registers; MOSI (Master Out Slave In) is the serial data input, used to program the mode registers.

MC is the serial bit clock, used to shift data in and out of the control port by falling edge of MC, and MS is the mode control enable with LOW active, used to enable the internal mode register access. If feedback from the device is not required, the MISO pin can be assigned to GPIO1 by register control.

8.9.1.1.1.1 Register Read/Write Operation

All read/write operations for the serial control port use 16-bit data words. Figure 71 shows the control data word format. The most significant bit is the read/write bit. For write operations, the bit must be set to 0. For read operations, the bit must be set to 1. There are seven bits, labeled IDX[6:0], that hold the register index (or address) for the read and write operations. The least significant eight bits, D[7:0], contain the data to be written to, or the data that was read from, the register specified by IDX[6:0].

Figure 71 and Figure 72 show the functional timing diagram to write or read through the serial control port. MS is held at a logic-1 state until a register access. To start the register write or read cycle, set MS to logic 0. Sixteen clocks are then provided on MC, corresponding to the 16 bits of the control data word on MOSI and read-back data on MISO. After the eighth clock cycle has completed, the data from the indexed-mode control register appears on MISO during the read operation. After the sixteenth clock cycle has completed, the data is latched into the indexed-mode control register during the write operation. To write or read subsequent data, MS is set to logic 1 once (See tMHH in Figure 76).

f_pcm51xx_mdi_ctrl_data_word_format.gifFigure 71. Control Data Word Format; MDI

NOTE

B8 is used for selection of “Write” or “Read”. Setting = 0 indicates a “Write”, while = 1 indicates a ”Read”. Bits 15–9 are used for register address. Bits 7–0 are used for register data. Multiple-byte write or read (up to 8 bytes) is supported while MS is kept low. The address field becomes the initial address, automatically incrementing for each byte.
f_pcm51xx_td_ser_ctrl_format_wr.gifFigure 72. Serial Control Format; Write, Single Byte
f_pcm51xx_td_ser_ctrl_format__burst_wr.gifFigure 73. Serial Control Format; Write, Multiple Byte
f_pcm51xx_td_ser_ctrl_format_rd.gifFigure 74. Serial Control Format; Read
f_pcm51xx_td_ser_ctrl_format__burst_rd.gifFigure 75. Serial Control Format; Read, Multiple Byte
f_pcm51xx_td_ctrl_if.gifFigure 76. Control Interface Timing

Table 37. Control Interface Timing

Parameters Min Max Units
tMCY MC Pulse Cycle Time 100 ns
tMCL MC Low Level Time 40
tMCH MC High Level Time 40
tMHH MS High Level Time 20
tMSS MS ↓ Edge to MC ↑ Edge 30
tMSH MS Hold Time(1) 30
tMDH MDI Hold Time 15
tMDS MDI Set-up Time 15
tMOS MC Rise Edge to MDO Stable 20
(1) MC falling edge for LSB to MS rising edge.

8.9.1.1.2 I2C Interface

The PCM5242 supports the I2C serial bus and the data transmission protocol for standard and fast mode as a slave device.

In I2C mode, the control terminals are changed as follows.

Table 38. I2C Pins and Functions

Signal Pin I/O Description
SDA 11 I/O I2C data
SCL 12 I I2C clock
ADR2 16 I I2C address 2
ADR1 24 I I2C address 1

8.9.1.1.2.1 Slave Address

Table 39. I2C Slave Address

MSB LSB
1 0 0 1 1 ADR2 ADR1 R/ W

The PCM5242 has 7 bits for its own slave address. The first five bits (MSBs) of the slave address are factory preset to 10011 (0x9x). The next two bits of the address byte are the device select bits which can be user-defined by the ADR1 and ADR0 terminals. A maximum of four devices can be connected on the same bus at one time. This gives a range of 0x98, 0x9A, 0x9C and 0x9E. Each PCM5242 responds when it receives its own slave address.

8.9.1.1.2.2 Register Address Auto-Increment Mode

f_pcm51xx_auto_inc_mode.gifFigure 77. Auto Increment Mode

Auto-increment mode allows multiple sequential register locations to be written to or read back in a single operation, and is especially useful for block write and read operations.

8.9.1.1.2.3 Packet Protocol

A master device must control packet protocol, which consists of start condition, slave address, read/write bit, data if write or acknowledge if read, and stop condition. The PCM5242 supports only slave receivers and slave transmitters.

f_pcm51xx_packet_protocol.gifFigure 78. Packet Protocol

Table 40. Write Operation - Basic I2C Framework

Transmitter M M M S M S M S S M
Data Type St slave address R/ ACK DATA ACK DATA ACK ACK Sp

Table 41. Read Operation - Basic I2C Framework

Transmitter M M M S S M S M M M
Data Type St slave address R/ ACK DATA ACK DATA ACK NACK Sp

M = Master Device; S = Slave Device; St = Start Condition Sp = Stop Condition

8.9.1.1.2.4 Write Register

A master can write to any PCM5242 registers using single or multiple accesses. The master sends a PCM5242 slave address with a write bit, a register address with auto-increment bit, and the data. If auto-increment is enabled, the address is that of the starting register, followed by the data to be transferred. When the data is received properly, the index register is incremented by 1 automatically. When the index register reaches 0x7F, the next value is 0x0. Table 42 shows the write operation.

Table 42. Write Operation

Transmitter M M M S M S M S M S S M
Data Type St slave addr W ACK inc reg addr ACK write data 1 ACK write data 2 ACK ACK Sp

M = Master Device; S = Slave Device; St = Start Condition Sp = Stop Condition; W = Write; ACK = Acknowledge

8.9.1.1.2.5 Read Register

A master can read the PCM5242 register. The value of the register address is stored in an indirect index register in advance. The master sends a PCM5242 slave address with a read bit after storing the register address. Then the PCM5242 transfers the data which the index register points to. When auto-increment is enabled, the index register is incremented by 1 automatically. When the index register reaches 0x7F, the next value is 0x0. Table 43 shows the read operation.

Table 43. Read Operation

Transmitter M M M S M S M M M S S M M M
Data Type St slave addr W ACK inc reg addr ACK Sr slave addr R ACK data ACK NACK Sp

M = Master Device; S = Slave Device; St = Start Condition; Sr = Repeated start condition; Sp = Stop Condition; W = Write; R = Read; NACK = Not acknowledge

8.9.1.1.2.6 Timing Characteristics

f_pcm51xx_td_reg_rd.gifFigure 79. Register Access Timing

Table 44. I2C Bus Timing

SYMBOL PARAMETER CONDITIONS MIN MAX UNIT
fSCL SCL clock frequency Standard 100 kHz
Fast 400 kHz
tBUF Bus free time between a STOP and START condition Standard 4.7 µs
Fast 1.3
tLOW Low period of the SCL clock Standard 4.7 µs
Fast 1.3
tHI High period of the SCL clock Standard 4.0 µs
Fast 600 ns
tRS-SU Setup time for (repeated)START condition Standard 4.7 µs
Fast 600 ns
tS-HD Hold time for (repeated)START condition Standard 4.0 µs
tRS-HD Fast 600 ns
tD-SU Data setup time Standard 250 ns
Fast 100
tD-HD Data hold time Standard 0 900 ns
Fast 0 900
tSCL-R Rise time of SCL signal Standard 20 + 0.1CB 1000 ns
Fast 20 + 0.1CB 300
tSCL-R1 Rise time of SCL signal after a repeated START condition and after an acknowledge bit Standard 20 + 0.1CB 1000 ns
Fast 20 + 0.1CB 300
tSCL-F Fall time of SCL signal Standard 20 + 0.1CB 1000 ns
Fast 20 + 0.1CB 300
tSDA-R Rise time of SDA signal Standard 20 + 0.1CB 1000 ns
Fast 20 + 0.1CB 300
tSDA-F Fall time of SDA signal Standard 20 + 0.1CB 1000 ns
Fast 20 + 0.1CB 300
tP-SU Setup time for STOP condition Standard 4.0 µs
Fast 600 ns
CB Capacitive load for SDA and SCL line 400 pF
tSP Pulse width of spike suppressed Fast 50 ns
VNH Noise margin at High level for each connected device (including hysteresis) 0.2VDD V

8.9.2 Choosing Between VREF and VCOM Modes

See Choosing Between VREF and VCOM Modes for information on configuring these modes.