SBAS989 April   2019 PCM1840

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Block Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements: TDM, I2S or LJ Interface
    7. 6.7 Switching Characteristics: TDM, I2S or LJ Interface
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Hardware Control
      2. 7.3.2 Audio Serial Interfaces
        1. 7.3.2.1 Time Division Multiplexed Audio (TDM) Interface
        2. 7.3.2.2 Inter IC Sound (I2S) Interface
        3. 7.3.2.3 Left-Justified (LJ) Interface
      3. 7.3.3 Phase-Locked Loop (PLL) and Clock Generation
      4. 7.3.4 Input Channel Configurations
      5. 7.3.5 Reference Voltage
      6. 7.3.6 Microphone Bias
      7. 7.3.7 Signal-Chain Processing
        1. 7.3.7.1 Digital High-Pass Filter
        2. 7.3.7.2 Configurable Digital Decimation Filters
          1. 7.3.7.2.1 Linear Phase Filters
            1. 7.3.7.2.1.1 Sampling Rate: 8 kHz or 7.35 kHz
            2. 7.3.7.2.1.2 Sampling Rate: 16 kHz or 14.7 kHz
            3. 7.3.7.2.1.3 Sampling Rate: 24 kHz or 22.05 kHz
            4. 7.3.7.2.1.4 Sampling Rate: 32 kHz or 29.4 kHz
            5. 7.3.7.2.1.5 Sampling Rate: 48 kHz or 44.1 kHz
            6. 7.3.7.2.1.6 Sampling Rate: 96 kHz or 88.2 kHz
            7. 7.3.7.2.1.7 Sampling Rate: 192 kHz or 176.4 kHz
          2. 7.3.7.2.2 Low-Latency Filters
            1. 7.3.7.2.2.1 Sampling Rate: 16 kHz or 14.7 kHz
            2. 7.3.7.2.2.2 Sampling Rate: 24 kHz or 22.05 kHz
            3. 7.3.7.2.2.3 Sampling Rate: 32 kHz or 29.4 kHz
            4. 7.3.7.2.2.4 Sampling Rate: 48 kHz or 44.1 kHz
            5. 7.3.7.2.2.5 Sampling Rate: 96 kHz or 88.2 kHz
      8. 7.3.8 Dynamic Range Enhancer (DRE)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Hardware Shutdown
      2. 7.4.2 Active Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.2.3 Left-Justified (LJ) Interface

The standard LJ protocol is defined for only two channels: left and right. In LJ mode, the MSB of the left slot 0 is transmitted in the same BCLK cycle after the rising edge of FSYNC. Each subsequent data bit is transmitted on the falling edge of BCLK. The MSB of the right slot 0 is transmitted in the same BCLK cycle after the falling edge of FSYNC. Each subsequent data bit is transmitted on the falling edge of BCLK. In master mode, FSYNC is transmitted on the rising edge of BCLK. Figure 20 and Figure 21 illustrate the protocol timing for LJ operation in slave and master mode of operation.

PCM1840 lj-01-pcm1840-sbas989.gifFigure 20. LJ Mode Protocol Timing In Slave Mode
PCM1840 lj-02-pcm1840-sbas989.gifFigure 21. LJ Mode Protocol Timing In Master Mode

For proper operation of the audio bus in LJ mode, the number of bit clocks per frame must be greater than or equal to the number of active output channels (including left and right slots) times the 32-bits word length of the output channel data. The device FSYNC high pulse must be a number of BCLK cycles wide that is greater than or equal to the number of active left slots times the 32-bits data word length. Similarly, the FSYNC low pulse must be number of BCLK cycles wide that is greater than or equal to the number of active right slots times the 32-bits data word length. The device transmit zero data value on SDOUT for the extra unused bit clock cycles.