SLOS809 March   2017 TAS6424L-Q1


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. Parameter measurement Information
  9. Detailed description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Serial Audio Port
        1. I2S Mode
        2. Left-Justified Timing
        3. Right-Justified Timing
        4. TDM Mode
        5. Supported Clock Rates
        6. Audio-Clock Error Handling
      2. 9.3.2  High-Pass Filter
      3. 9.3.3  Volume Control and Gain
      4. 9.3.4  High-Frequency Pulse-Width Modulator (PWM)
      5. 9.3.5  Gate Drive
      6. 9.3.6  Power FETs
      7. 9.3.7  Load Diagnostics
        1. DC Load Diagnostics
        2. Line Output Diagnostics
        3. AC Load Diagnostics
      8. 9.3.8  Protection and Monitoring
        1. Overcurrent Limit (ILIMIT)
        2. Overcurrent Shutdown (ISD)
        3. DC Detect
        4. Clip Detect
        5. Global Overtemperature Warning (OTW), Overtemperature Shutdown (OTSD)
        6. Channel Overtemperature Warning [OTW(i)] and Shutdown [OTSD(i)]
        7. Undervoltage (UV) and Power-On-Reset (POR)
        8. Overvoltage (OV) and Load Dump
      9. 9.3.9  Power Supply
        1. Vehicle-Battery Power-Supply Sequence
      10. 9.3.10 Hardware Control Pins
        1. FAULT
        2. WARN
        3. MUTE
        4. STANDBY
    4. 9.4 Device Functional Modes
      1. 9.4.1 Operating Modes and Faults
    5. 9.5 Programming
      1. 9.5.1 I2C Serial Communication Bus
      2. 9.5.2 I2C Bus Protocol
      3. 9.5.3 Random Write
      4. 9.5.4 Sequential Write
      5. 9.5.5 Random Read
      6. 9.5.6 Sequential Read
    6. 9.6 Register Maps
      1. 9.6.1  Mode Control Register (address = 0x00) [default = 0x00]
      2. 9.6.2  Miscellaneous Control 1 Register (address = 0x01) [default = 0x32]
      3. 9.6.3  Miscellaneous Control 2 Register (address = 0x02) [default = 0x62]
      4. 9.6.4  SAP Control (Serial Audio-Port Control) Register (address = 0x03) [default = 0x04]
      5. 9.6.5  Channel State Control Register (address = 0x04) [default = 0x55]
      6. 9.6.6  Channel 1 Through 4 Volume Control Registers (address = 0x05-0x08) [default = 0xCF]
      7. 9.6.7  DC Load Diagnostic Control 1 Register (address = 0x09) [default = 0x00]
      8. 9.6.8  DC Load Diagnostic Control 2 Register (address = 0x0A) [default = 0x11]
      9. 9.6.9  DC Load Diagnostic Control 3 Register (address = 0x0B) [default = 0x11]
      10. 9.6.10 DC Load Diagnostic Report 1 Register (address = 0x0C) [default = 0x00]
      11. 9.6.11 DC Load Diagnostic Report 2 Register (address = 0x0D) [default = 0x00]
      12. 9.6.12 DC Load Diagnostics Report 3 Line Output Register (address = 0x0E) [default = 0x00]
      13. 9.6.13 Channel State Reporting Register (address = 0x0F) [default = 0x55]
      14. 9.6.14 Channel Faults (Overcurrent, DC Detection) Register (address = 0x10) [default = 0x00]
      15. 9.6.15 Global Faults 1 Register (address = 0x11) [default = 0x00]
      16. 9.6.16 Global Faults 2 Register (address = 0x12) [default = 0x00]
      17. 9.6.17 Warnings Register (address = 0x13) [default = 0x20]
      18. 9.6.18 Pin Control Register (address = 0x14) [default = 0x00]
      19. 9.6.19 AC Load Diagnostic Control 1 Register (address = 0x15) [default = 0x00]
      20. 9.6.20 AC Load Diagnostic Control 2 Register (address = 0x16) [default = 0x00]
      21. 9.6.21 AC Load Diagnostic Impedance Report Ch1 through CH4 Registers (address = 0x17-0x1A) [default = 0x00]
      22. 9.6.22 AC Load Diagnostic Phase Report High Register (address = 0x1B) [default = 0x00]
      23. 9.6.23 AC Load Diagnostic Phase Report Low Register (address = 0x1C) [default = 0x00]
      24. 9.6.24 AC Load Diagnostic STI Report High Register (address = 0x1D) [default = 0x00]
      25. 9.6.25 AC Load Diagnostic STI Report Low Register (address = 0x1E) [default = 0x00]
      26. 9.6.26 Miscellaneous Control 3 Register (address = 0x21) [default = 0x00]
      27. 9.6.27 Clip Control Register (address = 0x22) [default = 0x01]
      28. 9.6.28 Clip Window Register (address = 0x23) [default = 0x14]
      29. 9.6.29 Clip Warning Register (address = 0x24) [default = 0x00]
      30. 9.6.30 ILIMIT Status Register (address = 0x25) [default = 0x00]
      31. 9.6.31 Miscellaneous Control 4 Register (address = 0x26) [default = 0x40]
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 AM-Radio Band Avoidance
      2. 10.1.2 Parallel BTL Operation (PBTL)
      3. 10.1.3 Demodulation Filter Design
      4. 10.1.4 Line Driver Applications
    2. 10.2 Typical Applications
      1. 10.2.1 BTL Application
        1. Design Requirements
        2. Communication
        3. Detailed Design Procedure
          1. Hardware Design
          2. Digital Input and the Serial Audio Port
          3. Bootstrap Capacitors
          4. Output Reconstruction Filter
        4. Application Curves
      2. 10.2.2 PBTL Application
        1. Design Requirements
          1. Detailed Design Procedure
        2. Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Electrical Connection of Thermal pad and Heat Sink
      2. 12.1.2 EMI Considerations
      3. 12.1.3 General Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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


Layout Guidelines

The pinout of the TAS6424L-Q1 was selected to provide flowthrough layout with all high-power connections on the right side, and all low-power signals and supply decoupling on the left side.

Figure 65 shows the area for the components in the application example (see the Typical Applications section).

The TAS6424L-Q1 EVM uses a four-layer PCB. The copper thickness was selected as 70 µm to optimize power loss.

The small value of the output filter provides a small size and, in this case, the low height of the inductor enables double-sided mounting.

The EVM PCB shown in Figure 65 is the basis for the layout guidelines.

Electrical Connection of Thermal pad and Heat Sink

For the DKQ package, the heat sink connected to the thermal pad of the device should be connected to GND. The heat slug must not be connected to any other electrical node.

EMI Considerations

Automotive-level EMI performance depends on both careful integrated circuit design and good system-level design. Controlling sources of electromagnetic interference (EMI) was a major consideration in all aspects of the design. The design has minimal parasitic inductances because of the short leads on the package which reduces the EMI that results from current passing from the die to the system PCB. Each channel also operates at a different phase. The design also incorporates circuitry that optimizes output transitions that cause EMI.

For optimizing the EMI a solid ground layer plane is recommended, for a PCB design the fulfills the CISPR25 level 5 requirements, see the TAS6424L-Q1 EVM layout.

General Guidelines

The EVM layout is optimized for low noise and EMC performance.

The TAS6424L-Q1 has an exposed thermal pad that is up, away from the PCB. The layout must consider an external heat sink.

Refer to Figure 65 for the following guidelines:

  • A ground plane, A, on the same side as the device pins helps reduce EMI by providing a very-low loop impedance for the high-frequency switching current.
  • The decoupling capacitors on PVDD, B, are very close to the device with the ground return close to the ground pins.
  • The ground connections for the capacitors in the LC filter, C, have a direct path back to the device and also the ground return for each channel is the shared. This direct path allows for improved common mode EMI rejection.
  • The traces from the output pins to the inductors, D, should have the shortest trace possible to allow for the smallest loop of large switching currents.
  • Heat-sink mounting screws, E, should be close to the device to keep the loop short from the package to ground.
  • Many vias, F, stitching together the ground planes can create a shield to isolate the amplifier and power supply.

Layout Example

TAS6424L-Q1 EVM_LAYOUT_TAS6424L.gif Figure 65. EVM Layout

Thermal Considerations

The thermally enhanced PowerPAD package has an exposed pad up for connection to a heat sink. The output power of any amplifier is determined by the thermal performance of the amplifier as well as limitations placed on it by the system, such as the ambient operating temperature. The heat sink absorbs heat from the TAS6424L-Q1 and transfers it to the air. With proper thermal management this process can reach equilibrium and heat can be continually transferred from the device. Heat sinks can be smaller than that of classic linear amplifier design because of the excellent efficiency of class-D amplifiers. This device is intended for use with a heat sink, therefore, RθJC will be used as the thermal resistance from junction to the exposed metal package. This resistance will dominate the thermal management, so other thermal transfers will not be considered. The thermal resistance of RθJA (junction to ambient) is required to determine the full thermal solution. The thermal resistance is comprised of the following components:

  • RθJC of the TAS6424L-Q1
  • Thermal resistance of the thermal interface material
  • Thermal resistance of the heat sink

The thermal resistance of the thermal interface material can be determined from the manufacturer’s value for the area thermal resistance (expressed in °Cmm2/W) and the area of the exposed metal package. For example, a typical, white, thermal grease with a 0.0254 mm (0.001 inch) thick layer is approximately 4.52°C mm2/W. The TAS6424L-Q1 in the DKQ package has an exposed area of 47.6 mm2. By dividing the area thermal resistance by the exposed metal area determines the thermal resistance for the thermal grease. The thermal resistance of the thermal grease is 0.094°C/W

Table 41 lists the modeling parameters for one device on a heat sink. The junction temperature is assumed to be 115°C while delivering and average power of 10 watts per channel into a 4 Ω load. The thermal-grease example previously described is used for the thermal interface material. Use Equation 1 to design the thermal system.

Equation 1. RθJA = RθJC + thermal interface resistance + heat sink resistance

Table 41. Thermal Modeling

Description Value
Ambient Temperature 25°C
Average Power to load 40W (4x 10w)
Power dissipation 8W (4x 2w)
Junction Temperature 115°C
ΔT inside package 5.6°C (0.7°C/W × 8W)
ΔT through thermal interface material 0.75°C (0.094°C/W × 8W)
Required heat sink thermal resistance 10.45°C/W ([115°C – 25°C – 5.6°C – 0.75°C] / 8W)
System thermal resistance to ambient RθJA 11.24°C/W