TIDUF05 August   2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 PCB and Form Factor
      2. 2.2.2 Power Supply Design
        1. 2.2.2.1 POC Filter
        2. 2.2.2.2 Power Supply Considerations
          1. 2.2.2.2.1 Choosing External Components
          2. 2.2.2.2.2 Choosing the Buck 1 Inductor
          3. 2.2.2.2.3 Choosing the Buck 2 and Buck 3 Inductors
        3. 2.2.2.3 Functional Safety
    3. 2.3 Highlighted Products
      1. 2.3.1 AR0820 Imager
      2. 2.3.2 DS90UB953-Q1
      3. 2.3.3 TPS650330-Q1
    4. 2.4 System Design Theory
  8. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1 Hardware Setup
      2. 3.1.2 FPD-Link III I2C Initialization
      3. 3.1.3 AR0820 Initialization
    2. 3.2 Test Setup
      1. 3.2.1 Power Supplies Start Up
      2. 3.2.2 Camera Functionality
    3. 3.3 Test Results
      1. 3.3.1 Power Supplies Start-Up
      2. 3.3.2 Power Supply Start-Up—1.8-V Rail and PDB
      3. 3.3.3 Power Supply Voltage Ripple
      4. 3.3.4 Power Supply Load Currents
      5. 3.3.5 Video Output
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 Bill of Materials
      3. 4.1.3 PCB Layout Recommendations
        1. 4.1.3.1 Layout Prints
        2. 4.1.3.2 PMIC Layout Recommendations
        3. 4.1.3.3 Serializer Layout Recommendations
        4. 4.1.3.4 Imager Layout Recommendations
        5. 4.1.3.5 PCB Layer Stackup Recommendations
      4. 4.1.4 Altium Project
      5. 4.1.5 Gerber Files
  10. 5Documentation Support
  11. 6Support Resources
  12. 7Trademarks

2.4 System Design Theory

The main design challenges to consider for automotive cameras are size, ease of use, and thermal efficiency. Automotive cameras are often placed in remote regions of the vehicle where area is limited, requiring an overall compact solution. Because of this, the system is designed around having the lowest number of components with a fully-integrated PMIC power solution. The ease of use and design flexibility offered by a PMIC solution is also critical to enable a single platform design and reduce development time as ADAS applications continue to grow. The DS90UB953-Q1 and TPS650330-Q1 additionally both provide compatibility with a wide range of imagers. Lastly, the small size and remote placement of these cameras increases their susceptibility to heat. A power-efficient system is crucial to preserve the image quality in these conditions. The TPS650330-Q1 device is optimized for efficiency with a three-buck and one-LDO regulator topology, enabling the support of medium- and high-quality imagers without sacrificing thermal performance. Due to the impact of thermals on the system performance, it is important to calculate total system efficiency as part of the design process. From the Buck 1 output power in Table 2-2, the TPS650330-Q1 efficiency is about 90%. Using this value, Equation 5 calculates a system input power of about 1.4 W. Equation 5 can then be used with the output power of Buck 2, Buck 3, and the LDO to calculate the overall system efficiency.

Equation 5. ηSYSTEM=POUTPIN=POUT,2+POUT,3+POUT,LDOPIN,1=75%