TIDUBF0 January   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 OX01F10 Imager
      2. 2.3.2 DS90UB933-Q1
      3. 2.3.3 TPS650320-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 OX01F10 Initialization
    2. 3.2 Test Setup
      1. 3.2.1 Power Supplies Start Up
      2. 3.2.2 Setup for Verifying I2C Communications
    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 I2C Communications
  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. 5Tools and Software
  11. 6Documentation Support
  12. 7Support Resources
  13. 8Trademarks

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 DS90UB933-Q1 and TPS650320-Q1 additionally both provide compatibility with a wide range of imagers. The choice of a two-board solution highlights this capability, as the power and serializer base board can be reused with different imager boards depending on the camera application. 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 TPS650320-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 TPS650320-Q1 efficiency is about 80%. Using this value, Equation 3 calculates a system input power of about 760 mW. Equation 7 can then be used with the output power of Buck 2, Buck 3, and the LDO to calculate the overall system efficiency.

Equation 7. η S Y S T E M = P O U T P I N = P O U T , 2 + P O U T , 3 + P O U T , L D O P I N , 1 = 68 %