TIDUF06 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
          4. 2.2.2.2.4 Functional Safety
    3. 2.3 Highlighted Products
      1. 2.3.1 DS90UB953-Q1
      2. 2.3.2 TPS650330-Q1
      3. 2.3.3 IMX623
    4. 2.4 System Design Theory
  8. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Required Hardware
      1. 3.1.1 Hardware Setup
      2. 3.1.2 FPD-Link III I2C Initialization
      3. 3.1.3 IMX623 Initialization
    2. 3.2 Testing and Results
      1. 3.2.1 Test Setup
        1. 3.2.1.1 Power Supplies Startup
        2. 3.2.1.2 Power Supply Startup – 1.8 V Rail and Serializer PDB Setup
      2. 3.2.2 Test Results
        1. 3.2.2.1 Power Supplies Start Up
        2. 3.2.2.2 Power Supply Output Voltage Ripple
        3. 3.2.2.3 Power Supply Load Currents
        4. 3.2.2.4 I2C Communications
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1 PMIC Layout Recommendations
      2. 4.3.2 PCB Layer Stackup
      3. 4.3.3 Serializer Layout Recommendations
      4. 4.3.4 Imager Layout Recommendations
      5. 4.3.5 Layout Prints
    4. 4.4 Altium Project
    5. 4.5 Gerber Files
    6. 4.6 Assembly Drawings
  10. 5Related Documentation
  11. 6Trademarks

2.2.2.2 Power Supply Considerations

This reference design targets automotive applications, so there are several requirements that shape the design choices:

  • The board area needs to be minimized to 20 mm × 20 mm. A fully-integrated PMIC power solution minimizes the external component count, making this requirement easier to achieve.
  • Switching frequencies must be lower than 540 kHz or higher than 1700 kHz to avoid interfering with the AM radio band. Choosing a higher switching frequency prevents harmonics encroaching in the AM band, and allows for smaller external components to aid the board area requirements.
  • All devices must be AEC Q100-Q1 rated.

    The system input voltage is a pre-regulated 9-V supply over coax. As the PMIC integrates supervisors and monitoring, the only system components requiring power are the imager, serializer, and oscillator. Table 2-1 shows the maximum power consumption of these devices:

Table 2-1 System Power Budget
PARAMETER VOLTAGE (V) CURRENT (mA) POWER (mW)
Imager
3.3 79 261
1.8 9 16
1.1 383 421
Serializer
1.8 225 405
Oscillator
1.8 3

5
Total
3.3 79 261
1.8 237 427
1.1 383 421