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

1 System Description

Many automotive applications require small form factors with reduced circuit area that enable compact and modular systems. As a result, most cameras along with electronic components must meet strict area constraints when designing ADAS camera applications. This reference design addresses this challenge by including a 8.3-megapixel imager, 4.16 Gbps serializer, and a single Power Management IC, and all components contained within an area of an 20-mm × 20-mm circuit board. The only connection required by the system is a single 50-Ω coaxial cable.

DC Power, the FPD-Link front-channel, and the FPD-Link back-channel enter the board through the FAKRA coax connector. The filter in Figure 1-1 blocks all of the high-speed content of the signal (without significant attenuation) while allowing the DC (power) portion of the signal to pass through inductor L5.

GUID-82ADE021-F123-4FFA-B412-B5789EAB6B87-low.gif Figure 1-1 FPD-Link III Signal Path

The DC portion is connected to the buck 1 input of the TPS650330-Q1 Power Management IC. This voltage powers buck 2 and buck 3 of the device, which are responsible for creating the supply rails to the imager and serializer. The LDO input pin is supplied 3.3 V, which is responsible for providing a low-noise, 2.8-V analog supply to the imager. Buck 3 outputs the imager-dedicated 1.1-V and buck 2 generates a universal 1.8-V digital supply that is shared by both the imager and serializer. The high-frequency portion of the signal is connected directly to the serializer. This is the path that the video data and the control back channel takes between the serializer and deserializer.

The output of the imager is connected through a MIPI 4-lane CSI-2 interface to the serializer. The serializer transmits this video data over a single LVDS pair to the deserializer located on the other end of the coax cable.

Additionally, on the same coax cable, there is a separate low-latency, bidirectional control channel that provides the additional function of transmitting control information from an I2C port. This control channel is independent of the video blanking period. It is used by the system microprocessor to configure and control the imager.