SNLA224A June   2014  – January 2024 DS90UB913A-Q1 , DS90UB954-Q1 , DS90UB960-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Theory of Operation for Power Over Coax
    1. 2.1 Inductor Characteristics
    2. 2.2 Capacitor Characteristics
    3. 2.3 Ferrite Bead Characteristics
  6. 3Design Considerations
    1. 3.1 Frequency Range
    2. 3.2 Power Considerations
    3. 3.3 Inductor Size Considerations
    4. 3.4 Layout Considerations
  7. 4FPD-Link PoC Requirements
    1. 4.1 Channel Requirements
    2. 4.2 PoC Noise Requirements
      1. 4.2.1 VPoC Noise and Pulse
      2. 4.2.2 RIN+ Noise
      3. 4.2.3 Causes of PoC Noise
      4. 4.2.4 Noise Measurement Best Practices
      5. 4.2.5 Reducing Effects of PoC Noise
  8. 5TI Recommended PoC Networks
    1. 5.1 PoC Network From FPD-Link III Data Sheet
    2. 5.2 Murata Networks
      1. 5.2.1 Murata Network 1
      2. 5.2.2 Murata Network 2
      3. 5.2.3 Murata Network 3
    3. 5.3 TDK Networks
      1. 5.3.1 TDK Network 1
      2. 5.3.2 TDK Network 2
      3. 5.3.3 TDK Network 3
      4. 5.3.4 TDK Network 4
      5. 5.3.5 TDK Network 5
      6. 5.3.6 TDK Network 6
      7. 5.3.7 TDK Network 7
      8. 5.3.8 TDK Network 8
    4. 5.4 Coilcraft Networks
      1. 5.4.1 Coilcraft Network 1
      2. 5.4.2 Coilcraft Network 2
      3. 5.4.3 Coilcraft Network 3
      4. 5.4.4 Coilcraft Network 4
  9. 6Summary
  10. 7References
  11. 8Revision History

4.2.1 VPoC Noise and Pulse

VPoC noise is the measurement of noise introduced into the system from serializer and sensor operation. Figure 4-2 shows a typical waveform measured from the input of the DC regulators. The supply noise is introduced from the switching of DC buck regulators, and the pulse is due to the switching of the sensor. During periods of blanking, the current draw from the sensor is significantly lower than during active periods, which causes the voltage to spike.

GUID-0F92603F-DB30-4659-997A-19EEBB19DEB1-low.svg Figure 4-2 VPoC Noise

The VPoC must meet the following requirements for proper FPD-Link operation.

  • VPoC supply noise must be less than 100mV peak-to-peak
  • VPoC pulse must be less than 500mV peak-to-peak (from image sensor blanking and valid periods)
  • VPoC pulse slew rate must be greater than 200μs/V

The VPoC of a PoC network can be measured with the following procedure.

  1. Connect the serializer to the deserializer through coax
  2. Measure the noise floor of the oscilloscope by shorting the probe to ground
  3. Power the entire system (sensor, serializer, deserializer, and so on.)
    1. Verify the image sensor is configured to capture video data
  4. Set the oscilloscope bandwidth to 0 – 50MHz
  5. Probe VPoC at the input of DC regulators on the serializer board
  6. Subtract the noise floor measurement from the VPoC noise measurement