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

4.2.2 RIN+ Noise

RIN+ noise is the noise measured on the deserializer board at the input of the RIN+ pin. The RIN+ noise must be less than 10 mV peak-to-peak between 0 and 50 MHz to prevent degradation of the FPD-Link signal.

To accurately measure RIN+ noise in the system, the image sensor and all other load carrying devices on the serializer side must be actively drawing current. The forward channel and back channel transmissions generated by the connected serializer and deserializer must also be disabled to prevent interference in the noise measurements. To disable the forward channel and back channel transmissions, the PDB pin on the serializer and deserializer devices must be pulled to GND. The image sensor is expected to contribute to the RIN+ noise when actively capturing video data. Therefore if the image sensor is not enabled at the time of measurement, the results do not accurately represent the RIN+ noise of the system. An example of the RIN+ noise measurement procedure is listed in the following:

  1. Rework the serializer and deserializer boards such that the PDB pin on the serializer and deserializer are both pulled to GND for the duration of the measurement
  2. Solder wire connections from the I2C bus (SCL, SDA, GND) on the serializer board to an external I2C Controller
  3. Connect the serializer and deserializer boards using a coax cable
  4. If not determined previously during VPoC measurement, measure the noise floor of the oscilloscope by shorting the probe to ground
  5. Power the entire system (sensor, serializer, deserializer, and so on)
  6. Configure the image sensor locally through the external I2C controller and confirm that video is being generated
  7. Set the oscilloscope bandwidth to 0 – 50MHz
  8. Probe RIN+ noise at a point close to the deserializer pin using a short probe tip for measuring ground
  9. Account for noise floor by subtracting the noise floor measurement from the RIN+ noise measurement