SNVAA88 December   2023 LM51581-Q1 , TPS1H000-Q1 , TPS92642-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2System Description
    1. 2.1 Dual Cable Concept
    2. 2.2 Single Cable Concept
  6. 3Camera Module Design with Single Coaxial Cable Connection
    1. 3.1 Power-Over-Coax Filter
    2. 3.2 Boost Converter
    3. 3.3 High-Side Switch
    4. 3.4 Buffer Capacitor
    5. 3.5 LED Driver
    6. 3.6 Serializer
    7. 3.7 Design Steps
  7. 4Test Results
    1. 4.1 LED and PoC Voltage Waveforms
    2. 4.2 Margin Analysis Program Result
    3. 4.3 Differential Supply Noise Level
    4. 4.4 Test Cases
  8. 5Summary
  9. 6References

4.3 Differential Supply Noise Level

The differential supply noise level is measured directly between the Dout+ and Dout- pins of the serializer and has direct impact on the FPD-Link back channel performance. The noise limit for FPD-Link III is 25 mVpp in the frequency range of 0 – 50 MHz. To correctly measure the differential supply noise, both the serializer and deserializer need to be powered down by pulling the PDB pins low on both devices. Figure 4-8 shows the noise level with pulsing LEDs.

GUID-20230928-SS0I-TSWN-WLM8-60Q8CJ52192P-low.png Figure 4-4 Differential Supply Noise

The measured noise level is 20 mVpp, which is below the mentioned limit of 25 mVpp specified for FPD-Link III.