SNVA964 June   2020 LP8866-Q1

 

  1.   LP8866-Q1 Typical Design Guidelines to Achieve CISPR 25 Class 5 Conducted and Radiated Emissions Compliance
    1.     Trademarks
    2. 1 Typical Reference Design
      1. 1.1 Design Overview
      2. 1.2 Test Condition
      3. 1.3 CISPR 25 Measurement Results
    3. 2 EMI Mitigation Techniques Discussion
      1. 2.1 Spread Spectrum
      2. 2.2 Gate Resistor
      3. 2.3 LED Current Sink Capacitors
      4. 2.4 Layout Consideration
      5. 2.5 Inductor Selection
      6. 2.6 Boost Output Ferrite Bead
      7. 2.7 Common Mode Filter
    4. 3 Summary

2 EMI Mitigation Techniques Discussion

In this section we’ll look at the effects of several different techniques and measures to see how they impact the EMI performance of this design. Conducted emissions (current probe method) and radiated emissions measurements are performed. In this case, the current probe method is used to measure conducted emissions on the input power supply wire harness. It measures the common mode current on the power lines which is closely correlated to the radiated emissions from the wires. In this case, the conducted emission measurement result is well correlated to the radiated emission measurement result in the frequency range of 30 MHz to 300 MHz, so the conducted/radiated EMI comparisons are shown together.