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

1.1 Design Overview

The LP8866-Q1 is an automotive high-voltage LED driver for automotive infotainment, clusters, HUD and other automotive display LED backlight applications. It integrates a boost controller and six current sinks. A reference board is built to evaluate its Electromagnetic Interference (EMI) performance. The schematic and board layout are shown in Figure 1, Figure 2 and Figure 3. A four-layer board is used with two internal ground planes. A LED load board is connected to the LP8866-Q1 driver board with seven 20-cm long jumper wires to simulate the load configuration in the real application.

LP8866-Q1 snva964-schematic.gifFigure 1. LP8866-Q1 Reference Design Schematic

LP8866-Q1 LP8866EVM Layout-top.pngFigure 2. Layout - Top Layer

LP8866-Q1 LP8866EVM Layout-bottom.pngFigure 3. Layout - Bottom Layer