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AN 1809 PL21 1810 124440 ILD8150/E 80 V high side buck LED driver IC with hybrid dimming Operation, design guide and performance About this document Scope and purpose This application note introduces Infineons hysteretic high-side MOSFET buck DC-DC LED driver IC ILD8150 for general lighting applications. It describes the device operation, features and component value calculations and selection. An example of the reference design performance is shown. ILD8150 provides a highly efficient solution up to 97 percent with superior hybrid dimming performance, and various protections such as cycle-by- cycle current limitation and over-temperature protection. Intended audience This document is intended for engineers and students who design highly efficient LED drivers with a wide dimming range. Table of contents About this document ....................................................................................................................... 1 Table of contents ............................................................................................................................ 1 1 Introduction .......................................................................................................................... 3 1.1 Features ................................................................................................................................................... 3 1.2 Applications ............................................................................................................................................. 3 2 Circuit description .................................................................................................................. 4 2.1 Operation ................................................................................................................................................. 4 2.1.1 Current regulation .............................................................................................................................. 4 2.2 Cycle-by-cycle current limitation ........................................................................................................... 5 2.2.1 OTP ..................................................................................................................................................... 5 2.2.2 UVLO ................................................................................................................................................... 5 2.2.3 Dimming ............................................................................................................................................. 6 2.2.4 Dim-to-off ........................................................................................................................................... 7 2.2.5 Soft-start ............................................................................................................................................. 7 2.2.6 Shut-down .......................................................................................................................................... 8 2.2.7 Floating driver and bootstrap supply ................................................................................................ 8 2.2.8 V pin ESD protection ........................................................................................................................ 9 IN 2.2.9 OVP by CS pin ..................................................................................................................................... 9 2.2.10 Microcontroller use .......................................................................................................................... 10 2.3 Component selection ............................................................................................................................ 11 2.3.1 Current Sense (CS) resistor .............................................................................................................. 11 2.3.2 Inductor and switching frequency selection ................................................................................... 11 2.3.3 Diode D selection ............................................................................................................................. 11 2.3.4 Input capacitor C selection ............................................................................................................ 12 IN 2.3.5 Output capacitor C selection ....................................................................................................... 12 OUT 2.3.6 Bootstrap capacitor CBOOT selection ................................................................................................ 13 Application Note Please read the Important Notice and Warnings at the end of this document V 1.1 www.infineon.com/ild8150 page 1 of 29 2021-03-10 ILD8150 80 V high side buck LED driver IC with hybrid dimming Introduction 2.4 Layout consideration ............................................................................................................................ 13 2.5 Design example ..................................................................................................................................... 13 2.5.1 Determine R ................................................................................................................................... 14 CS 2.5.2 Select switching frequency .............................................................................................................. 14 2.5.1 Inductor value and its current calculation ...................................................................................... 14 2.5.2 Diode selection ................................................................................................................................. 14 2.5.3 C capacitor selection...................................................................................................................... 14 IN 2.5.4 C capacitor selection ................................................................................................................... 15 OUT 2.5.5 Bootstrap capacitor C selection ................................................................................................ 15 BOOT 2.5.6 V capacitor C selection .............................................................................................................. 15 CC VCC 3 Application circuit ................................................................................................................. 16 3.1 Schematic layout ................................................................................................................................... 16 3.2 PCB layout ............................................................................................................................................. 17 4 Measurement results with reference design ............................................................................. 18 4.1 LED current vs supply voltage ............................................................................................................... 18 4.2 Dimming ................................................................................................................................................ 19 4.3 Soft-start ................................................................................................................................................ 20 4.4 Cycle-by-cycle current limitation ......................................................................................................... 20 4.5 Efficiency................................................................................................................................................ 21 4.6 Thermal behavior .................................................................................................................................. 21 4.7 Output current ripple ............................................................................................................................ 22 5 Application with flyback converter XDPL8219 .......................................................................... 24 6 Appendix A ........................................................................................................................... 25 7 References ........................................................................................................................... 27 Revision history............................................................................................................................. 28 Application Note 2 of 29 V 1.1 2021-03-10