INTRODUCTION
The number of applications that utilize white LEDs has steadily increased due to the increased usage of Liquid Crystal Displays (LCDs) in automotive and cellular telephone displays, PDAs, handheld electronic games and computer monitors. In order to view the information on these displays, a light source is needed. Typically, this light source has been provided by Cold Cathode Florescent Tubes (CCFT). However, since designers are tasked with improving efficiency, lowering cost and decreasing size, white LEDs are now being used. Powering white LEDs, which have a forward drop (VF) of 3.6V, typically, becomes more difficult when the application requires multiple LEDs. In this Application Note, a solution using the MCP1650 is discussed and shown to be greater than 85% efficient.
