This reference design contains two duplicate LED drivers. Each circuit drives a 10V to 60V series connected string of LEDs at 350mA. The input range is 70VDC to 90VDC. The TPS40210 boost controller is used in an upside-down" buck topology for a simple: low-cost solution. This circuit includes an enable: PWM dimming: current trimming: and a current sense functions for interfacing with an external microprocessor."