The LT®3599 is a fi xed frequency 2A step-up DC/DC converter designed to drive four strings of 100mA LEDs up to a 44V output voltage. The switching frequency is programmable from 200kHz to 2.5MHz through an external resistor. LED dimming can be achieved with analog dimming on the CTRL pin, and with pulse width modulation dimming on the PWM pin. The LT3599 accurately regulates LED current even when the input voltage is higher than the LED output voltage. Additional features include programmable LED current derating, switching frequency synchronization to an external clock, LED string disable control, OPENLED alert pin, SHORTLED alert pins and programmable maximum output voltage when all LED strings are disconnected. The LT3599 is available in the thermally enhanced 32-pin (5mm × 5mm) QFN and 28-pin TSSOP packages.