The AME5170 is a fixed off-time step-up DC/DC converterin a small SOT-25 package. The AME5170 is idealfor LCD panels requiring low current and high efficiencyas well as LED application for cellular phone backlighting,PDAs, and other hand-held devices. The low 400ns offtime allows the use of tiny external components.AME5170 is designed to drive up to four white LEDs inseries with a constant current from a single Li-lon battery.To control LED brightness, the LED current can beadjusted by applying a PWM (pulse width modulated)signal with a frequency range of 100Hz to 50KHz to theEN pin.