XC9503 series are PWM controlled, PWM/PFM automatic switching controlled, multi-functional, 2 channel step-down DC/DC controller ICs. Since the series has a built-in 0.9V reference voltage (accuracy ±2%), 0.9V to 6.0V can be set using external components. With a 300kHz frequency, the size of the external components can be reduced. Switching frequencies of 180kHz & 500kHz are also available as custom-designed products. The control of the XC9503 series can be switched between PWM control and PWM/PFM automatic switching control using external signals. Control switches from PWM to PFM during light loads when automatic switching is selected and the series is highly efficient from light loads through to large output currents. Noise is easily reduced with PWM control since the frequency is fixed. The series gives freedom to select control suited to the application. Soft-start time is internally set to 10msec and offers protection against in-rush currents when the power is switched on and also protects against voltage overshoot.