U40LPDCDC1P1V1 is a high efficiency, low quiescent-current buck converter, suitable for applications where the input voltage is higher than the output. The buck converter is based on a fixed frequency, pulse-width-modulation (PWM) controller using synchronous rectification to obtain the highest efficiency. At low load currents, the converter enters Power Save Mode to maintain high efficiency over the complete load current range. The PFM pin allows the user to select between automatic-PFM/PWM mode operation and forced-PWM operation.