The NCP1501 is a dual mode regulator that operates either as a PWM Buck Converter or as a Low Drop Out Linear Regulator. If a synchronization signal is present, the NCP1501 operates as a current mode PWM converter with synchronous rectification. The synchronization signal allows the user to control the location of the spurious frequency noise generated by a PWM converter. Linear mode is active when a synchronization signal is not present. The NCP1501 configuration allows an efficient high power operation and low noise during system sleep modes.