PURPOSE: To provide a simple current protection, linear power source characteristics, and the boost ability of a certain switching connection form as well by integrating both a linear type regulator circuit and a switching type regulator circuit into a power source.

CONSTITUTION: This power source is provided with a linear regulator 20, a switching regulator 40 and a feedback system 60 and a DC input signal Vraw of non-regulated 15-volt is supplied to the linear regulator 20. The regulator 20 is a simple transistor type current regulator. An output from the linear regulator 20 is sent to the switching regulator 40. The switching regulator 40 completely forms an open loop by itself and is simplified since any duty cycle control or any current mode control does not exist. The switching regulator 40 has the boost connection form and generates the regulated output of 30-volt. A feedback signal is supplied from the output of the switching regulator 40 to the control current source 20.