Semiconductor device, switching power supply control IC and switching power supply device

摘要

Aspects of the invention can include a semiconductor device, control IC for switching power supply and switching power supply unit, which allow input voltage detecting function to be realized without resistor-voltage dividing circuit. An npn-type element consisting of p-type region, collector region and emitter region is included inside of drain region of starting element. On a first interlayer insulating film, aspects of the invention can provide collector electrode wiring of npn-type element, emitter-drain electrode wiring serving as both emitter electrode wiring of npn-type electrode and drain electrode wiring of starting element, source electrode wiring of starting element, and gate electrode wiring of starting element. A first metal wiring can serve both as input terminal of starting element and input terminal of npn-type element is connected to collector electrode wiring. The npn-type element can function as input voltage detecting means for detecting input voltage drop applied to the first wiring.