A DC regulated power supply includes: a power transistor provided for each output
of a plurality of systems; a control IC, which compares a feedback value of an
output voltage and a reference voltage from a reference voltage source, and controls
a base current of the power transistor according to a difference of the feedback
value and the reference voltage, so as to regulate the output voltage; and an overheat
protection circuit, which lowers the reference voltage of the reference voltage
source upon detecting an overheated state in the power transistor. The DC regulated
power supply is able to simultaneously suppress transistor base currents of different
systems and eliminate regulation malfunctions in the overheat protection operation,
thereby suppressing fluctuations of output voltage.
