A voltage conversion circuit is provided for efficiently converting the
voltage of a DC power source into a lower voltage in accordance with load
currents of voltage converters. An electronic apparatus includes: a DC
power source for supplying a first DC supply voltage; a first DC voltage
converter for converting the first DC supply voltage into a second DC
supply voltage which is lower than the first DC supply voltage; a second
DC voltage converter for converting either the first DC supply voltage or
the second DC supply voltage at an input voltage terminal thereof into a
third DC supply voltage which is lower than the second DC supply voltage;
a switch for selecting and supplying one of the first DC supply voltage
of the DC power source and the second DC supply voltage of the first DC
voltage converter to the input voltage terminal of the second DC voltage
converter, in accordance with a control signal; a switching controller
for providing the control signal to the switch; and a plurality of
components, ones of the components receiving the second DC supply
voltage, ones of the components receiving the third DC supply voltage.