A semiconductor device has a DC-DC converter control circuit for
selectively carrying out a boosting operation and a deboosting operation
in accordance with a value of a power supply voltage supplied to the
DC-DC converter control circuit and for outputting an activation pulse
during a rise of the power supply voltage. The DC-DC converter control
circuit has a voltage detection circuit for monitoring the power supply
voltage to judge whether the DC-DC converter control circuit carries out
the boosting operation or the deboosting operation. A control circuit
controls the output of the activation pulse in accordance with an output
signal from the voltage detection circuit and stops the output of the
activation pulse when the voltage detection circuit judges that the DC-DC
converter control circuit carries out the deboosting operation.