A switching regulator includes a reference voltage generator and a
switching-regulating module. The reference voltage generator receives a
digital control signal and generates a reference voltage according to the
digital control signal. The switching-regulating module is connected to
the reference voltage generator and generates an output voltage according
to the reference voltage. The value of the digital control signal is
gradually increased to make the reference voltage being gradually
increased at the initial stage of the activation of the switching
regulator.