Patent ID: 7183757

Claim:
A switching power source having an integrator which integrates an input signal, a comparator which compares an output from the integrator with a quantization reference value, a sampling circuit which samples an output from the comparator in synchronism with a clock signal, and a modulator which quantizes the output from the integrator, outputs a quantized signal, and negative-feeds back the quantized signal to suppress a quantization error of the input signal, thereby modulating an analog signal or multi-bit digital signal by the modulator, and driving a power switching element in accordance with the quantized signal to supply power, the switching power source comprising: input means for externally inputting a control signal; and reference value control means for changing a hysteresis width of the quantization reference value of the comparator on the basis of the control signal input by said input means, wherein said reference value control means changes a constant of a circuit of the comparator and a constant of a circuit of the integrator to change the hysteresis width of the quantization reference value and a change rate in time of an output from the integrator.