DC to DC converter having fast transient-response of loading and method of the same

The present invention relates to DC-to-DC converter having fast transient-response of loading and method of the same, and includes the followings: an output stage; a sensing circuit; a conduction amplifier; a charging circuit; a driver; and a fast reaction circuit of transient response. The output stage is connected between an input voltage and lo voltage, and is controlled and switched to adjust one work cycle to generate an output voltage. The sensing circuit senses the output voltage and generates a feedback signal, and is compared with the first reference voltage through the conduction amplifier so as to generate the first current and generate the second current in response to the transient response. The first current is connected to the charging circuit to generate a charging voltage, which is compared with the first and the second reference signals through the driver to generate a driving signal having the work cycle and sent it to the output stage. The fast reaction circuit of transient response compares high-resistance current comparison node generated by the second current with the second reference voltage to generate bypass signal for driving the output stage.