A power-control device for generating and controlling a supply voltage (Vsupply) provided to a processing module, comprising: a power manager configured to select an expected operation frequency from a dynamic voltage-frequency scaling (DVFS) table according to expected performance of the processing module and to generate a control signal (S101B) according to the selected operation frequency; a clock generator configured to generate a clock signal according to the control signal (S101B); an initial signal generation circuit configured to generate an initial signal according to the clock signal; a variant delay chain with a delay length, wherein the variant delay chain is configured to receive the initial signal and to perform a delay operation to the initial signal according to the delay length to generate a delay signal; a sampling circuit configured to receive the delay signal and to perform a sampling operation to the delay signal to generate a sampled signal; a comparison circuit configured to receive the sampled signal and to compare the sampled signal with a reference signal to generate a comparison result signal, wherein the power manager is configured to receive the comparison result signal and to adjust the supply voltage (Vsupply) according to the comparison result signal; and a temperature sensor configured to sense an ambient temperature of the temperature sensor and to generate a temperature signal according to the sensed ambient temperature; wherein the power manager is configured to determine whether the ambient temperature reaches an upper threshold according to the temperature signal; and wherein when the power manager determines that the ambient temperature reaches the upper threshold according to the temperature signal, the power manager is further configured to lower a level of the supply voltage (Vsupply). a power manager configured to select an expected operation frequency from a dynamic voltage-frequency scaling (DVFS) table according to expected performance of the processing module and to generate a control signal (S101B) according to the selected operation frequency; a clock generator configured to generate a clock signal according to the control signal (S101B); an initial signal generation circuit configured to generate an initial signal according to the clock signal; a variant delay chain with a delay length, wherein the variant delay chain is configured to receive the initial signal and to perform a delay operation to the initial signal according to the delay length to generate a delay signal; a sampling circuit configured to receive the delay signal and to perform a sampling operation to the delay signal to generate a sampled signal; a comparison circuit configured to receive the sampled signal and to compare the sampled signal with a reference signal to generate a comparison result signal, wherein the power manager is configured to receive the comparison result signal and to adjust the supply voltage (Vsupply) according to the comparison result signal; and a temperature sensor configured to sense an ambient temperature of the temperature sensor and to generate a temperature signal according to the sensed ambient temperature; wherein the power manager is configured to determine whether the ambient temperature reaches an upper threshold according to the temperature signal; and wherein when the power manager determines that the ambient temperature reaches the upper threshold according to the temperature signal, the power manager is further configured to lower a level of the supply voltage (Vsupply).