| 摘要 |
A power supply device and a communication apparatus are provided to supply sufficient electric power to a secondary processing device certainly by controlling the electric power supplement into the secondary processing device according to the amount of the load at the primary processing device although the processing data amount is increased suddenly. A electric power controller(224_3) comprises an AD converter(311), a digital filter(312), a PWM control circuit(313), an electric power control circuit(314) and a pulse generator(315). An electric power source(223B) comprises a switch element(321) and a smoothing filter(322). Within the AD converter, an electric voltage added to a processing circuit(211B) is detected from the electric power source, and the detected voltage is converted into the digital signals to be transmitted to the digital filter. The digital filter calculates the difference between the detected voltage and the predetermined voltage, and error sign is generated by averaging the differences, and the error signal is transmitted to the PWM control circuit. Within the PWM control circuit, a pulse signal and a control signal of a pulse width which is created according to a control value which is transmitted from the electric power control circuit on the basis of the error signal transmitted from the digital filter, are transmitted to the switch element. Within the switch element, the pulse width of an input voltage is regulated by controlling the on/off operations according to the control signals transmitted from the PWM control circuit.
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