Voltage generation apparatus and voltage generation method

A voltage generation apparatus comprising:

• a booster circuit which outputs a direct-current voltage after having performed boosting processing, the voltage value of the direct-current voltage being specified on the basis of a pulse width of a series of pulse signals inputted thereto;
• a direct-current to alternating-current conversion circuit which generates a ringer voltage to be supplied to a device connectable to a telephone line by converting the direct-current voltage output by the booster circuit to an alternating-current voltage;
• a control unit which outputs a series of pulse signals to the booster circuit, the series of pulse signals having a feeding-voltage pulse width corresponding to a target voltage value of a feeding voltage or a ringer-voltage pulse width corresponding to a target voltage value of the ringer voltage, the feeding-voltage pulse width and the ringer-voltage pulse width being pulse widths having been set and stored in a voltage adjustment stage;
• and
• a voltage monitoring circuit which outputs a monitor voltage value of the direct-current voltage output by the booster circuit,
• wherein in the voltage adjustment stage, the control unit first outputs a series of pulse signals to the booster circuit, the series of the pulse signals having a pulse width corresponding to a voltage value higher than the target voltage value of the feeding voltage, subsequently, repeatedly changes a current pulse width of the series of pulse signals to a different pulse width thereof which makes a current monitor voltage value output by the voltage monitoring circuit be lower so that the monitor voltage value output thereby decreases to a target monitor voltage value corresponding to the target voltage value of the feeding voltage, and stores therein a certain pulse width thereof, which has made the monitor voltage value output thereby be equal to the target monitor voltage, as the feeding-voltage pulse width, and
• wherein the control unit stores therein a value resulting from multiplying the feeding-voltage pulse width by a voltage ratio of the feeding voltage and the ringer voltage as the ringer-voltage pulse width.