DIRECT CURRENT POWER SUPPLY CIRCUIT

摘要

A direct current power supply circuit includes an alternating-current power supply; a rectification circuit for generating a direct-current voltage from an alternating-current voltage; a charging switch having an input terminal connected to the rectification circuit, the charging switch outputting an output voltage according to an input value input to a control terminal; a capacitor and a control circuit, which are connected to an output terminal; and a charging switch control circuit for generating a switch-on signal when the output voltage is equal to or lower than a first reference voltage value, and for generating a switch-off signal when the output voltage is equal to or higher than a second reference voltage value higher than the first reference voltage value, wherein a charging period setting circuit including at least one of the rectification circuit and the charging switch control circuit sets a charging period in which a charging current flows into the capacitor and a non-charging period in which the charging current does not flow, and in a case where the switch-on signal is generated during the charging period, the charging current flows through the charging switch when the direct-current voltage becomes equal to or higher than the output voltage, and in a case where the switch-on signal is generated during the non-charging period, the charging current does not flow through the charging switch even if the direct-current voltage becomes equal to or higher than the output voltage.

主权项

1. A direct current power supply circuit comprising:
an alternating-current power supply; a rectification circuit for rectifying an alternating-current signal of the alternating-current power supply to generate a direct-current voltage; a first charging switch having a first input terminal connected to the rectification circuit, a first control terminal, and a first output terminal, the first charging switch outputting a first output voltage to the first output terminal according to a first input value input to the first control terminal; a first capacitor and a first control circuit, which are connected to the first output terminal; and a first charging switch control circuit connected to the first control terminal, wherein: the first charging switch control circuit generates a switch-on signal for turning on the first charging switch when the first output voltage is equal to or lower than a first reference voltage value, and generates a switch-off signal for turning off the first charging switch when the first output voltage is equal to or higher than a second reference voltage value higher than the first reference voltage value, a charging period setting circuit, which includes at least one of the rectification circuit and the first charging switch control circuit, sets a charging period in which a charging current flows into the first capacitor through the first charging switch and a non-charging period in which the charging current does not flow, in synchronism with the alternating-current signal, and in a case where the switch-on signal is generated during the charging period, the charging current flows through the first charging switch when the direct-current voltage becomes equal to or higher than the first output voltage, and in a case where the switch-on signal is generated during the non-charging period, the charging current does not flow through the first charging switch even if the direct-current voltage becomes equal to or higher than the first output voltage, while the charging current flows through the first charging switch when an operation enters a next charging period and yet the direct-current voltage becomes equal to or higher than the first output voltage.