Direct current power supply circuit
View Patent ↗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.
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.
2. The direct current power supply circuit according to claim 1 , wherein:
the charging period setting circuit includes the rectification circuit constituted from a half-wave rectification circuit, and
one of a period in which the alternating-current signal has a positive value and a period in which the alternating-current signal has a negative value is set as the charging period, and a remaining period is set as the non-charging period.
3. The direct current power supply circuit according to claim 1 , wherein
the charging period setting circuit includes:
the rectification circuit constituted from a full-wave rectification circuit; and
a charging inhibition signal generation circuit, which is connected to the alternating-current power supply, for generating a charging inhibition signal to control not to generate the switch-on signal, which is activated during a period in which the alternating-current signal has a positive value or a period in which the alternating-current signal has a negative value,
wherein:
the non-charging period is set when the charging inhibition signal is activated, and
the charging period is set when the charging inhibition signal is deactivated.
4. The direct current power supply circuit according to claim 3 , wherein
the charging inhibition signal is generated from a signal acquired by applying a half-wave rectification to the alternating-current signal.
5. The direct current power supply circuit according to claim 1 , wherein
the charging period setting circuit includes:
the rectification circuit constituted from a half-wave rectification circuit or a full-wave rectification circuit;
the first charging switch control circuit; and
a hysteresis control signal generation circuit, which is connected to the alternating-current power supply, for generating a hysteresis control signal which is activated during a predetermined period shorter than a cycle of the alternating-current power supply, when the direct-current voltage becomes equal to or lower than a predetermined voltage value which is equal to or lower than an average of absolute values of voltages of the alternating-current signal,
wherein:
a period during which the hysteresis control signal is activated is set to the charging period, and the first reference voltage value is changed to a third reference voltage value equal to or lower than the second reference voltage value, and
a period during which the hysteresis control signal is deactivated is set to the non-charging period, and the first output voltage does not become equal to or lower than the first reference voltage value.
6. The direct current power supply circuit according to claim 5 , wherein
the hysteresis control signal is generated from a signal acquired by applying a half-wave rectification to the alternating-current signal.
7. The direct current power supply circuit according to claim 1 , wherein:
the first control circuit has operation modes including a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the first reference voltage value is changed to a fourth reference voltage value equal to or lower than the second reference voltage value.
8. The direct current power supply circuit according to claim 2 , wherein:
the first control circuit has operation modes including a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the first reference voltage value is changed to a fourth reference voltage value equal to or lower than the second reference voltage value.
9. The direct current power supply circuit according to claim 3 , wherein:
the first control circuit has operation modes including a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the first reference voltage value is changed to a fourth reference voltage value equal to or lower than the second reference voltage value.
10. The direct current power supply circuit according to claim 4 , wherein:
the first control circuit has operation modes including a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the first reference voltage value is changed to a fourth reference voltage value equal to or lower than the second reference voltage value.
11. The direct current power supply circuit according to claim 5 , wherein:
the first control circuit has operation modes including a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the first reference voltage value is changed to a fourth reference voltage value equal to or lower than the second reference voltage value.
12. The direct current power supply circuit according to claim 6 , wherein:
the first control circuit has operation modes including a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the first reference voltage value is changed to a fourth reference voltage value equal to or lower than the second reference voltage value.
13. The direct current power supply circuit according to claim 1 , further comprising:
a second charging switch having a second input terminal connected to a rectification circuit, a second control terminal, and a second output terminal, the second charging switch outputting a second output voltage to the second output terminal according to a second input value input to the second control terminal;
a second capacitor and a second control circuit, which are connected to the second output terminal; and
a second charging switch control circuit connected to the second control terminal,
wherein:
the second control circuit has a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the second control circuit inhibits the second charging switch from being turned on.
14. The direct current power supply circuit according to claim 2 , further comprising:
a second charging switch having a second input terminal connected to a rectification circuit, a second control terminal, and a second output terminal, the second charging switch outputting a second output voltage to the second output terminal according to a second input value input to the second control terminal;
a second capacitor and a second control circuit, which are connected to the second output terminal; and
a second charging switch control circuit connected to the second control terminal,
wherein:
the second control circuit has a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the second control circuit inhibits the second charging switch from being turned on.
15. The direct current power supply circuit according to claim 3 , further comprising:
a second charging switch having a second input terminal connected to a rectification circuit, a second control terminal, and a second output terminal, the second charging switch outputting a second output voltage to the second output terminal according to a second input value input to the second control terminal;
a second capacitor and a second control circuit, which are connected to the second output terminal; and
a second charging switch control circuit connected to the second control terminal,
wherein:
the second control circuit has a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the second control circuit inhibits the second charging switch from being turned on.
16. The direct current power supply circuit according to claim 4 , further comprising:
a second charging switch having a second input terminal connected to a rectification circuit, a second control terminal, and a second output terminal, the second charging switch outputting a second output voltage to the second output terminal according to a second input value input to the second control terminal;
a second capacitor and a second control circuit, which are connected to the second output terminal; and
a second charging switch control circuit connected to the second control terminal,
wherein:
the second control circuit has a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the second control circuit inhibits the second charging switch from being turned on.
17. The direct current power supply circuit according to claim 5 , further comprising:
a second charging switch having a second input terminal connected to a rectification circuit, a second control terminal, and a second output terminal, the second charging switch outputting a second output voltage to the second output terminal according to a second input value input to the second control terminal;
a second capacitor and a second control circuit, which are connected to the second output terminal; and
a second charging switch control circuit connected to the second control terminal,
wherein:
the second control circuit has a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the second control circuit inhibits the second charging switch from being turned on.
18. The direct current power supply circuit according to claim 6 , further comprising:
a second charging switch having a second input terminal connected to a rectification circuit, a second control terminal, and a second output terminal, the second charging switch outputting a second output voltage to the second output terminal according to a second input value input to the second control terminal;
a second capacitor and a second control circuit, which are connected to the second output terminal; and
a second charging switch control circuit connected to the second control terminal,
wherein:
the second control circuit has a normal power mode and a low-power mode, which are switched based on a mode switching signal, and
during a period in which the mode switching signal corresponds to the low-power mode, the second control circuit inhibits the second charging switch from being turned on.