DC power supply device, current stabilizing circuit for DC power supply device, and method for reducing noise of power-supply line
AssigneeMitsumi Electric Co., Ltd.
InventorKoji Tochitani
Life of this patent
Estimating the term…
Abstract
A DC power supply device includes a switching power supply and a current stabilizing circuit connected in a pre-stage or a post-stage of the switching power supply. The DC power supply voltage device is configured to receive an input DC voltage from a DC power source via a power-supply line, convert the input DC voltage into a different DC voltage, and output the converted DC voltage.
Claims10
A DC power supply device comprising:
- a switching power supply;
- and
- a current stabilizing circuit connected in a pre-stage or a post-stage of the switching power supply,
- wherein the DC power supply device is configured to receive an input DC voltage from a DC power source via a power-supply line, convert the input DC voltage into a different DC voltage, and output the converted DC voltage,
- wherein the current stabilizing circuit includes:
- a resistor element and a transistor that are connected in series between a current-input terminal and a current-output terminal;
- a low-pass filter connected to the current-output terminal;
- and
- a control circuit that controls the transistor based on a potential difference between a voltage output by the low-pass filter and a voltage of a node connected between the resistor element and the transistor and that sends constant current to the transistor in response to a sudden change in load, and
- wherein the low-pass filter has a time constant that cuts off a frequency component of a switching operation performed by the switching power supply and passes a frequency component of servo control performed by the switching power supply.
A current stabilizing circuit comprising:
- a resistor element and a transistor that are connected in series between a current-input terminal and a current-output terminal;
- a low-pass filter connected to the current-output terminal;
- and
- a control circuit that controls the transistor based on a potential difference between a voltage output by the low-pass filter and a voltage of a node connecting the resistor element and the transistor and that sends constant current to the transistor in response to a sudden change in load,
- wherein the control circuit includes:
- an operational amplifier circuit that includes a first input terminal and a second input terminal, the first input terminal receiving the voltage of the node as an input voltage;
- a voltage-control voltage source circuit connected between the current-input terminal and the second input terminal of the operational amplifier circuit;
- and
- a capacitor that stabilizes an electric potential of the current-input terminal,
- wherein:
- the voltage-control voltage source circuit includes a pair of control terminals and generates a voltage that corresponds to a potential difference between the control terminals,
- an electric potential of one terminal of the control terminals is stabilized by the capacitor, and
- another terminal of the control terminals receives the voltage output by the low-pass filter.
A method for reducing radiated noise output from a power-supply line of a DC power supply system, the DC power supply system including a switching power supply and being configured to convert an input DC voltage supplied by a DC power source via the power-supply line into a different DC voltage and output the converted DC voltage to a load, the method comprising:
- regulating current that flows to the switching power supply via the power-supply line by using a current stabilizing circuit so as to restrain noise caused by switching operation of the switching power supply from being transmitted to the power-supply line,
- wherein the current stabilizing circuit includes:
- a resistor element and a transistor that are connected in series between a current-input terminal and a current-output terminal;
- a low-pass filter connected to the current-output terminal;
- and
- a control circuit that controls the transistor based on a potential difference between a voltage output by the low-pass filter and a voltage of a node connected between the resistor element and the transistor and that sends constant current to the transistor in response to a sudden change in the load, and
- wherein the low-pass filter has a time constant that cuts off a frequency component of a switching operation performed by the switching power supply and passes a frequency component of servo control performed by the switching power supply.
Dependencies are inferred from the claim text.