Power circuits, equipment, and ultrasonic flowmeters

Abstract

To suppress the generation of switching noise during the period in which a predetermined circuit processes a predetermined signal. [Solution] A power supply circuit comprising: a switching circuit that controls the switching so that the output voltage becomes a first voltage based on a feedback signal that changes according to the output voltage generated by the switching of a switching element, and stops the switching when the feedback signal changes to a first state where the output voltage is higher than the first voltage; and a control circuit that changes the feedback signal to the first state during a first period in which a predetermined circuit processes a predetermined signal.

Claims

1. A switching circuit controls the switching so that the output voltage becomes a first voltage based on a feedback signal that changes according to the output voltage generated by the switching of a switching element, and stops the switching when the feedback signal changes to a first state where the output voltage is higher than the first voltage. A power supply circuit comprising a control circuit that changes the feedback signal to the first state during a first period in which a predetermined circuit processes a predetermined signal.

2. The power supply circuit according to claim 1, wherein the switching circuit controls the switching based on the feedback signal so that the output voltage becomes a first voltage during a second period in which the change of the feedback signal to the first state is canceled by the control circuit.

3. The power supply circuit according to claim 2, wherein the second period is a period during which the predetermined circuit does not process the predetermined signal.

4. The switching circuit has a feedback circuit including a photocoupler through which the feedback current, which is the feedback signal, flows to the light-emitting side. The power supply circuit according to any one of claims 1 to 3, wherein the control circuit changes the feedback current to a first state during the first period.

5. The feedback circuit includes a shunt regulator that supplies a shunt current to change the feedback current. The power supply circuit according to claim 4, wherein the control circuit changes the feedback current to a first state during the first period by changing the shunt current.

6. The feedback circuit includes a shunt regulator that supplies a shunt current to change the feedback current. The power supply circuit according to claim 4, wherein the control circuit includes a switch connected in parallel with the shunt regulator, and by turning on the switch, the feedback current is changed to a first state during the first period.

7. The switching circuit has a voltage divider circuit that outputs a feedback voltage, which is the feedback signal. The power supply circuit according to any one of claims 1 to 3, wherein the control circuit changes the feedback voltage to a first state during the first period.

8. The power supply circuit according to claim 7, wherein the control circuit includes a switch connected to the voltage divider circuit, and the feedback voltage is changed to the first state during the first period by turning the switch on or off.

9. The power supply circuit according to any one of claims 1 to 3, wherein the control circuit includes a switch that changes the feedback signal to a first state during the first period.

10. A power supply circuit according to any one of claims 1 to 3, Sensors and, The predetermined circuit comprises, The predetermined signal is the output signal of the sensor, in this device.

11. A power supply circuit according to any one of claims 1 to 3, Ultrasonic sensor and, The predetermined circuit comprises, The predetermined signal is the output signal of the ultrasonic sensor, an ultrasonic flow meter.

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