| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit by which variation resulting from magnitude of an input voltage during a time period from the start of the input voltage supply until an output voltage reaches a desired magnitude is suppressed, and a lighting system.SOLUTION: This power supply circuit according to an embodiment includes a power conversion part, a power supply detection circuit, a first control circuit, and a second control circuit. The power conversion part has a switching element, and converts an input voltage to a dc output voltage by switching of the switching element to supply the output voltage to a dc load. The power supply detection circuit detects the input voltage. The first control circuit controls switching of the switching element. The second control circuit delays the start of the control of the switching element by the first control circuit at the start of the input voltage supply, when the detected value of the input voltage detected in the power supply detection circuit is not less than a threshold value, in comparison with when the value is less than the threshold value.SELECTED DRAWING: Figure 1 |
