US Patent No. 10,461,649


Patent No. 10,461,649
Issue Date October 29, 2019
Title Switched-mode Power Supply Circuit
Inventorship Hiroshi Maruyama, Matsumoto (JP)
Assignee FUJI ELECTRIC CO., LTD., Kanagawa (JP)

Claim of US Patent No. 10,461,649

1. A switched-mode power supply circuit that performs a burst-mode operation to stop and restart switching, comprising:a power supply that supplies DC voltage;
a switching element that is connected to the power supply and controls the switching;
a first comparator that detects whether an output voltage of the switched-mode power supply circuit is higher than a predetermined voltage;
a storage element that stores an output of the first comparator according to a timing of controlling the switching by the switching element; and
a determination unit that (i) comprises a latch timer that performs a measurement of a time period for which at least one of an output of the first comparator or an output of the storage element continues to be higher than the predetermined voltage, and (ii) if the latch timer is not reset within a predetermined elapsed time after the latch timer starts the measurement, determines that the switched-mode power supply circuit is in an overvoltage state, wherein
the switched-mode power supply circuit resets the latch timer at a timing corresponding to a switching stop timing in the burst-mode operation.