McClure, Qualey & Rodack, LLP
Switching-mode power supplies capable of operating at valley switching, and relevant control methods
Control methods and related power controllers diminish audible noise in a power supply capable of performing valley switching. The power supply has an inductive device and a power switch. When the power switch is OFF, a winding voltage of the inductive device oscillates to provide an oscillation signal with at least one signal valley. An occurrence number of the signal valley is detected, and is compared with a lock number. When the occurrence number and the lock number fit a predetermined condition, the power switch is turned ON to start a cycle time at a start moment. Whether the start moment falls within an expectation window is checked. The lock number is changed if the start moment falls outside of the expectation window.
LEADTREND TECHNOLOGY CORPORATION
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inventional inventional additional
Meng Jen Ming Chang Chih Chi
Tsai Tsou Chang