| 摘要 |
In accordance with an embodiment, a switch controller for a switched-mode power supply includes an oscillator, an advance timing generator, and a dead zone generator. The advance timing generator generates an advance timing output pulse having a first pulse width that is asserted when the oscillator reaches a first phase. The dead zone generator produces a dead zone output having a second pulse width when the advance timing output pulse is de-asserted. This dead zone output pulse is coupled to a freeze input of the oscillator that freezes the phase accumulation of the oscillator when asserted. The controller also has a primary switch logic circuit that produces primary switch drive signals having a dead zone coincident with the dead zone output, and a secondary switch logic circuit that generates a secondary switch drive signal that is de-asserted when the advance timing output pulse becomes asserted.
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