| 摘要 |
A resonant converter has a switching circuit having a first switch and a second switch, a control circuit and a resonant circuit. The control circuit has a slope sensing circuit providing a slope sense signal based on a voltage variation at the common node of the first switch and the second switch, a slope judge circuit providing a slope judge signal, and a turn-ON control circuit providing a first reset signal to adjust a first dead-time period from turning OFF the first switch to turning ON the second switch based on the slope judge signal, the slope signal, and a current flowing through the resonant tank, and providing a second reset signal to adjust a second dead-time period from turning OFF the second switch to turning ON the first switch based on the slope judge signal, the slope signal, and the current flowing through the resonant tank. |
| 主权项 |
1. A control circuit for a resonant converter, the resonant converter having a first switch, a second switch and a resonant tank, the control circuit comprising:
a slope sensing circuit, configured to provide a slope signal based on a voltage variation at a common node of the first switch and the second switch; a capacitive mode judge circuit, configured to provide a mode signal based on a current flowing through the resonant tank to indicate a working mode of the resonant converter, wherein the working mode of the resonant converter comprises a capacitive mode and an inductive mode; a slope judge circuit, configured to provide a slope judge signal based on the slope signal to indicate if the slope signal is effective to indicate the voltage variation at the common node of the first switch and the second switch, wherein if the slope signal is detected less than a first slope threshold within a predetermined time period after turning OFF the first switch, the slope signal is judged effective, and if the slope signal is detected larger than a second slope threshold within the predetermined time period after turning OFF the second switch, the slope signal is judged effective; an oscillator, configured to provide a clock signal, wherein the second switch is turned OFF when the clock signal is at a first status, and wherein the first switch is turned OFF when the clock signal is at a second status; and a turn-ON control circuit, configured to adjust a first dead-time period and a second dead-time period based on the mode signal, the slope judge signal, the slope signal, and the current flowing through the resonant tank, wherein the first dead-time period is a time period from turning OFF the first switch to turning ON the second switch, and the second dead-time period is a time period from turning OFF the second switch to turning ON the first switch, and wherein when the slope signal is judged effective, the first dead-time period is adjusted to turn ON the second switch based on comparing the slope signal with a third slope threshold, and the second dead-time period is adjusted to turn ON the first switch based on comparing the slope signal with a fourth slope threshold. |
