| 摘要 |
<p>The switching frequency of an LLC converter is controlled by a control unit to which a feedback circuit provides a first current dependent upon the output voltage of the converter. An oscillator circuit produces a sawtooth waveform at a frequency dependent upon the first current, up to a limit equal to a second current set by a resistor. Two complementary switch control signals are produced for controlling two switches of the converter for conduction in alternate cycles of the sawtooth waveform. A timer produces dead times between the two complementary switch control signals in dependence upon the second current. Another resistor provides a current constituting a minimum value of the first current, and a charging current of a capacitor in series with a resistor modifies the first current for soft starting of the converter.</p> |
