| 摘要 |
The present invention relates to a control circuit for a switched mode power supply (101), and to a related method for controlling the switching elements (201, 202) in a power train of a switched mode power supply. The control circuit comprises a mode controller (107) being configured to monitor the output current (lout) to determine whether the output current exceeds a current threshold. The mode controller is configured to control the switching controller (105) to generate the switch control signals such that, when the current exceeds the current threshold, the power train operates in a continuous conduction mode, and upon determining that the output current has fallen to or below the current threshold the operation of the power train is changed from the continuous conduction mode to a pulse skipping mode such that the pulse skipping mode is entered from the continuous conduction mode, wherein the pulse skipping mode involves determining the amount of energy stored in a secondary circuit (204) of the power train. The secondary circuit being operatively connected to the output terminal, and when the amount of energy stored in the secondary circuit has fallen to or below an energy threshold the mode controller instructs the switching controller to enable energy transfer from the primary circuit to the secondary circuit by means of the switch control signals, when the amount of energy stored in the secondary circuit exceeds said energy threshold the energy transfer from the primary circuit to the secondary circuit is disabled by means of the switch control signals. |
