Patent ID: 7957162

Claim:
A switch mode power supply (SMPS) comprising: a main switch; a power supply including a transformer having a primary coil coupled to the main switch, and configured to supply power to a secondary coil of the transformer according to the operation of the main switch; an output unit coupled to the secondary coil of the transformer and configured to output the power supplied to the secondary coil; and a switch controller, configured to receive a feedback signal corresponding to an output voltage of the output unit, a sense signal corresponding to the current flowing to the main switch, and a sync signal corresponding to a voltage difference across the main switch, and to control the on/off state of the main switch, wherein burst mode determiner is configured to determine the switch mode power supply to be driven by the burst mode driving and notifies the burst mode controller of the determination when a first voltage corresponding to the feedback signal is less than a burst threshold voltage during a burst enable time the switch controller is configured to determine whether to start a burst mode by using the feedback signal, to drive the switch mode power supply in the burst mode when the feedback signal is less than a burst threshold voltage during a burst enable time, and to maintain a switching-operation-off-period for at least a predetermined time by using a switching-operation-forcibly-off-period in the burst mode so that the main switch remains in off state even when the feedback signal is greater than the burst threshold voltage.