Patent ID: 7394669
Filing Date: 2008-07-01
Classification: H02M,Y02B

Abstract:
1. A switching mode power supply comprising: a transformer, a transistor operably coupled to switch current through a primary of the transformer, and a control unit comprising a first comparator and a second comparator configured to control the switching of the transistor to generate current pulses through the transformer, the control unit further configured to receive a signal related to power drawn by a load from a secondary side of the transformer and the first comparator configured to compare the signal with a first threshold level and the second comparator configured to compare the signal with a second threshold level, two threshold levels defining a range, the control unit configured to enable switching of the transistor in the case that a characteristic of the signal is outside the range in a first direction, and disabling switching of the transistor in the case that the characteristic of the signal is outside the range in a second direction, and a blanking window definition circuit configured to prevent the control unit from disabling switching of the transistor in the case that the signal is below the second lower threshold value for less than a preset period of time.