LED Power Supply

摘要

A method can be used for controlling the switching operation of a switching power converter that includes a semiconductor switch coupled in series to an inductor. The switching power converter consumes an input current from a power supply and provides an output current to a load. In each switching cycle a switch-on time instant is detected for the semiconductor switch. The semiconductor switch is closed thus enabling, at the detected switch-on time instant, the input current passing through the semiconductor switch. The semiconductor switch is opened after a desired on-time, during which the input current rises from zero to a peak value, has passed. A time interval is detected, in which the instantaneous output current is not zero. A first value that represents the peak of the input current is obtained during the on-time.

主权项

1. A method for controlling the switching operation of a switching power converter that comprises a semiconductor switch coupled in series to an inductor, the switching power converter consuming an input current from a power supply and providing an output current to a load, wherein the method comprises in each switching cycle:
detecting a switch-on time instant for the semiconductor switch; closing the semiconductor switch thus enabling, at the detected switch-on time instant, the input current passing through the semiconductor switch; opening the semiconductor switch after a desired on-time, during which an input current rises from zero to a peak value, has passed; detecting a time interval, in which an instantaneous output current is not zero; obtaining a first value that represents the peak of the input current during the on-time; generating a first signal which has the first value during the detected time interval and is zero otherwise; averaging the first signal thus providing an averaged signal being an estimation of an average output current; and adjusting the desired on-time such that the averaged first signal approximately matches a pre-defined target value.