Freely oscillating switched-mode power supply

摘要

A freely oscillating switched-mode power supply includes a transformer having a power winding for providing an output voltage, a drive winding for providing a switching voltage and a regulating winding for providing a measuring voltage. A switching transistor provides a cutoff voltage to change the output voltage. A rectifier receives the measuring voltage and generates a control voltage representative of the measuring voltage. A first voltage divider receives the control voltage and turns the switching transistor on when the cutoff voltage is above a first threshold value. A second voltage divider receives the control voltage and turns the switching transistor off when the cutoff voltage is below a second threshold value.