Self-oscillating step=down converter with complete demagnetisation

摘要

The step-down converter has a transistor switch (T1) connected in series with a first inductance (L1) between the input (1) and output (3) terminals. A first capacitor (C2) is connected between the output and a second output terminal (4). A freewheel diode (D1) is connected in reverse over the inductor and capacitor. A controller is connected to the control terminal of the transistor switch. A second transistor switch (TH) is connected so it blocks the first transistor switch in response to the measured current when it attains a predetermined threshold. The voltage at the terminals of the inductance is coupled (L2) to cancel the current in the first inductance to trigger the first transistor switch.