| 摘要 |
A switched mode power supply for converting an input voltage and comprising: a series arrangement of an inductor (L1), a power switch (S2) and a control switch (S1) for controlling the power switch (S2); a controller (110) configured to control the control switch (S1) and having a supply terminal (114) and a ground terminal (112); a capacitor (C2) coupled between the controller ground terminal (112) and supply terminal (114) and for providing power to the controller (110); a first current path (D4) arranged to provide charge to the capacitor (C2) only when the control switch (S1) is open and the power switch (S2) is closed; a connectable second current path (D3) arranged to draw current from the control terminal of the power switch (S2) thereby opening the power switch, and a connection switch (S3) configured to connect the second current path in response to a voltage across the capacitor exceeding a threshold voltage. A controller, lighting circuit and corresponding method are also disclosed. |
