| 摘要 |
<p>A power supply circuit that can operate for input voltages above or below a predetermined output voltage. The circuit comprises input (1) and output nodes (2), to which input voltages are applied and output voltages produced respectively, an inductor (13) adapted to store electrical energy, an input switching stage which in a first state applies a first voltage and in a second state a second, lower, voltage to the input side (4) of the inductor (13), an output switching stage adapted to have a first state which connects the output (5) of the inductor (13) to a third voltage permitting current from the inductor (13) to flow to the output node (2) and control means (17) to control the state of the two switching stages such that the voltage of the output node (2) at the predetermined value. <IMAGE></p> |
