F-shaped characteristic

One method of short-circuit current limiting circuits (short-circuit protection) used in switching power supplies. It is named because the protection characteristic curve of output voltage versus output current when the protection function operates resembles the shape of the Japanese character "fu," and it is also called foldback characteristic. With the reverse L-shaped drooping characteristic commonly used in short-circuit current limiting circuits, even when the protection function operates and the output voltage drops, the circuit attempts to supply a constant current. In contrast, with the foldback characteristic, as the protection function operates and the output voltage decreases, the overcurrent setting value is reduced. Switching power supplies with foldback characteristics may have loads that fail to start, so it is necessary to confirm whether they can be used.