Characteristics of the Fu shape

One method of short-circuit source current reduction (short-circuit protection) in switching power supplies. It is named after the shape of the protection characteristic curve of output voltage and output current when the protection function is activated, which resembles the Japanese katakana character "fu", and is also called the "fu-shaped drooping characteristic". Unlike the reverse-L drooping characteristic commonly used in short-circuit current reduction circuits—which tries to maintain a constant current even when the protection function is activated and the output voltage drops—the fu-shaped characteristic lowers the overcurrent threshold as the output voltage decreases. In switching power supplies with fu-shaped characteristics, some loads may fail to start up, so it is necessary to confirm whether they can be used.