In the event of a system failure, for example, when the load connected to the VOUT pin is short-circuited to GND, the overcurrent protection function limits the output current to protect the load switch IC and the system in which it is used. When a drop in output voltage (VOUT) causes excessive current to flow, Toshiba’s load switch ICs limit the output current to the set output limited current (ICL) level by tripping a current limiting circuit. When VOUT drops further, Toshiba’s load switch ICs perform current limiting called foldback. In the event of excessive current higher than the internal threshold, foldback reduces the output current (IOUT) as the output voltage (VOUT) decreases. Even when the output voltage is zero, a short-circuit current (ISC) continues flowing at the internally set level. The term “foldback” is derived from the shape of the output current (IOUT)-vs-output voltage (VOUT) curve that folds back during protection operation. When a faulty condition causing overcurrent disappears, the load switch IC automatically recovers from overcurrent protection, returning the output voltage to the normal level.
The following links also provide descriptions of overcurrent protection:
Application note: Basics of Load Switch ICs
Application note: Overcurrent Protection and Reverse Current Blocking of the Load Switch IC