USB power switches are power management devices used to charge electronic devices on USB ports and hubs on computers, docking stations, handheld devices and automotive devices.
They work by monitoring the current on a device and latch a switch off if the output current is shorted. They often have an auto reset feature which reactivates the switch once the short circuit is removed. They work in the same way as hot swap controllers, which allow circuit boards and electronic cards to be inserted into equipment, removing the need to power down during use.
Most USB power switches have multiple safety features. For instance, built in thermal-overload protection limits junction temperature and dissipation of power.
The internal circuity is limited to an accurate figure to protect the input supply against short circuit conditions as well as overload. They're also fitted with fault signals that notify the microprocessor whenever there's a current-limit, under voltage lockout (UVLO), short-circuit fault or thermal overload.