Selecting a Power Switch IC

Power switch with various protection functions
Power switch with various protection functions

Power Switch ICs

Safety and reliability are important aspects of power supplies. Most converters will include protection features which safely shut down the supply in case of overload or too high operating temperature.

Power switches can be used to enable and disable power rails. The EN pin is used to activate the pass element which is usually a MOSFET with a special well construction to eliminate reverse current flow via the body diode. A current limit circuit will open the switch when output current exceeds the current limit threshold. The FAULT pin will be pulled low in case any of the protection functions is activated, and can be used to signal the system that a fault condition has been encountered.

Power switches are often used to protect USB ports, which have specific maximum current requirements and must be short-circuit proof. The main selection criteria for power switches is the current limit level, which can either be fixed or adjustable.

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