The UCCx913 family of negative voltage circuit breakers provides complete power management, hot-swap, and fault handling capability. The device is referenced to the negative input voltage and is driven through an external resistor connected to ground, which is essentially a current drive as opposed to the traditional voltage drive. The on-board 10-V shunt regulator protects the device from excess voltage and serves as a reference for programming the maximum allowable output sourcing current during a fault. In the event of a constant fault, the internal timer limits the on-time from less than 0.1% to a maximum of 3%. The duty cycle modulates depending on the current into the PL pin, which is a function of the voltage across the FET, and limits average power dissipation in the FET.