Electronic circuit breakers and systems for isolating a load from a power-supply unit are provided. One electronic circuit breaker includes a current sensor, a switching element coupled to the current sensor, and a switch controller coupled to the current sensor and the switching element. The switch controller is powered by the power-supply unit and is configured to switch OFF the switching element when the current sensor detects an amount of current from the power-supply unit greater than a predetermined amount. An electronic system includes a power-supply unit, a load, and the above-referenced electronic circuit breaker coupled to the power-supply unit and the load.