Intelligent circuit breakers with detection circuitry configured to detect fault conditions

A circuit breaker, comprising:

• a switch and a sense resistor, which are connected in series in an electrical path between a line input terminal and a load output terminal of the circuit breaker;
• a zero-crossing detection circuit configured to (i) sample a sense voltage that is generated across the sense resistor in response to load current flowing through the sense resistor, (ii) detect a zero-crossing of the load current based on the sampled sense voltage and (iii) output a zero-crossing detection signal in response to detecting the zero-crossing of the load current;
• and
• a switch control circuit configured to control operation of the switch based on the output of the zero-crossing detection circuit;
• wherein the zero-crossing detection circuit comprises:
• a polarity change detection stage configured to detect change a change in polarity between positive and negative half-cycles of the load current;
• an edge detection stage, coupled to an output of the polarity change detection stage, wherein the edge detection stage is configured to generate a control pulse in response to a detected change in polarity of the load current by the polarity change detection stage;
• and
• an output stage configured to output the zero-crossing detection signal based on the control pulse generated by the edge detection stage.

A circuit breaker, comprising:

• a switch and a sense resistor, which are connected in series in an electrical path between a line input terminal and a load output terminal of the circuit breaker;
• a zero-crossing detection circuit configured to (i) sample a sense voltage that is generated across the sense resistor in response to load current flowing through the sense resistor, (ii) detect a zero-crossing of the load current based on the sampled sense voltage and (iii) output a zero-crossing detection signal in response to detecting the zero-crossing of the load current and
• a switch control circuit configured to control operation of the switch based on the output of the zero-crossing detection circuit;
• wherein the switch control circuit comprises a processor, wherein the processor is configured to process zero-crossing detection signals output from the zero-crossing detection circuit and control one or more operations of the circuit breaker based on the zero-crossing detection signals.