A current sensing apparatus may include a common mode core surrounding two or more current conductors and a current sensing element proximate the common mode core.

A current sensing apparatus may include a common mode core surrounding two or more current conductors and a current sensing element proximate the common mode core.

A differential sensing system for sensing a current through a circuit element of a circuit, the differential sensing system comprising: a first current sense path having an input for coupling to a first node of the circuit element, the first current sense path comprising a first plurality of replica devices; a second current sense path having an input for coupling to a second node of the circuit element, the second current sense path comprising a second plurality of replica devices, wherein the second plurality is equal to the first plurality; a first cross-coupling switch operable to couple the input of the first current sense path to the second plurality of replica devices; a second cross-coupling switch operable to couple the input of the second current sense path to the first plurality of replica devices; differential amplifier circuitry having first and second inputs, wherein the differential amplifier circuitry is configured to output a differential replica current pair indicative of the current through the circuit element; and a controller, wherein the differential sensing system is operable in a chopping mode to perform a chopping operation in which: the first cross-coupling switch and a replica device of the first current sense path are controlled by the controller to couple the first input of the differential amplifier circuitry to the input of the first current sense path in a first phase of a chopping operation and to the input of the second current sense path in a subsequent phase of the chopping operation; and the second cross-coupling switch and a replica device of the second current sense path are controlled by the controller to couple the second input of the differential amplifier circuitry to the input of the second current sense path in the first phase of the chopping operation and to the input of the first current sense path in the subsequent phase of the chopping operation.

A differential sensing system for sensing a current through a circuit element of a circuit, the differential sensing system comprising: a first current sense path having an input for coupling to a first node of the circuit element, the first current sense path comprising a first plurality of replica devices; a second current sense path having an input for coupling to a second node of the circuit element, the second current sense path comprising a second plurality of replica devices, wherein the second plurality is equal to the first plurality; a first cross-coupling switch operable to couple the input of the first current sense path to the second plurality of replica devices; a second cross-coupling switch operable to couple the input of the second current sense path to the first plurality of replica devices; differential amplifier circuitry having first and second inputs, wherein the differential amplifier circuitry is configured to output a differential replica current pair indicative of the current through the circuit element; and a controller, wherein the differential sensing system is operable in a chopping mode to perform a chopping operation in which: the first cross-coupling switch and a replica device of the first current sense path are controlled by the controller to couple the first input of the differential amplifier circuitry to the input of the first current sense path in a first phase of a chopping operation and to the input of the second current sense path in a subsequent phase of the chopping operation; and the second cross-coupling switch and a replica device of the second current sense path are controlled by the controller to couple the second input of the differential amplifier circuitry to the input of the second current sense path in the first phase of the chopping operation and to the input of the first current sense path in the subsequent phase of the chopping operation.

A zero-crossing detection circuit includes a variable resistor, a first switch, a first capacitor, a first selector, a second selector, a first transistor, and a comparator. Variable resistor is connected to power supply voltage via reference resistor. First switch has first terminal coupled to first terminal of variable resistor. First capacitor has first terminal coupled to second terminal of first switch. First selector makes second terminal of first capacitor receive switching voltage or reference ground voltage according to first control signal. First transistor has first terminal coupled to second terminal of variable resistor. Second terminal of first transistor receives reference ground voltage. Second selector couples control terminal of first transistor to first terminal of first transistor or to first terminal of first capacitor according to first control signal. Comparator compares voltage on second terminal of variable resistor with reference voltage to generate final zero-crossing detection output signal.

A zero-crossing detection circuit includes a variable resistor, a first switch, a first capacitor, a first selector, a second selector, a first transistor, and a comparator. Variable resistor is connected to power supply voltage via reference resistor. First switch has first terminal coupled to first terminal of variable resistor. First capacitor has first terminal coupled to second terminal of first switch. First selector makes second terminal of first capacitor receive switching voltage or reference ground voltage according to first control signal. First transistor has first terminal coupled to second terminal of variable resistor. Second terminal of first transistor receives reference ground voltage. Second selector couples control terminal of first transistor to first terminal of first transistor or to first terminal of first capacitor according to first control signal. Comparator compares voltage on second terminal of variable resistor with reference voltage to generate final zero-crossing detection output signal.

System and method for detecting one or more currents. For example, a system for detecting one or more currents includes: one or more current sampling units coupled to one or more terminal transistors respectively and configured to sample one or more terminal currents that flow between a system terminal of a power management system and one or more port terminals through the one or more terminal transistors respectively; one or more operational amplifiers coupled to the one or more current sampling units respectively and configured to generate one or more detection currents respectively, the one or more detection currents representing one or more magnitudes of the one or more terminal currents respectively; and a signal combiner configured to receive the one or more detection currents, generate a combined detection voltage representing a sum of the one or more magnitudes of the one or more terminal currents.

System and method for detecting one or more currents. For example, a system for detecting one or more currents includes: one or more current sampling units coupled to one or more terminal transistors respectively and configured to sample one or more terminal currents that flow between a system terminal of a power management system and one or more port terminals through the one or more terminal transistors respectively; one or more operational amplifiers coupled to the one or more current sampling units respectively and configured to generate one or more detection currents respectively, the one or more detection currents representing one or more magnitudes of the one or more terminal currents respectively; and a signal combiner configured to receive the one or more detection currents, generate a combined detection voltage representing a sum of the one or more magnitudes of the one or more terminal currents.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.