A current monitoring circuit includes: an output terminal configured to be coupled to a controller; an inverter having an output coupled to the output terminal; a first transconductance amplifier having first and second inputs configured to be coupled across a sense resistive element, and an output coupled to an input of the inverter; and a current generator having a second transconductance amplifier configured to generate a reference current at an output of the current generator based on a reference voltage, the output of the current generator being coupled to the input of the inverter, where the output of the inverter is configured to be in a first state when a load current flowing through the sense resistive element is higher than a predetermined threshold, and in a second state when the load current is lower than the predetermined threshold, and where the predetermined threshold is based on the reference current.

A DC monitoring system is configured to measure and analyze VFD (Variable Frequency Drive) operational characteristics. The VFD is configured to receive three-phase input power from a standardized source and to provide variable frequency three-phase output power to a three-phase motor. In some applications, the VFD and motor operate at a medium voltage. The VFD can include multiple inverter modules consisting of a DC section and switching section, also referred to as a multiple bus configuration. The DC monitoring system includes a measurement module coupled to each DC bus of the VFD, a data communication network, and a PQube monitoring device for transmitting data signals corresponding to voltage values of the VFD DC bus obtained in a medium voltage compartment to a low voltage compartment for processing and analysis. Processing of the data signals enables comparative and predictive analysis to determine early warning for possible capacitance failure in the VFD.

A smart-home device may include a solid state relay (SSR) switching integrated circuit (IC). SSR switching IC may include switching elements configured to open and close a connection between a power wire and a return wire of an environmental system; a voltage sensor that measures a voltage across the one or more switching elements; a current sensor that measures a current through the one or more switching elements; and a temperature sensor that measures a temperature near the one or more switching elements. The smart-home device may also include a wireless communication device that periodically receives voltage, current, or temperature data originating from the SSR switching IC and transmits the voltage, current, or temperature data to a device management server. The device management server may receive batches of voltage, current, or temperature data from a plurality of smart-home devices.

A foreign substance detecting circuit may include a voltage detector that may detect a voltage level from a first pin of a connector, a slope detector that may detect a voltage slope indicating a change of the voltage level based two voltage levels from the first pin, and a foreign substance determining device that may determine a presence of a foreign substance in the connector. The foreign substance determining device may determine whether a resistance range of an external device is detected from the at least one first pin based on the detected voltage level. The foreign substance determining device may, when the resistance range is detected, determine that the foreign substance is present in the connector, based on the voltage slope having a value determined to correspond to charge and discharge characteristics due to a capacitance element of the foreign substance.

An indicating circuit for a switching power supply is provided. An LED and a resistor are connected in series, and then are connected in parallel with a capacitor, and the parallel-connected circuit and a diode are connected in series in the same direction, and then are connected in parallel with an inductor to form the indicating circuit. The cathode of the indicating circuit is a terminal 1, and the anode of the indicating circuit is a terminal 2. A charging loop between a rectifying bridge and an electrolytic capacitor for filtering in a fly-back switching power supply is broken to insert the indicating circuit; when the electrolytic capacitor for filtering is normal, an excitation current of a main power stage basically does not appear in the inductor, and the LED does not emit light; when the ESR of the electrolytic capacitor rises greatly, the excitation current of the main power stage appears in the inductor; furthermore, when a switching transistor in the switching power supply is switched off, the excitation current flowing through the inductor may not be changed abruptly, and is freewheeled by the diode; after being filtered by the capacitor, the excitation current drives the LED to emit light; the LED may be a light emitter of a photocoupler to notify a user that: the ESR of the filter capacitor has risen and the switching power supply has a risk of failure, thereby avoiding aggravation of loss; and the indicating circuit has the characteristics of low cost and easiness in implementation.

A system for automatically commissioning a solar panel array comprises a plurality of panel monitoring devices, each panel monitoring device connected between a positive and negative terminal of a solar panel. Each panel monitoring device comprises a switching device, the switching device configurable to disconnect an output from the solar panel. The system further comprises logic configured to automatically obtain a relative position of each panel monitoring device in the system by appointing serially a series of masters from among the panel monitoring devices, each master in turn broadcasting a unique identifier and enabling its output. Each panel monitoring device listens to the masters' broadcasts and stores in memory the unique identifier and information indicating whether the panel monitoring device detected the masters' voltage. The panel monitoring devices determine their respective locations by analyzing the information broadcast by, and the voltage detected from, the masters.

Methods and devices for detecting USB devices attached to a USB charging port including a USB port having a first data line D+, a second data line D, and a power line are disclosed. A USB device is attached to the USB port; applying power to the USB device by the power line; applying a first voltage to the line D+ at the USB port by a first impedance; applying a second voltage to the line D at the USB port by a second impedance. The voltages on the line D+ and the line D are then monitored at the USB port. If the voltage on the line D+ is approximately equal to a first predetermined value for a predetermined period and the voltage on the line D is below a second predetermined value, then the USB device is determined to be of an alpha type device.

A zero current detection system for a switching regulator is provided. The switching includes an inductor. In the zero current detection system, a comparator has a positive input coupled to a terminal of the inductor and an output terminal for outputting a comparison result signal; a first signal latch circuit has a clock terminal for receiving the comparison result signal and outputting a latched output signal; a delay line module starts counting upon receipt of the latched output signal, and then outputs a zero current detection signal after counting a delay time; in response to the zero current detection signal, a voltage sampling module samples a node voltage at two different time points, to generate two sampling voltages; a delay control module adjusts the delay time of the delay line module according to the two sampling voltages.

A DC monitoring system is configured to measure and analyze VFD (Variable Frequency Drive) operational characteristics. The VFD is configured to receive three-phase input power from a standardized source and to provide variable frequency three-phase output power to a three-phase motor. In some applications, the VFD and motor operate at a medium voltage. The VFD can include multiple inverter modules consisting of a DC section and switching section, also referred to as a multiple bus configuration. The DC monitoring system includes a measurement module coupled to each DC bus of the VFD, a data communication network, and a PQube monitoring device for transmitting data signals corresponding to voltage values of the VFD DC bus obtained in a medium voltage compartment to a low voltage compartment for processing and analysis. Processing of the data signals enables comparative and predictive analysis to determine early warning for possible capacitance failure in the VFD.

A DC monitoring system is configured to measure and analyze VFD (Variable Frequency Drive) operational characteristics. The VFD is configured to receive three-phase input power from a standardized source and to provide variable frequency three-phase output power to a three-phase motor. In some applications, the VFD and motor operate at a medium voltage. The VFD can include multiple inverter modules consisting of a DC section and switching section, also referred to as a multiple bus configuration. The DC monitoring system includes a measurement module coupled to each DC bus of the VFD, a data communication network, and a PQube monitoring device for transmitting data signals corresponding to voltage values of the VFD DC bus obtained in a medium voltage compartment to a low voltage compartment for processing and analysis. Processing of the data signals enables comparative and predictive analysis to determine early warning for possible capacitance failure in the VFD.