In accordance with at least one aspect of this disclosure, a system can include a positive input line configured to connect between a voltage input and a load, and a negative input line configured to connect between the voltage input and the load. A logic module can be operatively connected to and/or configured to detect a fault (e.g., a short circuit) in either of the positive input line or the negative input line 104 between the voltage input and the load.

A system for measuring voltage includes a pulse-width modulator or voltage controlled oscillator (VCO) configured to receive an input voltage waveform from a DUT, and to output a pulse-width modulated (PWM) signal or frequency modulated (FM) signal mapped to the input voltage waveform, respectively; an optical transmitter configured to be modulated by the PWM signal or the FM signal to output an optical pulse signal having pulse widths corresponding to pulse widths of the PWM signal or equal to the frequency of the FM signal, respectively; an optical receiver configured to receive the optical pulse signal over an optical link and to convert the optical pulse signal to an electrical current; a transimpedance amplifier (TIA) configured to convert the electrical current to a voltage signal; and at least one filter or detection circuit configured to recover the input voltage waveform or provide numeric values corresponding to the input voltage waveform.

A circuit system for providing thermal stability to a transistor may include: a comparing circuit in electrical communication with the transistor for receiving a present voltage from the transistor and comparing a present voltage to a predetermined bias voltage; a logic gate electronically coupled to an output of the comparing circuit, the logic gate, gate having a high, open position and a low, closed position; and a heating element thermally coupled to the transistor and electrically coupled to the output of the comparing circuit, wherein when the present voltage is lower than the predetermined bias voltage, the gate is in the high, open position providing current to the heating element, and wherein when the present voltage is higher than the predetermine bias voltage the gate is in the low, closed position.

An output circuit includes a level adjustment circuit and a determination circuit. The output circuit is employed for generating an output to an output terminal of the output circuit, where the output terminal is coupled to a connecting port. The level adjustment circuit is coupled to the output terminal and is employed for generating at least one adjusted signal according to a first voltage signal at the output terminal in a first period and a second voltage signal at the output terminal in a second period. The determination circuit is coupled to the level adjustment circuit and is employed for generating a determination signal according to the at least one adjusted signal, wherein the determination signal indicates whether a load is connected to the connecting port.

A switching regulator with constant on time control adopts a timer to time when the system is in discontinuous current mode (DCM). If the DCM lasted for a set time, a power stage in the switching regulator is controlled to be ON for a minimum on time duration, so as to ensure the switching regulator enters sleep mode.

A bidirectional voltage differentiator circuit comprises start-up circuitry, sensing circuitry, and output circuitry coupled to logic circuitry. The start-up circuitry acts to start-up the sensing circuitry when the circuit is powered on, and accelerates the response of the sensing circuitry thereafter. The sensing circuitry senses variation in an input voltage applied to an input node. Responsive to the voltage variation sensed by the sensing circuitry, the output circuitry produces a state change at a first or second output node. The logic circuitry receives the states of the output nodes and produces a logic output signal to indicate the occurrence of the variation sensed in the input voltage. The voltage sensing circuit is operable to sense variation of the input voltage regardless of whether the voltage is rising or falling and without regard to the DC value of the input voltage.

A method and a system for diagnosing a fault of a three-phase three-level rectifier are relate to the technical field of fault diagnosis of power electronic equipment, and provided to implement identification and location of an open-circuit fault of a power switching device thereof. A deviation between an expected value and an actual value of a phase-to-phase voltage is adopted as a diagnosis variable. The diagnosis variable is calculated by adopting a screening technique, thereby reducing calculation error to ensure accuracy of diagnosis. Only existing voltage current signals in a control system of the rectifier are required to calculate the diagnosis variable, so no additional hardware is required and low-cost fault diagnosis can be implemented. Different voltage thresholds are adopted for different fault characteristic sections, and the voltage thresholds are updated in real time according to a direct current side voltage, which improves diagnosis speed while ensuring higher robustness.

A voltage sensing circuit includes voltage regulators, oscillator circuits, delay circuits, and a detector circuit. The detector circuit detects characteristics of signaling received from a first oscillator circuit and characteristics of signaling received from a second oscillator circuit. The detector circuit compares the detected characteristics of the signaling from the first oscillator circuit and the second oscillator circuit to determine whether the detected characteristics from the first oscillator circuit and the second oscillator circuit meet a particular criterion for providing voltage manipulation for the voltage sensing circuit.

A method and apparatus for an active discharge of an X-capacitor are provided. A sensor signal, indicative of a voltage at the capacitor, is compared with a lower and upper threshold values. A first value of a smaller one of the lower and upper threshold values is increased to a first new value that is greater than a second value of a larger one of the lower and upper threshold values in response to a first control signal indicating the sensor signal is greater than the upper and lower threshold values. A third value of the greater one of the lower and upper threshold values is decreased to a second new value that is less than the value of the larger one of the lower and upper threshold values in response to a second control signal indicating the sensor signal is less than the upper and lower threshold values.

A method for detecting a fault condition in a light detection and ranging transmitter includes generating a control signal that comprises an address and desired drive voltage and current information for a laser in a laser array. A drive signal is generated for the laser in the laser array in response to the generated control signal and applied to a contact associated with that address of the laser array, thereby energizing the laser at a desired output power for a desired time. A determination is made on whether the drive signal has a parameter with a value that is outside a threshold range for eye safety. The address and the fault condition is stored if the parameter has the value outside the threshold range for eye safety and reported to a host that takes an action on the LiDAR transmitter in response to the fault condition.