There are provided apparatuses and methods. The apparatus comprise a power input and a power output and a first isolation circuit comprising a charge store. The first isolation circuit is configured to switch between a first mode and a second mode at a switching frequency. In the first mode the charge store is coupled to the power input and is electrically isolated from an intermediate power node. In the second mode the charge store is coupled to the intermediate power node and is electrically isolated from the power input. The apparatus further comprises a second isolation circuit electrically coupled to the intermediate power node and the power output. The second isolation circuit is configured to output an output voltage at the power output. The second isolation circuit is configured to generate the output voltage by filtering the intermediate voltage signal to reduce signal components at the switching frequency.

Capacitively isolated current-loaded or current-driven charge pump circuits and related methods transfer electrical energy from a primary side to a secondary side over a capacitive isolation boundary, using a controlled current source to charge isolation capacitors with constant current, as opposed to current impulses, while maintaining output voltage within tolerance. The charge pump circuits provide DC-to-DC converters that can be used in isolated power supplies, particularly in low-power applications and in such devices as sensor transmitters that have separate electrical ground planes. The devices and methods transfer electrical energy over an isolated capacitive barrier in a manner that is efficient, inexpensive, and reduces electromagnetic interference (EMI).

Disclosed herein is a AC direct LED driving apparatus. The light emitting diode (LED) driving apparatus includes: a rectifier configured to receive and rectify an alternating current (AC) voltage; an LED configured to emit light based on a rectified voltage received from the rectifier; a capacitor connected to a first terminal of the LED, and configured to drive the LED while alternating between charging and discharging sections according to a preset cycle; a first current driver connected to a second terminal of the LED and configured to control a path of current flowing in the LED and the capacitor based on different input voltage levels; a second current driver configured to control charging and discharging of the capacitor; and a first diode connected onto a current path of the capacitor and the second current driver, and configured to form a discharging path for driving the LED based on a charged voltage of the capacitor.

A low-pass filter, a switching control circuit, a driving system, a chip and methods are disclosed. The low-pass filter performs digital differential-integral process on a voltage of an acquired analog signal and a predefined reference voltage to generate differential-integral signals, accumulates a count of the differential-integral signals, and convert the result to an analog signal. By performing differential-integral process accumulating a count of the differential-integral signals, a low-pass filtered signal is obtained in a way that solves the problem of low integrity of circuits in conventional driving systems, reduces the complexity of external circuits for such driving systems and increases their circuit stability.

An inductive charging circuit coupled to a winding of a power converter and a supply terminal of a controller of the power converter. The inductive charging circuit comprising an input coupled to the winding, the input coupled to receive a switching voltage generated by the power converter, an inductor coupled to the input to provide an inductor current in response to the switching voltage, a first diode coupled to the inductor to enable the inductor current to flow from the input of the inductive charging circuit to an output of the inductive charging circuit; and the output of the inductive charging circuit coupled to the supply terminal of the controller, the output of the inductive charging circuit configured to provide an operational current responsive to the switching voltage, the controller is configured to control a power switch of the power converter to generate the switching voltage.

Systems and methods for a capacitive coupler for high-voltage step-down include an actively-controlled current-steering circuit connected in series with a current-limiting capacitor in order to transform a higher and potentially variable AC voltage to a lower regulated DC voltage. The actively-controlled current-steering circuit includes a switching element which, during operation, is predominantly either fully open or fully closed, and comparatively spends only a small fraction of operating time in a transition-state between the open and closed positions.

A step-down circuit, an electronic device, and a step-down method are disclosed. The step-down circuit includes a positive input terminal and a negative input terminal for receiving an input voltage; and a positive output terminal and a negative output terminal for outputting a target voltage. The negative input terminal and the negative output terminal are grounded together. The step-down circuit also includes a switch circuit, a rectifier circuit, an isolation circuit, and a control unit for outputting control signals to control for turning on or off a switch in the switch circuit and for turning on or off a switch in the rectifier circuit, allowing the input voltage to sequentially pass through the switch in the switch circuit, a capacitor in the isolation circuit, and the switch in the rectifier circuit to obtain a target voltage.

The present invention is directed to provide a semiconductor device capable of protecting a switching element even though having a capacitor connected to a control signal input terminal of the switching element. Semiconductor device includes an IGBT including a gate configured to be input a gate signal and a current detection terminal used to detect at least one of overcurrent or short-circuit current, a gate capacitor arranged between the gate and a reference potential terminal, the gate capacitor being disconnected from the gate as needed, and a disconnection unit configured to disconnect a connection between the gate capacitor and the gate when a detection current being a current output from the current detection terminal is equal to or larger than a first current set on a basis of a minimum current causing oscillation in a loop circuit formed by including the IGBT and the gate capacitor.

A circuit includes a rectifier, a charge pump, and a clamp control circuit. The rectifier has an input configured to be coupled to an alternating current (AC) power source. The rectifier rectifies an AC signal from the AC power source to produce a rectified voltage on a first voltage node. The rectifier includes a first transistor coupled to a ground node and to the input. The first switch has a first control input. The charge pump is coupled to the first voltage node. The charge pump is configured to generate a second voltage on a second voltage node. The voltage regulator is coupled to the second voltage node. The clamp control circuit is coupled to the first and second voltage nodes and has an output node coupled to the first control input.

The invention relates to photoluminescent signs, in particular to signs in which one or more light emitting diodes (LEDs) emit light that excites one or more photoluminescent (PL) elements. In one aspect, a sign may include one or more photoluminescent elements; one or more light emitting diodes (LEDs) arranged to excite the one or more photoluminescent elements; and circuitry arranged for connection to an AC power supply and supplying power to the LEDs.