A micro-electro-mechanical device, wherein a platform is formed in a top substrate and is configured to turn through a rotation angle. The platform has a slit and faces a cavity. A plurality of integrated photodetectors is formed in a bottom substrate so as to detect the light through the slit and generate signals correlated to the light through the slit. The area of the slit varies with the rotation angle of the platform and causes diffraction, more or less marked as a function of the angle. The difference between the signals of two photodetectors arranged at different positions with respect to the slit yields the angle.

A voltage feed-forward circuit, a multiplier using the voltage feed-forward circuit, and a power factor correction circuit using the multiplier. The voltage feed-forward circuit is used to maintain and output a peak voltage (Vff) of an input voltage (Vin), and includes first switch element (S1), a logic control unit (U1), a second switch element (S2), a first capacitor (C1), a third switch element (S3) and a second capacitor (C2). The first control signal (Φ1) and the second control signal (Φ2) begin to be provided at the same time, and the first control signal (Φ1) stops being provided when a voltage of the second end of the first capacitor (C1) is greater than the peak voltage (Vff) of the input voltage (Vin).

A switched power converter (102) is arranged for supplying lighting means (108) as a load, having at least one (M40, M41) switch controlled by a control unit (106), wherein the control unit (106) comprises: a feedback controller, such as an ASIC or microcontroller, generating a switch control signal based on a feedback signal (Imeas), such as e.g. the load current (ILED), and
a separate sweep block, supplied with a signal representing a characteristic of the load (LED), such as e.g. the load voltage (VLED), and modulating the switch control signal (tout-ctrl) by a cyclic sweep, wherein the modulated switch control signal (tout-sweep) is provided directly or indirectly to the at least one switch (M40, M41).

An active gain control circuit includes a dynamic voltage divider having a variable resistance configured to attenuate a rectified input line voltage to produce a reference signal, a filter-divider circuit configured to extract a DC-level attenuated reference voltage from the reference signal, and an operational amplifier configured to receive the DC-level attenuated reference voltage and a regulation voltage, and to generate a gate control signal based on a difference between the regulation voltage and the DC-level attenuated reference voltage, the variable resistance of the dynamic voltage divider being controlled by the gate control signal, and a comparison voltage generator configured to attenuate a comparison voltage to generate the regulation voltage.

An integrated single stage ac-dc driver for powering LED loads includes a boost converter operating in a Discontinuous Conduction Mode, DCM, comprising a half-bridge, and a Zeta Asymmetrical Half Bridge, ZAHB, integrated with the boost converter such that the boost converter and the ZAHB share the half-bridge to perform power factor control, PFC, with a fixed duty cycle and control an output voltage.

A switched mode power supply (SMPS) includes a filter (202), a power factor correction (PFC) circuit (204), and a control circuit (206, 406) configured to determine various electrical parameters of the SMPS. In some embodiments, the control circuit (206, 406) is configured to determine a power line frequency and an AC input voltage based on an AC line voltage and an AC neural voltage. In other embodiments, the control circuit (206, 406) is configured to determine an AC input current based on a reactive current flowing through the filter (202) and a PFC AC current. In further embodiments, the control circuit (206, 406) is configured to report a value of an electrical parameter if value is determined to be accurate. Other example switch mode power supplies, control circuits and methods are also disclosed.

Structures and functions of power supplies are disclosed. In an example, a power supply includes a power factor correction circuit and a bypass circuit. The bypass circuit bypasses the power factor correction circuit when the switch of the bypass circuit is on in response to a predetermined range of input power of the power supply. The bypass circuit also includes a delay circuit to delay the activation of the bypass circuits in response to the predetermined range of input power of the power supply for a predetermined time period.

A method for reducing current ripple at an output of a power supply includes sensing an alternating current (AC) input voltage waveform; determining a correction factor for a switching frequency of the power supply based on the sensed AC input voltage; and applying the correction factor to the switching frequency of the power supply to modify the power supply switching frequency. A modification of the switching frequency synchronizes the switching frequency of the power supply to the AC input voltage waveform.

A dual-input power conversion system includes a first primary side power network comprising a first hold-up capacitor, wherein the first primary side power network has inputs configured to be coupled to a first power source, and outputs coupled to a transformer, a second primary side power network comprising a second hold-up capacitor, wherein the second primary side power network has inputs configured to be coupled to a second power source, and outputs coupled to the transformer, and a secondary side power network having inputs coupled to a secondary side of the transformer, and outputs coupled to a load, wherein the first primary side power network and the second primary side power network are configured such that a voltage across one of the first hold-up capacitor and the second hold-up capacitor is maintained by a voltage reflected from the secondary side to a corresponding primary side.

An electronic apparatus includes: an operator; and a power circuit configured to supply power to the operator, wherein the power circuit includes a first voltage converter configured to output a first voltage based on input power, and a power factor corrector (PFC) configured to output a second voltage by performing power factor correction for the first voltage, and supplies power based on the first voltage or the second voltage to the operator, wherein the power circuit stops an operation of the PFC, lowers the first voltage to have a level corresponding to the second voltage, and supplies power based on the lowered first voltage to the operator, based on power consumption of the operator lower than or equal to a predetermined value.