Abstract: A two-level LED security light with a motion sensor. At night, the LED is turned on for a low level illumination. When the motion sensor detects any intrusion, the LED is switched from the low level illumination to a high level illumination for a short duration time. After the short duration time, the LED security light returns to the low level illumination for saving energy. The LED security light includes a power supply unit, a light sensing control unit, a motion sensing unit, a loading and power control unit, and a lighting-emitting unit. The lighting-emitting unit includes one or a plurality of LEDs which may be turned-on or turned-off according to the sensing results from the light sensing control unit. When the motion sensing unit detects an intrusion, the illumination of the LED security light can be immediately turned on to the high level to scare away the intruder.

Abstract: A power supply device includes a first inverter that converts a first direct-current voltage into a first alternating-current voltage and outputs the first alternating-current voltage, and a second inverter that has an output connected in series with an output of the first inverter and converts a second direct-current voltage into a second alternating-current voltage synchronized with the first alternating-current voltage and outputs the second alternating-current voltage.

Abstract: A two-level LED security light is operated with a motion sensor. When an electric power is supplied, the LED security light is turned on for a low level illumination. When the motion sensor detects any intrusion, the LED security light is switched from the low level illumination to a high level illumination for a short duration time to scare away the intruder. After the short duration time, the LED security light returns to the low level illumination for saving energy. The LED security light includes a power supply unit, a motion sensing unit, a loading and power control unit, and a lighting-emitting unit. The lighting-emitting unit includes one or a plurality of LEDs which may be turned-on or turned-off by control signal generated from the loading and power control unit.

Abstract: An electronic device includes a multi-functional optical sensor configured to couple to one or more light sources within a space. The multi-functional optical sensor is configured to detect occupancy of the space, ambient light within the space, and visible light communication (VLC) signals optically communicated in the space.

Abstract: A motion sensor network method for lighting in group units by using an infrared communication sensor according to the present invention comprises the steps of: sensing a first motion of a person or a vehicle by means of a first sensor module and turning on one lighting module; implementing infrared communication with another sensor module adjacent to the first sensor module and turning on another lighting module; maintaining the turning-on of the first lighting module and the other lighting module when the first sensor module or the other sensor module senses a second motion of the person or the vehicle; and turning off the first lighting module and the other lighting module when the first sensor module or the other sensor module fails to sense the second motion of the person or the vehicle for a certain time.

Abstract: A two-way load control system comprises a power device, such as a load control device for controlling an electrical load receiving power from an AC power source, and a controller adapted to be coupled in series between the source and the power device. The load control system may be installed without requiring any additional wires to be run, and is easily configured without the need for a computer or an advanced commissioning procedure. The power device receives both power and communication over two wires. The controller generates a phase-control voltage and transmits a forward digital message to the power device by encoding digital information in timing edges of the phase-control voltage. The power device transmits a reverse digital message to the controller via the power wiring.

Abstract: A detecting circuit and method thereof are configured to detect whether an LED array is open is described. The detecting circuit includes a resistance unit, a first switching unit, and an output unit. The resistance unit is operatively connected in series to the LED array. The switching unit is configured to be turned on when a voltage of the resistance unit is greater than or equal to a predetermined voltage level. The output unit is configured to produce an output indicative of whether the LED array is open, based whether the first switching unit is turned on.

Abstract: In accordance with embodiments of the present disclosure, an apparatus may comprise a controller to provide compatibility between a load and a secondary winding of an electronic transformer. The controller may be configured to operate a single-stage power converter in a first power mode for a first period of time, such that the single-stage power converter is enabled to transfer energy from the secondary winding to the load during the first power mode and operate the single-stage power converter in a second power mode for a second period of time prior to the first period of time, such that the single-stage power converter is enabled to transfer energy from the secondary winding to the load during the second power mode, wherein the first power mode and the second power mode occur within a half-line cycle of an electronic transformer secondary signal present on the secondary winding.

Abstract: The present disclosure provides a first LED lighting device. The first LED lighting device includes a lighting source, a first detecting module, a first processing module, a first wireless communication module for communicating with a wireless router in an LED lighting device-based wireless mesh network, and a second wireless communication module for communicating with at least one second lighting device in the LED lighting device-based wireless mesh network. The first detecting module receives a detection request sent by the second wireless communication module and detects a signal strength of the wireless router based on the detection request. The first processing module sends a start signal to the first wireless communication module. The first wireless communication module receives the start signal, forms a connection with the wireless router based on the start signal, and sends an LED network-forming request to the second wireless communication module.

Abstract: The invention provides a High Intensity Discharge (HID) lamp acoustic resonance suppression method. Whether acoustic resonance is produced or not is judged, and a frequency-modulated current frequency provided by a ballast when the acoustic resonance is produced to fulfill the aim of suppressing the acoustic resonance. The ballast includes an acoustic resonance elimination module. The invention has the beneficial effects that due to the additional arrangement of the acoustic resonance elimination module, acoustic resonance is maximally suppressed, and the optimal stability of a discharge arc is ensured. These characteristics enable the product to stably run for each type of lamp tube and different power.

Abstract: A method of utilizing a light replication luminaire to match the spectral characteristics of light that is output from the luminaire to the spectral characteristics of a target light spectrum is provided. In one example, the method permits the user to assign a weight to one or more characteristics of the target light spectrum to be replicated. A best approximation of the target light spectrum is then determined, taking into account the weight assigned to each characteristic. In another example, the target light spectrum is provided to the luminaire by the user through the specification of various characteristics of the target light spectrum.

Abstract: The invention provides a method for controlled lighting of an area (2) with a lighting system (1). The method comprises providing with the lighting system (1), according to a predetermined time program, general lighting (11) during a predetermined general lighting period and colored lighting (21) during a predetermined first colored lighting period. The time program runs for at least 6 hours. Further, in the method a control unit (30) is applied, configured to control the lighting system (1) according to the predetermined time program.

Abstract: A control chip of a driving circuit for driving a LED array shares a ground terminal with the LED array so that, without an additional winding, the driving circuit can provide a supply voltage for the control chip, implement a zero-current switching function, and implement an over-voltage protection function. Since no additional windings are needed, the related costs and the size of the driving circuit are decreased.

Abstract: Technologies are described for an emergency power module and a method of providing emergency power. The emergency power module has an emergency power driver, a DC power supply, and a programmable emergency power controller. The emergency power driver is configured to sense an interruption of power and direct power from the DC power supply, through the programmable emergency power controller, and to the at least one electrical device, upon the interruption of power in the external electrical power source. The programmable emergency power controller is programmable through a program interface and control a programmed voltage of power to flow from the DC power supply to the at least one electrical device.

Abstract: A two-level LED security light with a motion sensor. At night, the LED is turned on for a low level illumination. When the motion sensor detects any intrusion, the LED is switched from the low level illumination to a high level illumination for a short duration time. After the short duration time, the LED security light returns to the low level illumination for saving energy. The LED security light includes a power supply unit, a light sensing control unit, a motion sensing unit, a loading and power control unit, and a lighting-emitting unit. The lighting-emitting unit includes one or a plurality of LEDs which may be turned-on or turned-off according to the sensing results from the light sensing control unit. When the motion sensing unit detects an intrusion, the illumination of the LED security light can be immediately turned on to the high level to scare away the intruder.

Abstract: A self-excited power conversion circuit for secondary side control output power includes a comparator unit and a transistor installed directly in a secondary side output module, and the comparator unit is electrically coupled to at least one load, and the transistor is electrically coupled between to a conversion module of the circuit and the load. The comparator unit is provided for adjusting the duty cycle of the transistor after detecting the amount of energy outputted from the conversion module to the load from, so as to adjust the amount of energy actually received by the load to achieve a constant power effect.

Abstract: A protection circuit for lighting drivers is provided, wherein a lighting driver is coupled to an AC voltage source. The protection circuit comprises a loading circuit, coupled to the AC voltage source and operable to load it with a loading current, and a monitoring and control (M&C) circuit. The M&C circuit is coupled to the AC voltage source for detecting interference pulses thereon and causes the loading circuit to load the AC voltage source with the loading current during a certain loading time starting upon detecting an interference pulse, indiscriminately of the interference pulse polarity. The protection circuit thereby prevents the AC source current from dropping to zero in response to the interference pulse. When the AC voltage source comprises a lighting dimmer, preventing the current from dropping to zero prevents cutout of the lighting dimmer due to an interference pulse that causes a momentary drop of the AC voltage.

Abstract: A luminaire includes an electric light source, a light source driver configured to turn on the light source, and a controller configured to control the light source driver. The controller is configured to control the light source driver to transmit, with a probability lower than 50% at a prescribed time interval, an optical signal with light of the light source as a medium while the light source is in ON. The prescribed time interval is longer than a time period during which the optical signal is transmitted.

Abstract: The present disclosure relates to an LED driving circuit and method using a single inductor. A constant current controller controls a power stage circuit to provide a constant output signal, and thus to provide a constant current signal for an LED load. A dimming controller regulates luminance of the LED load. A constant voltage generating circuit receives the current signal at an output terminal of the power stage circuit and a reserve supply voltage for providing a supply voltage for the dimming controller. Compared with the prior art, the present disclosure does not need an independent power supply chip, and reduces components such as inductors and rectifying transistors. Thus, a peripheral circuit is simplified, and an overall size of the system is reduced.

Abstract: Various embodiments may relate to a Light Engine Module including a plurality of series connected LEDs, a positive power supply line, a common ground line, a communication line, a current set resistor) coupled to the communication line, with its value of conductance being indicative for the current demand of the Light Engine Module, and a variable current generator connected to the communication line. The variable current generator is responsive to at least one measurement signal provided by at least one sensor. Various embodiments may further relate to a Power Supply Unit, and a lighting system including the Power Supply Unit with at least one Light Engine Module.

Abstract: An integrated circuit component can include an integrated circuit package and a plurality of terminals provided on the exterior of the integrated circuit package. The terminals are configured to provide electrical connectivity to an interior of the integrated circuit package and a plurality of light emitting diode (LED) segments that includes an LED string in the interior of the package, coupled to the plurality of terminals.

Abstract: A device includes a connection receiving power from a power source under normal conditions and circuitry configured to determine, based on an input from the connection, when the power from the power source is absent; output, when the power source is absent, a test signal at the connection; and generate a detection signal based on current flow generated following the output of the test signal, wherein the detection signal indicates a position of a switch connecting the circuitry to the connection and the generated detection signal indicates the switch is closed when the current flow is above a threshold. The circuitry is configured such that when the power from the power source is absent, the switch is closed, and plural devices are connected on the supply side of the switch, the plurality of devices on the supply side appear as a substantially open circuit to the test signal.

Abstract: A lighting device which changes a hue of light which the lighting device outputs, by changing a brightness proportion between a first light source and a second light source, the lighting device including: a light source which includes the first light source and the second light source, storage which stores control values for causing the light source to output light having a same hue as a hue of light which is output from a light source included in another lighting device; a current adjuster which calculates a first current value, and a second current value, using the control values; and a power source which supplies a first current to the first light source according to the first current value and supplies a second current to the second light source according to the second current value.

Abstract: The invention relates to a method for controlling a lighting system, wherein the lighting system comprises a plurality of light-emitting ceiling tiles and a control unit for controlling the plurality of light-emitting tiles. The method comprises the step of controlling the plurality of light-emitting tiles to provide a predetermined luminance contrast in the ceiling. The method further comprises the step of, for the predetermined luminance contrast, controlling the plurality of light-emitting tiles to provide a substantially uniform light distribution incident on a target surface such as a horizontal work plane. The method enables the lighting conditions in a room to be adjusted for improving visual comfort and illumination without affecting the illumination at a task level.

Abstract: Dimming or illumination control of an LED-based lighting fixture can utilize a combination of pulse width modulation and constant current reduction. A light emitting diode driver can implement pulse width modulation to control light over a first light intensity range and constant current reduction over a second light intensity range. The first light intensity range can be less intense than the second light intensity range. Thus, the driver can practice constant current reduction for dimming at higher light intensities and pulse width modulation for dimming at lower light intensities.

Abstract: A luminaire having an electronically adjustable light beam distribution is disclosed. In some embodiments, the disclosed luminaire includes a plurality of solid-state lamps mounted on one or more surfaces of a housing. The lamps can be electronically controlled individually and/or in conjunction with one another, for example, to provide highly adjustable light emissions from the luminaire (e.g., pixelated control over light distribution). In some cases, a given solid-state lamp may include tunable electro-optic componentry to provide it with its own electronically adjustable light beam. One or more heat sinks optionally may be mounted on the housing to assist with heat dissipation for the solid-state lamps. The luminaire can be configured to be mounted or as a free-standing lighting device, in accordance with some embodiments. In some embodiments, the aperture through which the lamps provide illumination is smaller than the distribution area of the solid-state lamps of the luminaire.

Abstract: An LED based illumination device includes a receiver and a transmitter for communications adhering to a lighting control communications protocol and a high speed communications protocol. The LED based illumination device may be part of a lighting control network, wherein the data transmission rate of the high speed communications protocol is more than twice that of the lighting control communications protocol. The lighting control network may be coupled to a digital communications gateway, including a digital communications interface configured to be coupled to a network operating in accordance with an internet protocol and a lighting control network interface coupled to the lighting control network. A processor determines a summary status value of the LED based illumination device based on information stored in memory of the digital communications gateway. The digital communications gateway may periodically transmit the time of day to the LED based illumination device over the lighting control network.

Abstract: A lighting device employs at least one string of LEDs as a lighting source. The string of LEDs may be coupled in series between a power supply node and ground. In order to accurately determine a drive current running through or drive voltage across the string of LEDs, the drive current through the string of LEDs or the drive voltage across the string of LEDs is sampled randomly or semi-randomly, and a moving average is determined from each one of the samples. By sampling the drive current through or drive voltage across the string of LEDs randomly or semi-randomly, inaccuracies due to synchronization of the sampling with interference in the drive current signal or the drive voltage signal are effectively prevented. Accordingly, an accurate measurement of the drive current through or the drive voltage across the string of LEDs may be obtained.

Abstract: In accordance with an embodiment, a method includes receiving an indication of a changed load condition or voltage characteristic of a power supply providing power to a load via an output port of the power supply in a first mode, and switching regulation of the power supply from sourcing a current to the load in the first mode to sinking the current from the load in a second mode in response to receiving the indication of the changed load condition or voltage characteristic. Sinking the current from the load in the second mode includes controlling the power supply to transfer energy from the output port of the power supply to an input port of the power supply.

Abstract: Disclosed is a lighting apparatus for reducing total harmonic distortion (THD). The lighting apparatus may include a lighting unit having a plurality of LED groups divided into first and second lighting groups, and the lighting unit may provide a current path for light emission corresponding to a change of a rectified voltage, using two or more drives having the same structure.

Abstract: A driving circuit includes: a switching element having a first terminal to receive an input voltage, and a second terminal; an inductor coupled to the second terminal of the switching element; a switch and a current sensing element coupled in series to the second terminal of the switching element; and a control module compensating a voltage sensed by the current sensing element based on at least one of the input voltage and an output voltage across the switching element and the inductor to generate a compensated signal, and switching the switch from an ON state to an OFF state when the compensated signal exceeds a reference threshold for a delay time.

Abstract: An electro-optic device includes: an electro-optic panel displaying a display image with illumination light emitted from an illumination device; a display control circuit controlling the electro-optic panel to display a right-eye image during a right display period and display a left-eye image during a left display period; a glasses control circuit controlling a right-eye shutter of stereoscopic vision glasses so as to maintain an open state during the right display period, controlling a left-eye shutter of stereoscopic vision glasses so as to maintain an open state during the left display period, and controlling both the right-eye shutter and the left-eye shutter so as to maintain a close state during a blocking period; and an illumination control circuit controlling the illumination device to vary an intensity of the illumination light in a pulsed shape during the blocking period.

Abstract: A lighting device of a vehicle is provided. The lighting device comprises a light fitting, which comprises a first and a second light source with different color locations. Furthermore, the lighting device has a first sensing module, which senses the actual value of the color location of the light fitting. In addition, the lighting device comprises a set value generator module which presets a set value for the color location of the light fitting, and a control module which reduces the difference between set value and actual value by means of an actuator module. Here, the set value of the color location of the light fitting is dependent on a driving situation of the vehicle or a personalized driving setting.

Abstract: A power supply circuit for supplying power to at least two loads which are connected to said power supply circuit comprises a current source which can be operated in a clocked manner and has a control input for adjusting the power. At least two load strings are connected in parallel between a power supply connection, which is coupled to the current source, and a reference connection. Each load string has a load and charge storage means which is connected in parallel with the load. A switch is used to selectively switch the current path of the load string. A sensor having a sensor resistor which is connected in the current path of the load string is used to detect a current flowing through the connected load string. Furthermore, the controlled power supply circuit comprises a control circuit which is coupled to the switch and to the sensor of each load string for the purpose of activating each load string in a time-multiplexed manner.

Abstract: A light-emitting diode (LED) lamp which can replace a typical fluorescent lamp is provided. The LED lamp comprises external connection pins connected to terminals of an electronic or magnetic fluorescent lamp ballast, capacitors connected to each of the external connection pins, diodes connected to each of the capacitors and a LED array connected between the diodes, wherein an first external connection pin, a first capacitor, a first diode, an LED array, a second diode, a second capacitor and a second external connection pin are connected in series. The LED lamp also further comprises a diode connected in anti-parallel with a series circuit of the second diode and the LED array, and another diode connected in anti-parallel with a series circuit of the first diode and the LED array.

Abstract: A light emitting diode (LED) lighting system and method are disclosed. The LED lighting system and method include an LED controller to accurately control a current in an LED system. The LED controller includes components to calculate, based on the current and an active time period of an LED current time period, an actual charge amount delivered to the LED system wherein the LED current time period is duty cycle modulated at a rate of greater than fifty (50) Hz and to utilize the actual charge amount to modify and provide a desired target charge amount to be delivered during a future active time period of the LED current time period. The LED system and method further involve components to compare the actual charge amount to a desired charge amount for the active time period and compensate for a difference between the actual charge amount and the desired charge amount during the future active time period.

Abstract: A programmable lighting device includes a power stage, a controller, a nonvolatile memory and a near field communication device. The power stage is configured to receive power from an external supply and supplying power to at least one light source. The controller is configured to control operation of the power stage according to an operating parameter and/or configuration setting for the programmable lighting device. The nonvolatile memory device stores the operating parameter and/or configuration setting. The near field communication device receives a radio frequency signal which communicates the operating parameter and/or configuration setting, and in response thereto stores the operating parameter and/or configuration setting in the nonvolatile memory. The near field communication device generates a supply voltage for powering the nonvolatile memory device from the RF signal.

Abstract: LED-based light source modules can incorporate color tunability and brightness control, allowing a user to select a desired color temperature and/or brightness and to change either or both dynamically. An emitter can include multiple independently addressable groups of LEDs, each emitting light of a different color. By controlling the relative operating current provided to each group, a desired color temperature can be achieved, and by controlling the absolute operating currents, the brightness of the output light can be controlled. Pulse width modulation (PWM) can be used to control the relative and absolute operating currents. Smooth, gradual transitions between brightness and/or color temperature settings in response to changes can be provided.

Abstract: An emergency lighting module for providing emergency power to a solid state luminaire includes a microcontroller, and a detector coupled to the microcontroller and configured to detect a status signal indicative of a status of an AC line voltage, the emergency lighting module is configured to output a dimming control signal to the solid state luminaire in response to a reduction of the AC line voltage. The microcontroller is further configured to output a select signal to the solid state luminaire to cause the solid state luminaire to dim in accordance with the dimming control signal when the dimming control signal is output.

Abstract: The invention provides advances in the arts with useful and novel driver methods. The invention provides circuit driver and control methods for relatively high-current drivers, usable with relatively low-voltage battery power sources. Preferred embodiments include one or more high series resistance capacitors electrically connected with a power source. A low resistance driver circuit regulates power supplied from the capacitors to the load.

Abstract: An LED driver can include: a rectifying bridge configured to receive an AC current from an electrical ballast, and to generate a DC current; a rectifying and filtering circuit coupled to the rectifying bridge, and configured to rectify and filter the DC current, and to drive an LED load; a power switch coupled between an input of the rectifying and filtering circuit and ground, and configured to be controlled by a switching control signal; a first detecting circuit configured to sample a current that flows through the LED load, and to generate a first detection signal; a second detecting circuit configured to sample an output current of the rectifying bridge, and to generate a second detection signal; and a control circuit configured to generate the switching control signal according to the first and second detection signals.

Abstract: A fully integrated circuit configuration that can be used to control the slew rate of a PMOS load switch is described. The circuit also integrates a multichannel temperature sensing system which can be coupled to an external set of temperature sensors, preferably non-linear PTC (positive temperature coefficient) sensors to provide both current inrush control as well as thermal overload protection. A communications data bus, such as an I2C bus, is employed to provide temperature feedback for the system controller so that the system can better control the temperature of its own environment.

Abstract: Various embodiments may relate to a power supply unit, including an output for outputting an operating current depending on an internal measurement signal, a communications line, and a current-measuring device, which is connected to the communications line. The current-measuring device is designed to generate a current on the communications line which is proportional to the conductance of a current-setting resistance. The current-measuring device has a current mirror, which is designed to mirror the generated current on the communications line. The current-measuring device is designed to convert the mirrored current into an internal measurement signal with a reference potential which is different than the communications line. At least one light source module is connectable to the output, wherein the at least one light source module has the current-setting resistance, which is connectable to the communications line.

Abstract: A lighting device employs an array of LEDs as a lighting source. The array of LEDs may be coupled in series between a power supply node and ground. In order to determine whether the input drive signal to the array of LEDs is a pulse width modulated (PWM) signal or a linear signal, the voltage across the string of LEDs is sampled and stored in a cyclical buffer. The variance of the samples stored in the cyclical buffer is then calculated and used to determine whether the input signal provided to the string of LEDs at the power supply node is a PWM signal or a linear signal. In one embodiment, the variance is compared to a predetermined threshold value to determine whether the input signal is a PWM signal or a linear signal.

Abstract: A dimming system comprises a controller and an AC-to-DC converter. The controller outputs a control signal in response to a dimming signal. The controller comprises a frequency adjustment circuit and a duty cycle adjustment circuit. The frequency adjustment circuit adjusts the frequency of the control signal in response to the dimming signal. The duty cycle adjustment circuit adjusts the duty cycle of the control signal in response to the dimming signal. The AC-to-DC converter converts an external power and to output a DC signal in response to the control signal so as to drive a light source by the DC signal. When the controller is operated at a first mode, the control signal has a first frequency and a first duty cycle. When the controller switches to a second mode, the control signal has a second frequency and a second duty cycle.

Abstract: A sensor lighting control system comprises a voltage input received from an AC source so as to be an AC voltage input. A voltage output for connection to lamps. A microcontroller controlling the voltage output and powered by the voltage input. A wireless mesh network transceiver connected to the microcontroller, where the wireless mesh network transceiver is configured to communicate with a wireless mesh network that can receive a global remote control and Internet, and the wireless mesh network transceiver is connected to a mesh network coordinator. Passive infrared motion sensors are connected to the microcontroller, where the passive infrared motion sensors include at least three passive infrared motion sensors. An acoustic sensor for detecting environmental acoustics is connected to the microcontroller, where a triggering level of the acoustic sensor is programmable via the mesh network controller to trigger the microcontroller to activate or deactivate the voltage output.

Abstract: A power conversion system includes a power transfer estimator that is operable to provide a determination of the cumulative amount of power transferred through the power supply, without additional sensing elements and at extremely low power levels, and to provide such determinations periodically over potentially long periods of time commensurate with the lifetime of a limited power source such as a battery. In a power conversion system operating in a discontinuous conduction mode (DCM), the power transfer estimator determines the charge transferred during each switching cycle, and the total number of switching cycles, to calculate the cumulative amount of power transferred. The power transfer estimator is optionally operable to calculate a value for the inductance to be used in the determination of the cumulative amount of power transferred through the power supply.

Abstract: A blood analyzing device (100) comprises a light source (120) arranged to generate light (40) of a wavelength at which a Hb species in a hemolyzed blood sample (30) has absorbance. A detector system (130) is arranged to detect output light (50) from the sample (30) and generate a Hb signal representative of an amount of the Hb species in the sample (30) and a parasite signal representative of an amount of malaria parasites in the sample (30). A processor (140) generates a red blood cell value based on the Hb signal and generates a parasitemia value based on the parasite signal and the red blood cell value. A display (160) displays the parasitemia value representing a percentage of the red blood cells that are infected by malaria parasites.

Abstract: It is an object to reduce the region of a photoelectric conversion element which light does not reach, to suppress deterioration of power generation efficiency, and to suppress manufacturing cost of a voltage conversion element. The present invention relates to a transmissive photoelectric conversion device which includes a photoelectric conversion element including an n-type semiconductor layer, an intrinsic semiconductor layer, and a p-type semiconductor layer; a voltage conversion element which is overlapped with the photoelectric conversion element and which includes an oxide semiconductor film for a channel formation region; and a conductive element which electrically connects the photoelectric conversion element and the voltage conversion element. The photoelectric conversion element is a solar cell. The voltage conversion element includes a transistor having a channel formation region including an oxide semiconductor film. The voltage conversion element is a DC-DC converter.

Abstract: The present document relates to Direct Current (DC) to DC power converters. In particular, the present document relates to DC to DC power converters which comprise one or more bipolar transistors as power switches. A control circuit configured to control a power switch of a switched-mode power converter is described. The power switch comprises a bipolar transistor. The control circuit is configured to determine an indication of a time instant, at which the power switch is switched off; and to adjust a basis current for controlling the power switch based on the determined indication of the time instant.