Abstract: A method, which is applied in a driving circuit including an analog-to-digital convertor (ADC) and a switching circuit including an inductor and coupled to a load, includes steps of: performing an analog-to-digital conversion on a load voltage of the load at a first rate; and producing at least a current pulse flowing through the inductor at a second rate. Wherein, each current pulse among the at least a current pulse is accomplished within a second cycle corresponding to the second rate, all of the at least a current pulse are accomplished within a first cycle corresponding to the first rate, and a first length of the first cycle is longer than twice of a second length of the second cycle.

Abstract: Disclosed are a system and method for controlling an active clamp flyback (ACF) converter. The system includes: a drive module configured to control turning-on or turning-off of a main switching transistor SL and a clamp switching transistor SH; a main switching transistor voltage sampling circuit configured to sample a voltage drop between an input terminal and an output terminal of the main switching transistor SL; a first comparator connected to the main switching transistor voltage sampling circuit and configured to determine whether a sampled first sampling voltage is a positive voltage or a negative voltage; and a dead time calculation module configured to adjust, according to an output of the first comparator and a main switching transistor control signal DUTYL of a current cycle, a clamp switching transistor control signal DUTYH of next cycle outputted by the drive module.

Abstract: A USB-power delivery integrated circuit controller includes: one or more driver circuits configured to control operation of a buck-boost converter; a regulator configured to regulate an internal supply voltage of the controller from a variable input voltage of the buck-boost converter in a regulation mode, and to pass the variable input voltage as the internal supply voltage without regulation in a bypass mode, the regulator being in the bypass mode when the variable input voltage is below the internal supply voltage, the regulator including an amplifier and a pass transistor configured to pass a current that is inversely proportional to an output of the amplifier; a clamping circuit configured to limit an overdrive voltage of the pass transistor during an inrush current event; and an override circuit configured to deactivate the clamping circuit in the bypass mode when the current passed by the pass transistor is below a current threshold.

Abstract: A telematics device coupled to an input/output expander is provided. The telematics device includes a controller, an input/output expander interface for coupling the telematics device to the controller and a memory. The memory has machine-executable programming instructions which configure the telematics device to power-cycle the input/output expander interface by a plurality of power cycles having progressively increasing power-off durations, in response to detecting a power fault condition on the input/output expander interface.

Abstract: A method for handling input/output (I/O) expansion power faults in a telematics device is provided. The method includes setting an I/O expander power-off duration to an initial value and powering on an I/O expander interface. In response to detecting a power fault at the I/O expander interface, the I/O expander interface is powered-off dur the power-off duration and the power-off duration is increased. If the power-off duration is greater than the power-off duration limit, the I/O expander interface is permanently powered-off. The steps are repeated until either the power fault does not recur, or the I/O expander interface is permanently powered-off.

Abstract: A power converter powers an LED fixture from a power supply, and comprises a primary circuit a primary winding; and a switch in series connection with the primary winding to in a conductive state of the switch connect the primary winding to the power supply; a secondary circuit comprising a secondary winding that is magnetically coupled with the primary winding for providing power to the LED fixture in response to a switching of the switch; the power converter further comprising: the power converter further comprising: a sensing circuit configured to generate a signal representative of the output voltage of the secondary winding, an edge of the signal representing an edge of the output voltage of the secondary winding in response to the switching of the switch; and a detecting circuit configured to derive timing data from the edges of the signal, to estimate a load of the power converter from at least one output parameter of the power converter, and to determine a momentary value of a voltage of the

Abstract: The power supply apparatus includes a rectifying and smoothing unit configured to rectify and smooth an AC voltage of an AC power supply, a transformer having a primary winding, first and second secondary windings, a detecting unit connected to the second secondary winding, the detecting unit configured to detect a second voltage according to a voltage output from the rectifying and smoothing unit, and a first control unit configured to control a state of the load based on a result detected by the detecting unit.

Abstract: An energy-saving charger capable of automatically powering off includes a bridge rectifier circuit, a switch control circuit, a high-frequency transformer, and a low-voltage output circuit that are sequentially connected. The charger further includes: an electronic switch connected in series between the bridge rectifier circuit and the switch control circuit; a low-voltage-end control detection circuit connected to the low-voltage output circuit, used for feeding back a magnitude of a current output by the charger and outputting a control signal; an isolating drive circuit connected to the low-voltage-end control detection circuit; and a power-on self-holding circuit connected to the isolating drive circuit and a control end of the electronic switch, used for controlling on and off of the electronic switch according to the isolated control signal, and providing a short-time ON level to the control end of the electronic switch at the beginning of power-on of the charger.

Abstract: A controller circuit for an AC-DC converter includes a first controller circuit block configured to drive one or more switches at the primary side of a transformer in the AC-DC converter. A second controller circuit block is configured to sense, at a secondary side of the transformer in said AC-DC converter, a secondary side signal indicative of the output signal from said AC-DC converter. The second controller circuit block generates switching control signals for the first controller circuit block as a function of the secondary side signal. An isolator circuit block between the first controller circuit block and the second controller circuit block includes an isolated transmission channel of the switching control signals from the second controller circuit block to the first controller circuit block.

Abstract: A switching power converter is provided that cycles a power switch during a group pulse mode of operation to produce a train of pulses within a group period responsive to a control voltage being within a group mode control voltage range. Depending upon the control voltage, the number of pulses in each train of pulses is varied to provide a linear power delivery to the load.

Abstract: A PD device comprises: a DC/DC converter disposed between an input and a VBUS output; a primary-side controller configured to control an input current of the DC/DC converter; a signal conversion and switching circuit coupled to a control input and configured to executes signal conversion and switching; an output capacitor CO connected between the VBUS output and the signal conversion and switching circuit; and a secondary-side controller coupled to the signal conversion and switching circuit, and configured to receive the control input signals subjected to the signal conversion and switching executed in the signal conversion and switching circuit, and to feed back the control input signals to the primary-side controller. The primary-side controller varies an output voltage value and an available output current value (MAX value) of the DC/DC converter by controlling the input current on the basis of the control input signals fed back from the secondary-side controller.

Abstract: A constant on-time isolated converter comprising a transformer is disclosed. The transformer primary side connects to an electronic switch and secondary-side connects to a load and a processor. The processor connects to a driver on primary side through at least one coupling element and to the electronic switch. The processor receives an output voltage or an output current across the load generating a control signal. The driver receives control signal through the coupling element and accordingly changes the electronic switch ON/OFF state, regulating output voltage and current via the transformer, where the electronic switch ON/OFF duration is determined between the moment control signal changes from negative to positive and the moment it changes from positive to negative to achieve a high-speed response to load transient.

Abstract: An apparatus and a method for controlling vehicle start-up modify a sequence order in which control units of the vehicle are started up to improve reliability. In operation, a processor determines whether a voltage of a low-voltage battery is less than a reference voltage when a start key is turned on, and determines a voltage classification level corresponding to the voltage of the low-voltage battery when the voltage of the low-voltage battery is less than or equal to the reference voltage. The processor then determines a sequence order in which to start up driving units of the vehicle including a power conversion device of the vehicle based on the determined voltage classification level, and controls startup of the vehicle by reflecting the determined sequence order of the power conversion device.

Abstract: A power source device includes a transformer including a primary winding and a secondary winding; a switching element for enabling or disabling supply of electric power to the primary winding by a switching operation; a controller for controlling the switching operation, wherein the controller is capable of effecting continuous control in which the switching operation is continued and intermittent control in which a switching period in which the switching operation is performed and a rest period in which the switching operation is at rest are repeated, a calculating portion not operating in the rest period; and a measuring portion continuing operation even in the rest period. When a predetermined time has elapsed from a start of the rest period, the measuring portion causes the calculating portion to resume the operation thereof, and starts the switching period.

Abstract: A synchronous rectifier driving method, a synchronous rectifier circuit and a switching power supply are provided, and the method includes: detecting an output current in a secondary winding of a transformer unit, and generating a first driving signal according to the output current; obtaining a protection signal according to a voltage signal of the secondary winding of the transformer unit in a synchronous rectifier circuit; correcting the first driving signal by using the obtained protection signal to obtain a second driving signal; and driving a rectifier in the synchronous rectifier circuit according to the second driving signal.

Abstract: A flyback converter includes a primary-side switch that controls conduction of current on a primary side of a transformer and a synchronous rectifier on a secondary side of the transformer. A synchronous rectifier driver controls the conduction of the synchronous rectifier by adaptively adjusting a turn-off threshold of the synchronous rectifier.

Abstract: System and method for regulating a power converter. The system includes a comparator configured to receive a first signal and a second signal and generate a comparison signal based on at least information associated with the first signal and the second signal. The first signal is associated with at least an output current of a power converter. Additionally, the system includes a pulse-width-modulation generator configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, and a driver component configured to receive the modulation signal and output a drive signal to a switch to adjust a primary current flowing through a primary winding of the power converter. The modulation signal is associated with a modulation frequency corresponding to a modulation period.

Abstract: The power supply apparatus includes a transformer, a switch connected to a primary side of the transformer, a first line connected to a secondary side of the transformer to output a voltage of a first polarity, a second line connected to the secondary side of the transformer to output a second polarity voltage whose polarity is opposite to the first polarity, a first diode connected to the first line in a direction, a first capacitor connected to the first line, a second diode connected to the second line in another direction opposite to the direction of the first diode, a second capacitor connected to the second line, a resistor connected to the first line on an output side of the first diode, and a controller controlling a frequency of the switch to control an output from the second line constant.

Abstract: This invention proposes using a feed forward quasi universal converter for energy harvesters, and uses it to power IoTs (Internet of things). A typical DC to DC converter uses voltage feedback control or current feedback control. It is not easy for the input impedance to closely match the output impedance of the power source. In the meantime, it also meets its output voltage and power targets. The Feed forward Quasi Universal Converter proposed in this invention controls the input impedance and the output voltage/power within a range that meets the design targets. It is also achieved with a simple electronic adjustment when the source impedance changes or the output requirements change. It has the potential to shorten the IoTs system industry's product development cycle, reduce installation and maintenance costs and facilitate the adoption of hybrid energy sources.

Abstract: A method for controlling a dead time of a secondary side of a power converter includes giving a previous first turning-on time and a current first turning-on time corresponding to a primary side of the power converter, generating a first voltage and a second voltage according to the previous first turning-on time and the current first turning-on time, respectively, generating a current first target voltage according to the first voltage, the second voltage, and an ideal voltage corresponding to a previous ideal second turning-on time of the secondary side, and determining a current second turning-on time of the secondary side according to the current first target voltage and a first ramp voltage corresponding to a current ideal second turning-on time of the secondary side. A difference between the current second turning-on time and the current ideal second turning-on time is a current dead time.

Abstract: A system may include a power module that includes a group of power supplies, particular ones of the group of power supplies being operable at a group of voltages ranging from a first voltage to a second voltage. The system may further include a controller coupled to the particular ones of the group of power supplies, the controller being to ramp up an output voltage, associated with the group of power supplies, from the first voltage to the second voltage in a group of discrete steps; where ramping up the output voltage by a particular one of the group of discrete steps is performed while a load is receiving power from the group of power supplies; and where ramping up the output voltage by a particular one of the group of discrete steps prevents over-current protection on the group of power supplies from being activated.

Abstract: Examples of electronic circuits and methods are provided. A power adapter is coupled to load device such that a power node and a signal node and a ground node are common to both entities. A supply voltage is regulated and provided by the power adapter to the load device in accordance with a voltage sensed at the signal node. Electrical current drawn by the load device is limited in accordance with a voltage sensed at the signal node.

Abstract: The present invention relates to a feedback device for a power supply, including a main feedback module, an auxiliary feedback module and a feedback control module. The main feedback module is adapted to sample a voltage on a main output branch of the power supply, and output a main feedback voltage to the feedback control module. The auxiliary feedback module is adapted to reduce the main feedback voltage when a voltage on an auxiliary output branch of the power supply drops. The feedback control module is adapted to control the power supply to increase its power output when the main feedback voltage decreases, so that the voltage on the auxiliary output branch is restored to normal. By using the power supply feedback device of the present invention, the circuit is simple, not only solving voltage sag problems, but also ensuring the power density and cost.

Abstract: A light-emitting diode (LED) driver apparatus is provided. The LED driver apparatus includes a pulse width modulation (PWM) signal generating unit, a DC-DC converter, and a comparison voltage generating unit. The PWM signal generating unit generates a PWM signal according to a comparison voltage. The DC-DC converter supplies a driving voltage of an LED array by using the PWM signal. The comparison voltage generating unit measures a feedback voltage of the LED array and supplies a difference between the measured feedback voltage and a target voltage as a comparison voltage to the PWM signal generating unit. The comparison voltage generating unit supplies a second reference voltage as a comparison voltage to the PWM signal generating unit from a time when the driving voltage is higher than or equal to a first reference voltage to a time when the driving voltage reaches the target voltage.

Abstract: A protection circuit of a power converter without an input capacitor is disclosed. The protection circuit comprises a high voltage switch, a detection circuit and a control circuit. The switch senses an input voltage of the power converter via a resistor for generating a first signal. The detection circuit coupled to a transformer senses the input voltage of the power converter for generating a second signal. The control circuit controls a switching signal in response to the first signal and the second signal. The switching signal is utilized to switching the transformer for regulating the power converter; and the level of the first signal and the second signal is correlated a level of the input voltage of the power converter.

Abstract: A switched mode power converter (SMPC) has an isolation transformer for power transfer and a communication circuit for data communication between the primary side and the secondary side. The SMPC includes a primary switch controller configured to transfer power from a primary side to a secondary side by controlling a primary switch ON for an ON time period and then controlling the primary switch OFF for an OFF time period. The primary switch controller controls the ON time period of the subsequent power transfer cycle to start a time delay after the end of the OFF time period of the previous power transfer cycle. The communication circuit comprises a magnetically coupled transmission winding and reception winding, a communication switch, and a communication controller to control the communication switch to allow charge flow through the transmission winding during at least part of the time delay for data communication.

Abstract: A galvanically isolated DC/DC converter includes at least one first side converter circuit coupled between a pair of first side DC terminals, and at least one second side converter circuit coupled between a pair of second side DC terminals. The second side converter circuit has at least a first and a second switching element, each including a switch and a diode connected in parallel. When the DC/DC converter is in power transfer operation from the pair of first side DC terminals to the pair of second side DC terminals, the diodes of the first and second switching elements are alternately in a conductive state, with each of the first and second switching elements being controlled such that a closed state of the respective switch extends beyond a transitioning of the diode of the same switching element from the conductive state to a blocking state.

Abstract: In one embodiment, a zero-crossing detection circuit can include: (i) a first detection circuit configured to detect a current through a main transistor of a main circuit of a switching power supply, and to generate a voltage sense signal that represents the current through the main transistor; (ii) a second detection circuit configured to detect if quasi-resonance occurs in the main circuit, the second detection circuit being configured to generate at least one pulse signal when the quasi-resonance is detected; and (iii) a control circuit configured to receive the at least one pulse signal and the voltage sense signal, to turn the main transistor off when the current through the main transistor reaches a predetermined value, and to turn the main transistor on when the at least one pulse signal is active.

Abstract: The present disclosure describes a power supply with multiple operating modes, to detect a load condition of an electronic device, and to automatically change between the multiple operating modes to supply an output direct current (DC) signal to the electronic device based on the load condition detected by the load detection mechanism. The power supply includes multiple control topologies that are each associated with one of the operating modes. Changing from a first operation mode to a second operation mode includes changing from a first control topology associated with the first operation mode to a second control topology associated with the second operating mode to supply the output DC signal at a predetermined voltage level.

Abstract: A control device controls a switching circuit of a DC-DC converter. The switching circuit includes a half-bridge with at least first and second switches connected between an input voltage and a reference voltage. The converter comprises a transformer with a primary coupled with the center point of the half-bridge and a secondary coupled with a load. The control device comprises an error detector configured to determine an error signal representing a difference between a first signal representative of the voltage across the load and a first reference signal and a frequency controller configured to increase the switching frequency of the half-bridge when the error signal is kept below a second signal.

Abstract: A power conversion apparatus, including a transformer, a switch, an analog controller, a digital controller, and a voltage converter-based feedback circuit, is provided. The primary side of the transformer is coupled to an input voltage, and the secondary side of the transformer is coupled to an output voltage provided to a load. The switch intermittently transmits the input voltage to the primary side of the transformer. The analog controller is disposed at one of the primary side and the secondary side of the transformer and configured to control the operation of the switch in response to an analog feedback signal. The digital controller is disposed at the other one of the primary side and the secondary side and configured to generate a digital feedback signal. The voltage converter-based feedback circuit is configured to convert the digital feedback signal to the analog feedback signal based on a voltage conversion characteristic thereof.

Abstract: A motor-drive circuit includes a detection circuit to detect a reverse current to flow in a direction from a first sink-side transistor to a second source-side transistor or in a direction from a second sink-side transistor to a first source-side transistor, a disable circuit to disable a detection output of the detection circuit during a predetermined time period from a start of detection of the reverse current performed by the detection circuit, a first inhibit circuit to inhibit synchronous rectification according to a detection output of the detection circuit when the predetermined time period has elapsed from a start of detection of the reverse current performed by the detection circuit, and a second inhibit circuit.

Abstract: Apparatus and methods for filtering the transients of an input signal of an integrated circuit while maintaining a constant voltage at an input terminal of the integrated circuit are disclosed. In one example, the integrated circuit can be a controller of a switched-mode power supply. The controller can include a line sensing circuit coupled to receive an input signal representative of the line voltage and operable produce an output signal that can be used by other circuits within the controller. The input signal may include a current through a sense resistor coupled between the input of the power supply and the line sensing circuit. The output signal may include a scaled and filtered version of this current. The line sensing circuit can be coupled to the input terminal of the controller to receive the input signal or can directly receive the input signal.

Abstract: A method of controlling a switching converter and a related controller suitable for the switching converter allow to implement a burst-mode functioning without generating acoustic noise and with a relevantly reduced ripple of the regulated DC voltage or current provided in output to a supplied load. The method includes sensing the difference between the error signal and the burst-stop threshold at the beginning of a burst period. If the error signal has surpassed (either upwards or downwards) the burst-stop threshold, the method sets the switching stage in a high impedance state at a new active edge of a clock signal, keeps the switching stage in the high impedance state for an integer number of cycles of the clock signal, and re-enables the switching stage to switch the energy tank circuit up to the end of the burst period.

Abstract: A high voltage power supply system includes: a high voltage power supply; a current detector; a voltage detector; a conversion section configured to obtain a converted-current value by dividing a detected-current voltage value by a predetermined resistance value; a selector configured to select one of the detected-current voltage value and the detected-voltage voltage value; a resistance variable section configured to change the predetermined resistance value; a temperature detector; a humidity detector; and a control section configured to create a voltage setting signal, a selection signal, and a resistance variable signal on the basis of the detected-voltage voltage value, the detected-temperature value, and the detected-humidity value, and to apply the voltage setting signal to the high voltage power supply, the selection signal to the selector, and the resistance variable signal to the resistance variable section.

Abstract: A power converter is disclosed that includes an active valley fill (AVF) capacitor that is actively switched to provide current to a load during a portion of an alternating current (AC) input cycle. The current supplied to the load includes some current supplied by the AC input and some current supplied by the AVF capacitor. Circuitry is configured to regulate the amount of current flowing through the load, including controlling the amount of current supplied by the AVF capacitor. The duty cycle on the AVF capacitor can be adjusted to shape the AC input current waveform.

Abstract: System and method for regulating a power converter. The system includes a comparator configured to receive a first signal and a second signal and generate a comparison signal based on at least information associated with the first signal and the second signal. The first signal is associated with at least an output current of a power converter. Additionally, the system includes a pulse-width-modulation generator configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, and a driver component configured to receive the modulation signal and output a drive signal to a switch to adjust a primary current flowing through a primary winding of the power converter. The modulation signal is associated with a modulation frequency corresponding to a modulation period.

Abstract: An embodiment provides a control method capable of controlling a switching-mode power supply to provide an output power source. The switching-mode power supply has a winding coupled to an input power source and controlled by a switch to be energized or de-energized. The maximum current peak through the winding is set to be a predetermined value. A discharge time of the winding in a switching cycle period is detected. The switching cycle period of the switch is controlled to keep the ratio of the discharge time to the switching cycle period as a constant.

Abstract: A control device for a QR switching power converter is described; said power converter is adapted to convert an input signal to a DC output signal and comprises a power switch connected to said input signal and adapted to regulate said DC output signal and magnetic storage means. The control device is able to determine the switching frequency of the power switch and it is supplied by a feedback signal deriving from a feedback circuit coupled to the output signal of the power converter; said control device performs a control loop regulating the DC output signal by controlling a control variable. The control device comprises modulating means adapted to modulate said control variable as a function of at least one modulating signal having a frequency higher than the control loop bandwidth.

Abstract: A controller of a power converter with adjustable jitter amplitude includes a feedback pin, a logic circuit, an auxiliary pin, and a current sensing pin. The feedback pin is used for receiving a feedback voltage from a secondary side of the power converter. The feedback voltage corresponds to an output voltage of the secondary side of the power converter. The logic circuit is used for generating a jitter signal according to a clock, the feedback voltage, and a first resistor. The auxiliary pin is used for receiving a voltage corresponding to an auxiliary winding of the power converter. The current sensing pin is used for generating a detection voltage according to a current flowing through a primary side of the power converter. The voltage, the jitter signal, and the detection voltage determine turning-on time of the primary side of the power converter.

Abstract: An example integrated circuit controller for a power converter includes a digital peak detector and a switching block. The digital peak detector is coupled to output a digital count signal representative of a peak input voltage of the power converter. The switching block is coupled to control switching of a power switch of the power converter to regulate an output of the power converter. The switching block is further coupled to control the switching of the power switch in response to the digital count signal.

Abstract: A power converting device includes a main switch, a synchronous rectifier switch, a rectifier-filter circuit which outputs an output voltage, and a synchronous rectifier control circuit which includes a sampling circuit coupled to the rectifier-filter circuit for outputting a voltage variation signal, a differential amplifier circuit that outputs an amplified signal by adding the output voltage and an offset voltage to the voltage variation signal attenuated thereby, and a comparison circuit that compares the amplified signal with the output voltage so as to output a trigger signal, such that the synchronous rectifier switch is turned on when the main switch is turned off, and is turned off prior to conduction of the main switch.

Abstract: A power converting device includes a transformer, a first switch coupled to a primary winding of the transformer, a PWM controller which generates a first PWM signal for controlling conduction and non-conduction of the first switch and which generates a control signal that leads the first PWM signal, a rectifier-filter circuit which rectifies an induced voltage generated by a secondary winding of the transformer, a second switch coupled to the secondary winding, and a synchronous rectifier controller which controls conduction and non-conduction of the second switch, and which controls, according to the control signal, the second switch to become non-conductive prior to conduction of the first switch.

Abstract: An example power supply controller includes a signal separator circuit that generates a feedback signal. An error signal generator generates an error signal in response to the feedback signal. A control circuit generates a drive signal in response to the error signal. The drive signal controls switching of a switch. A multi-cycle modulation circuit is included in the control circuit and generates a skip signal in response to a start skip signal, a stop skip signal and a skip mask signal. The skip mask signal is generated in response to the skip signal. The start skip and stop skip signals cause the drive signal to start skipping or stop skipping, respectively, on-time intervals of cycles. The skip mask signal disables the start skip signal from causing the drive signal to start skipping the on-time intervals of cycles.

Abstract: A controller for controlling power to a light source includes a first sensing pin, a second sensing pin, a third sensing pin, and a driving pin. The first sensing pin receives a first signal indicating an instant current flowing through an energy storage element. The second sensing pin receives a second signal indicating an average current flowing through the energy storage element. The third sensing pin receives a third signal indicating whether the instant current decreases to a predetermined current level. The driving pin provides a driving signal to a switch to control an average current flowing through the light source to a target current level. The driving signal is generated based on one or more signals selected from the first signal, the second signal and the third signal.

Abstract: One controller for a power supply includes an oscillator, a first circuit, a counter, and a pause circuit. The first circuit generates a drive signal to control switching of a switch to regulate an output of the power supply. The first circuit initiates an on time period of the switch in response to both a clock signal of the oscillator and an enable signal that is generated in response to a feedback signal of the power supply. The counter receives the enable signal and generates an output signal when the counter reaches a count value indicating that the enable signal has been idle for an amount of time. The pause circuit generates a pause signal in response to the output signal of the counter. The oscillator is paused in response to the pause signal and a maximum on time period of the switch is extended while the oscillator is paused.

Abstract: An image forming apparatus includes an image carrier, a charging unit, an exposure unit, a developing unit, and a transfer unit. The transfer unit includes a transfer bias power supply and transfers a developed image onto a transfer body. The transfer bias power supply includes a first power supply unit that generates a non-transfer electric field, a second power supply unit that generates a transfer electric field, a first switching controller, and a second switching controller. The first switching controller controls start of supply of the transfer electric field in accordance with a first time constant when switching from the non-transfer electric field to the transfer electric field is performed. The second switching controller controls stop of supply of the transfer electric field in accordance with a second time constant when switching from the transfer electric field to the non-transfer electric field is performed.

Abstract: A novel system and methodology for providing a volt-second clamp. A DC/DC conversion system configured for producing an output voltage in response to an input voltage has a transformer with a primary winding responsive to the input voltage and a secondary winding for producing the output voltage. The conversion system has a power switch coupled to the primary winding of the transformer and controlled with a converter control signal, such as a PWM control signal. The power switch is further controlled by a comparator that compares an input value supplied to its input with a variable reference value so as to prevent magnetic flux density of the transformer from increasing to an undesired level. The input value of the comparator is produced by a comparator input circuit as a function of the input voltage and an on-time of the power switch. A reference circuit produces the reference value that varies as a function of the input voltage.

Abstract: A power supply includes an energy transfer element, a switch, and a controller. The controller includes a modulator, a drive signal generator, a comparator, and a variable current limit generator. The modulator generates an enable signal having logic states responsive to a feedback signal. The drive signal generator either enables or skips enabling a switch of the power supply during a switching period in response to the logic state of the enable signal. The comparator asserts an over current signal to disable the switch if the switch current exceeds a variable current limit. The variable current limit generator sets the variable current limit to a first current limit in response to one logic state of the enable signal and sets the variable current limit to a second current limit if the enable signal transitions logic states and the over current signal is asserted during the switching period.

Abstract: A resonance-type power supply is provided in which no short circuit occurs and driving is performed with a constant switching period by performing switching control using a change of magnetic flux of a magnetic component as a trigger. When the change of magnetic flux of the transformer is detected, the first switching control signal is caused to transition to the Hi level. The detection voltage signal is A/D-converted, a first on-time is determined from the level thereof, and a second on-time is calculated by subtracting the first on-time from the constant switching period. When the first switching control signal is caused to transition to the Low level based on the first on-time, the change of magnetic flux of the transformer is detected, and the second switching control signal is caused to transition to the Hi level and is caused to transition to the Low level after the second on-time has elapsed.