Abstract: According to one embodiment, the power converter includes a power conversion circuit and a power outage detection circuit. The power converter includes a power conversion circuit including an isolation transformer including a primary winding, a secondary winding electromagnetically coupled to the primary winding, and an auxiliary winding, a first DC voltage source which outputs DC power with an input AC power, a switching circuit which switches connection between the first DC voltage source and the primary winding, an auxiliary power supply circuit which supplies the DC power to the switching circuit using a power generated in the auxiliary winding, a second DC voltage source which rectifies and smooths the power generated in the secondary winding and outputs DC power to a load.

Abstract: A switching power supply device includes a voltage conversion transformer, a primary-side control semiconductor device, a rectification and smoothing circuit, an output voltage detection circuit, a failure detection circuit, and a switch. The primary-side control semiconductor device generates a driving signal which controls a switching element connected to a primary winding of the transformer. The rectification and smoothing circuit is connected to a secondary winding of the transformer. The output voltage detection circuit detects a secondary-side output voltage of the transformer and transmits a feedback signal corresponding to the output voltage to the primary-side control semiconductor device through an insulated signal transmitter. The failure detection circuit detects a failure on a secondary side of the transformer. The switch cuts off a current flowing to the insulated signal transmitter if the failure detection circuit detects a failure.

Abstract: A flexible transformer system includes conductive windings extending around a magnetic core of a transformer phase and impedance-varying windings extending around the magnetic core of the transformer phase. The conductive windings and the impedance-varying windings are configured to conduct electric current around the magnetic core of the transformer phase. The system includes an impedance switch coupled with the impedance-varying windings and with the conductive windings. The impedance switch is configured to change an impedance of the system by changing which impedance-varying winding of the impedance-varying windings is conductively coupled with the conductive windings and which impedance-varying winding of the impedance-varying windings is disconnected from the conductive windings.

Abstract: In an example, a system comprises a boost power factor correction (PFC) converter including a thermistor, an inductor, and a transistor coupled to a common node. The system also comprises a PFC controller coupled to the common node. The PFC controller includes a comparator coupled to a threshold voltage source and to a non-control terminal of the transistor; a first flip-flop coupled to the comparator and to a control terminal of the transistor; a zero current detector coupled to the inductor; a timer coupled to the comparator and to the zero current detector; a second flip-flop coupled to the timer and to the control terminal of the transistor; an AND gate coupled to the first and second flip-flops; a third flip-flop coupled to the second flip-flop and to the control terminal of the transistor; and a fourth flip-flop coupled to the AND gate and to the control terminal of the transistor.

Abstract: A power controller in collocation with a rectification unit, a transformer, a switching unit, a current sensing resistor, an output rectification unit, and an output capacitor is disclosed, and includes a working voltage pin, a ground pin, a PWM driving pin, a current sensing pin, and a load feedback pin for converting an external AC input power into an output power to supply a load. In particular, the power controller simultaneously performs active detection on load power to provide overload protection. Specifically, a load feedback signal related to a load power and a threshold load voltage representative of a preset threshold load power is compared, and a power counter representative of a calculated load power is increased by one, decreased by one, or kept without change according to the comparison result. Then, the power counter is employed to determine whether an overload abnormal event occurs.

Abstract: A power conversion system includes a switch mode power converter including a switch coupled to regulate an output voltage to a regulation value in response to a feedback signal. A controller is coupled to deliver a gate drive signal to the switch during an enabled control condition. The controller is further coupled to inhibit the gate drive signal to the switch during an inhibited control condition. A duty cycle state machine included in controller is coupled to adjust a duty cycle of the gate drive signal according to a plurality of discrete duty cycle states.

Abstract: An RF switch circuit and method for switching RF signals that may be fabricated using common integrated circuit materials such as silicon, particularly using insulating substrate technologies. The RF switch includes switching and shunting transistor groupings to alternatively couple RF input signals to a common RF node, each controlled by a switching control voltage (SW) or its inverse (SW_), which are approximately symmetrical about ground. The transistor groupings each comprise one or more insulating gate FET transistors connected together in a “stacked” series channel configuration, which increases the breakdown voltage across the series connected transistors and improves RF switch compression. A fully integrated RF switch is described including control logic and a negative voltage generator with the RF switch elements. In one embodiment, the fully integrated RF switch includes an oscillator, a charge pump, CMOS logic circuitry, level-shifting and voltage divider circuits, and an RF buffer circuit.

Abstract: A synchronous rectification controller includes: a drain terminal connected to a drain of a synchronous rectification transistor; a first comparator configured to compare a drain voltage of the drain terminal with a first threshold voltage; a second comparator configured to compare the drain voltage of the drain terminal with a second threshold voltage; a flip-flop to which an ON signal output from the first comparator and an OFF signal output from the second comparator are input; a driver configured to output a gate signal to the synchronous rectification transistor based on an output signal of the flip-flop; and a threshold adjusting part configured to adjust the second threshold voltage based on the drain voltage.

Abstract: Provided is a charge pump including a flying capacitor, an output capacitor, a switch group arranged to switch connection states of the capacitors so as to generate an output voltage from an input voltage, and a feedback control unit arranged to adjust an interterminal voltage of the flying capacitor to a predetermined target value when charging the same. On the basis of a first node voltage applied to a first terminal of the flying capacitor, the feedback control unit adjusts a second node voltage at a second terminal of the flying capacitor. The feedback control unit includes a voltage detection unit arranged to detect the interterminal voltage of the flying capacitor, and a voltage adjustment unit arranged to adjust the second node voltage according to a result of detection by the voltage detection unit.

Abstract: A power conversion system includes a switch mode power converter including a switch coupled to regulate an output voltage to a regulation value in response to a feedback signal. A controller is coupled to deliver a gate drive signal to the switch during an enabled control condition. The controller is further coupled to inhibit the gate drive signal to the switch during an inhibited control condition. A duty cycle state machine included in controller is coupled to adjust a duty cycle of the gate drive signal according to a plurality of discrete duty cycle states.

Abstract: A system, method and apparatus of balancing a direct current load across a multiple direct current power sources includes receiving multiple direct current inputs to the inputs of a multiple input, single output DC to DC converter. The output current of each one of the direct current inputs is compared to a reference current. The direct current inputs are adjusted in corresponding DC to DC converter modules until the output current of each one of the direct current inputs is equal to the reference current. The adjusted output of the DC to DC converter modules is combined to a single output current that can be output to supply the single output current to a load.

Abstract: A device and method for controlling a power supply. The method includes: monitoring a feedback signal of a feedback terminal; determining whether the feedback signal of the feedback terminal is not a pulse signal; and terminating an on/off operation of a switching element when the feedback signal of the feedback terminal is not a pulse signal. Therefore, an abnormal status of the device can be correctly detected with a simple structure when the feedback terminal is open or is shorted with other terminals, while an error operation and a damage of the device can be avoided.

Abstract: A power supply is disclosed. The power supply includes a switch to regulate an input voltage and a current sense transistor to sense current through the switch. The power supply further includes a switching control to control a switching frequency of the switch. A programmable pulse skip circuit coupled to the switching control is also included. The switching control is configured to alter the switching frequency based on a pulse skip control signal received from the programmable pulse skip circuit. The programmable pulse skip circuit produces the pulse skip control signal based on an external control signal inputted to the programmable pulse skip circuit and the sensed current by the current sense transistor.

Abstract: Circuits and methods within a switched-mode power supply (SMPS) controller are provided. The SMPS controller includes an SMPS power stage which is integrated within the same package, and which has a first power switch. The first power switch is used to supply current to a power supply for the SMPS controller during a start-up phase of the SMPS, thereby charging this power supply prior to normal operational mode of the SMPS. A lead of the SMPS controller is connected to a control terminal of the first power switch during the start-up phase. After the start-up phase, this same lead is instead routed to an input source voltage monitor, and is used for detecting overvoltage or undervoltage conditions at the SMPS input power source.

Abstract: The invention describes an isolated driver (2) comprising a converter module (21) realized to provide voltage and current output to a load (3); a feedback arrangement (22) realized to monitor voltage and/or current during operation of the driver (2); and a converter controller (1) for providing converter control signals (CI, CF, VCON) to the converter module (21), and wherein the converter controller (1) comprises a single optocoupler (10) connected by input terminals to the feedback arrangement (22); and a switching circuit arrangement (11) connected to output terminals of the optocoupler (10), comprising a number of semiconductor switches (Q20, Q25, Q30, . . . , Q34) arranged to generate a converter control signal (CI, CF, VCON) for placing the converter module (21) of the driver (2) into a low-output mode (MLO) when a voltage across the optocoupler output terminals indicates a fault condition.

Abstract: A secondary controller drives a light emitting element of a photocoupler such that a detection voltage VOUTS corresponding to an output voltage VOUT generated in an output capacitor C approximates to a reference voltage VREF. A primary controller controls a switching transistor M according to a feedback signal VFB. A protection circuit is activated and drives the light emitting element of the photocoupler when detecting an abnormal state. An auxiliary power supply circuit includes a power supply capacitor C provided separately from the output capacitor C and supplies a power supply voltage VCC to the protection circuit and an anode of the light emitting element of the photocoupler.

Abstract: A power converter controller includes a primary controller and a secondary controller. The primary controller is coupled to receive one or more request signals from the secondary controller and transition a power switch from an OFF state to an ON state in response to the received request signals. The secondary controller is coupled to transmit the request signals to the primary controller and control the amount of time between the transmission of each of the request signals. The secondary controller includes a timing circuit that sets a minimum amount of time between the transmission of the request signals. The secondary controller also includes a secondary switch control circuit coupled to trigger the timing circuit in response to transmitting a request signal.

Abstract: One aspect of the present disclosure can include an electronic signal processing system and method used in a control system (e.g., for hour meter functionality, intelligent start/stop functionality, etc.). The system can include a rectifier component to receive a voltage input from an operation source during use. The voltage input can indicate that an engine is running. The rectifier component to convert the voltage input to a positive voltage input. The system can also include a constant current component to receive the positive voltage input from the rectifier circuit and to control a current based on the positive voltage input. The system can also include an optical component to provide an output based on the current and to communicate the output to a microcontroller during use of the operation source. For example, electronic signal processing methods and apparatuses are also described.

Abstract: This disclosure describes an AC/DC power converter that produces multiple output voltage levels. The AC/DC power converter may include a gain adjustment circuit. The gain adjustment circuit may adjust the gain of a feedback signal of the converter in accordance with the converter's output voltage level. The gain adjustment circuit provides sufficient gain and phase margins to the converter and thus enhances the converter's stability.

Abstract: A power converter controller controls a power stage to produce a regulated voltage at a converter output node, using an input signal. A circuit uses an opto-coupler circuit that has an input node connected to a compensation circuit, to generate the input signal. The compensation circuit has a shunt regulator having an output that is connected to the opto-coupler circuit through series-connected first and second current limiting elements. An input of the shunt regulator is connected to the converter output node. A feedback element has one end connected between the series-connected current limiting elements and another end connected to the input of the regulator. Other embodiments are also described and claimed.

Abstract: A device for current protection comprises a switch-mode power supply controller. The switch-mode power supply controller includes an inrush current comparator that is arranged to compare a primary winding current with an inrush current threshold at least during at least one of a startup phase or a burst phase. The switch-mode power supply controller also includes a switch controller that is arranged to control regulation of an output voltage by controlling turning of a primary switch on and off based on a feedback signal that is based, at least in part, on the output voltage. The switch controller is further arranged to, if the inrush current comparator determines that the primary winding current has reached the inrush current threshold, control the primary switch to turn off and remain turned off until at least a next switching cycle.

Abstract: A power converter includes a primary side controller configured to operate the power converter in the discontinuous conduction mode during low to mid-power requirements and to operate the power converter in the continuous conduction mode during high or peak power requirements. The power converter includes a primary side auxiliary winding that provides a feedback signal to the primary side controller, and an adjusted resistor and diode circuit which is coupled to a multi-function feedback (FB) pin of the primary side controller. The primary side controller monitors for a peak power demand, upon detection of which a negative supply rail is enabled, which is used to compensate for voltage losses due to non-zero current while operating in the CCM, thereby enabling output voltage regulation while operating in the CCM during peak power demand.

Abstract: A power supply device includes an output port, a transformer, a power switch, a current sensor, a voltage-dividing controller, a voltage-feedback unit, a voltage comparator, a main controller, and a pulse width modulator. The transformer has two inductances. The power switch is electrically connected to a primary winding of the transformer, the pulse width modulator, and the current sensor coupled to the voltage-dividing controller. The voltage-feedback unit is electrically connected to the voltage-dividing controller, the voltage comparator, and the output port. The main controller is coupled to the pulse width modulator and the voltage comparator.

Abstract: A power converter has a transformer including a primary winding coupled to an input voltage, a secondary winding coupled to an output of the power converter, and an auxiliary winding is configured to detect an open connection fault of the auxiliary winding. The power converter includes a current source coupled to the auxiliary winding that, when activated, supplies a current to the auxiliary winding. A controller measures a voltage across the auxiliary winding. Responsive to detecting an increase in the voltage across the auxiliary winding while the current source is activated, the controller disables the power converter.

Abstract: A bus for distributing electrical power to a plurality of sets of electrical devices is disclosed. The bus includes one or more bus separators and a plurality of bus sections. The plurality of bus sections includes at least a first bus section and a second bus section electrically coupled to each other via a bus separator, where the first bus section is electrically connectable to a first set of electrical devices having a first importance metric and the second bus section is electrically connectable to a second set of electrical devices having a second importance metric different from the first importance metric. The bus separator is configured to isolate the first bus section and the second bus section based on occurrence of a fault condition. A Direct Current power distribution system employing the bus and a method for distributing electrical power via the bus are also disclosed.

Abstract: A method and voltage regulator comprises a generator that generates an error difference between a reference and regulated voltage. A clocked ADC samples the voltage as a digital stream. A DAC converts the stream to analog signal(s). A current source driven by the signal(s) generate(s) the regulated voltage. The generator may be an op-amp or comparator comprising a buffer and/or a latch. The N-bit ADC may be a ?-? modulator or N 1-bit ADC latches. The N-bit DAC may comprise 1-bit DACs comprising a switched-capacitor summer and a one stage RC LPF. Sampling the error up-converts flicker noise to the clock frequency which the DAC filters out. The current source may comprise N transistors with gates driven by a signal and sources tied to an independent power supply. Each signal may be weighted by a DAC weight. The apparatus may comprise a decoupling capacitor between the regulated voltage and ground.

Abstract: A mains voltage zero-crossing detector has a constant voltage forced on an external node by driving transistor devices with appropriate control signals provided by a feedback loop around a highly power efficient class B configuration comprising an operational amplifier having single ended dual outputs and a class B control circuit. Mains power zero crossings may then be detected by monitoring the drive current of devices driven by this amplifier. Wherein Class B control and current mode detection provide accurate detection of the driven signal without depending on any voltage threshold that may depend on temperature, process fabrication and/or supply voltage.

Abstract: Disclosed are a feedback circuit and a power supply device including the same. The power supply device converts input voltage into output voltage suitable for load condition according to a switching operation of a power switch. The feedback circuit includes a first diode connected to a first sensing voltage corresponding to output voltage and a second diode connected to the output voltage. The feedback circuit generates feedback voltage by using voltage passing through a conducted diode of the first and the second diodes. The power supply device controls a switching operation of the power switch depending on the feedback voltage.

Abstract: In aspects of the invention, a photocoupler output signal receiving circuit includes a first constant current circuit, connected between an input terminal and the high potential side of a direct current power source, that discharges current, a second constant current circuit, connected between the input terminal and the low potential side of the direct current power source, that takes in current, and switching elements that operate the first and second constant current circuits in a complementary way, wherein the switching elements are operated so that current is taken in by the second constant current circuit after a photocoupler is turned on, and are operated so that current is discharged by the first constant current circuit after the photocoupler is turned off, and a discharge current value in a current discharge period is reduced after a certain period elapses from the start of discharging.

Abstract: A method of optimizing a gain adjustment value Kadj for a digital controller in an isolated switched mode power supply. The power supply includes an opto-coupler having a current transfer ratio (CTRX) within a range defined by a minimum current transfer ratio (CTRMIN) and a maximum current transfer ratio (CTRMAX). The method includes determining the CTRX of the opto-coupler, determining an optimal gain adjustment value KadjX based on the determined CTRX of the opto-coupler, and storing the optimal gain adjustment value KadjX in the digital controller. The method can be performed by the digital controller or by a programming device external to the power supply.

Abstract: A reverse shunt regulator includes a MOSFET connected between a cathode and an anode, a switch and a current source serially connected between the cathode and the anode, and an error amplifier having a positive input node to receive an internal reference voltage, a negative input node connected to the reference electrode, and an output node connected to a control electrode of the MOSFET. When the voltage of the reference electrode is within a range, the larger the voltage of the reference electrode is, the less the current of the MOSFET is. Application of this reverse shunt regulator to a flyback converter for output feedback will reduce the power loss in a green mode of the flyback converter.

Abstract: In a normal mode, the power supply is fed back in a close loop, but in a power saving mode, the power supply is fed back in an open loop. When it is detected that the power supply is continuously fed back in the open loop and in a substantially zero output status, the power supply circuit enters a power down status. If the back-stage circuit needs power supply again, then the feedback is switched to the close loop and the power supply circuit enters the normal mode.

Abstract: A solar-powered automated system for the operation of drapery, roller blinds, and similar window coverings. The solar panel (102), or photovoltaic source provides the sole power to drive common types of window drapery and blinds in a compact system having a solar panel (photovoltaic source), actuator (104) and head rail (120). The solar panel (102) is to be mounted onto the frame of a window or elsewhere to collect sufficient light. A connecting cable links the solar panel (102) to the actuator (104) to draw electrical power from the solar panel. The actuator is attached to the head-rail (120) to provide the required driving force. The actuator (104) includes the control circuit boards, a single rechargeable battery (110), an electric motor (106) and output mechanism. An RF remote control receiver (116) is built inside the actuator (104). A low voltage control port (114) allows the actuator (104) to be accessible by a control interface.

Abstract: To provide a switching power supply device, and an operation condition setting method thereof, wherein it is possible to set an operation condition during an initialization period by adjusting the resistance value of a resistor that grounds an OUT terminal or IS terminal.

Abstract: A switching power conversion circuit receives an input voltage and generates an output voltage to a system circuit. The switching power conversion circuit includes a power circuit, a feedback circuit, a control circuit, and an initiation circuit. The power circuit includes a first switch circuit. The feedback circuit generates a feedback signal according to a power-status signal and the output voltage. The first switching circuit is conducted or shut off according to the feedback signal under control of the control circuit, so that the input voltage is converted into the output voltage and the first auxiliary voltage by the power circuit. If the power-status signal is in an off status, a ratio of the feedback signal to the output voltage is equal to a first feedback ratio and the magnitude of the first auxiliary voltage is lower than a normal operating voltage value, so that the control circuit is disabled.

Abstract: A secondary circuit of a flyback power converter has a resistor network to monitor the output current of the flyback power converter, so as to generate a voltage to apply to a base of a bipolar junction transistor to thereby provide a collector signal for output feedback. The resistor network has a temperature-dependent resistance to compensate the temperature dependence of the base-emitter voltage imparted to the output current and thereby stable the output current.

Abstract: An integrated optical receiver architecture may be used to couple light between a multi-mode fiber (MMF) and silicon chip which includes integration of a silicon de-multiplexer and a high-speed Ge photo-detector. The proposed architecture may be used for both parallel and wavelength division multiplexing (WDM) based optical links with a data rate of 25 Gb/s and beyond.

Abstract: Disclosed is an overload protection delay circuit for use in a switching power supply for enabling the switching power supply to detect overload problems with high accuracy. The overload protection delay circuit is connected between a photo coupler and a pulse-width modulator of the switching power supply, and is consisted of an energy storage device such as a capacitor and a charging controller such as a zener diode. The charging controller is configured to set a limit value for allowing the energy storage device to be charged by an internal current source of the pulse-width modulator when the feedback signal of the switching power supply reaches the limit value. By charging the energy storage device, a time delay is added to the feedback signal so that the pulse-width modulator can accurately activate the internal overload protection mechanism without the interference of load transients.

Abstract: Techniques to compensate for parameter variations in a feedback circuit are disclosed. In one embodiment, a regulator circuit includes an energy source coupled to output a generated current in response to a control current. A feedback resistor is coupled to an output of the regulator circuit. The feedback resistor is coupled to conduct a feedback current responsive to the output of the regulator circuit. A current amplifier is coupled to the feedback resistor to generate the control current in response to the feedback current. A compensation network is coupled to the current amplifier to adjust the control current in response to an extrinsic parameter of the regulator circuit. The compensation network includes a transistor and first, second and third resistors. The first resistor is coupled between the feedback resistor and a collector of the transistor. The second resistor coupled between the collector and the base of the transistor.

Abstract: A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

Abstract: Techniques to compensate for parameter variations in a feedback circuit are disclosed. In one embodiment, a regulator circuit includes an energy source coupled to output a generated current in response to a control current. A feedback resistor is coupled to an output of the regulator circuit. The feedback resistor is coupled to conduct a feedback current responsive to the output of the regulator circuit. A current amplifier is coupled to the feedback resistor to generate the control current in response to the feedback current. A compensation network is coupled to the current amplifier to adjust the control current in response to an extrinsic parameter of the regulator circuit. The compensation network includes a transistor and first, second and third resistors. The first resistor is coupled between the feedback resistor and a collector of the transistor. The second resistor coupled between the collector and the base of the transistor.

Abstract: A circuit for controlling the power in a load supplied by an A.C. voltage and directly connected to a first terminal of application of the A.C. voltage, including two isolated-gate bipolar transistors, connected in anti-parallel between a second terminal of application of the A.C. voltage and the load; circuitry for detecting the zero crossing of the A.C. supply voltage in a first direction; circuitry for generating, at each period of the supply voltage, a pulse of predetermined duration for controlling a first one of said transistors, the time of occurrence of the pulse being conditioned by the detection of the zero crossing of the A.C. voltage and by a desired power reference setting a variable delay of occurrence of the pulse with respect to the detected zero crossing; and circuitry for inverting and transferring said pulse to the second transistor.

Abstract: A switched mode power supply (SMPS) is disclosed. The switched mode power supply (SMPS) includes a controller sub-circuit that generates an output signal that drives a switch. The controller sub-circuit generates a bias voltage without using a bias regulator for a sub-circuit of the switched mode power supply that is different from the controller sub-circuit when the controller sub-circuit is coupled to the sub-circuit of the switched mode power supply.

Abstract: If an intermittent oscillation pulse in a case in which the power consumption in the standby state is reduced at the maximum is supplied to a connection point from an output port of a microcomputer through a capacitor and a resistor, a DC component of the intermittent oscillation pulse is removed and is then supplied to the connection point. At this time, even when a voltage of the connection point becomes larger than a power supply voltage of the microcomputer, since a current does not flow backward from the connection point to the microcomputer, the microcomputer is normally operated. As such, the microcomputer is normally operated, so that the intermittent oscillation pulse is effectively supplied to the connection point. Thereby, a transistor is intermittently operated, the oscillation circuit intermittently performs oscillation operation, and the power consumption in the standby state is reduced.

Abstract: In one embodiment, a power supply controller generates a PWM control signal that is subsequently used to control a portion of current flow in a primary side of a power supply system. THE PWM control signal is coupled to a secondary of the power supply system and used to control a synchronous rectifier that is coupled within the secondary side.

Abstract: A novel switching power supply device no more in need of a stand-by signal for turning on/off a switching element is provided. The switching power supply device is configured as having a main switching element Q1, wherein the switching power supply circuit is connected with a pulse oscillation circuit IC1 for outputting pulse signal; the pulse oscillation circuit and an output terminal of the main switching element are connected with an input section of an internal detection circuit 12; the internal detection circuit 12 is configured so as to control timing of switching of the main switching element Q1 upon detection of the pulse signal supplied from the pulse oscillation circuit IC1.

Abstract: There is provided a power supply apparatus that can raise the power supply efficiency while an appliance in which the power supply apparatus is installed is in a standby state, with a simple construction, without performing complicated control, and can reliably achieve improved power consumption due to the raise in the power supply efficiency, as well as noise reduction. According to the power supply unit, Conduction and interruption of a current flowing in the primary winding 103 of the transformer T21 is controlled. A voltage generated in the secondary winding 104 of the transformer T21 is rectified and smoothed by the rectifier and smoothing circuit 101. An output voltage of the rectifier and smoothing circuit 101 is compared with a reference voltage and a voltage corresponding to a difference between the output voltage and the reference voltage is outputted by error detection circuit 102.

Abstract: An overcurrent output protector is electrically connected to a constant-voltage switching power supply provided with a switching transistor which converts a DC voltage obtained by smoothing an AC voltage supplied from an AC power source into a cyclic pulse signal. In the overcurrent output protector, duty ratio monitor judges whether an ON duty ratio of the cyclic pulse signal is a predetermined ratio or more. A deactivator turns off the switching transistor in a case where the duty ratio monitor judges that the ON duty ratio is the predetermined ratio or more.

Abstract: Apparatus and method for increasing the bandwidth of an optocoupler includes cascode coupling the optocoupler driver transistor with a buffer so as to reduce voltage variations across the driver transistor.

Abstract: A power supply feedback circuit includes a regulating element at an input side of an optical isolator. The control lead for the regulating element is connected to a voltage divider to receive the divided voltage. A bypass circuit is provided on the voltage divider to change the resistance in a bypassed branch of the voltage divider during start up of the circuit. The bypass time depends on charging of a capacitor at a control lead, base or gate, of an active element by the bypass circuit. The output voltage of the circuit is brought gradually to the desired level as the capacitor charges and the active element removes the bypass from the voltage divider or applies the bypass to the voltage divider.