Abstract: A power converter includes a dc input having first and second terminals. A main converter is coupled to the first terminal of the dc input. A standby circuit coupled to the second terminal of the dc input and the main converter. The main converter is coupled to control a transfer of energy from the dc input through the standby circuit to a main output of the main converter during a normal operating condition of the power supply. The standby circuit is coupled to decouple the main converter from the second terminal of the dc input during a standby operating condition of the power converter. A standby converter is coupled to the first and second terminals of the dc input to control a transfer of energy from the dc input to a standby output of the standby converter during the standby operating condition of the power converter.

Abstract: The present invention provides a switched-mode power converter with regulation demand pulses sent across a galvanic isolation barrier.

Abstract: A control circuit can be provided with a comparator detecting a turning-off of a semiconductor switch from a voltage generated in an auxiliary winding of a transformer and inputted to a zero current detecting terminal, a timer outputting a signal after a specified length of time from the time at which the turning-off of the semiconductor switch is detected, and a comparator detecting from voltages inputted to a current detecting terminal a second voltage signal different from an ordinary first voltage signal inputted when the semiconductor switch is made turned-on. Thus, the second voltage signal supplied from mode switching circuits as an externally inputted mode switching signal can be made also detected by the existing current detecting terminal. By detecting the second voltage signal after the specified length of time from the turning-off of the semiconductor switch, switching of an operation mode becomes possible without newly providing any specialized terminal.

Abstract: A switching regulator can include a transformer having a primary winding and a secondary winding, a switching circuit including a switching element that is connected in series to the primary winding, the series-connected circuit of the switching element and the primary winding being connected in parallel to a DC power supply and a rectifying circuit connected to the secondary winding. The switching regulator can also include a control circuit to control switching of the switching element to generate DC output voltage from the DC power supply, the DC output voltage being insulated from the DC power supply, an output voltage detecting circuit including a photo-coupler for insulated detection of the DC output voltage, the photo-coupler having a photo-transistor and a load quantity detector for detecting a state in which power consumption in the load connected to the DC output has reached a predetermined value.

Abstract: A control circuit of a power converter according to the present invention comprises a switching circuit and a sample circuit. The switching circuit generates a switching signal in accordance with a feedback signal and a sampled signal. The switching signal is coupled to switch a transformer of the power converter for regulating an output of the power converter. The feedback signal is generated in accordance with the output of the power converter. The sample circuit generates the sampled signal by sampling a signal of the transformer. The sampled signal is correlated to an output voltage of the power converter.

Abstract: In a switching power supply, a current detection resistor is connected to a switching unit to detect a current flowing through the switching unit. A diode is connected in parallel to the current detection resistor to reduce heat generated in the switching unit by back electromotive force generated by an inductance component of the current detection resistor.

Abstract: A control circuit includes a feedback circuit, a drive signal generator, an unregulated dormant mode and output reset control circuit, and a counter. The feedback circuit generates an enable signal and in response, the drive signal generator regulates the output of the power converter. The unregulated dormant mode and output reset control circuit powers down the drive signal generator such that the regulation is ceased when the energy requirement at the output has fallen below a threshold. The drive signal generator is then powered up after a first period of time such that the regulation resumes. The counter then counts cycles of a clock signal for which the enable signal indicates an increase in the energy requirement at the output. The counter disables the drive signal generator when a count of the counter reaches a threshold number to discharge the output to less than a regulation output voltage value.

Abstract: A control circuit of a power converter according to the present invention comprises an output circuit, at least one input circuit and an input-voltage detection circuit. The output circuit generates a switching signal for regulating an output of the power converter in response to at least one feedback signal. The switching signal is coupled to switch a transformer of the power converter. The input circuit samples at least one input signal for generating the feedback signal. The input signal is correlated to the output of the power converter. The input-voltage detection circuit generates an input-voltage signal in response to the level of the an input voltage of the power converter. The input circuit will not sample the input signal when the input-voltage signal is lower than a threshold. The control circuit can eliminate the need of the input capacitor for improving the reliability of the power converter.

Abstract: A switching regulator that decreases power loss and resolves thermal issues by jumping its switching frequency to a maximum frequency when its load reaches a peak load.

Abstract: A switching power supply apparatus includes a PFC converter, a DC-DC converter, and primary-side and secondary-side digital control circuits that control the PFC converter and the DC-DC converter. On the basis of a voltage detected by an output voltage detection circuit, the primary-side digital control circuit transmits data about the on-time of a switching element of the DC-DC converter to the primary-side digital control circuit. On the basis of this data, the primary-side digital control circuit controls the on-time of the switching element.

Abstract: One embodiment of the invention relates to a power apparatus. The power apparatus includes a power converter configured to convert an input voltage to an output voltage for providing power at an output thereof to which a load is connectable. The converter can include an isolation barrier configured to electrically isolate the output and the load from an input source that provides the input voltage. The system also includes a control loop that includes indirect sense circuitry configured to indirectly derive an indication of at least one of output current and output power of the converter. The control loop is configured to control output current or output power based on the indirectly derived indication of output current or output power, respectively.

Abstract: An isolated switching power supply apparatus includes a transformer, a primary-side circuit that includes at least a switching element and supplies input power from an input terminal to a primary winding by controlling on/off of the switching element, and a secondary-side circuit that is electrically isolated from the primary-side circuit and that outputs output power resulting from power conversion performed by the transformer from a secondary winding to an output terminal. The apparatus includes a first circuit board to which the primary winding is connected and that includes the primary-side circuit and the input terminal, and a second circuit board to which the secondary winding is connected and that includes the secondary-side circuit and the output terminal. The first and second circuit boards are stacked in a multilayer manner. The primary and secondary windings are arranged around a core that extends through the first and second circuit boards.

Abstract: A method, in a power supply controller, of responding to an increase in current through a terminal of the power supply controller, is disclosed. The method includes regulating the terminal to a first voltage level and sensing a magnitude of a first current through the terminal while the controller is regulating the terminal to the first voltage level. The method also includes providing an initial response by the power supply controller in response to the magnitude of the first current exceeding a first threshold current level and then regulating the terminal to a second voltage level after the magnitude of the first current exceeds the first threshold current level. The magnitude of a second current through the terminal is sensed while the controller is regulating the terminal to the second voltage level and the controller determines a final response based on the magnitude of the second current.

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 pulse width modulation controller and method for output ripple reduction of a jittering frequency switching power supply detect the current of a power switch of the switching power supply to generate a current sense signal, and adjust the gain or the level of the current sense signal according to the switching frequency of the power switch to adjust the on time of the power switch, to reduce the output ripple of the switching power supply caused by the jittering frequency of the switching power supply.

Abstract: An example control circuit for use in a power converter includes an input voltage sensor, a current sensor, and a drive signal generator. The input voltage sensor generates a first signal representative of an input voltage (Vin) of the power converter. The current sensor generates a second signal representative of a switch current through a power switch of the power converter. The drive signal generator generates a drive signal to control switching of the power switch in response to the first and second signals. The drive signal generator sets a switching frequency of the drive signal based on a product K×Vin×t to control a maximum output power of the power converter, where K is a fixed number and t is a time it takes the second signal to change between two values of the switch current when the power switch is in an on state.

Abstract: A power device includes a power supply module, a first electrical isolation unit, a second electrical isolation unit, a feedback control unit, and a comparing unit. The power supply module includes a feedback compensating terminal and an output terminal, the feedback compensating terminal provides a related voltage of output power, and the output terminal provides an output voltage. When the related voltage of output power is smaller than the predetermined voltage, the comparing unit controls the first electrical isolation unit to change operation of the feedback control unit and the second electrical isolation unit, to allow the power supply module to adjust the output voltage.

Abstract: A switching control IC outputs a rectangular wave signal from an output terminal thereof to a driving circuit. A feedback circuit compares a value of a divided voltage of a voltage across output terminals of a switching power supply device with a reference voltage, generates a feedback signal, and inputs the feedback signal into a feedback terminal of the switching control IC. A capacitor and a Zener diode are connected between the feedback terminal and a ground terminal. The Zener diode is selectively connected, and a voltage at the feedback terminal is changed in accordance with the presence of the Zener diode. A voltage at the feedback terminal is detected, and one of a latch method and a hiccup method is selected as a method for an overcurrent protection operation in accordance with the detected voltage.

Abstract: A power converter controller includes a drive signal generator coupled to generate a drive signal to control switching of a power switch to regulate a flow of energy to a power converter output in response to an energy requirement of a load. A voltage supply rail is coupled to supply a voltage to the drive signal generator. The supplied voltage is used by the drive signal generator to generate the drive signal. A control circuit is coupled to generate a power down signal that stops the supply of the voltage to the drive signal generator to stop the generation of the drive signal and the control of the switching of the power switch for a period of time. Timer circuitry determines a duration of the period of time and triggers the control circuit to restart the supply of the voltage by the supply rail to the drive signal generator.

Abstract: In accordance with various embodiments a converter is provided, including: a transformer comprising a primary side and a secondary side; a primary side circuit arrangement coupled to the primary side of the transformer; a secondary side circuit arrangement coupled to the secondary side of the transformer, wherein the secondary side circuit arrangement is configured to provide at least one of an output voltage and an output current; a coupling component configured to provide information about at least one of the output voltage and the output current to the primary side circuit arrangement; a first energy supply configured to provide the coupling component with a first current; and second energy supply configured to provide the coupling component with a second current, wherein the second current is lower than the first current.

Abstract: System and method for providing control for switch-mode power supply. According to an embodiment, the present invention provides a system for regulating a power converter. The system comprises a signal processing component that is configured to receive a first voltage and a second voltage, to process information associated with the first voltage and the second voltage, to determine a signal based on at least information associated with the first voltage and the second voltage, and to send the signal to a switch for a power converter. The switch is regulated based on at least information associated with the signal. The signal processing component is further configured to determine the signal to be associated a first mode, if the first voltage is higher than a first threshold.

Abstract: A power source controlling IC controlling a current flown through the primary side winding of a transformer is provided with an external terminal to which a detected voltage from the secondary side is fed back through a photocoupler; a control circuit generating and outputting a control signal of a switching element controlling the current according to an input voltage; a voltage generating circuit generating an internal reference voltage based on the input voltage; a pull-up section connected to the terminal to pull up the potential of the terminal to the internal reference voltage to give a bias voltage to a light receiving element of the photocoupler; and a voltage comparing circuit comparing the voltage of the external terminal and a predetermined reference voltage, wherein the control circuit stops outputting the control signal based on the output of the first voltage comparing circuit when detecting an abnormality.

Abstract: A feedback circuit for an isolated power converter includes an opto-coupler and a reversed polarity regulator. The opto-coupler provides a current related to an output voltage of the isolated power converter. When the isolated power converter enters light load, the output voltage rises and the reversed polarity regulator reduces the current to decrease the power consumption and thus improve the light load efficiency of the isolated power converter.

Abstract: Some of the embodiments of the present disclosure provide an apparatus comprising a voltage sensor circuit configured to generate a voltage feedback signal indicative of an output voltage of the apparatus, a current sensor circuit configured to generate a current feedback signal indicative of a load current of the apparatus, a converter configured to receive the current feedback signal, and generate a fault signal that is indicative of a fault condition associated with the load current, and an optocoupler configured to receive the voltage feedback signal and the fault signal, and generate a feedback signal that is indicative of the output voltage and indicative of the fault condition. Other embodiments are also described and claimed.

Abstract: A control circuit includes a drive signal generator controlling switching of a power switch to regulate a flow of energy to one or more loads coupled to a power converter output. A regulator circuit charges a capacitor to a first voltage and stops charging the capacitor if an energy requirement of the one or more loads falls below a threshold. The regulator again charges the capacitor after the capacitor is discharged from the first voltage to a second voltage. An unregulated dormant mode control circuit renders dormant the drive signal generator and the regulator circuit while the capacitor is discharged from the first voltage to the second voltage causing the regulation of the flow of energy to the power converter output to cease. The drive signal generator and the regulator circuit are powered up after the capacitor is discharged from the first voltage to the second voltage.

Abstract: A feedback circuit for an isolated power converter includes an opto-coupler and a reversed polarity regulator. The opto-coupler provides a current related to an output voltage of the isolated power converter. When the isolated power converter enters light load, the output voltage rises and the reversed polarity regulator reduces the current to decrease the power consumption and thus improve the light load efficiency of the isolated power converter.

Abstract: Embodiments of circuits and methods for a switching mode power supply are described in detail herein. In one embodiment, a switching mode power supply includes a transformer having a primary winding and a secondary winding to supply power to a load, a feedback circuit that generates a feedback signal that varies in relation to the load on the secondary winding, a switching circuit coupled to the primary winding to control current flow through the primary winding, and a control circuit coupled to the switching circuit to control the on/off status of switching circuit in response to the feedback signal and the current flow through the primary winding. The control circuit comprises a spectrum shaping circuit configured to generate a spectrum shaping signal in response to the feedback signal. The spectrum shaping signal can then be used to regulate the switching frequency and the spectrum shaping range.

Abstract: A switching mode power supply (SNIPS) includes a rectifying unit transforming AC power input from outside to DC power, a main transformer transforming and outputting the rectified DC power, a pulse width modulation control unit controlling output voltage by applying a pulse signal to a primary winding of the main transformer, and a feedback control unit controlling an output signal of the pulse width modulation control unit by detecting output voltage of the main transformer, including: a first state transform unit, including: a second photo diode; and a second photo transistor included between an AC power input unit and the pulse width modulation control unit to form a photo coupler with the second photo diode, and a second state transform unit, including: a comparator connected to a secondary winding of the main transformer to apply the output voltage and reference voltage to an inverting terminal and a noninverting terminal, and compare the output voltage with the reference voltage and output the voltage t

Abstract: A switching “power (100) includes a single, power switching Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) (Q1) that without any additional transistor provides both self-oscillation and over-current protection. A transformer (Tr1) that is included in a positive feedback path of the MOSFET has a tapped (intermediate terminal 103) auto-transformer winding. A source terminal (102) of the MOSFET is coupled via a current limiting resistor (R2) to a junction terminal between first (n1)and second (n2) windings of the tapped auto-transformer (Tr1). The first winding forms the primary winding of the transformer and the second winding is coupled to a gate terminal of the MOSFET to form a regenerative feedback path. The second winding is direct-current (DC) coupled to the gate terminal to avoid the need for any discrete capacitor in the positive feedback path.

Abstract: The invention relates to a method for operating a switched mode power supply as an isolating transformer. According to said method, magnetic energy is stored in the core of a transformer during a storage stage via a primary coil that is connected to an intermediate circuit current and the stored magnetic energy is delivered to a load in a subsequent discharge phase, for the most part by means of a secondary coil, a small part of said magnetic energy being discharged on the primary side. The energy that is discharged on the primary side charges a capacitor in such a way that the capacitor current is always held above the secondary current multiplied by the transmittance ratio of the transformer.

Abstract: One example controller for a power supply includes an oscillator, a drive signal generator, and a restart circuit. The oscillator generates a clock signal and the drive signal generator controls switching of a switch to regulate an output of the power supply in response to the clock signal. The restart circuit generates a restart signal in response to a current through the switch and in response to an absolute maximum on time period. The oscillator generates the clock signal to have a fixed maximum frequency in response to the restart signal indicating that the current through the switch reaches a current limit threshold within the absolute maximum on time period. The oscillator also generates the clock signal to have a variable minimum frequency in response to the restart signal indicating that the current through the switch has not reached the current limit threshold within the maximum on time period.

Abstract: An insulated power supply device includes: an electric power conversion unit, a rectifier, a filter, a detection unit, a control circuit, and a signal transmission unit. The control circuit generates and outputs a control signal for a switching element that controls a current to be flown through a primary side of the electric power conversion unit. The signal transmission unit transmits, to the control circuit, a detection signal by the detection unit for detecting an output current or an output voltage. An output control pulse signal having control information in a duty ratio can be supplied as an outputted control signal individually to both of the control circuit and a secondary side of the electric power conversion unit. The output current or the output voltage can be thereby controlled.

Abstract: A power supply for converting AC to a regulated DC output current, utilizing two serial switched mode power supplies, the first providing an intermediate DC output voltage with only moderate ripple properties, this output being input to the second, which operates as a DC/DC converter to provide the desired output with low ripple and good regulation. The diode rectifier assembly has no reservoir/smoothing capacitor, or one of much smaller capacitance than in prior art power supplies. The large resulting rectifier output ripple is overcome by use of the two power supply units, at least the first having a smoothing capacitor at its output. A majority of the energy stored in this capacitor is utilized during each AC half cycle. Such power supplies also provide improved hold-up times. The power supply is also constructed to have low standby power consumption, by use of a double burst configuration.

Abstract: According to an example embodiment, a controller for a Switched Mode Power Supply having opto-coupler-based feedback from secondary to primary side, is disclosed, in which the optocoupler current varies inversely with the output voltage over a voltage control range. The converter is thereby enabled to consume less power than do conventional converters, when in lower-power standby mode. Also disclosed are low-voltage startup and over-voltage protection arrangements combined with such a controller. Corresponding methods are also disclosed.

Abstract: An example power supply controller includes a switch duty cycle controller coupled to receive a feedback signal and a duty cycle adjust signal. The switch duty cycle controller is coupled to generate a drive signal coupled to control switching of a switch, which is coupled to an energy transfer element, to regulate energy delivered from an input of a power supply to an output of the power supply. The power supply controller also includes a gain selector circuit coupled to receive an input voltage signal, which is representative of an input voltage to the power supply, to generate the duty cycle adjust signal received by the switch duty cycle controller. The duty cycle of the drive signal to be varied in response to a plurality of linear functions over a range of values of the input voltage signal.

Abstract: A switching power supply device including: a power transformer including a primary winding, a secondary winding, and an auxiliary winding; a switching element which is connected to the primary winding; an output voltage generation circuit which converts, into a direct-current voltage, a voltage induced in the secondary winding; a secondary-side on-time signal generation circuit which generates a secondary-side on-time signal indicating a secondary-side on-time; and a switching control circuit which controls a switching operation of the switching element so that the second direct-current voltage falls within a specified range, wherein the switching control circuit controls the switching operation so that the direct-current voltage becomes equal to or below an overvoltage specified value when the secondary-side on-time becomes smaller than a set value.

Abstract: The present invention provides a control circuit for a power converter. The control circuit includes a switching circuit, an input-voltage detection circuit and a current-limit threshold. The switching circuit generates a switching signal coupled to switch a transformer of the power converter for regulating an output of the power converter in response to a feedback signal. The input-voltage detection circuit generates a control signal when an input voltage of the power converter is lower than a low-input threshold. The feedback signal is generated in response to the output of the power converter. A maximum duty of the switching signal is increased in response to the control signal. The current-limit threshold is for limiting a maximum value of a switching current flowing through the transformer. The current-limit threshold is increased in response to the control signal. An input of the power converter doesn't connect with electrolytic bulk capacitors.

Abstract: A method of operating a DC-DC converter according to the current mode control is provided. A current measuring signal for determining a turn-off time of a converter switching element is supplied to a PWM controller and a voltage that is proportional to the current measuring signal is compared by a comparator to a reference voltage. When the reference voltage is exceeded, the converter switching element is turned off.

Abstract: A power supply for an LED lamp has a set of coupled coils, primary-side power circuitry including a converter power switch for conducting input power, and secondary-side power circuitry including a dimming power switch. Power control circuitry includes converter control circuitry which generates a converter control signal for the converter power switch to maintain a desired undimmed level of lamp current at a normal operating value of a lamp voltage. Dimming control circuitry generates a dimming control signal for the dimming power switch to pulse-width modulate the lamp current at a duty cycle corresponding to a desired dimming. Operation of the converter control circuitry is modified during dimming to prevent an automatic increase of the lamp voltage in response to a decrease in lamp current, avoiding undesirable overshooting of the lamp current and providing more accurate and effective control over dimming operation.

Abstract: In one embodiment, a quasi-resonant power supply controller is configured to select particular valley values of a switch voltage to determine a time to enable a power switch. The valleys values are selected responsively to a range of values of a feedback signal.

Abstract: An implementation of an unregulated dormant mode with an output reset controller in a power converter is disclosed. An example method for controlling an output of a power converter includes generating a drive signal with a drive signal generator to regulate a flow of energy to one or more loads coupled to an output of the power converter in response to an energy requirement of the one or more loads. The drive signal generator is rendered dormant to cease for a first time period the regulation of energy flow to the one or more loads when the energy requirement of the one or more loads falls below a threshold value. The energy requirement of the one or more loads is not responded to during the first time period. The drive signal generator is then powered up to resume after the first time period has elapsed the regulation of energy flow to the one or more loads. After the first time period has elapsed, it is identified whether there is an increase in the energy requirement of the one or more loads.

Abstract: A power transistor chip with built-in enhancement mode metal oxide semiconductor field effect transistor and application circuit thereof provides an enhancement mode metal oxide semiconductor field effect transistor in association with two series connected resistors to act as a start-up circuit for the AC/DC voltage converter. The start-up circuit can be shut off after the pulse width modulation circuit of the AC/DC voltage converter circuit works normally and still capable of offering a function of brown out detection for the pulse width modulation circuit as well. Besides, the enhancement mode metal oxide semiconductor field effect transistor is built in the power transistor chip without additional masks and processes during the power transistor chip being fabricated such that the entire manufacturing process is simplified substantively with the economical production cost.

Abstract: An isolated alternating current (AC)-direct current (DC) converter is disclosed. The isolated AC-DC converter comprises a slave control circuit including a slave driver module configured to receive a command and to control coupling of the slave control circuit to a primary-side inductor of a transformer based on the command, a master control circuit coupled to a secondary-side inductor of the transformer, the master control circuit including a master control module configured to sense a feedback voltage across a load and to generate the command based on the feedback voltage and a reference voltage, and a coupler configured to communicate the command from the master control module to the slave driver module and to provide isolation between the master control module and the slave driver module.

Abstract: A power converter with low power consumption during a standby operating condition. An example power controller includes a main converter coupled to a dc input of the power converter to control a transfer of energy from the dc input of the power converter to a main output of the power converter. A standby converter is also included and is coupled to the dc input of the power converter to control a transfer of energy from the dc input of the power converter to a standby output of the power converter during a standby operating condition of the power converter. A standby circuit is also included and is coupled to the dc input of the power converter and coupled to the main converter. The standby circuit decouples the main converter from the dc input of the power converter during the standby operating condition of the power converter.

Abstract: The present invention proposes a switching controller of a flyback power converter. The switching controller includes a switching circuit, a sample-and-hold circuit, a voltage detection circuit, an oscillation circuit, and a comparator. The voltage detection circuit generates a holding signal when a level of an input voltage of the flyback power converter is lower than a low-threshold. The oscillation circuit limits the maximum frequency of switching signal. The maximum frequency is increased in response to a decrement of a modulation signal. The modulation signal correlated with a level of the input voltage is used to generate a control signal when the level of the input voltage is lower than an ultra-low-threshold. The control signal is enabled to operate the flyback power converter in continuous current mode operation. Therefore, an input capacitor can be eliminated and manufacturing cost is saved.

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 switching regulator of a power converter is provided and includes a feedback-input circuit, a programming circuit, and a peak-current-threshold circuit. The feedback-input circuit is coupled to a terminal of the switching regulator for receiving a feedback signal. The feedback-input circuit is operated in a first range of a terminal signal. The programming circuit is coupled to the terminal for generating a programming signal. The programming signal is operated in a second range of the feedback signal. The peak-current-threshold circuit generates a threshold signal in accordance with the programming signal. The feedback signal is coupled to regulate the output of the power converter, and the threshold signal is coupled to limit a peak switching current of the power converter.

Abstract: A control system for a power converter with reduced power dissipation at light loads and method of operating the same. In one embodiment, the control system includes a first controller configured to control a duty cycle of a power switch to regulate an output characteristic of the power converter. The control system also includes a second controller configured to provide a signal in response to a dynamic change of the output characteristic to the first controller to initiate the duty cycle for the power switch.

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: A switching power supply device includes a transformer, a switching unit which is connected with a primary winding of the transformer and configured to switch a current flowing to the primary winding, a start unit configured to start the switching unit, a voltage drop unit configured to lower output voltage from a secondary winding of the transform, and a current control unit configured to control an amount of a current flowing in the start unit when the switching unit is in an off state by lowering output voltage by the voltage drop unit.