Abstract: A system and a method that uses primary side sensing to regulate the output voltage at a cable end without any remote sensing of cable connections back from the load. This is accomplished by approximating the current from the control voltage in the control loop through the relationship that defines the Ton time in terms of the control voltage Vc. Once the approximation of the output current is known, it is multiplied by a known fixed cable resistance, and this value is subtracted from the feedback sensor output before it is subtracted from the digital reference. This forces the regulator to raise the output voltage by the amount of drop across the cable, causing the output of the cable to be maintained at the targeted regulation point.

Abstract: A lower-cost and more precise control methodology of regulating the output voltage of a flyback converter from the primary side is provided, which works accurately in either continuous voltage mode (CCM) and discontinuous mode (DCM), and can be applied to most small, medium and high power applications such cell phone chargers, power management in desktop computers and networking equipment, and, generally, to a wide spectrum of power management applications. Two highly integrated semiconductor chips based on this control methodology are also described that require very few components to build a constant voltage flyback converter.

Abstract: In a switching power supply device, a first switch element, which defines a main switch element of a DC-DC converter, and a third switch element, which defines a switch element of a power-factor correcting circuit, are controlled such that turn-on timings are synchronized while on-period control is independently performed to thereby prevent an increase in switching frequency and prevent noise by eliminating intermittent oscillation. Thus, it is possible to prevent intermittent oscillation control due to an increase in switching frequency of the first switch element under a light load state or a no load state. This eliminates problems of the frequency of intermittent oscillation that falls within an audible frequency range causing noise and increasing ripple voltage.

Abstract: A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls an inductor switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the pulse width controls the peak of the inductor current.

Abstract: The present invention relates to a switch mode power supply and a driving method for reducing switching loss and audible noise in the burst mode. The switch mode power supply includes a main switch, a power supply, an output unit, and a switch controller. The power supply includes a transformer having a primary coil connected to the main switch, and supplies power to a secondary coil of the transformer according to the operation of the main switch. The output unit is connected to the secondary coil of the transformer and outputs power supplied to the secondary coil of the transformer.

Abstract: A control circuit for use in a power converter with an unregulated dormant mode of operation is disclosed. In one aspect a power converter includes a drive signal generator coupled to generate a drive signal to control switching of a power switch to be coupled to the control circuit to regulate a flow of energy to a power converter output in response to an energy requirement of one or more loads to be coupled to the power converter output. An unregulated dormant mode control circuit is included and is coupled to render dormant the drive signal generator thereby ceasing the regulation of the flow of energy to the power converter output by the drive signal generator when the energy requirement of the one or more loads falls below a threshold. The drive signal generator is coupled to be unresponsive to changes in the energy requirements of the one or more loads when dormant. The unregulated dormant mode control circuit is coupled to power up the drive signal generator after a period of time has elapsed.

Abstract: A power supply controller is provided for providing a drive current to a control terminal of a power transistor in three time intervals. The controller includes control circuits configured to control the drive current in multiple stages. During a first time interval, first drive current includes a current spike for turning on the power transistor in response to a start of the control signal pulse. During a second time interval, a second drive current includes a ramping current substantially proportional to a magnitude of a current through the power transistor. During a third time interval, current flow to the power transistor is at least partially turned off before an end of the control signal pulse.

Abstract: A semiconductor device for switching power supply control limits the startup current supplied from a high-voltage input terminal, and prevents heat generation and combustion in case of an anomaly. A high-voltage input terminal is connected to the main winding of a transformer, and is supplied with a startup voltage upon input of a power supply to the switching power supply device. A power supply terminal is connected to a capacitor, and outputs a startup current to charge the capacitor after input of the power supply input. A startup circuit is connected between the high-voltage input terminal and the power supply terminal, and charges the capacitor while increasing the startup current with magnitude proportional to the voltage value of the power supply terminal, and after startup, turns off the startup current and supplies the power supply voltage only from the auxiliary winding of the transformer.

Abstract: This invention relates to SMPS controllers employing primary side sensing. We describe a system for identifying a knee point in a sensing waveform, at which the output voltage of the SMPS may be sampled accurately on the primary side. The system identifies the knee point by fitting a tangent to a portion of a power transformer voltage waveform, and samples the voltage waveform at the knee point to determine the SMPS output voltage. In preferred embodiments this technique is implemented using a decaying peak detector, providing a timing signal indicating detection of the knee point. Sample/hold and error amplifier circuits may be employed to achieve output voltage regulation.

Abstract: A primary-side feedback control device for a power converter includes a control unit for generating a pulse signal according to a feedback signal for controlling on and off states of a switching transistor of the power converter, a comparator coupled to an auxiliary winding of a primary side of the power converter for generating at least one control signal according to a voltage on the auxiliary winding and a reference voltage, a sample-and-hold unit coupled to the auxiliary winding, the comparator, and the control unit for generating the feedback signal according to the voltage on the auxiliary winding and the at least one control signal, and a voltage generator coupled to the control unit, the comparator, and the sample-and-hold unit for generating the reference voltage according to the feedback signal.

Abstract: Disclosed is a compact inverter plug that can be used with LED lighting strings. The inverter plug has a size and shape that is comparable to a standard wall plug and is capable of plugging into a standard wall socket. The inverter plug is waterproof and can be easily assembled. A unique inverter circuit is utilized that is compact and highly efficient. Monitoring is performed by a transformer coil that generates a monitoring signal. The inverter is controlled by controlling the modulation frequency of a direct current signal using a controller.

Abstract: An example power converter includes a power switch, a controller, and a current offset circuit. The controller is coupled to switch the power switch between an ON state and an OFF state to regulate an output of the power converter. The controller is adapted to terminate the ON state of the power switch in response to a switch current flowing through the power switch reaching a switch current threshold. The current offset circuit is coupled to generate an offset current in response to an input voltage of the power converter and an input current of the power converter is adjusted in response to the offset current.

Abstract: A startup circuit for a switching-mode power supply (SMPS) includes a first voltage detector configured to trigger the switching-mode power supply from a startup mode to a normal operation mode when an input supply voltage exceeds a first threshold voltage, a current consumption in the first voltage detector in the startup mode being determined by a reverse leakage current of a diode. A feedback circuit is coupled to the first voltage detector and being capable of maintaining a positive feedback loop with a current consumption of no more than a microampere. A second voltage detector is coupled to the first voltage detector and the feedback circuit, and is configured to trigger the switching-mode power supply to switch from the normal operation mode to the startup mode when the input supply voltage is below a second threshold voltage.

Abstract: A flyback switching power supply capable of regulating an operation frequency based on a current regulation mechanism is disclosed. The flyback switching power supply includes a transformer, a switch, a switch control circuit, and a regulation circuit. The transformer includes a primary winding for receiving an input voltage, a secondary winding for generating an output voltage, and an auxiliary winding. The switch is serially connected to the primary winding for controlling a current flowing through the primary winding. The switch control circuit has a frequency control port and functions to work around an operation frequency for controlling the switch. The operation frequency is under control by a frequency setting current flowing through the frequency control port. The regulation circuit is electrically coupled between the auxiliary winding and the frequency control port. The regulation circuit adjusts the frequency setting current based on an induced current generated by the auxiliary winding.

Abstract: A flyback converter with forced primary regulation is disclosed. An example flyback converter includes a coupled inductor including a first winding, a second winding, and a third winding. The first winding is coupled to an input voltage and the second winding is coupled to an output of the power converter. A switched element is coupled to the second winding. A secondary control circuit is coupled to the switched element and the second winding. The secondary control circuit is coupled to switch the switched element in response to a difference between a desired output value and an actual output value to force a current in the third winding that is representative of the difference between the desired output value and the actual output value. A primary switch is coupled to the first winding. A primary control circuit is coupled to the primary switch and the third winding.

Abstract: A power adapter with voltage-stabilized compensation includes a pulse frequency modulation circuit to generate a driving pulse which has a variable OFF time interval to control power transformed and output by a transformer. The power adapter also has an ancillary coil to induce a feedback signal on the secondary coil of the transformer. The pulse frequency modulation circuit includes a time interval modulation unit to receive the feedback signal and a feedback compensation unit. The time interval modulation unit sets a level voltage compared with the feedback signal to generate a sample signal to modulate the OFF time interval. The feedback compensation unit provides a compensation signal to the time interval modulation unit to change the size of the feedback signal or sample signal thereby to compensate the voltage output from the secondary side.

Abstract: A circuit for reducing the variations of auto-supply voltage of a control circuit of a switching power supply, where the control circuit supplies an activation or deactivation signal of a power transistor, includes an auto-supply voltage generator, a controlled switch capable of selectively connecting the generator to the control circuit, and a driving circuit of the controlled switch that supplies a closing signal of the controlled switch after a predefined delay of time starting from the deactivation command.

Abstract: Techniques are disclosed to regulate an output of a power converter. One example power converter controller circuit includes a line sense input to be coupled to receive a signal representative of an input voltage of a power converter. A feedback input to be coupled to receive a feedback signal representative of an output of the power converter is also included. A drive signal generator is also included to generate a drive signal coupled to control switching of a switch to provide a regulated output parameter at the output of the power converter in response to the feedback signal. The drive signal generator is coupled to receive a plurality of inputs including the line sense input and the feedback input. The drive signal generator is coupled to latch the power converter into an off state in response to a detection of a fault condition in the power converter as detected by the plurality of inputs if the power converter input voltage is above a first threshold level.

Abstract: An exemplary DC to DC converter (2) includes a transistor (29), a first rectifying and filtering circuit (21), a pulse generating circuit (27) and a transformer (25). The first rectifying and filtering circuit transforms an external AC voltage to a first DC voltage. The transformer includes a primary winding (251), an assistant winding (252) connected with the primary winding in a flyback mode, and a secondary winding (253). The first DC voltage is connected to ground via the primary winding, the transistor in series. The pulse generating circuit includes a controlling terminal, a diode, a resistor, and a capacitor. One terminal of the assistant winding is connected to ground, and the other terminal of the assistant winding is connected to an anode of the diode. A cathode of the diode is connected to ground via the resistor and the capacitor in series. The controlling terminal is connected to gate electrode of the transistor.

Abstract: The present invention discloses a power supply system for reducing reverse current, the system comprising a primary side circuit, for receiving alternating current; a transformer circuit, for transforming voltage; a secondary side rectifier circuit, for rectifying voltage; a secondary side filter circuit, for filtering voltage and providing direct current to a device; a first voltage division circuit, for providing a first voltage division signal; a switch circuit, for deciding the conducting condition based on the first voltage division signal and a reference voltage signal; a second voltage division circuit, for providing a second voltage division signal; and a control circuit, for deciding the charging condition based on the second voltage division signal; wherein the second voltage division circuit comprising a rectifier component and a filter component, for rectifying and filtering the source of the second voltage division signal.

Abstract: A power converter operates in continuous conduction mode and outputs a regulated output voltage. A feedback-derived signal is used to regulate the output voltage. The feedback-derived signal is sampled at multiple time points during an OFF cycle of a power switch. A current-sense signal is also sampled at one or more time points during an ON cycle of the power switch. The current-sense signal is indicative of an output inductor current of the power converter. A calibrated feedback-derived voltage is then generated based on the multiple voltage samples of the feedback-derived signal and the one or more voltage samples of the current-sense signal. The calibrated feedback-derived voltage is less sensitive to an output inductor current loop resistance than the original voltage samples of the feedback-derived signal. The calibrated feedback-derived voltage also compensates for the nonlinearity of a diode of the output inductor current loop.

Abstract: A controller for providing a constant output current control signal in a switched mode power supply (SMPS) includes a conduction time compensation circuit that is configured to produce a compensated conduction time interval signal that includes compensation for a ringing waveform of a feedback signal. The compensated signal reflects more accurately the actual conductive time of a rectifying diode in a secondary winding of the switched mode power supply. In one embodiment, the compensated conduction time interval signal is used to generate a fixed ratio between the conduction time and the non-conduction time of the rectifying diode. In another embodiment, the controller also provides a constant voltage control signal.

Abstract: A plurality of arrangements for detecting an overload of energy supplied to an output part enables selecting latch-off or auto-recovery overload protection by the operation of a switching device. When the drain current peak of the switching device exceeds a predetermined level denoting an overload, the FB pin voltage also rises to latch off, and when the drain current peak then reaches a maximum level, the CC pin voltage drops to a predetermined level and limits the oscillation period of the switching device because output power cannot be increased even if the load increases further. Latch-off overload protection can be applied when the drain current peak exceeding a predetermined level is detected, and auto-recovery overload protection can be applied when the CC pin voltage is detected to drop to a predetermined level.

Abstract: A control circuit controls the output current of the power converter at the primary side of the transformer. The control circuit includes a current-detection circuit for generating a primary-current signal in response to the switching current of the transformer. A voltage-detection circuit is coupled to the transformer to generate a period signal and a discharge-time signal in response to the reflected voltage of the transformer. A signal-process circuit is utilized to generate a current signal in response to the primary-current signal, the period signal and the discharge-time signal. The period signal is correlated to the switching period of the switching signal of the power converter. The discharge-time signal is correlated to the duty cycle of switching current at the secondary-side of the transformer. The current signal is correlated to the output current of the power converter.

Abstract: The present invention includes a turn-off signal modulating circuit that periodically varies a turn-off timing of a switching element 2 at a preset modulation time after a current detection by a drain current detecting circuit 15, and by modulating the peak of a current flowing through the switching element 2, diffuses switching noise while preventing concentration of an oscillating frequency at a constant frequency even under a constant input voltage and a constant load.

Abstract: A switching mode power supply includes a power supply circuit, a feedback circuit, and a switching controller. The power supply circuit includes a main switch coupled to a primary coil of a transformer, and supplies power to a secondary coil of the transformer according to an operation of the main switch. The feedback circuit generates a feedback voltage corresponding to an output voltage provided to the secondary coil of the transformer. The switching controller controls the main switch to turn off according to a sense voltage corresponding to the current flowed by the main switch. In this instance, the switching controller quickly senses the output short phenomenon by using the duty ratio of the main switch and the feedback voltage and shuts down the main switch to protect the circuit.

Abstract: A control circuit for use in a power converter with an unregulated dormant mode of operation includes a drive signal generator coupled to generate a drive signal to control switching of a power switch to be coupled to the control circuit to regulate a flow of energy to a power converter output in response to an energy requirement of one or more loads to be coupled to the power converter output. An unregulated dormant mode control circuit is included and is coupled to render dormant the drive signal generator thereby ceasing the regulation of the flow of energy to the power converter output by the drive signal generator when the energy requirement of the one or more loads falls below a threshold for more than a first period of time. The drive signal generator is coupled to be unresponsive to changes in the energy requirements of the one or more loads when dormant. The unregulated dormant mode control circuit is coupled to power up the drive signal generator after a second period of time has elapsed.

Abstract: In one embodiment, a switching mode power supply (SMPS) includes a rectifier for generating an input DC voltage from an input AC voltage. A switching transistor, coupled to a primary coil of a transformer, converts the input DC voltage and supplies power to a secondary side of the transformer according to an operation of the switching transistor. A switching controller receives a feedback voltage corresponding to a voltage of the secondary side of the transformer, a sense signal corresponding to current flowing at the switching transistor, and a first signal corresponding to a voltage difference between first and second electrodes of the switching transistor. The switching controller controls the turning on and off of the switching transistor. After the switching transistor is turned off, the switching controller detects and counts a number of times that a voltage level of the first signal and a reference voltage are equal.

Abstract: A power converter has a transformer including a primary winding connected between a power input and a power switch, the power switch is switched to deliver power from the power input to a power output, an auxiliary winding provides an induced voltage in such a manner that when the power switch is at a first switch state, the induced voltage reflects an input information of the power converter, and when the power switch is at a second switch state, the induced voltage reflects an output information of the power converter. Two detection signals are generated from the input and output information, respectively, to implement multiple functions and protections.

Abstract: A power converter control method and apparatus is disclosed. An example power converter controller according to aspects of the present invention includes feedback sampling circuitry to be coupled to an output of a power converter. The feedback sampling circuitry is to generate feedback signal samples after a conduction of a power switch is terminated during enabled switching cycles. Switch conduction control circuitry is coupled to the feedback sampling circuitry. The switch conduction circuitry includes switch conduction enable circuitry that is coupled to enable or disable the conduction of the power switch during a switching cycle in response to the feedback signal samples. The power switch is caused to conduct during at least a portion of an enabled switching cycle and prevented from conducting during an entirety of a disabled switching cycle.

Abstract: A DC-DC flyback converter that has a controlled synchronous rectifier in its secondary circuit, which is connected to the secondary winding of a main transformer. A main switch (typically a MOSFET) in the primary circuit of the converter is controlled by a first control signal that switches ON and OFF current to the primary winding of the main transformer. To prevent cross-conduction of the main switch and the synchronous rectifier, the synchronous rectifier is turned ON in dependence upon a signal derived from a secondary winding of the main transformer and is turned OFF in dependence up a signal derived from the first control signal. In one embodiment the first control signal is inverted and delivered to a logic circuit along with the voltage across the main transformer secondary winding and the voltage across the synchronous rectifier.

Abstract: An exemplary power supply circuit (20) includes a first commutating and filter circuit (21), a transformer (24), a second commutating and filter circuit (25), a transistor (27), a pulse width modulation circuit (26) outputting a control signal to control operation state of the transistor, and a feedback circuit (29). An external alternating current voltage is converted into a direct current with a cooperation operating of the transistor, the first commutating and filter circuit, the transformer, and the second commutating and filter circuit. The feedback circuit feeds an operating state of the transformer back to the pulse width modulation circuit, and the pulse width modulation circuit outputs corresponding control signals to turn on or turn off the transistor.

Abstract: An improved valley-mode switching (VMS) scheme and circuitry for implementing the improved VMS switching scheme in a switch-mode power converter are disclosed. For a given switching cycle, a desired switch turn-on time is determined based on a pulse width modulation, pulse frequency modulation, or other suitable power converter control scheme. Also, one or more times corresponding to local minimums (valleys) are predicted for the voltage across a power switch of the switching power converter. The power switch is turned on at a valley immediately subsequent or otherwise subsequent to the desired switch time determined according to the power converter control scheme. Thus, the improved VMS scheme enables low-voltage switch operation to reduce switching loss and EMI noise without restricting the control scheme of the power converter.

Abstract: A switching power supply apparatus which includes a DC power supply, an isolation transformer having primary, secondary and tertiary windings, and a switching element, and in which, by turning the switching element on and off, the high-frequency voltage appearing in the secondary windings of the isolation transformer is rectified to obtain a DC output, power consumption can be decreased during standby (in burst mode) in particular by means of a control circuit which controls the turn-on and turn-off of the element and similar.

Abstract: A flyback converter with forced primary regulation is disclosed. An example flyback converter includes a coupled inductor including a first winding, a second winding, and a third winding. The first winding is coupled to an input voltage and the second winding is coupled to an output of the power converter. A switched element is coupled to the second winding. A secondary control circuit is coupled to the switched element and the second winding. The secondary control circuit is coupled to switch the switched element in response to a difference between a desired output value and an actual output value to force a current in the third winding that is representative of the difference between the desired output value and the actual output value. A primary switch is coupled to the first winding. A primary control circuit is coupled to the primary switch and the third winding.

Abstract: A flyback switching power supply capable of regulating an operation frequency based on a current regulation mechanism is disclosed. The flyback switching power supply includes a transformer, a switch, a switch control circuit, and a regulation circuit. The transformer includes a primary winding for receiving an input voltage, a secondary winding for generating an output voltage, and an auxiliary winding. The switch is serially connected to the primary winding for controlling a current flowing through the primary winding. The switch control circuit has a frequency control port and functions to work around an operation frequency for controlling the switch. The operation frequency is under control by a frequency setting current flowing through the frequency control port. The regulation circuit is electrically coupled between the auxiliary winding and the frequency control port. The regulation circuit adjusts the frequency setting current based on an induced current generated by the auxiliary winding.

Abstract: System and method for regulating a power converter. The system includes a first signal generator configured to receive at least an input signal and generate at least a first output signal associated with demagnetization and a second output signal associated with sampling. Additionally, the system includes a sampling component configured to receive at least the input signal and the second output signal, sample the input signal based on at least information associated with the second output signal, and generate at least a third output signal associated with one or more sampled magnitudes. Moreover, the system includes an error amplifier configured to receive at least the third output signal and a first threshold voltage and generate at least a fourth output signal with a capacitor, the capacitor being coupled to the error amplifier.

Abstract: According to the present invention, when a secondary current on period T2on reaches a predetermined maximum secondary current on-period, an overload is detected and an output power is controlled to decrease. Further, a maximum secondary current on-period signal is set so as to correspond to a secondary current on-period when constant voltage control is performed on an output voltage.

Abstract: When an AC power supply (9) is powered up, a constant current supply section (14) supplies a constant current to a capacitor (C3) to charge the capacitor (C3). When a voltage across the capacitor (C3) becomes equal to or greater than a predetermined voltage, a switch control section (17) sets a switch (13) off. When an output current drops to lead to a light load, a load detecting circuit (15) stops the operation of a PWM control circuit (12) and activates a timer (16). The timer (16) supplies a switch-ON signal to the switch control section (17) when it is activated and a predetermined time measured elapses. When supplied with the switch-ON signal, the switch control section (17) sets the switch (13) on. When the switch (13) is set on, the capacitor (C3) is charged again, applying a voltage to the PWM control circuit (12).

Abstract: A discontinuous mode flyback converter for limiting output current using primary feedback is disclosed. A transformer stores magnetic energy using field current and transfers the magnetic energy using a primary winding and a secondary winding closely coupled to the primary winding. A switching element is coupled to one end of the primary winding of the transformer and controls the current of the primary winding of the transformer. A control unit controls the switching element. A voltage error feedback unit feeds back the error of the output voltage of the transformer to the control unit, thereby regulating the output voltage. An output current feedback circuit detects the flyback period of the transformer, detects the output current information of the transformer from the rate of a flyback period in a cycle, and feeds it back to the control unit, thereby limiting the output current of the transformer.

Abstract: A switching mode power supply includes: a power supply unit that comprises a switch that is coupled to a primary coil at a primary side of a transformer for converting an input DC voltage, and that supplies power to a secondary coil and a tertiary coil at a secondary side of the transformer according to an operation of the switch; a switching controller that receives a feedback voltage corresponding to a first voltage generated in the secondary coil at the secondary side of the transformer, and receives a detection signal corresponding to a current flowing to the switch to control an on/off operation of the switch; and a feedback signal generator that receives the first voltage and the switching control signal, samples the first voltage by using first pulse strings, and generates the feedback voltage according to a level of the first voltage sampled by a first pulse in the first pulse strings, wherein a toggling time of the first pulse strings is changed in a first period for sampling the first voltage, and a

Abstract: An amplifier is driven by DC voltage from a switchmode power supply, whereby the switchmode power supply includes on the primary side a primary winding and bias supply winding. The bias supply winding supplies a reflected voltage from a secondary winding to a bias supply capacitor. The bias supply capacitor drives the control circuit and provides a sensing to the control circuit. The power supply further includes an active clamp circuit for controlling the voltage stress on a main switch. In another embodiment, boost inductors and a balancing transformer are added on the primary side of the transformer to prevent overvoltage conditions at light loads.

Abstract: A converter and a driving method thereof are provided. The converter includes a main switch and a switching controller. The switching controller controls on/off of the main switch by using a first voltage corresponding to an output voltage and a first current flowing to the main switch. The switching controller determines a reference count according to the first voltage, and determines a peak value of the first current corresponding to a reference count and a switching frequency of the main switch.

Abstract: A circuit and a method for detecting a voltage of a transformer are provided. The circuit includes a current output circuit coupled to a winding of a transformer to generate a current signal. A current-to-voltage circuit is coupled to the current output circuit to generate a voltage signal in response to the current signal. A sample-and-hold circuit generates an output signal by sampling the voltage signal. An input voltage is applied to the transformer. The output signal is correlated to the input voltage of the transformer.

Abstract: A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls an inductor switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the pulse width controls the peak of the inductor current.

Abstract: The present invention includes a voltage clamping circuit 6 for outputting a voltage signal, which has been clamped to a predetermined voltage, from the drain voltage of a switching element 1, and a turn-on detection circuit 7 for detecting the turn-on timing of the switching element 1 from the voltage signal. Thus it is possible to turn on the switching element 1 at the minimum value of the drain voltage without adding external terminals.

Abstract: In a RCC type switching power supply circuit, a sensing coil connected magnetically closely with an output coil is equipped in a fly-back transformer. The sensing coil is connected with a timing condenser through a Zener diode and an alternate current voltage output from the sensing coil is rectified and smoothed. Then, the difference between a detection voltage detected as a direct current voltage of the secondary side and the basic voltage of the Zener diode is supplied to the timing condenser to change the discharge/charge time and then change the timing of the switching of a first switching element in order to control the switching time of the first switching element. At the same time, applying the voltage which results from rectifying and smoothing the output voltage from the sensing coil, the charge and discharge of the timing condenser at the non-loading time is controlled in order to prolong the cycle of the switching oscillation and consequently, reduce the power loss.

Abstract: A switching mode power supply (SMPS) and a driving method thereof are provided. The SMPS includes a power supply block that includes a first switch coupled to a first coil of a primary side of a transformer for converting an input voltage, wherein the power supply block supplies power to a second coil and a third coil of a secondary side of the transformer according to operation of the first switch; and a PWM signal generator determines a turn-on time of the first switch according to the input voltage, and the turn-on time is determined regardless of a power magnitude of an output terminal connected to the second coil. Accordingly, screen noise due to a ripple can be eliminated and stress on the switch breakdown due to excessive power input can be reduced to enable an SMPS with stable driving.

Abstract: A power converter operates in continuous conduction mode and outputs a regulated output voltage. A feedback-derived signal is used to regulate the output voltage. The feedback-derived signal is sampled at multiple time points during an OFF cycle of a power switch. A current-sense signal is also sampled at one or more time points during an ON cycle of the power switch. The current-sense signal is indicative of an output inductor current of the power converter. A calibrated feedback-derived voltage is then generated based on the multiple voltage samples of the feedback-derived signal and the one or more voltage samples of the current-sense signal. The calibrated feedback-derived voltage is less sensitive to an output inductor current loop resistance than the original voltage samples of the feedback-derived signal. The calibrated feedback-derived voltage also compensates for the nonlinearity of a diode of the output inductor current loop.

Abstract: Switching-mode power conversion system and method thereof. The system includes a primary winding configured to receive an input voltage, and a secondary winding coupled to the primary winding and configured to, with one or more first components, generate, at an output terminal, an output voltage and an output current. Additionally, the system includes an auxiliary winding coupled to the secondary winding and configured to, with one or more second components, generate, at a first terminal, a detected voltage. Moreover, the system includes an error amplifier configured to receive the detected voltage and a first reference voltage and generate an amplified voltage based on at least information associated with a difference between the detected voltage and the first reference voltage. Also, the system includes a compensation component configured to receive the amplified voltage and generate a second reference voltage based on at least information associated with the amplified voltage.