Abstract: A common mode noise cancellation circuit eliminates common mode noise generated by one or more high-frequency switching devices. A common mode noise waveform generated by the one or ore switching devices is capacitively coupled from the primary winding to the first secondary winding of a transformer. A set of cancellation secondary windings generates a common mode cancellation waveform, and cancels the common mode noise waveform because the common mode cancellation waveform is approximately equal in amplitude and opposite in phase to the common mode noise waveform. A triac control circuit receives an AC input and determines whether the AC input is within a range where multiplying of the DC voltage is implemented. If the triac control circuit determines the AC input is within the range, the triac control circuit transmits a triac firing signal to the triac circuit. The triac circuit charges a capacitor bank to multiply the DC voltage.

Abstract: A power converter is provided that operates with a wide range input and provides the required hold up time using a smaller, less costly hold-up capacitor. A charging circuit is provided to charge a capacitor through an auxiliary winding. The power converter includes circuitry for channeling the energy from the capacitor to the converter to provide hold-up time during input power loss conditions, while having better utilization of stored energy. The power converter of the present invention also provides this function using fewer and lower cost components than prior art devices.

Abstract: A start-up circuit for converters with controller power supply connected at output side. With this start-up circuit, all the control and supporting circuitries are connected at the converter output low voltage side and protected from high input DC voltage. After the converter is started and the controller starts generating normal switching pulses, the start-up circuit may be disabled.

Abstract: A power factor correction circuit structure is described. The circuit connects a bridge rectifier and a first capacitor in series. The first capacitor, a winding and a first switching device are also connected in series. The first switching device is the low-side switching device in a bridge converter. The first switching device, a second switching device and a second capacitor are also connected in series. The second switching device is the high-side switching device in the bridge converter and the second capacitor is the boost capacitor in the PFC circuit. The winding can be one additional winding of the main transformer in the bridge converter or an independent inductor.

Abstract: A low loss DC/DC converter uses the reset technique to reset the magnetizing current from the forward transformer during the OFF period, reducing voltage stress and extend the maximum work duty. The third winding reset circuit is an improved version of a conventional third winding reset circuit for a forward converter.

Abstract: The invention employs a coreless isolated transformer, with associated electronic circuitry, for providing an initial bias and enable signal for control and drive circuitry that is referenced to the output of a converter. The improvement is accomplished by embedding the transformer primary and secondary windings into a multi-layer PCB so that the transformer does not occupy space on the top and bottom surfaces of the PCB The initial bias voltage is used to initialize operation of the control circuit when referenced to the output side of the converter. Thus, complete regulation and drive signals are generated on the output side.

Abstract: A low loss DC/DC converter uses the reset technique to reset the magnetizing current from the forward transformer during the OFF period, reducing voltage stress and extend the maximum work duty.

Abstract: A bias supply circuit and a method of operating a bias supply circuit for use with a switching power supply employing a main switch and an auxiliary switch and having an input voltage and a voltage across a clamp capacitor coupled to a transformer. In one embodiment, the bias supply circuit includes a bias supply winding associated with the transformer and configured to provide a first voltage dependent on at least one of the input voltage and the voltage across the clamp capacitor during a conduction period of the main switch or the auxiliary switch. Additionally, the bias supply circuit further includes a bias supply storage capacitor coupled to the bias supply winding and configured to provide a second voltage dependent on at least another of the input voltage and the voltage across the clamp capacitor during a conduction period of another of the main switch or the auxiliary switch. A sum of the first voltage and the second voltage provides a bias supply voltage.

Abstract: An insulating-type switching electric power source device has an input voltage Vin of a primary side that is converted at an input/output ratio determined by switching operations of a switching device, and then is output. Voltage subjected to rectifying and smoothing by a primary-side rectification smoothing circuit is used as detecting signals of the output voltage, to control the time ratio of the switching device. A load regulation correcting circuit outputs load regulation correcting signals correlated with the amount of output current. A temperature compensating circuit corrects the load regulation correcting signals according to the ambient temperature. The load regulation correcting signals correct the output voltage detecting signals according to the fluctuations of the output voltage according to fluctuations in the output current and fluctuations in the ambient temperature.

Abstract: A switching power supply device in which a transformer, a first switch circuit, and an input power source are connected in series. A series circuit formed of a second switch circuit and a capacitor is connected to one end of the first switch circuit. The transformer has a driving winding which is wound in the same direction as that of the primary winding of the transformer. A capacitive impedance element including a series circuit formed of a capacitor and an inductive ferrite bead, is connected between the termination of the driving winding and the input power source. The switching power supply device uses a less capacitive impedance and thus provides higher radiation noise reduction performance, thereby preventing switching devices from being damaged due to high voltage increase rate of the switching devices.

Abstract: A switching power supply unit includes a control circuit including a turn-off circuit for turning of a first switch element Q1, which has been in an ON state, and an off-period control circuit for, based on a feedback signal from an output-voltage detecting circuit, controlling the turning-on of the first switch element to be further delayed as a load is lighter. The off-period control circuit includes a transistor as a second switch element which is provided in series between a feedback winding and the control terminal of the first switch element and which is controlled to be turned on and off based on the feedback signal from the output-voltage detecting circuit. A switching frequency is set to be lower as the load is lighter, such that power consumption at the light load is reduced.

Abstract: A switching power supply circuit including a transformer having a primary winding, a secondary winding, and a feedback winding; a direct-current power supply of which one end is connected to one end of said primary winding; a switching element connected in series between the other end of said direct-current power supply and the other end of said primary winding; a control circuit provided between the control terminal of said switching element and said feedback winding; a rectifying circuit connected to said secondary winding; and a constant-current circuit provided between the one end of said primary winding and the control circuit or the control terminal of said switching element.

Abstract: The present invention provides an off-time modulation in PWM controller to increase the switching period for saving power consumption in the light load and no load conditions. The off-time modulation is achieved by keeping the charge current as a constant and moderating the discharge current of the saw-tooth-signal generator of the PWM controller. Decreasing the discharge current increases the switching period. A feedback voltage, which is derived from the voltage feedback loop, is taken as an index. The discharge current is modulated to be a function of the feedback voltage. A threshold voltage defines the level of the light load condition. The differential of the feedback voltage and the threshold voltage is converted to a current, which is then amplified and turned into the discharge current. A limiter clamps the maximum discharge current to decide the switching period in normal load and full load conditions and determines the dead time of PWM signal.

Abstract: A method and circuit for clamping a voltage across a switching element in a forward converter circuit to a value equal to or less than the DC bus voltage. The disclosed circuit and method achieves voltage clamping in a circuit configuration in which two series connected direct current (DC) bus capacitors are connected in parallel with a switching element to be clamped. Clamping is further achieved by selecting capacitor values to be sufficiently large so as to maintain a constant voltage throughout each switching cycle of the switching element. The capacitors serve a second function in that they recover energy stored in the windings of an isolation transformer which would otherwise be dissipated in a conventional circuit design.

Abstract: Circuit and method for reducing voltage level variation in a bias voltage generated in a power converter device are provided. The method allows providing a first voltage source configured to supply a first voltage during one respective mode of operation of the power converter, wherein the level of the voltage supplied by the first voltage source is directly proportional to variation in an input voltage of the converter device. The method further allows providing a second voltage source configured to supply a second voltage during another respective mode of operation of the power converter, wherein the level of the voltage supplied by the second voltage source has a generally inverse proportional relationship relative to variation in the input voltage of the converter device. At least one circuit parameter is selected in the voltage sources to adjust the respective levels of the first and second voltages.

Abstract: A switching power supply apparatus has a transformer having a primary winding, a secondary winding and a tertiary winding; a primary switching element connected to the primary winding of the transformer for providing the primary winding with an input voltage in accordance with an on-off operation of the main switching element; an output circuit connected to the secondary winding of the transformer for receiving a voltage based on the input voltage from the secondary winding, rectifying the voltage and outputting an output voltage; a detection circuit in which the output voltage output from the output circuit is indirectly detected using the tertiary winding, and the detected voltage is output; a compensating-voltage-superposition circuit which generates a compensating voltage, in accordance with the detection voltage, for compensating a deviation of the detection voltage of the detection circuit to the output voltage of the output circuit in accordance with a change of the input voltage and which superposes t

Abstract: A regulated power supply in which square wave output of a switching rectifier is applied to a filter comprises a series inductor and a parallel capacitor. This filter lacks a series resistor. The ramp signal is developed across a second capacitor in series with a first resistor, and in parallel with the rectifier output. An amplifier adds the ramp signal to a signal representing the error in the DC output voltage of the power supply, producing an output that is fed to a control circuit. The control circuit in response generates a voltage control signal that controls the switching of the rectifier.

Abstract: A bias circuit with a coreless transformer to provide isolated initial bias and enable signal for a switch-mode power converter with the control circuit located on the output side. A coreless transformer is used for initializing operation of the control circuit, because of its simplicity and low profile on a printed circuit board due to lack of a magnetic core. Exemplary embodiments are further disclosed that provide a means to enable or disable the power converter using input signals from the input side, such as an ON/OFF feature, as well as from input signals from the output side, such as secondary protection logic.

Abstract: A switched-mode power supply with a control loop and a microprocessor has a normal mode and a low-power mode with a burst mode. The microprocessor is connected via an output to the control loop and uses this to control the burst mode of the switched-mode power supply directly. The control loop of the switched-mode power supply monitors, in particular, a secondary output voltage, so that the output of the microprocessor is connected to the control loop, for example via a simple resistor network or a transistor stage. The clock frequency and the duty cycle of the burst mode are permanently stored in the microprocessor and can be defined for the switched-mode power supply directly, for example using TTL logic.

Abstract: Switching power amplifier and uninterruptible power system each can be built using only 6 power components, including battery and output capacitor. Moreover, line isolation is accomplished. An inductive block includes an inductor and/or a transformer, and provides a return voltage. A first switch selectively applies at least one supply voltage to the inductive block. A first rectifier limits the return voltage, e.g. to the battery voltage. Another capacitor stores a DC voltage and the series-coupled output capacitor provides the output voltage. A sum of the capacitor voltages is positive even at negative peak of the output voltage. A second switch and a second rectifier apply the sum to the inductive block. The output voltage and a current charging the battery can be pure sinusoidal.

Abstract: A DC-DC converter includes a primary side circuit for allowing a switching device to perform on/off operations to output energy in a primary coil of a transformer to a secondary coil. A secondary side circuit rectifies and smooths a voltage outputted from the secondary coil so as to output a DC-DC voltage. A voltage-detecting circuit rectifies and smooths a voltage outputted from a voltage-detecting coil provided in the transformer so as to output the voltage as a detected voltage corresponding to a voltage to be outputted from the secondary side circuit. A control circuit applies to the switching device a pulse control signal used for controlling on/off operation of the switching device according to the voltage outputted from the voltage-detecting circuit.

Abstract: A voltage boost power converter circuit, having an input inductor, active switch, and a transformer having primary, secondary and auxiliary windings. A clamping capacitor and a first passive switch are in series across the primary winding. The auxiliary winding and a second passive switch are in series, connected to the node between the clamping capacitor and first passive switch. The active switch is connected between ground the primary winding. A bulk capacitor forms a series loop including the active switch and primary winding. The method efficiently resets a the transformer, by transferring power to a load through the primary winding, and discharging a clamping capacitor through a separate inductively linked winding of the transformer during an ON state; and clamping the active switch voltage with the clamping capacitor, charging the clamping capacitor with a leakage inductance of the transformer, and charging the bulk capacitor during an OFF state.

Abstract: In a PDP power circuit, a rectifier circuit is connected to an external commercial power source, and a high voltage power circuit is connected to the rectifier circuit and outputs a first voltage. A first capacitor is connected between an output terminal of the high voltage power circuit and the ground potential. A low voltage power circuit is also connected to the rectifier circuit and outputs a second voltage lower than the first voltage. The input terminal of a DC/DC converter is connected to the high voltage side of the first capacitor, while the output terminal of the DC/DC converter is connected to the output terminal of the low voltage power circuit. A voltage detector circuit is also connected to the output terminal of the high voltage power circuit. The first voltage is supplied to a PDP drive circuit, while the second voltage is supplied to a PDP control circuit.