Abstract: A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps is described. A common-mode choke is used between the cold cathode fluorescent lamps. The common-mode choke balances the currents respectively flowing through the cold cathode fluorescent lamps.

Abstract: A solid state switching circuit utilizes a transformer in series with the circuit's switching device by which energy initially stored in the primary of the transformer is recovered in resonant circuitry connected to the secondary of the transformer for transfer of the energy to the load when the switching device is not conducting.

Abstract: In a preferred embodiment, there is provided a switched mode power supply operable in start-up mode, normal mode and standby mode. The power supply may comprise a transformer having a primary winding on a primary side and a secondary winding on a secondary side, the primary winding being coupleable to a DC input voltage, and circuitry on the secondary side being arranged to provide a DC output voltage; and a power controller. The power controller may comprise a regulation controller for regulating a DC supply voltage on a supply line during standby mode, and a high voltage device coupled to the DC input voltage and the supply line. The current through the high voltage device to the supply line, during standby mode, may be controlled by the regulation controller. During standby mode, when the supply voltage is greater than or equal to a reference voltage, the current through the high voltage device to the supply line is substantially zero.

Abstract: The provided method and control circuit are employed to alternately control the dual boost PFC circuits. The control circuit for alternately controlling parallel-connected first and second boost circuits of a dual boost PFC circuit to achieve a current-sharing of the first and the second boost circuits includes: a first control circuit having a first current control loop for employing an output voltage of the PFC circuit, a feed-forward voltage, and an input reference voltage to generate a current reference, and sending the current reference to an input terminal of the first current control loop to generate a first PWM signal to drive the first boost circuit, and a second control circuit having a second current control loop for receiving the current reference through an input terminal of the second current control loop to generate a second PWM signal to drive the second boost circuit.

Abstract: A control circuit for a switched mode power converter is adapted to receive a current sense signal reflecting the output current of the power converter and a feedback signal reflecting the output voltage of the power converter. The control circuit includes a first over-current protection circuit adapted to shut off operation of the switched mode power converter if a sum of the current sense signal and the feedback signal exceed a first predetermined limit, and a second over-current protection circuit adapted to regulate operation of said primary side power switch responsive a comparison of the sum of the current sense signal and the feedback signal to a second predetermined limit. The second predetermined limit is less than the first predetermined limit.

Abstract: An inventive inverter has a semiconductor switch circuit connected to the primary winding of a transformer. The semiconductor switch circuit is respectively controlled by PWM to supply a constant current to the load connected to a secondary winding of the transformer. The inverter is capable of deliberately regulating its ac power output to the load and lowering the lower limit of the output power through control of the intermittent operation, in which an error signal for carrying out the PWM control is reduced to zero during each off-duty period. In addition, the error signal for the PWM control is slowly decreased or increased in each shift from an off-duty period to on-duty period, and vise versa, by charging or discharging the capacitor in a feedback circuit, thereby allowing slow start or slow end of the respective on-off operations for the constant current control through the PWM.

Abstract: A power supply with high pulse width modulation gain and low noise sensitivity has been disclosed. In one embodiment, a power supply includes a regulator circuit controlling a power switch. The regulator circuit includes a control input that receives a current, which is the sum of a consumption current of the regulator and a feedback current. The consumption current of the regulator is varied as a function of the duty cycle of the power switch. The feedback current is the current in a shunt regulator, which is control current in excess of the internal consumption of the regulator.

Abstract: The invention relates to a power supply device having several switch-mode power supplies connected in parallel to supply at least one consuming unit, each switch-mode power supply generating an output current I0 and an output voltage U0(I0, RL) that is a function of the output current I0 and a load resistance RL, and having a control device for each switch-mode power supply, the control device having a first stage with a P element (54) that receives a P element input voltage which is derived from the output voltage U0(I0, RL), and generates a P element control voltage UVS, that is used to control the respective switch-mode power supply, the first stage being active when 0?I0?I0P, a second stage having a current reproduction circuit which reproduces the output current I0 of the respective switch-mode power supply and generates an output current control voltage UP which is used to control the respective switch-mode power supply, the second stage being active when I0P?I0?I0S, and a third stage having an amplifie

Abstract: A linear predictive system for a DC—DC converter including a linear predictive controller, first and second adders and a multiplier. The DC—DC converter generates an output signal and includes a digital compensation block that converts a feedback error signal into a main duty cycle signal. The linear predictive controller predicts linear changes of the main duty cycle signal in response to changes of the output signal and provides a predictive duty cycle signal. The first adder subtracts the predictive duty cycle signal from the main duty cycle signal to provide a duty cycle delta. The multiplier multiplies the duty cycle delta by a gain factor to provide a duty cycle delta sample. The second adder adds the duty cycle delta sample to the first duty cycle signal to generate an adjusted duty cycle signal.

Abstract: In the present invention, the safeguarding of the circuit and the step-up transformer can be devised without using the special high-cost components. Voltage supplied by the primary coil (21) of a step-up transformer (2) is switched by a transistor (TR) and the secondary coil (22) of the step-up transformer causes the generation of secondary voltage. In addition to applying said secondary voltage to a cold cathode tube (1), the current flowing through the cold cathode tube (1) is detected, and the transistor (TR) switching function is controlled based on the detection results. To detect the voltage generated by the secondary coil of the aforementioned step-up transformer, a voltage detection coil wrapped around the aforementioned step-up transformer (2) is provided. Abnormalities in the voltage supplied to aforementioned cold cathode tube (1) are detected based on voltage detected by this voltage detection coil (23). Switching by the aforementioned transistor (TR) is stopped when an abnormality is detected.

Abstract: A circuit configuration for generating a switching signal for a current controlled switched mode power supply includes a transformer with windings, a controlled power breaker, in series with a primary winding and a supply DC voltage, a control circuit, for cycle clocked switching of the power switch, a current measuring device measuring the current flowing through the power switch and generating a measured signal as a measure of the measured current value, a reference signal source generating a time-independent constant reference signal, and a comparator circuit comparing the measured signal with the reference signal and signaling the control circuit to switch off the power switch when the measured signal is greater than the reference signal. The reference signal source is connected to a compensation signal source to generate a compensation signal changing over time, the reference signal arising from the sum of the constant reference signal and the compensation signal.

Abstract: A pulse width modulation controller is coupled to a feedback voltage that is proportional to the power supply output voltage. The controller adjusts a current sense threshold in the controller in response to the feedback voltage. An offset voltage is generated for a predetermined time after the power-up of the power supply. A sum of the offset voltage and a primary current sense node voltage is applied to a current sense input of the controller. The controller generates a switch control signal in response to the sum voltage being less than the current sense threshold. The duty cycle of an output control switch is changed by the switch control signal thus adjusting the output voltage ramp.

Abstract: A pulse width modulation controller is coupled to a feedback voltage that is proportional to the power supply output voltage. The controller adjusts a current sense threshold in the controller in response to the feedback voltage. An offset voltage is generated for a predetermined time after the power-up of the power supply. A sum of the offset voltage and a primary current sense node voltage is applied to a current sense input of the controller. The controller generates a switch control signal in response to the sum voltage being less than the current sense threshold. The duty cycle of an output control switch is changed by the switch control signal thus adjusting the output voltage ramp.

Abstract: A power supply control circuit connectable with an input power monitor that monitors an input power value to the power supply, an output power monitor that monitors an output power value from the power supply, and an output power controller that varies the output power value from the power supply, the power supply control circuit having an output power determiner that determines a determined output power value depending on the input power value and a power adjuster that adjusts the output power value to the determined output power value by controlling the output power controller.

Abstract: An integrated LED driving device for multiple LED strings which employs a single linear regulator or other controller and a multiple-output current mirror which is almost independent of the DC input voltage source, almost independent of the transistor's or MOSFET's variations from the semiconductor integration process, and almost independent of temperature variation. The multiple-output current mirror includes a plurality of transistors or MOSFETs each of which are integrated on the same substrate, with identical width-to-length channel ratios and with identical source and gate connections. The integrated LED driving device provides for automatic current sharing in a DC mode and, alternately, with minimized phase delays in a PWM mode. The mirror-output current mirror may include mirror-cascode transistor pairs.

Abstract: In a normal operation mode, a mode changeover controller 8 continuously operates a PWM control circuit 6 so as to operate a switching element 5 at the basic oscillation frequency. In a standby mode, the mode changeover controller 8 intermittently operates the PWM control circuit 6 so as to turn on the switching element 5 at a given repetition interval and for a given time period. This repetition interval is shorter than a time for decreasing an output voltage from a rectifying and smoothing circuit 20 down to a guaranteed load operating voltage due to power consumption of the load and the rectifying and smoothing circuit 20 in the standby mode and is longer than a time for entering a sonic frequency band. That time period is longer than a time for stabilizing an output from the rectifying and smoothing circuit 20 and is longer than a time for entering a sonic frequency band.

Abstract: A DC-DC converter includes a reverse current detector for detecting a reverse current and a reverse current suppressor for increasing an input-output conversion ratio when a reverse current is detected. A choke coil increases the inductance in a current flowing region in which a very small reverse current flows and reduces the inductance in a current flowing region in which the current flowing is greater than or equal to that in a normal operation mode. In a reverse current flowing region in which the output current is negative, the DC-DC converter has unique regulation characteristics in which the amount of change in the output voltage relative to the amount of change in the output current is very large. Thus, an increase in the reverse current is prevented, the components are protected from damage by the reverse current flowing, and an increase in the loss is prevented.

Abstract: A power supply apparatus includes a semiconductor switching device for outputting power and a control circuit for controlling the on/off operation of the semiconductor switching device. The control circuit includes a circuit for applying, when turning on the semiconductor switching device, a first control signal corresponding to the difference between the output voltage of the power supply apparatus and a first reference value to the semiconductor switching device in accordance with the increase in the output voltage from the power supply apparatus thereby to operate the semiconductor switching device in a non-saturated area, so that the semiconductor switching device is turned on gradually.

Abstract: A power saving circuit of an AC/DC adaptor for a portable computer including an input until converting an AC voltage into a DC voltage; a power transistor; a transformer inputting the DC voltage and inducing an AC voltage based on the state of the power transistor; an output unit converting the AC voltage into a DC voltage; a feedback unit producing a feedback voltage based on an output voltage of the output unit; a driver outputting a PWM control signal to the power transistor based on the feedback voltage; an output load sensor outputting a sensing signal if a sensed load of the output unit is below a predetermined level; an output voltage dropping unit dropping an output voltage of the output unit based on the sensed signal; and a switching frequency reducer reducing a switching frequency of the PWM control signal based on the sensing signal.

Abstract: A switching power source in which the voltage error of a secondary side DC output is fed back to a switching circuit through an insulating element, thereby to stabilize the output voltage. In the switching power source, irrespective of the voltage of the secondary side DC output, a pulse of the level with which an error detecting circuit determines that the voltage of the secondary side DC output has been increased is applied to the error detecting circuit, whereby the switching operation of the switching circuit is changed into an intermittent operation corresponding to the pulse.

Abstract: An improved switching power supply which saves power when under a small to no load, wherein a transformer is provided comprising a primary winding to which a DC current is supplied by turning ON and OFF a switching device and a secondary winding for supplying an output signal to the load; an ON state control circuit turns ON the switching device by using the output signal induced at the secondary winding; an OFF state control circuit turns OFF the switching device using a current control signal obtained from the output signal from the secondary winding and a reference signal; and wherein a delay circuit prolongs the time at which the switching device makes the OFF to ON transition.

Abstract: The circuit arrangement for connecting a consumer to an alternating voltage source includes a switch actuator (16) connectable in series with the consumer (12) and an electronic circuit (22) associated with the switch actuator and supplied with a direct voltage by means of it. The switch actuator (16) includes a rectifier for supplying the direct voltage to the electronic circuit, a transformer (24) comprising a secondary winding (32) supplying power to the rectifier, a first low inductance primary winding (26) and a second high inductance primary winding (28) and a switching device (36,42) controlled by the electronic circuit (22) to switch between the primary windings. Another switching device (44) is connected in parallel with the first primary winding (26) in order to short-circuit it for a predetermined short-circuit duration as a function of a nominal power consumed by the consumer. The switching device (36,42) can be a relay or a semiconductor component.

Abstract: A power chip set for a switching mode power supply includes a high voltage chip and a control unit chip. The high voltage chip contains a switching power metal-oxide-semiconductor (MOS) transistor being turned on/off under control of an output signal from the control unit, and a junction field effect transistor (JFET) coupled between a drain of the switching power MOS transistor and a power terminal of the control unit to serve as a start up element for driving the control unit during initiation, in which the JFET has a negative threshold voltage and the absolute value thereof is equal to the voltage for driving the control unit. The JFET structure in the high voltage chip further includes a Zener diode for over voltage protection of the control unit. The high voltage chip further contains a current-sense power MOS transistor coupled with the drain of the switching power MOS transistor for detecting a drain current of the switching power MOS transistor. The chip set can be packaged into a power module.

Abstract: A drive circuit for a converter and a method of driving a converter. The converter includes an inverter and a synchronous rectifier. The drive circuit includes: (1) a modulation circuit for generating a drive waveform for controlling the inverter and the synchronous rectifier employing a negative feedback loop, (2) a modification circuit, coupled to the modulation circuit, for sensing an operating condition of the converter and shifting a portion of the drive waveform as a function of the operating condition, the modification circuit thereby creating a variable drive waveform from the drive waveform without employing negative feedback and (3) a transmission circuit, coupled to the modification circuit, for applying the variable drive waveform to the converter, thereby allowing a variable nonconcurrent change in state of the inverter and the synchronous rectifier according to the function of the operating condition.