Abstract: A controller for a synchronous switching regulator is arranged to control a switch with a control signal, and to control a synchronous switch with a synchronous switch control signal. The controller disables the synchronous switch control signal at power-up so that the regulator operates with asynchronous rectification. Also, the controller is arranged to detect whether the regulator is in discontinuous or continuous conduction mode by determining whether a switch node voltage at the switch node a switch node stays negative. The regulator keeps operating with asynchronous rectification until the switch node voltage stays negative for the entire off period of the switch, which indicates the regulator is operating in continuous conduction mode. At this point, the controller enables assertion of the synchronous switch control signal, so that the regulator operates with synchronous rectification. The controller is arranged to enable the output voltage to rise monotonically when driving a prebiased load.

Abstract: The invention relates to a control means and method for a transistor switch circuit controlling a power supply circuit for providing electric power to a load, comprising: a power supply stage having an LC circuit with an inductor, and a control stage having an estimation of the inductor current as a feedback signal. According to the invention, the current through the inductor is measured by means of a measuring winding (17) and an integrator having the function of an RC network. The current measuring circuit is very stable and absolutely free from any source of offset signals. Also, it has no frequency limitations.

Abstract: A power circuit is provided which has a small current peak value from a power source even when a load current repeats periodically, and a burst flow in a burst period and a non-burst flow in a non-burst period alternates. The power circuit includes a power source section, a power controlling section, and an energy storing section having a storage capacitor being connected to an output terminal, a current controlling circuit to control values of detecting a voltage input from a power source section and a control switching device having a field effect transistor switch and a circuit made up of a capacitor in which a flowing period of an output current is controlled by exerting the field effect transistor switch according to a control signal being produced by detecting a change in an input power voltage using a voltage occurring at another terminal of the detecting resistor.

Abstract: A switching mode converter, having a switching transistor and an inductor, has a discontinuity detector coupled to the inductor which detects when the converter enters the discontinuous mode. The discontinuity detector determines the portion of the cycle of the switching transistor in which the converter is in the discontinuous mode. A feedback controller is coupled to the output of the converter and to the discontinuity detector which alters a feedback control signal of the converter.

Abstract: A voltage regulator includes a linear mode regulator having a high pass filter circuit connected between its output and an output node, and a switch mode regulator having an low pass filter circuit connected between its output and the same output node. The high pass filter passes high frequency AC current provided by the linear mode regulator to the output node and reduces the low frequency AC and DC currents to substantially zero, and the low pass filter prevents the high frequency AC current produced by the linear mode regulator from being drawn by the switch mode regulator and passes the low AC and DC currents provided by the switch mode regulator to the output node. Thus, the present regulator offers the high response speed and low noise of a linear mode regulator, and the high power efficiency and large continuous output current capability of a switch mode regulator.

Abstract: A switching power supply unit generates a pulse signal having a duty factor based on the voltage associated with the difference between a reference voltage and the output voltage of the unit, and the voltage associated with the current flowing through a smoothing coil. Upon receipt of the pulse signal and a light-load determination signal, a delay-control unit of the power supply unit outputs as an instruction signal supplied to the switching circuit the pulse signal as it is when the light-load determination signal indicates that the load is not light, but otherwise outputs the pulse signal after delaying and widening the pulse width thereof. Thus, when the load is light, the switching power supply unit may hold its switching frequency substantially low and constant without rendering the frequency bursting discontinuously.

Abstract: A power delivery system and a method for setting the parameters of the power delivery system. The effective resistance of the capacitors for each stage may be set to be substantially equal to the effective resistance of the previous stage, and the time capacitive constant of the capacitors may be set to be substantially equal to the effective inductive time constant of the previous stage.

Abstract: Circuits and methods to correct the load sharing in multiphase switching regulators are provided. Using these systems and methods, the input capacitor voltage signal can be sampled and used for current sensing of the regulator's stages. Differences in the amount of output current for a converter stage can then be determined. Corrections needed to equalize the output current of the converter stages can then be determined and carried out.

Abstract: A control device for a power output stage is proposed, which includes a power output stage control which generates a triggering signal as a function of at least one control signal, for triggering at least one power output stage, which switches an electric load, preferably an inductive load having a recovery diode, a recording device being provided which records a measure for an electrical magnitude, which is applied to electric load. A feedback system is also provided, which supplies the power output stage control with at least one feedback signal as a function of the measure for the electrical magnitude, so as to influence the trigger signal.

Abstract: A battery charger controller is coupled to DC output terminals of an AC-DC (or DC-DC) adapter containing an AC-DC (or DC-DC) converter. A controlled current flow path between input and output terminals of the battery charger controller circuit is controlled to provide a substantially constant current to charge the battery to a nominal battery voltage. When a constant voltage output of the said adapter transitions to a value that limits available charging current to a value less than programmed constant charging current, current flow drive for the controlled current flow path is increased for a limited time interval. Thereafter, the controlled current flow path gradually reduces charging current as the battery voltage remains at its nominal battery voltage until the charge is complete or otherwise terminated.

Abstract: In the UPS and communication power supply system, the output voltage of the PFC circuit is relativly high. The phenomenon of reverse recovery is also relativly serious for the use of a high voltage diode. A simple L-D snubber, which is suitable for PFC circuit of every kind of power system is provided for suppressing the phenomenon of reverse recovery of the diode so as to reduce all kinds of switch loss caused by the phenomenon and improve the efficiency of power system.

Abstract: A switching power supply unit generates a pulse signal having a duty factor based on the voltage associated with the difference between a reference voltage and the output voltage of the unit, and the voltage associated with the current flowing through a smoothing coil. Upon receipt of the pulse signal and a light-load determination signal, a delay-control unit of the power supply unit outputs as an instruction signal supplied to the switching circuit the pulse signal as it is when the light-load determination signal indicates that the load is not light, but otherwise outputs the pulse signal after delaying and widening the pulse width thereof. Thus, when the load is light, the switching power supply unit may hold its switching frequency substantially low and constant without rendering the frequency bursting discontinuously.

Abstract: A voltage regulator for an automotive alternator includes a switching transistor that controls an amount of field current supplied to a field coil of the alternator. The switching transistor is controlled in an ON-OFF fashion, and output voltage of the alternator is always monitored by a detector circuit that detects disconnection in a circuit for charging an on-board battery with the output voltage. It is determined that the disconnection occurred when a difference between the output voltage at a time when the switching transistor is turned off and the output voltage at a time when the switching transistor is turned on exceeds a predetermined value.

Abstract: An external power adapter prevents damage to contacts of power connectors by reducing current in-rush when the powered-up external power adapter is coupled to an information handling system. A control signal from the information handling system is used to initiate a voltage output of the external power adapter such that substantially no voltage is present on the contacts of the power connectors until the control signal is detected by the external power adapter. The external power adapter may determine the presence of an electrical load before applying the output voltage to the information handling system. The output voltage may be ramped from substantially no voltage to operating voltage over a period of time.

Abstract: The switching power supply comprises a main circuit having a switching circuit for converting a DC input voltage to an AC voltage and an output circuit for rectifying the AC voltage to generate a DC output voltage, a control circuit for controlling the operation of the main circuit, and an abrupt load change detector circuit for detecting an abrupt change in the load current supplied from the main circuit, characterized in that the abrupt load change detector circuit comprises a first filter and a second filter for receiving the output voltage and detection signal generating means for generating an abrupt load change detection signal based on the outputs of the first filter and the second filter. This eliminates a power loss or operation delay caused when a resistor or a current transformer is used to directly detect the output current. Proper use of an abrupt load change detection signal allows dramatic improvement in transient response.

Abstract: A power supply apparatus having an AC power supply, a transformer, a switching element and a control circuit for controlling an operation of the switching element: where an electrical current is supplied to the primary side of the transformer intermittently when a main unit of an electrical appliance to which the power supply apparatus is applied is in a standby mode so that unnecessary power consumption is reduced. Further, a capacitance is provided between the AC power supply and the control circuit instead of the conventional initializing resistance and the control circuit is driven using an electrical current going through a reactance component of the capacitor, so that the energy loss is not caused any more by the initializing resistance.

Abstract: Briefly, in accordance with one embodiment of the invention, an integrated circuit has a voltage regulator and a clock divider that may be used to adjust the operational frequency and/or voltage potential of the integrated circuit to reduce the power consumption of the integrated circuit while in operation.

Abstract: A DC-DC converter that does not need a series resistance element on the output side, and can make use of the parasitic resistance of a coil to improve output characteristics and prevent a decrease in efficiency. In switching unit 40, transistors M1 and M2 are turned ON/OFF alternately in correspondence with pulse signal Sp; input voltage Vin is fed intermittently to node ND1; in output filter unit 10, output voltage Vout that is smoothed with coil Le and capacitor Cout is output to terminal Tout. In feedback control unit 100, divided voltage Vo1 obtained by dividing the voltage at node ND1 is compared with reference voltage Vref, and the result of the comparison is integrated to generate control voltage Vc. In PWM modulation unit 30, pulse signal Sp with pulse width controlled is generated according to control voltage Vc and sent to switching unit 40.

Abstract: The invention relates to a switch-mode power supply comprising an input circuit (1) for periodically switching an input voltage (Ue) or an input current (Ie) on and off with a switching frequency (fS), a transmission circuit (2) connected thereto, and an output circuit (3), which is connected to the latter and to which a load (4) can be connected. In order to provide a switch-mode power supply which has a smaller size and lower costs, compared with conventional switch-mode power supplies, it is provided that the transmission circuit (2) is formed by a bandpass filter (7), which is constructed from at least one capacitance (C) and at least one inductance (L) and whose resonant frequency (f0) lies outside, in particular above, the switching frequency (fS) of the input circuit (1). By omitting the transformer that is usually used, it is possible to avoid the disadvantages of said transformer.

Abstract: In a DC-DC converter, a technique for sensing current supplied to a load and establishing an output voltage that conforms to a predetermined load line. The current carried by an inductor is sensed and used to control the duty cycle of the voltage applied to the inductor, thereby controlling the output voltage. A current sensing circuit includes a feedback network. A pole attributable to the feedback network cancels a zero attributable to the inductor so that a control voltage is developed that varies substantially linearly with the load current.

Abstract: A voltage regulator formed on an integrated circuit is provided that includes an amplifier and a feedback circuit. The amplifier is operable to receive a reference voltage and a feedback voltage. The amplifier is also operable to generate a regulated output voltage based on the reference voltage and the feedback voltage. The feedback circuit, which is coupled to the amplifier, is operable to generate the feedback voltage. The feedback circuit includes an inductor-capacitor network. The inductor-capacitor network is operable to remove high frequencies from the output voltage.

Abstract: A multi-channel interleaved power converter includes first and second per-channel conversion circuits, each including a pulse width modulator (PWM), a driver PWM, an output inductor carrying load current, and a current controlled current source (CCCS) coupled to sense the inductor current. The inductors of the different channels are coupled in common to an output node of the power converter. Summing circuitry is operative (i) to subtract the output current of the second channel CCCS from the output current of the first channel CCCS, (ii) to convert the difference current into an offset, and (iii) to apply the offset to a first PWM control signal to generate a second PWM control signal for the second channel. The PWM control signals cause respective currents to be established in the inductors of the different channels according to a predetermined desired current relationship, such as equality.

Abstract: An active filter (100) suppresses current harmonics generated in a dc bus (300) by generating a compensating current that is approximately equal-but-opposite in polarity to the current harmonics. In one implementation, the active filter (100) includes: an energy storage capacitor (103); a choke (104); a switch circuit (120); and a controller (150). The controller (150) receives a current harmonics measurement for the dc bus (300) and generates switch gating signals (156a, 156b) as a function of the current harmonics measurement. The switch circuit (120) receives the switch gating signals (156a, 156b) from the controller (150) and is operatively connected to the energy storage capacitor (103) and the choke (104) to selectively discharge the energy storage capacitor (103) to inject current into the dc bus (300) and to selectively draw current from the dc bus (300) via the choke (104).

Abstract: A switching power supply includes a switching element, a diode, a choke coil, a comparator-detector, and a drive circuit. A first resistor and a second resistor are connected in series between one end of the choke coil and the ground, and the connection point thereof is connected to one input end of the comparator-detector. A third resistor and a parallel circuit including a fourth resistor and a capacitor are connected in series between the other end of the choke coil and the ground, and the connection point thereof is connected to the other input end of the comparator-detector. In addition, the output end of the comparator-detector is connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the control end of the switching element.

Abstract: A multi-phase power supply utilizes a current sensor including a sensor inductor winding connected in parallel with a filter inductor winding at the output of each phase for sensing the phase currents and balancing the current by adjusting the duty cycle of each phase through feedback control. In addition, in a multi-module power supply configuration, current between power supply modules is balanced through use of the same current sensor and current sharing technique. Each phase of the power supply includes at least one input power source and a current sensor. The sensor inductor winding and the filter inductor winding have the same number of turns and are wound about a magnetic core also present at each phase. A differential amplifier at each phase senses and amplifies any voltage difference between the outputs of the sensor inductor winding and the corresponding filter inductor winding.

Abstract: A dual-mode modular pulse-width-modulator capable of outputting low-speed and high-speed control signals is presented. In one mode, a control signal is generated based on timing parametric data stored in a memory. In a second mode, a control signal is generated based on timing parametric data stored in a memory and an external input. Timing parametrics and control variables used to determine the operational mode can be pre-loaded in the memory or loaded through a communication link.

Abstract: An active filter (100) suppresses current harmonics generated in a dc bus (300) by generating a compensating current that is approximately equal-but-opposite in polarity to the current harmonics. In one implementation, the active filter (100) includes: an energy storage capacitor (103); a choke (104); a switch circuit (120); and a controller (150). The controller (150) receives a current harmonics measurement for the dc bus (300) and generates switch gating signals (156a, 156b) as a function of the current harmonics measurement. The switch circuit (120) receives the switch gating signals (156a, 156b) from the controller (150) and is operatively connected to the energy storage capacitor (103) and the choke (104) to selectively discharge the energy storage capacitor (103) to inject current into the dc bus (300) and to selectively draw current from the dc bus (300) via the choke (104).

Abstract: A power converter is comprised of a hysteretic controller including a feedback circuit that monitors the output frequency of the controller, compares it to a reference generated either internally or externally by the user, and then adjusts the hysteresis of the controller accordingly. The adjusted hysteresis levels will then cause the switching frequency to either increase or decrease thereby controlling the switching frequency of the power supply controller and maintaining it at a desired level.

Abstract: A driver for producing a desired pulse width modulated current through a load has a driver control for storing diagnostics codes in a diagnostic register responsive to detection of at least one electrical fault condition in a circuit including the load. A short circuit detection signal is generated in response a sensed current exceeding a programmed load current range for the driver, whereupon the driver control disables the load current and generates an interrupt signal to a microprocessor. Open circuits and shorts across the load are distinguished by way of a minimum current signal representative of a sensed current flowing through the load exceeding a predetermined minimum.

Abstract: A power control apparatus is described that includes a power level adjusting circuit (11) for adjusting an input signal to a desired power level in accordance with a control voltage to output a obtained result; a control voltage generating circuit (12 to 18) for comparing a current output power of the power level adjusting circuit (11) with a target power level to generate the control voltage based on a result of comparison; a low-pass filter (19a) operating in accordance with either a first time constant or a second time constant which is smaller than the first time constant, for filtering the control voltage generated by the control voltage generating circuit (12 to 18) to be supplied to the power level adjusting circuit (11); and filter controlling means (19b) for causing the low-pass filter (19a) to operate in accordance with the second time constant at a first transition of the output power of the power level adjusting circuit (11) and for causing the low-pass filter (19a) to operate in accordance with t

Abstract: A multi-phase power supply utilizes a current sensor including a sensor inductor winding connected in parallel with a filter inductor winding at the output of each phase for sensing the phase currents and balancing the current by adjusting the duty cycle of each phase through feedback control. In addition, in a multi-module power supply configuration, current between power supply modules is balanced through use of the same current sensor and current sharing technique. Each phase of the power supply includes at least one input power source and a current sensor. The sensor inductor winding and the filter inductor winding have the same number of turns and are wound about a magnetic core also present at each phase. A differential amplifier at each phase senses and amplifies any voltage difference between the outputs of the sensor inductor winding and the corresponding filter inductor winding.

Abstract: A switching power supply, eliminating effect of a potential difference generated in a driving circuit, in which a rapid operation speed of a switching transistor Q1 and a high efficiency are obtained. An auxiliary bias circuit forming a polarity inversion circuit together with the switching transistor Q1 is constructed by connecting a capacitor C3 and a diode D2 in series between a collector of the switching transistor Q1 and a ground, and by connecting a diode D3 and a capacitor C4 in series between a connection point of the capacitor C3 and the diode D2 and a ground. One end of a main current path of the transistor Q3 which conducts when the switching transistor Q1 is in an OFF state, is connected to a connection point of the diode D3 and the capacitor C4 in the auxiliary bias circuit 5a, thereby supplying a voltage obtained in the auxiliary bias circuit 5a to the switching transistor Q1 via the transistor Q3.

Abstract: A control for controlling the DC output voltage of a boosting active filter constant. When a load changes from a rated condition to a light load or a no-load condition and the output voltage rises, a conventional active filter control device externally forces the active filter to stop and restart to suppress the voltage rise. In this process, an excessive inrush current occurs and the reactor produces abnormal sound. In addition, the conventional technique cannot be adapted to the PAM control. Accordingly, in the disclosed control of an active filter, first and second resistors and a control power supply are provided between an output terminal of a main circuit and ground, and the voltage at a node is input to one input end of a first differential amplifier and one input end of a hysteresis comparator. The output of the comparator is connected to an output end of a second differential amplifier through a signal line.

Abstract: A DC/DC converter for use in a wide variety of electronic applications to convert higher level unregulated DC signals to lower lever regulated DC signals. The converter overcomes traditional converter problems such as inefficiencies, high cost and signal noise using a switching regulator circuit. The switching regulator circuit has a switching means (6) for switching the unregulated DC signal received, a current sense amplifier (4) for modulating the switching means, a hysteresis generator (10) for modulating the current sense amplifier and an output circuit for controlling delivery of a regulated DC signal to a converter output. The switching means is formed to deliver a substantially constant signal to the current sense amplifier using modulation.

Abstract: The DC output of a power conversion unit is controlled based on a pulse signal generated by a PWM unit. An operations unit detects an output current Iout, and determines the operation mode of a load based on the detected current value. When the output current Iout is weak, a value smaller than usual is written to a cycle register. The PWM unit generates a pulse signal according to the data stored in the cycle register and an on-time register.

Abstract: A protected, transformerless power converter for converting an AC mains power source to a low voltage DC power source is presented. The AC input voltage is rectified to supply pulsating DC voltage to a pass element resistor. An electronic switch located between the pass element resistor and an output filter capacitor interrupts the current flowing into the output filter capacitor. The output filter capacitor averages the pulse current drawn from the AC input line to provide a constant DC output voltage to a load. The instantaneous AC input voltage, the average value of the AC input voltage, and the output voltage are used to calculate the optimal times of conduction of the electronic switch. Controlling the time of conduction in this manner maximizes the power efficiency of the converter and protects the supply from an output overload or short circuit condition over a wide range of AC input voltages.

Abstract: A computer monitor having a universal serial bus system comprises a primary power supply that supplies power to the associated circuits of the computer monitor, a hub power supply that supplies hub power through universal serial bus ports to peripheral devices, and a hub power controller that cuts off the hub power to the peripheral devices when the hub power exceeds a predetermined power level. The computer monitor includes an on-screen display controller that displays the status of hub power on a partial area of a computer monitor screen.

Abstract: The invention provides buck switching regulator circuits that include voltage slew rate limiting circuitry and current slew rate limiting circuitry. The specification describes current-mode and voltage-mode control implementations that provide efficient low-noise switching regulator circuits.

Abstract: A method of controlling the charging of a bootstrap capacitance incorporated into a switching regulator of a power transistor includes the steps of comparing, at each switching cycle, the voltage value at the bootstrap capacitance and a predetermined threshold voltage, to change the mode of operation of the regulator following said comparison. More particularly, the control on the transistor is taken off the regulator when the voltage at the bootstrap capacitance is lower than the threshold voltage, while the transistor is forced into the "on" state through a full cycle. In this way, the minimum current to operate the regulator can be minimised.

Abstract: A voltage boost circuit having a voltage output and a single input receives a DC voltage from an external source which is fed to an inductor. The input voltage is boosted to provide a constant voltage at the output at a level higher than the voltage input. A switch is coupled to the output of the inductor for controlling current through the inductor to induce a boosted voltage across the inductor.

Abstract: A method and circuit for modifying the clamping level (VCLAMP) of the error signal voltage (VERROR), which clamp in turn limits the peak current in the inductor of a slope-compensated, current mode DC/DC converter. VCLAMP may be modified and/or variable such that it is a function of average current in the inductor, peak current in the inductor, the converter duty cycle and/or the level of slope compensation used in the converter. The modification of VCLAMP may result in the peak current limit being independent of the converter duty cycle and/or the level of slope compensation used in the converter. Further, the modification of VCLAMP does not compromise the operational stability of the converter which is achieved by the use of a slope compensation. In addition, the clamping of the error signal before slope compensation rather than after slope compensation avoids instability at high duty cycles.

Abstract: A process for the fuzzy control of switching power supplies which have at least one inductor and at least one switching device, and a device for performing this control, the particularity whereof resides in the fact that it comprises the following steps: measuring the value of the current on the inductor; measuring the value of the input voltage of the switching power supply; measuring an error generated between a reference voltage and an output voltage of the power supply; defining fuzzy membership functions for the value of the current on the inductor, for the input voltage value, and for the error; defining an output membership function for the value of the duty cycle of the power supply; defining multiple fuzzy inference rules to which the measured values and the membership functions are applied calculating the corresponding weight functions of the membership functions; defuzzifying the results obtained by means of the weight function calculation and the application of fuzzy rules so as to obtain a real v

Abstract: Ac-to-dc switching converters employ bidirectional voltage switches, preferably magnetic amplifiers in series with a fast recovery diode, as controllable series input switches that couple ac rectifiers to single-stage dc-to-dc converters in order to provide unity power factor operation by control of current through the input inductor achieved by modulating the duty ratio d1 of the bidirectional voltage switch while independent regulation of load voltage is maintained by voltage feedback to modulate the switch duty ratio d of the converter (where d1<d) in an independent fast output regulation loop.

Abstract: The present invention is a concentric servo method and apparatus using two servo loops to control and stabilize the output of an electronic voltage regulator. An inner and outer servo loop are employed. The inner servo loop resembles the control loop of a conventional voltage regulator while the outer servo loop controls the sense threshold of the inner servo loop. The outer servo loop senses the voltage delivered to an external load resistance and controls the sense threshold of the inner servo loop to compensate for the voltage loss which may occur between the regulator output and the actual load resistance. The inner loop retains its high speed to regulate out any input voltage irregularities such as ripple and noise. The present invention gives better stability than conventional remote sensing voltage regulator circuits.

Abstract: A power supply system employs a control circuit to regulate the voltage across a load capacitor by monitoring the capacitor voltage by means of a differential voltage sensor and by monitoring the drain-source voltage of a switching power FET connected in series with the load capacitor across input terminals that supply a full wave rectified voltage derived from a commercial AC supply voltage. The control circuit controls the switching action of the power FET in a manner such that the load capacitor is charged at least once during each cycle of the rectified voltage (unfiltered). This method of voltage regulation by monitoring the load capacitor voltage and the FET voltage (V.sub.ds) provides significant advantages over other forms of voltage regulation.

Abstract: A two-state modulation system includes a hysteretic comparator with variable thresholds, a two-state processor and an integrating element. A summing circuit combines a signal coupled from the output of the two-state processor, the signal output, the signal input and a delay compensating signal feedback input and a feedback input from an integrating element at the output of the two-state processor. The hysteretic comparator receives a hysteresis control signal that varies the threshold. The hysteresis control signal may be provided by analog switches switched by the switching signal to provide the switched two-state levels to a low pass filter. Rectifying circuitry may also be used for supplying the hysteresis control signal. Limiters and compressors may be connected to the input with the limiter limiting levels tracking the two-state levels, and the compression proportional to the switching frequency.

Abstract: A current sink includes an electronic component having a switched current path and a control terminal. The current path can be switched to a low-impedance condition by the control terminal to sink a current flowing into it. A component having a frequency-dependent passband is connected to the control terminal for passing signals of a predetermined frequency range.

Abstract: A charge regulation circuit provides regulation of an unregulated voltage supply in the range of 0.01%. The charge regulation circuit is utilized in a preferred embodiment in providing regulated voltage for controlling the operation of a laser.

Abstract: A converter circuit operable in a current control mode is disclosed. The circuit is of the type including an (1) inductor, (2) a clock for providing a clocking signal so that the circuit operates as a synchronous converter and (3) switching means, responsive to the clocking signal and a threshold current, for controlling the load voltage across the inductor between at least two different levels of voltage as a function of one or more supply voltages so that the inductor conducts (a) increasing inductor current for one level of load voltage from the beginning of each cycle of the clocking signal until the inductor current equals the threshold current during each cycle, and (b) decreasing inductor current for the other level of voltage from the time in each cycle the current equals the threshold current until the end of each said cycle.

Abstract: A synchronized switching system for use in a power converter. A pulse-width modulation controller is provided to alternately turn on and off a switching device and control the on/off duty cycle. When the switching device is turned off, initial commutating or flyback current from an inductor is conducted by a protective diode connected to ground. The diode is paralleled by a more efficient secondary switching device that is synchronized to conduct during the nonconduction period of a main switching device. A sense winding is added on the inductor for synchronizing the secondary switching device. A digital logic circuit controls the conduction time of the secondary switching device based on signals from a pulse-width modulation controller and from the sense winding of the inductor. After the main switching device has been conducting for the required time, the pulse-width modulation controller turns it off.