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 dual-mode converter for converting power from an input voltage level to an output voltage level, the dual-mode converter including an inductor section having an input side and an output side, the input side receiving an input signal and the output side outputting at least one output signal based on a power value of the input signal, a feedback loop section which receives a feedback signal from one or more of the at least one output signals, the feedback loop section including a first transistor, a second transistor and a comparator unit which outputs a comparator output signal based on a comparison of the feedback signal to a comparator reference signal, wherein the respective states of the first and second transistors configure the feedback loop section to function as either a linear mode or a comparator mode, a current mode controller unit which receives the input signal, the feedback signal, and a current sense signal representing a sensed current flowing through the input side of the inductor section, t

Abstract: An AC power supply supplied from an outlet 11 is rectified by a rectifying circuit 13 through an input filter 12. The rectified power is supplied to a primary winding N1 of a transformer 14. A controlling circuit 19 has a switching device Q1 that controls on/off at predetermined timing. An FB signal that represents a power state of a load circuit 15 is supplied to the controlling circuit 19 through a transistor Q2. A comparator 20 compares a rectified voltage V3 of a tertiary winding of the transformer with a reference voltage REF3 and outputs an error signal. With the error signal, the transistor Q2 is controlled. Thus, the voltage for the controlling circuit supplied from the tertiary winding can be prevented from lowering against abrupt load variation. In addition, the output voltage Vo can be prevented from largely varying.

Abstract: A current detection method for an electric motor which detects phase currents of the electric motor driven by a power converter that provides ON/OFF control of bridge-connected switching elements, based on a pulse-width modulation excitation pattern, to convert a direct current into poly-phase alternating currents. The method includes connecting a current detecting element which produces a signal corresponding to a current value at the direct current side of the power converter and changing the pulse-width modulation excitation pattern by executing a shift of time of any of the phases of the pulse-width modulation excitation pattern so that a signal directly or indirectly corresponding to the phase currents is produced at the current detecting element. The method also includes detecting the phase currents of the electric motor based on the signal produced at the current detecting element and the excitation pattern which has been changed.

Abstract: A method of regulating voltage at an output of a switching power converter includes sensing an output voltage feedback signal; comparing the sensed feedback signal to a reference at a determined time during a cycling of the switch; and regulating the output voltage by either enabling or inhibiting cycling of a switch by a cycle of a drive signal produced by pulse generation circuitry in response to an output of the comparison.

Abstract: Switching power converters for regulating voltage at an output of a load include digital control circuitry for sensing an output voltage feedback signal, comparing the sensed feedback signal to a reference at a determined time during a cycling of the switch; and regulating the output voltage by either enabling or inhibiting cycling of a switch by a cycle of a drive signal produced by pulse generation circuitry in response to the comparison.

Abstract: A PFC-PWM controller with a power saving means is disclosed. A built-in current synthesizer generates a bias current in response to feedback voltages sampled from the PWM circuit and the PFC circuit. The bias current modulates the oscillation frequency to further reduce the switching frequencies of the PWM signal and the PFC signal under light-load and zero-load conditions. Thus, power consumption is greatly reduced. The PFC and the PWM switching signals interleave each other, so that power can be transferred more smoothly from the PFC circuit to the PWM circuit. The saturation of the switching components can be avoided by limiting the maximum on-time of the PWM signal. Further, an external resistor is used to start up the PFC-PWM controller and provide an AC template signal for PFC control.

Abstract: A system and method for DC/DC conversion are provided in which a high accuracy digital pulse width modulator controller circuit controls a power switch to obtain a desired DC output. The control circuit amplifies the difference of a DC output sample in relation to voltage reference. The amplified difference is then compared with a portion of the DC output. The compared result is used for controlling the power switch. A ripple coming from the DC output side is overlaid upon either one of the inputs to the comparator depending upon the polarity of the ripple signal.

Abstract: A system and method for DC/DC conversion are provided in which a high accuracy digital pulse width modulator controller circuit controls a power switch to obtain a desired DC output. The control circuit amplifies the difference of a DC output sample in relation to voltage reference. The amplified difference is then compared with a portion of the DC output. The compared result is used for controlling the power switch. A ripple coming from the DC output side is overlaid upon either one of the inputs to the comparator depending upon the polarity of the ripple signal.

Abstract: A PWM controller according to the present invention provides a technique to control the output voltage and output current of the power supply without the feedback control circuit in the secondary side of the transformer. In order to achieve better regulation, an adaptive load and a feedback synthesizer are equipped into the PWM controller, which associated with the auxiliary winding of the transformer regulate the output voltage of the power supply as a constant. Furthermore, a programmable power limiter in the PWM controller controls the power that is delivered from the primary side to the output of the power supply. The threshold of the power limit is varied in accordance with the change of output voltage. Because the output power is the function of the output voltage of the power supply, a constant current output is realized when the output current of the power supply is greater than a maximum value.

Abstract: The present invention provides an apparatus and method for reducing the voltage stress in a single-stage single-switch (SSSS) converter by modulating the predetermined operating frequency of the converter lower responsive to increasing voltage stress. A control circuit (116) and associated cooperable frequency setting capacitance (CT) and resistance (RT) are coupled to the primary circuit (112) and the secondary circuit (114) of the SSSS converter via a switch (120). A frequency foldback device (180) is coupled to CT or RT and cooperable therewith to lower bus voltage stress by modulating the switch frequency. The operating frequency is modulated (i.e. reduced) from the predetermined operating frequency upon detection of a voltage threshold transition.

Abstract: A switching power supply (30) includes a compensation circuit (58) which monitors a transformers (36) primary side to provide a voltage compensation signal, COMPV. A transistor inductor current, VTRAN is fed to the compensation circuit (58) to establish a DC level proportional to the peak primary side inductor current flowing through a power transistor (38). VTRAN is fed to a multiplier circuit (98). The output of the multiplier circuit (98) is scaled by a resistor (80) to establish the compensation signal, COMPV at the output to the compensation circuit (58). When at current limit, an amplifier (66) becomes saturated causing a diode (68) to reverse bias, effectively removing compensation signal COMPV from operation. An amplifier (70) falls into a linear region and a diode (74) becomes forward bias forcing compensation signal COMPC into operation providing regulation to the output of the switching power supply (30) at current limit.

Abstract: The present invention provides an integrated controller for use with a power supply employing a pulse width modulator and a method of operation thereof. In one embodiment, the integrated controller includes a primary control circuit configured to provide a control signal to the pulse width modulator. Additionally, the integrated controller includes a feedback circuit configured to monitor an output signal of the pulse width modulator and to modify the control signal thereby enabling a substantially monotonic increase in an output voltage of the power supply output voltage during a non-steady state period of operation thereof.

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: The present invention provides a simple circuit for a DC power supply. The power supply circuit of the present invention includes a transformer in combination with a switching power supply circuit. The transformer includes a primary winding to which a wide range of AC input voltages is applied and a secondary winding for supplying the resultant AC voltage range as an input voltage to the switching power supply circuit. The switching power supply circuit further includes an input terminal having the input voltage applied thereto by the secondary winding and further having an output terminal from which a DC power supply output is generated. The transformer can be selected from a group of transformers consisting of step-down, step-up and repeater transformers. The switching power supply circuit may be selected from any convention switching power supply circuit including step-up, step, down and inverter converters, and combinations thereof, or even linear configurations.

Abstract: A DC-to-DC switch-mode power converter. The converter includes a transformer having first and second series-connected primary windings, a first capacitor connected in series to the second primary winding, a first switch for cyclically coupling an input voltage to the first primary winding, a second capacitor, and a second switch for cyclically coupling the first and second primary windings to the second capacitor. The converter may also include a control circuit for alternately driving the first and second switches such that the first and second switches are not simultaneously conductive. The transformer includes at least one secondary winding having a secondary circuit coupled thereto. The secondary circuit may include a rectification circuit employing self-driven synchronous MOSFETs.

Abstract: The output-side referenced pulse width modulator (PWM) in an isolation-providing voltage converter receives at least initial bias voltage (Vbias) from a charge-pump like Vbias generator. The Vbias generator includes an input-side referenced periodic waveform generator whose output signal can be amplified differentially with an input-side referenced circuit and then AC-coupled via isolation-maintaining capacitors to an output-side referenced rectifier circuit whose output is Vbias. The Vbias thus generated can power the PWM at least from power-up through commencement of steady-state operation, when a more robust Vbias can be derived from the output-side voltage itself. Since the PWM is output-side referenced, high feedback bandwidth is maintained.

Abstract: The output-side referenced pulse width modulator (PWM) in an isolation-providing voltage converter receives at least initial bias voltage (Vbias) from a charge-pump like Vbias generator. The Vbias generator includes an input-side referenced periodic waveform generator whose output signal can be amplified differentially with an input-side referenced circuit and then AC-coupled via isolation-maintaining capacitors to an output-side referenced rectifier circuit whose output is Vbias. The Vbias thus generated can power the PWM at least from power-up through commencement of steady-state operation, when a more robust Vbias can be derived from the output-side voltage itself. Since the PWM is output-side referenced, high feedback bandwidth is maintained.

Abstract: A DC-to-DC switch-mode power converter. The converter includes a transformer having first and second series-connected primary windings, a first capacitor connected in series to the second primary winding, a first switch for cyclically coupling an input voltage to the first primary winding, a second capacitor, and a second switch for cyclically coupling the first and second primary windings to the second capacitor. The converter may also include a control circuit for alternately driving the first and second switches such that the first and second switches are not simultaneously conductive. The transformer includes at least one secondary winding having a secondary circuit coupled thereto. The secondary circuit may include a rectification circuit employing self-driven synchronous MOSFETs.

Abstract: A DC/DC converter having a control circuit to reduce losses at light load, wherein a first control device turns ON and OFF power to the primary winding of the transformer of the DC/DC converter according to the difference between the output voltage of the DC/DC converter and the desired output voltage, and a second control device turns ON a switching device of a clamping circuit connected to the primary winding for a desired length of time after the first control device turns OFF the power to the primary winding.

Abstract: A pwm controller 10 which includes a Vcc node (pin 6); a start-up current source 180 connected to the Vcc node; and a driver circuit 150, 190 also connected to the Vcc node, wherein the pwm controller 10 is arranged to operate in a first phase in which the start-up current source supplies 180 current to the Vcc node but the driver circuit is turned off; a second phase in which the driver circuit 150, 190 is enabled and draws current from the Vcc node; and a third phase in which both the start-up current source 180 and the driver circuit 150, 190 are turned off whereby very little current may be drawn from the Vcc node (pin 6) during the third phase.

Abstract: A switching regulator (18) for use in a switching power supply (10) detects a fault condition by looking for presence of feedback signals during a timer period. If feedback is present but less than a threshold value during the timer period, then the switching power supply (10) is operating normally. If feedback is not present during the timer period, then the switching power supply is in a fault condition. One way of implementing the timer is to charge and discharge by-pass capacitor (23). The timer period is the time for the VCC voltage to drop from a maximum value to a predetermined threshold. When a fault is detected, the gate drive signal from the switching regulator is disabled for a period of time before attempting auto-restart.

Abstract: A high efficiency switching controller for use in a switching power supply (SPS) includes a current control device coupled to a voltage source of the SPS and a switch connected between the current control device and an output voltage circuit of the SPS. An under voltage lockout regulator coupled to the output voltage circuit of the SPS and the switch controls the state of the switch based on a voltage of the output voltage circuit and a bias unit coupled to the under voltage lockout regulator provides current to circuitry within the switching controller based on the voltage of the output voltage circuit. A protector within the high efficiency switching controller provides a control signal to the pulse width modulator unit to control the gate drive signal in response to an operating condition of the switching controller.

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.