Abstract: In the case of known switched-mode power supplies with integrated preconditioner, the control curves are largely congruent, but deviate from one another in low-load operation, whereby the unregulated intermediate circuit voltage increases. To improve efficiency in low-load operation, closed-loop control of the burst cycle is effected on the primary side of the voltage transformer. The intermediate circuit voltage is limited to a permissible limit value. The closed-loop control device in the switching stage taps the intermediate circuit voltage at a voltage divider which is arranged between the preconditioner functional unit and the switching stage. An assembly additionally monitors the output voltage, for example by means of an optocoupler. Burst mode comprises one or more burst cycles. A burst cycle is started when the intermediate circuit voltage reaches its limit value. At this time, the voltage transformer is switched off. A burst cycle ends when the output voltage reaches a minimum value.

Abstract: A close-loop PWM controller for a primary-side controlled power converter is provided. A voltage-waveform detector produces a voltage-feedback signal and a discharge-time signal. A current-waveform detector generates a current-waveform signal by measuring a primary-side switching current. An integrator generates a current-feedback signal by integrating the current-waveform signal with the discharge-time signal. A time constant of the integrator is correlated with a switching period of the switching signal, therefore the current-feedback signal is proportional to the output current of the power converter. The close-loop PWM controller further including a voltage-loop error amplifier and a current-loop error amplifier. A PWM circuit and comparators control the pulse width of the switching signal in response to the outputs of the voltage-loop error amplifier and the current-loop error amplifier. The output voltage and the maximum output current of the power converter are therefore regulated.

Abstract: A system connecting a printer and a host computer includes a signal processing unit, a printing unit, a DC/DC converter converting a power supply voltage into a lower voltage required by the signal processing unit and outputting the converted voltage to the signal processing unit, an input unit receiving a printing command, and a power supply controlling device. The power supply controlling device includes a first switching unit, a pulse width modulating unit, a power supply switch providing a power on/off signal from a user, and a power supply controlling unit outputting a control signal to the pulse width modulating unit to control the first switching unit to perform an on/off operation corresponding to the power on/off signal from the user.

Abstract: A radiation tolerant electrical component is provided without a radiation hardened material FET. A p-channel MOSFET provides switching capabilities in radiated environments because its gate voltage starts at a negative value and becomes more negative with exposure to radiation. Therefore, the gate is still controllable when exposed to radiation.

Abstract: Disposed in a secondary side circuit and is connected to a constant voltage control circuit (22), to an overcurrent detection circuit (24), and to an overvoltage detection circuit (26), a photocoupler control circuit (28) controls a photocoupler (IC1) so as to feed a constant voltage detection control signal as a feedback signal back to a primary side circuit. The photocoupler control circuit (28) controls the photocoupler (IC1) so as to turn it off when the photocoupler control circuit is supplied with at least one of an overcurrent detected signal and an overvoltage detected signal. A voltage detection circuit (18) makes a latch circuit (16) operate when the voltage detection circuit detects a voltage induced in an auxiliary winding (NSLD) of a transformer with the photocoupler turned off, thereby making a switching operation of a switching type AC adapter circuit stop.

Abstract: The use of low permeability magnetic material (NSME) with the disclosed design strategies form a two-stage isolated output converter system with the distinct advantages of superior density, efficiency, thermal operating bandwidth, service life, transient survival, and form factor flexibility over the prior art. These improvements are realized by, optimized application of NSME, efficient rectifying flyback management techniques, inclusion of switching buffers that substantially reduce switching losses. The instant invention provides power factor correction, output regulation, inrush limiting, over voltage, over current, over temperature, and transient protection, multi-converter load sharing, hot swapability, and fault signals. The disclosed system is designed, specified, and certified to function from ?40 deg. C. to +65 deg. C. from a 180 vac to 264 vac 50/60 Hz input line and supports 1000 watts of output or 600 watts from 90 vac to 120 vac 50/60 Hz line input at greater then 0.

Abstract: Disclosed is a portable charging apparatus having a built-in charging battery, which can easily charge the charging battery of a cellular phone even in a place where home AC power or car power cannot be used and can be used for various kinds of portable equipment by means of using one charger. The present invention can charge a charging battery of a cellular phone using home AC power or car power. Furthermore, the charger of the present invention can easily charge the charging batteries of various digital mobile devices such as cellular phones using an internal charging battery included therein even in a place where home AC power or car power cannot be used.

Abstract: A switching power supply includes a control circuit disposed between a feedback winding and a switching device. The control circuit includes an on-period control circuit that, in an operation under a non-low load condition, controls an on-period of the switching device such that the on-period decreases with decreasing load, a minimum on-period setting circuit that disables the on-period control circuit in an operation under a low load condition so that the on-period of the switching device does not become shorter than a predetermined minimum on-period, and an off-period control circuit that controls an off-period of the switching device in the operation under the low load condition such that the off-period increases with decreasing load. As a result, the output voltage is maintained at a constant value in accordance with a feedback signal.

Abstract: A power supply and power supply control device for an electronic equipment having a key-off function. A switching mode power supply is controlled by a key-off part and a power supply control part. A power key outputs a key-off signal in response to a manipulation of a user. The power supply is controlled by controlling an output of a pulse width modulator of the switching mode power supply. The key-off part outputs a power-off signal to stop an operation of the pulse width modulator in response to detecting that the key-off signal is output for a predetermined time. The power supply control part outputs a signal to start the operation of the pulse width modulator in response to an externally supplied power-on signal or an on state of a power switch. Holding the power switch in the on state for greater than the predetermined time generates an equivalent key-off signal.

Abstract: A power supply includes a power supply unit having an input end for receiving an oscillating voltage, and an output end for outputting a steady state voltage from the oscillating voltage according to a feedback signal, and a control circuit having a micro-controller having a first input port for receiving a measuring signal from a load, and decision logic for generating a control voltage according to the measuring signal, and a feedback controller having a first input end electrically connected to the output end of the power supply for receiving the steady state voltage, a second input end electrically connected to the micro-controller for receiving the control voltage from the micro-controller, and a output end for outputting the feedback signal according to the control voltage and the steady state voltage.

Abstract: An AC adapter which reduces the amount of power drawn from an AC power source when a system is disconnected from the adapter, includes: a rectifier bridge for rectifying an AC voltage from an AC power supply; a conversion circuit coupled to the rectifier bridge for converting the rectified AC voltage to a DC voltage; and an opto-coupler coupled to the conversion circuit for monitoring an output connection of the circuit, wherein when a system is not coupled to the output connection, the opto-coupler substantially prevents the AC voltage from being drawn from the AC power supply. The adapter circuit uses an opto-coupler comprising a diode and a transistor to reduce the amount of current drawn from an AC power supply when a system is not connected to the AC adapter. In this manner, the AC adapter is prevented from becoming heated when no system is connected.

Abstract: The present invention provides a primary-side flyback power converter that supplies a constant voltage output and a constant current output. To generate a well-regulated output voltage under varying load conditions, a PWM controller is included in the power converter in order to generate a PWM signal controlling a switching transistor in response to a flyback voltage sampled from a first primary winding of the power supply transformer. Several improvements are included in this present invention to overcome the disadvantages of prior-art flyback power converters. Firstly, the flyback energy of the first primary winding is used as a DC power source for the PWM controller in order to reduce power consumption. A double sample amplifier samples the flyback voltage just before the transformer current drops to zero. Moreover, an offset current is pulled from a detection input of the double sample amplifier in order to generate a more accurate DC output voltage.

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: An overcurrent output protector is electrically connected to a constant-voltage switching power supply provided with a switching transistor which converts a DC voltage obtained by smoothing an AC voltage supplied from an AC power source into a cyclic pulse signal. In the overcurrent output protector, duty ratio monitor judges whether an ON duty ratio of the cyclic pulse signal is a predetermined ratio or more. A deactivator turns off the switching transistor in a case where the duty ratio monitor judges that the ON duty ratio is the predetermined ratio or more.

Abstract: A switched mode power supply apparatus is equipped with a start-up device supplying electrical energy to a controller which controls the switching of a switching transistor. The start-up device is bypassed by a bypass device. During start-up of the power supply, the bypass device is open. After a successful start-up, the bypass device is closed, eliminating further dissipation in the start-up device, and, therefore, increasing the overall energy efficiency of the power supply. By connecting the start-up device to a stand-by power supply or to a primary voltage, use of an additional winding on the transformer to supply the controller is obviated. The power supply has an electronic overload protection, and will stop and periodically attempt a restart when an overload condition occurs.

Abstract: Methods and apparatuses to sense current and voltage in circuits with voltage drop. A sense circuit includes a series combination of a diode and a resistor in the path of the current to be sensed, the voltage across this series combination coupled to drive a light emitting diode (LED).

Abstract: A switching power source device includes a peak current limiting circuit in which peak current flowing through a first switching element is detected, and when the current reaches a predetermined value, transistors are turned on in succession to increase the quantity of an electrical signal whereby the first switching element is rapidly turned off, and an on-time limiting circuit for reducing the on-time using reduction of the output voltage. The switching power source device is operated so as to repeat starting and stopping due to a turn-on delay circuit when the output is shortcircuited for reduction of the shortcircuit current.

Abstract: A switched mode power supply includes a primary coil, a switch element, a secondary circuit, and a control circuit. The switch element is wired in series with the primary coil, for applying a DC voltage to the primary coil according to a control signal. The secondary circuit is coupled to the primary coil with output terminals providing an output voltage. The control circuit prepares the control signal with a feedback signal dependent on the output voltage supplied to the control circuit. The control circuit includes a signal generation circuit to create the control signal and a protection circuit. The protection circuit has the effect that no control signal is delivered to the switch element, if the feedback signal reaches the value of a first reference signal after a first period after starting the control circuit.

Abstract: The coupling device comprises a transformer having a primary winding in series with a two-way switch controlled via an optocoupler and a three-position selector switch by a control circuit. In standby mode, the switch is connected to an oscillator defining a switching frequency (49 kHz) ensuring power supply of the control circuit, which circuit is able to detect the presence of a carrier on the transformer secondary winding. In receipt mode, the switch is closed and the control circuit analyzes the modulated information received on the transformer secondary winding. In transmission mode, the control circuit causes switching of the switch at the information modulation frequency (132 khz), performing both power supply of the control circuit and transmission of the information.

Abstract: A power converter having a transformer with a primary side winding and a secondary side winding, each having a switch. When the primary master switch is switched on, the transformer charges. When it is switched off, the intrinsic capacitance of the secondary slave switch discharges generating the zero voltage switching condition for the secondary slave switch. The secondary slave switch is switched on at a time determined in accordance with the waveform generated by the transformer. When the secondary slave switch is switched on, the transformer discharges and ultimately the charge from an output capacitor flows into the transformer as a backflow which charges the transformer. The secondary slave switch is switched off at a time determined in accordance with a current flowing through said secondary switch. The intrinsic capacitance of primary master switch discharges generating the zero voltage switching condition for primary master switch which is then switched on.

Abstract: An isolated switching-mode power supply with a volt-second clamp circuit is provided. A control circuitry for an isolated switching-mode power supply includes a transformer having a primary winding electrically connected to voltage supply terminals and a secondary winding for providing an output voltage, a volt-second clamp circuit electrically connected to the primary winding for controlling conduction and non-conduction states of the primary winding so as to achieve a maximum volt-second product limit of an input voltage at the primary winding, and a voltage feedback controller electrically connected to the volt-second clamp circuit for generating a feedback signal with reference to a magnitude of the output voltage and then modulating the volt-second product of the input voltage at the primary winding to stabilize the output voltage.

Abstract: A circuit for controlling the welding power of a welding power supply includes a control circuit, a switch, and an isolation circuit. The control circuit is configured to generate a command signal. The isolation circuit has a flyback transformer and is configured to receive the command signal and to provide a switch drive signal to the switch in response to the command signal. The switch provides welding power in response to the switch drive signal.

Abstract: A printer is connected to a host via an interface having a data wire and a power supply wire. The printer includes a power supply portion to convert an external power to a driving power and to supply the driving power to the respective electronic components of the printer, a switch portion to determine whether to supply the driving power to the respective electronic components, and a controller capable of operating from the voltage applied through the power supply wire, to control the switch portion according to a transmission of printing data through the data wire. The controller controls the switch portion to stop a supply of the driving power to the respective electronic components when the printing data is not transmitted for a predetermined time, and when the voltage is not applied through the power supply wire of the interface. Accordingly, unnecessary power consumption is reduced and convenience is improved.

Abstract: A power converter, and more particularly a switched AC/DC converter, is provided with an input current shaping (ICS) function. The ICS function is carried out by adjusting the conducting angle of the input current for a rectifier coupled to a central tap of a main transformer, thereby obtaining a higher power factor. Owing to the action of the ICS, the ripples in the feedback signal are usually larger. The ripples are used to modulate the switching frequency to effectively disperse and planarize the electromagnetic energy distribution of the power supply, and to suppress the electromagnetic interference problems of the power supply.

Abstract: A power converter having a transformer with a primary side winding and a secondary side winding, each having a switch. When the primary master switch is switched on, the transformer charges. When it is switched off, the intrinsic capacitance of the secondary slave switch discharges generating the zero voltage switching condition for the secondary slave switch. The secondary slave switch is switched on at a time determined in accordance with the waveform generated by the transformer. When the secondary slave switch is switched on, the transformer discharges and ultimately the charge from an output capacitor flows into the transformer as a backflow which charges the transformer. The secondary slave switch is switched off at a time determined in accordance with a current flowing through said secondary switch. The intrinsic capacitance of primary master switch discharges generating the zero voltage switching condition for primary master switch which is then switched on.

Abstract: The driver circuit for light emitting diodes (LEDs) of the present invention provides power to LEDs using pulse width modulation (PWM). The driver circuit 100 uses current feedback to adjust power to LED arrays 54 and provides a full light and a dim mode.

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: The power supply for LEDs of the present invention provides power to a variable number of LEDs wired in series or in parallel. The power supply uses current feedback to adjust power to the LEDs and provides protection against open circuits and circuit malfunctions. A current controller compares sensed current to a reference current and generates a feedback signal, which is processed by a power factor corrector to adjust the current flow through the transformer supplying current to the LEDs.

Abstract: A switching power supply device is arranged such that a switching of a main switching element is controlled by a control circuit in accordance with output voltage information fed back from the secondary winding side. On this account the switching power supply device has an output voltage being stabilized to be a target value. Moreover, fluctuation of the control is detected only under the light load in accordance with a nonlinear characteristic of a fluctuation detection circuit. A fluctuation in an output of the fluctuation detection circuit is extracted by a differentiating circuit composed of a capacitor and dividing voltage resistors, and the output of the differentiating circuit is superposed on a value of the divided output voltage so as to be fed back. In this manner the fluctuation component, having relatively short change periodicity (like A.C.), of the control fluctuation is superposed on the output voltage information having relatively long change periodicity (like D.C.

Abstract: A switching power supply has a bottom detection circuit (55), which judges whether or not a bottom has been reached, based on a voltage of a capacitor (C9) that determines an off time of a switching element (Q1) that generates a voltage at the secondary side of a transformer (13) and, in the case in which the judgment is made that a bottom has not occurred, a charging voltage for the capacitor (C9) is switched to a high-potential side.

Abstract: Providing a power supply system having a plurality of power supply apparatuses connected in parallel to each other, each of which is not affected by a voltage fluctuation of a reverse flow-preventive diode provided in an output line thereof, and can provide a stable output voltage controlled with high accuracy. Each of the power supply apparatuses includes a positive output terminal 33 connected to a load 13, a reverse flow-preventive diode 31 connected to the positive output terminal 33, a VF correcting circuit 46 for detecting a forward voltage of the reverse flow-preventive diode 31 and providing a controlling unit with the detected voltage in a feedback manner, an output current detecting/correcting circuit 45 for detecting a forward current of the reverse flow-preventive diode 31 and providing the controlling unit with the detected current in a feedback manner, and the controlling unit for controlling the anode potential of the reverse flow-preventive diode 31.

Abstract: A switching power supply unit and an electronic apparatus including the same, has a photocoupler that is used for providing feedback from the secondary side to the primary side. The photocoupler is shielded by a heat sink so that incorrect operation of the photocoupler caused by electromagnetic waves emanating from cellular phones or other electronic apparatuses is prevented, thereby preventing incorrect operation of the switching power supply unit and the electronic apparatus.

Abstract: A transformer has a primary winding connected between a pair of d.c. input terminals via an on-off switch, and a secondary winding connected between a pair of d.c. output terminals via a rectifying and smoothing circuit. The output voltage applied from the rectifying and smoothing circuit to the load is held constant by switching the input voltage through feedback control. For intermittently operating the switch under light load, a sawtooth generator circuit is provided which provides a sawtooth voltage having a frequency less than that of the on-off operation of the switch. The sawtooth voltage is compared with a voltage indicative of the magnitude of a current flowing through the switch. The result of this comparison is utilized for modifying the delivery of switching pulses to the switch.

Abstract: A transformer has a primary winding connected between a pair of d.c. input terminals via an on-off switch, and a secondary winding connected between a pair of d.c. output terminals via a rectifying and smoothing circuit. The output voltage applied from the rectifying and smoothing circuit to the load is held constant by switching the input voltage through feedback control. The switch is driven in either of two different prescribed modes depending upon whether the converter is under normal or light load. In order to ascertain the load magnitude a flyback period determination circuit is connected to a tertiary winding of the transformer for providing a signal indicative of a flyback period during which a flyback voltage exists across the transformer tertiary after the switch is turned off each time. Each flyback period is compared with two different reference periods of time for hysteretic determination of whether the converter is under normal or light load. Several other embodiments are disclosed.

Abstract: A DC/DC converter converts a voltage of a DC power supply to another DC voltage by switching on and off a switching element, which determines an oscillating period and a forced stop period of the switching element based on a comparison signal obtained by comparing an output of an output-voltage detecting and adjusting circuit, which controls the output of the DC/DC converter at a certain voltage, and an output of a triangular-wave generating circuit in a second comparator. The DC/DC converter facilitates confining the pulsation of the output voltage of the DC/DC converter caused by the maximum load in the state of light load including the state of no load, within an allowable range.

Abstract: To start a switching power supply in an energy saving manner, the method and device according to the invention transmits the energy that is collected by the Y-capacitors through a diode to a capacitor that is located on the secondary side. Once the voltage in the capacitor reaches a first predefinable minimum value, the voltage is applied to an impulse generator as an input voltage and the generator starts the switching power supply. Once the voltage in an additional capacitor on the secondary side reaches a second predefinable minimum value, the voltage in the capacitor is also applied as an input voltage to a control unit, preferably, a microprocessor, that controls the impulse generator.

Abstract: A switching power supply unit includes first and second switching circuits which alternately turn first and second switching elements on and off with an intermediate period in which both are turned off, and energy is stored in a primary winding of a transformer during an ON period of the first switching element and the energy is discharged from a secondary winding of the transformer during an OFF period of the first switching element. A control circuit includes an OFF period extending circuit connected to a control terminal of the first switching element, such that a transistor remains turned on for a desired period even after the energy has been discharged from the secondary winding, extending the OFF period of the first switching element for the desired period. In a light load operation, a phototransistor in the second control circuit is turned on so that the ON period of the second switching element will be shorter than the time required to discharge the energy from the secondary winding.

Abstract: The power supply for LEDs of the present invention provides power to a variable number of LEDs wired in series or in parallel. The power supply uses current feedback to adjust power to the LEDs and provides protection against open circuits and circuit malfunctions. A current controller compares sensed current to a reference current and generates a feedback signal, which is processed by a power factor corrector to adjust the current flow through the transformer supplying current to the LEDs.

Abstract: The present invention relates to an isolated-type switching power supply apparatus, which includes a power supply, a transformer being connected to said power supply, a switching element for switching an electric current going through a primary coil of the transformer so that energy generated on the primary side of the transformer is sent to the secondary side in accordance with the operation of the switching element. The present invention has a modulating circuit for modulating an output on the secondary side of said transformer, a transmitting rout for transmitting an output of the modulating circuit to the primary side of the transformer, a demodulating circuit for demodulating the output transferred through the transferring rout; and the controlling circuit controls the switching element in accordance with an output of the demodulating circuit and the controlling circuit is disposed on the primary side of the transformer.

Abstract: A switching power supply has a bottom detection circuit (55), which judges whether or not a bottom has been reached, based on a voltage of a capacitor (C9) that determines an off time of a switching element (Q1) that generates a voltage at the secondary side of a transformer (13) and, in the case in which the judgment is made that a bottom has not occurred, a charging voltage for the capacitor (C9) is switched to a high-potential side.

Abstract: Methods and apparatuses for fault condition protection of a switched mode power supply. In one aspect of the invention, a power supply circuit having an auto-restart function to turn the power supply on and off repeatedly under fault conditions is included. In one embodiment, one or more off-times following detection of a fault condition is smaller than subsequent off-times.

Abstract: A serial circuit of the primary winding (21) of a transformer (2), a switching device (3) and a current-detecting resistor (4) is connected between a pair of dc terminals (18, 19). A smoothing capacitor (7) is connected to the secondary winding (22) of the transformer (2) via a diode (6). A resonance capacitor (5) is connected in parallel with the serial circuit of the switching device (3) and the current-detecting resistor (4). The current detection signal, the output voltage detection signal, and the switch voltage detection signal are combined to provide control pulses for the switching device (3). A control circuit (13) includes a minimum non-conducting period determination circuit for setting a first and a second minimum nonconducting period with hysteresis. The nonconducting periods of the switching device are placed under the limitation of the minimum nonconducting periods when the load is light.

Abstract: A switching power supply having two or more DC outputs includes a DC power supply, a transformer having a primary winding, at least two secondary windings, and a feedback winding, a main switching element having an off-state period and an on-state period, connected in series to the primary winding and to be turned on by a voltage generated in the feedback winding, the main switching element having a control terminal and a threshold voltage to turn the main switching element on; and a rectifying circuit connected to each secondary winding, a starting circuit which initially turns on the main switching element at startup of the power supply and a switching circuit provided between the two DC outputs, and wherein, when the switching circuit is turned on, a voltage generated in the feedback winding is lowered during the off-state period of the main switching element and a voltage to be applied to the control terminal of the main switching element is controlled so as to be less than the threshold voltage, and the

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: A DC/DC converter converts a voltage of a DC power supply to another DC voltage by switching on and off a switching element, which determines an oscillating period and a forced stop period of the switching element based on a comparison signal obtained by comparing an output of an output-voltage detecting and adjusting circuit, which controls the output of the DC/DC converter at a certain voltage, and an output of a triangular-wave generating circuit in a second comparator. The DC/DC converter facilitates confining the pulsation of the output voltage of the DC/DC converter caused by the maximum load in the state of light load including the state of no load, within an allowable range, and reducing the switching and conduction losses.

Abstract: A clamp circuit for limiting output voltage from a power supply secondary inductor to a ground when a first secondary node has a first secondary node voltage above a predetermined value relative to ground includes a silicone controlled rectifier and a control circuit. The silicone controlled rectifier has a first anode that is electrically coupled to the first secondary node of the secondary inductor, a first cathode that is electrically coupled to the secondary ground, and a first gate. The control circuit is electrically coupled to the first secondary node and to the gate of the silicon controlled rectifier. The control circuit senses the first secondary node voltage and applies a control voltage to the gate of the silicon controlled rectifier when the first secondary node voltage is above the predetermined value.

Abstract: A switch mode power supply (200, FIG. 2; 600, FIG. 6) includes a transformer (208), a transistor (212) that drives the primary winding of the transformer, and a controller (210, 610). The controller senses whether or not the transformer is reset and applies a switching control signal to a control terminal (220) of the transistor, accordingly. The signal is produced at a switching frequency, and the signal has a duty cycle that is limited based on whether or not the transformer is reset.

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 method and a power conversion apparatus having a substantially direct current input voltage, an output transformer having a primary inductor and at least a secondary winding, and a transistor for controlling the transfer of energy from the primary inductor to the secondary winding and coupled to a controller for switching the transistor on and off at a predetermined rate. A sensor for sensing the power required at the output of the conversion apparatus and for generating a voltage representative thereof is provided, as is provided a sensor for sensing the peak current in the primary inductor and for developing a voltage representative thereof.

Abstract: Control circuitry for controlling the delivery of power from a source voltage to a load in a transformer coupled power converter. The control circuitry includes a power switch having an input coupled to the source, an output, and an activation gate, the power switch, when cycled ON and OFF, defining a pulses of power at the load. A pulse generator is coupled to the power switch, the pulse generator producing a train of constant frequency, constant ON time switching pulses for driving the power switch activation gate. A pulse rate controller responsive to an error signal is coupled between the pulse generator and the power switch, the pulse rate controller regulating an output voltage at the load by controlling the rate of switching pulses delivered to the power switch activation gate over time. The error signal is derived by estimating the output voltage at each switching cycle from the primary side current, while compensating for the expected loss between the source and the load for each power switch cycle.