Abstract: The switched mode power supply contains a transformer, which has a primary winding and at least one secondary winding, a switching transistor in series with the primary winding and a control circuit for controlling an output voltage of the switched mode power supply. The control circuit contains an oscillator, whose oscillation frequency can be set via a terminal, and which is coupled to a secondary winding of the transformer. The wiring for the terminal is connected such that the switched mode power supply starts up at a relatively low oscillation frequency once it has been connected, and, during operation when an additional voltage is supplied to the input via the secondary winding, the oscillation frequency of the switched mode power supply is increased. The terminal is connected in particular via a bandpass filter to a voltage generated by the secondary winding.

Abstract: Embodiments of the invention provide a power supply unit that operates in a standby mode and in a normal mode. The power supply unit comprises a first power supply providing output voltages during the standby mode and a second power supply providing output voltages during the normal mode. A pre-converter provides a stabilized supply voltage for the first and second power supply. The pre-converter operates as an up-converter during the normal operation mode and is switched off during the standby mode together with the second power supply.

Abstract: The switching DC-DC converter comprises an inductor, a diode, a transistor and an integrated control circuit with an output switch, the output switch and the diode being coupled to the inductor for providing a DC output voltage. The transistor is coupled with a current input to an input voltage, with a control input to a current input of the output switch, and with a current output to a current output of the output switch.

Abstract: A power supply has first and a second switch-mode power supply (SMPS) units, which both contain a transformer having a primary winding and at least one secondary winding, and a driver stage. The power supply furthermore has a normal operating mode, in which both SMPS units are in operation, and a standby operating mode, in which the first SMPS unit is switched off by a control voltage. In the standby mode, the control voltage is also used to reduce the switching frequency of the second SMPS unit, for example by means of a connection, which reduces the oscillation frequency of the oscillator of the second driver stage. In a preferred exemplary embodiment, the output of a first driver stage is furthermore connected via a series circuit to the oscillator input of a second driver stage, for synchronization purposes.

Abstract: The switching converter contains a switching transistor, a first inductance and a first diode, which are connected so as to form a step-down converter for the purpose of producing a first rectified output voltage from an input voltage. The switching transistor is connected on the input side to the input voltage via a second inductance, and a second diode is coupled to a tap being arranged between the second inductance and the switching transistor for the purpose of producing a second rectified output voltage. The second rectified output voltage is in this case unregulated, but can be used in particular as a supply voltage for a television tuner.

Abstract: A PFC circuit using a step down regulator includes an input port receiving input AC mains voltage, an output port providing an output DC mains voltage, a mains rectifier connected to the input port, a step down circuit connected to the mains rectifier for providing the output DC mains voltage to the output port, a switch connected to the step down circuit, a current source circuit generating a current signal corresponding to a level of the output DC mains voltage, a current sense resistor connected to the switch to provide a voltage signal corresponding to a level of a current flowing through the switch, and a PFC control unit receiving the current signal and the voltage signal and controlling the switch in accordance therewith to selectively enable and disable the step down circuit. The PFC circuit according to the present invention reduces the supply voltage of the SMPS and thus reduces the size of the SMT device and the cost for making such SMT device.

Abstract: The protection circuit serves for the monitoring of output voltages of a power supply unit which has a normal mode and a standby mode. The protection circuit comprises a first switching stage (T1), coupled to the current input (1) of which are output voltages (U5–U8) which are present both in the normal mode and in the standby mode and coupled to the control input of which are output voltages (U1–U3) which are only present in the normal mode. A control signal (Us), by which the power supply unit is switched over between normal mode and standby mode, is coupled to the control input (2) of this switching stage (T1). As a result, by means of the control signal, the output voltages which are only present in the normal mode are blocked in the standby mode by the control signal, so that in the standby mode only the output voltages (U5–U8) which are coupled to the current input (1) are monitored.

Abstract: The switching DC-DC converter comprises an inductor, a control circuit with an oscillator and an output stage, the output stage being coupled to the inductor, a diode coupled to the inductor, and a feedback loop for generating a stabilized output voltage. An output voltage of the output stage is coupled with an oscillator input of the control circuit, for example via an impedance, for synchronizing an oscillation cycle of the oscillator with a current pulse of the output stage.

Abstract: The power supply has a first and a second SMPS, which both contain a transformer having a primary winding and at least one secondary winding. The power supply furthermore has a normal operation, in which both SMPS units are in operation, and a standby operation, in which the first SMPS unit is switched off by a control voltage. In this case, the control voltage is simultaneously used to reduce the switching frequency of the second SMPS unit in standby operation, for example by means of a connection, which reduces the oscillation frequency of the oscillator of the second driver stage. In a preferred exemplary embodiment, the output of the first driver stage is furthermore connected via a series circuit to the oscillator input of the second driver stage, for synchronization purpose.

Abstract: The protection circuit serves for the monitoring of output voltages of a power supply unit which has a normal mode and a standby mode. The protection circuit has here a first switching stage, coupled to the current input of which are output voltages which are present both in the normal mode and in the standby mode and coupled to the control input of which are output voltages which are only present in the normal mode. A control signal, by which for example the power supply unit is switched over between normal mode and standby mode, is coupled to the control input of this switching stage. As a result, by means of the control signal, the output voltages which are only present in the normal mode are blocked in the standby mode by the control signal, so that in the standby mode only the output voltages which are coupled to the current input are monitored.

Abstract: The protection circuit for a power supply unit comprises a switching stage, at which at least two output voltages to be monitored are connected, these voltages being isolated from one another by means of resistors. Arranged here in the connection path of the output voltages is a diode, which turns on and thereby triggers the switching stage in the event of a fault, when there is a drop in one of the output voltages. In this way, the switching stage provides information which acts on a control loop of the power supply unit, so that the power supply unit switches off. The protection circuit also includes a passive network with a resistor and a capacitor, which prescribes a time constant, after which the protection circuit permits renewed starting of the power supply unit. The switching stage may be realized, for example, by a transistor stage, which provides the information signal for the event of a fault for the power supply unit when turning on occurs.

Abstract: The protection circuit for a switch has an energy-storage means, which is connected to a control input of the switch and which is charged with a delay via resistance means when a control voltage is present and is discharged via switching means when the control voltage is low or absent, and has a switching stage which is connected to a supply voltage, is switched on when a specific threshold voltage is present across the energy-storage means and in this way reduces the supply voltage. In one exemplary embodiment, when the switching stage is switched on, the charge which is dissipated from the supply voltage is at least partially routed to the energy-storage means via a diode which is connected in parallel with the said energy-storage means, so that the phase during which the switching stage is switched on is lengthened and the energy-storage means, in this case a capacitor, is completely discharged.

Abstract: A switched-mode power supply has a storage capacitor, a transformer with a primary winding and at least one secondary winding, and also a switching transistor which is connected in series with the primary winding. The primary winding is subdivided into sub-windings with at least one tap. A capacitance is disposed in parallel with each sub-winding, as a damping network. The numbers of windings of the sub-windings and the values of the capacitors disposed in parallel with the sub-windings are selected in such a way that the oscillations occurring when the switching transistor becomes blocked have different resonant frequencies and thereby partially cancel each other. This results in an effective damping of the resonant voltage over the switching transistor. Since the capacitors are connected in series, the effective total capacitance is low, so that the resulting discharge current at the time when the switching transistor becomes conductive is comparably low.

Abstract: The switched-mode power supply comprises a transformer, a switching transistor connected in series with a primary winding of the transformer, a primary-side control circuit and a secondary-side regulating stage. The regulating stage is coupled to a coupling element for transiting a regulating signal from the secondary side to the primary side. A first switch is situated between the control input of the switching transistor and a primary-side operating voltage, and a second switch is situated between the regulating stage and a secondary-side operating voltage, with the two operating voltages being able to be disconnected using a single control signal. In this case, the isolating element transmits both the regulating information for the primary-side control circuit and the turn-off signal for the first switch. If the second switch is turned off by the control signal, the regulating stage and the optocoupler become completely currentless and consume no further power.

Abstract: A switched mode power supplier having an improved power factor, that is to say a reduced harmonic load on the mains comprising a switch mode power supply with a reduced harmonic load on mains, comprising a mains rectifier being coupled to a charge capacitor and to a series circuit, the series circuit comprising a decoupling element, a primary winding of a transformer, a switching transistor, and an energy storage capacitor coupled in parallel with the primary winding and the switching transistor, with the voltage thereacross being a smoothed DC voltage, the charge capacitor being further coupled to a tap of said primary winding via a second series circuit comprising an inductor and a diode, and the inductor and the diode being connected via a second diode to a point with a fixed voltage.