Telefonaktiebolaget Lm Ericsson (publ)

Flex Ltd.

Optis Wireless Technology, LLC

Mikael Appelberg

Oscar Persson

Magnus Karlsson

Jonas Malmberg

Martin Svensson

Andreas Larsson

Anders Kullman

Marko Leskovec

Jörgen Olsson

Qiuhong Wang

An apparatus includes a first circuit path including a series combination of a primary winding of a transformer and a first secondary winding of the transformer and a second circuit path including a second secondary winding of the transformer. The primary winding of the transformer is magnetically coupled to the first and second secondary windings of the transformer and the primary winding of the transformer is detachably coupled to each of the first and second secondary windings of the transformer. The primary winding of the transformer is operative to generate a portion of an output current based on energy received from the primary winding of the transformer, and the second secondary winding of the transformer is operative to generate a remaining portion of the output current based on energy received from the second secondary winding of the transformer.

Non-isolated pulse width modulated (PWM) full bridge power converter with interconnected windings

A power conversion circuit has a multilayer transformer and a plurality of rectifying transistors coupled to the secondary windings of the multilayer transformer. The multilayer transformer is formed as multiple layers within a PCB stack, where primary winding conductors and secondary winding conductors are vertically aligned and stacked. The secondary winding conductors are constructed to have one or more secondary winding arms that provide area to which the plurality of rectifying transistors are physically connected. The primary winding conductors are constructed to have a primary winding arm. A footprint of each primary winding conductor is configured to substantially overlap an entire footprint of each of the secondary winding conductors. As such, an entirety of the secondary current flowing through the secondary winding conductors is vertically aligned with the primary winding conductors, and therefore with the primary current flowing through the secondary winding conductors.

Multilayer transformer structure comprising multiple rectification elements

A circuit and method provide improved trimming of a DCR sensing circuit where a sensing element is sensitive to self-heating or having a large tolerance. The circuit includes a resistive divider circuit coupled to a sensing element. The resistive divider circuit includes a trim resistor and two test points. Prior to trimming the trim resistor, an actual resistance of the sensing element is determined. A target voltage across the trim resistor to be trimmed is calculated according to the determined sensing element resistance and a known small trim current that is to be injected into the circuit during the trimming process. This injected trim current has a low current value so there is no self-heating of the sensing element. Then, the trim resistor is trimmed while injecting this small trim current into the resistive divider circuit and the voltage across the trim resistor is monitored.

Trimming method of DCR sensing circuits

An electronic circuit comprising an ACRF comprising an active component, an energy storage unit, an input port and an output port. The electronic circuit comprises a control unit to control the ACRF. A detector detects a short circuit at the input port or the absence of an energy supply at the input port. The control unit controls the ACRF to function as an ACRF if the detector detects a power supply connected to the input port or that there is no short circuit at the input port, and controls the ACRF to stop functioning as an ACRF and to discharge energy from its energy storage unit to its output port if the detector detects a short circuit at the input port or no power supply connected to the input port.

Electronic circuit with a current ripple filter

A switched mode power supply (), comprising a transformer () having a primary winding (-), a transformer core (-) configured to store energy transferred thereto from the primary winding (-) during operation, and a secondary winding (-) having a first terminal (T) and a second terminal (T). The switched mode power supply also has a primary side circuit (Q, Q, C) arranged to generate voltage pulses and thereby to drive the primary winding (-) of the transformer (), and a secondary side circuit comprising a rectification circuit connected to the secondary winding (-) at the first and second terminals (T, T). The rectification circuit is arranged such that during a forward phase of operation of the switched mode power supply, in which the primary winding (-) is driven by the primary side circuit to magnetize, and store energy in, the transformer core (-), a current induced to flow in the secondary winding (-) from the second terminal (T) to the first terminal (T) is output by the rectification circuit. The rectification circuit is further arranged such that during a fly-back phase of operation of the switched mode power supply, in which the magnetization of the transformer core (-) is reset, a current induced to flow in the secondary winding from the first terminal (T) to the second terminal (T) of the secondary winding (-) is output by the rectification circuit so that energy stored in the transformer () during the forward phase of operation is output by the rectification circuit.

Forward-flyback topology switched mode power supply

A switched mode power supply (SMPS) is disclosed in which a simple primary side controller is used to send a single pulse of energy to the secondary side to switch on an output voltage controller. The pulse is sent across the main power train and a filtering arrangement is provided on the secondary side to minimize the energy at the output of the SMPS while maximizing the energy supplied to the output voltage controller. Advantageously, the SMPS is configured such that the maximum amount of energy transferred from the primary side to the secondary side during a start-up operation is inherently limited. Protection against short circuit conditions and malfunctions is therefore provided without requiring complicated circuitry.

Switched mode power supply with a simplified start-up supply

A control circuit generates a control signal to control a duty cycle of a switched mode power supply such that the magnetic flux density in the transformer is balanced, thereby preventing saturation of the transformer core. This permits the use of unsymmetrical duty cycles within the switch cycle. The control circuit comprises a flux density calculator and a regulator. The flux density regulator receives a signal indicative of the input voltage of the switched mode power supply and a feedback signal comprising the generated control signal, and it generates therefrom an average flux density signal. The regulator receives the generated average flux density signal and a signal indicative of the output voltage of the switched mode power supply, and generates the control signal in dependence upon the average flux density signal, the reference flux density signal, the signal indicative of the output voltage and a reference voltage signal.

Control of transformer flux density in an isolated switched mode power supply

A switched mode power supply includes a switching device, the switched mode power supply being operable to convert an input voltage (V) to an output voltage (V) by switching the switching device, and a voltage regulator operable to generate a feedback signal based on at least one of the output voltage and an output current of the switched mode power supply. The power supply further comprises an overload detector, which is arranged to receive the feedback signal and operable to determine whether the feedback signal is outside a predetermined range. If the feedback signal is outside the predetermined range, the overload detector is operable to determine that the switched mode power supply is in an overload state, and when an overload state is determined, perform control to place the switched mode power supply in a non-operational state.

Overload detection in a switched mode power supply

A push-pull converter configured to convert an input voltage to an output voltage according to a transfer ratio is provided. The push-pull converter comprises a transformer, a first and a second switch transistor arranged to operatively provide the input voltage to the transformer such that the transfer ratio is obtainable, a first and a second rectification transistor arranged to operatively receive a first and a second part, respectively, of the output voltage from the transformer such that the transfer ratio is obtainable. The push-pull converter is further configured to synchronously operate the first switch transistor and the first rectification transistor, synchronously operate the second switch transistor and the second rectification transistor, and operate the first and second switch transistors 180 degrees out of phase with respect to each other.

Synchronous non-isolated push-pull converter

A power supply and method for reliable turn-on of a switched mode power supply (SMPS) in which the same transformer is used for providing power from the primary side to both the main output of the SMPS and a secondary side voltage regulator a train of voltage pulses are transmitted, from the primary side to the secondary side. The voltage regulator generates a feedback signal indicating when it has turned on and is operating, and the transmission of pulses within the train is controlled based on the detection of feedback signal. In this way, only the required amount of power to switch on the voltage regulator is transferred to the secondary side during a start-up operation and excess power at the main output is prevented, thereby avoiding distortion of the desired start-up ramp figure.

Switched mode power supply with voltage regulator

For a more stable start-up procedure, a switch mode power converter has at least one inductive component including an output inductor Land a synchronous rectification element, said power converter comprising a control device and being characterized in that the control device is arranged, at startup of the power converter, to determine a duty-cycle of the control signal, including a normal pulse width of the control pulse, and provide an initial control signal to the at least one switch element that is designed to balance the current in the at least one inductive component of the converter. The initial control signal preferably has a duration of 50% of the normal pulse width.

Switch mode converter and a method of starting a switch mode converter

An isolated power converter comprising a transformer arranged in such a way that the mirrored primary voltage on the secondary side has a positive potential relative to ground, said converter comprising a derivating net arranged to cause the second transistor to conduct in dependence of the voltage across the secondary winding, the source of the second transistor being connected to the negative end of the secondary winding, the drain of a third transistor further being connected to the positive end of the secondary winding, a second capacitor and a second resistor being connected between the gate and the source of the third transistor, a third resistor connected between the second resistor and the drain of the second transistor, a third capacitor connected between the sources of the second and third transistors to provide a first output voltage on one terminal of the third capacitor and a second output voltage on the other terminal of the third capacitor.

Power converter utilizing a RC circuit to conduct during the rising edge of the transformer voltage

The present invention relates to voltage converters and especially to a control circuit with an input from the voltage converter output and arranged to control the voltage level on the voltage converter output. The problem addressed relates to the situation when there is a pre-bias voltage on the converter output at the moment it is switched on. The object of the control circuit is to increase the voltage on the converter output fast and avoiding any drain of voltage or current from the output at the start up sequence. This is performed by a comparator in the control circuit that is arranged to compare the reference voltage with a division of the output voltage and if the reference voltage is lower that the divided output voltage the reference voltage is increased at the comparator output. The comparator circuit includes an OP-amplifier.

Growing community of inventors

Göteborg, Sweden

Mikael Appelberg