Stmicroelectronics S.r.l.

Giuseppe Scappatura

Alberto Bianco

Francesco Ciappa

Claudio Adragna

Alberto Iorio

Maurizio Foresta

Silvio De Simone

Matteo Sucameli

Dino Ciambellotti

Gabriele Gherdovich

Marco Dell'Oro

Luca Longhi

The present disclosure relates to solutions for operating a flyback converter comprising an active clamp. The flyback converter comprises two input terminals and two output terminals. A first electronic switch and the primary winding of a transformer are connected in series between the input terminals. An active clamp circuit is connected in parallel with the primary winding. The active clamp circuit comprises a series connection of a clamp capacitor and a second electronic switch. A third electronic switch and the secondary winding of the transformer are connected in series between the two output terminals. In particular, the present disclosure relates to solutions for switching the first, second and third electronic switch in order to achieve a zero-voltage switching of the first electronic switch.

Method of operating a flyback converter with active clamp, corresponding control circuit and flyback converter

An electronic device includes a circuit board that manages supply of electricity to the electronic device. The circuit board includes an integrated circuit and an external capacitor coupled to a supply terminal of the circuit board. During a startup operation of the integrated circuit, the integrated circuit supplies a first charging current to charge the capacitor to a supply voltage value. The circuit board includes a boost circuit that receives a portion of the first charging current and outputs a second charging current that augments charging of the capacitor. The second charging current is an amplification of the first charging current. The integrated circuit enables operation of the electronic device after the capacitor is charged to the supply voltage value.

High voltage startup booster

An embodiment provides a circuit including a transformer having a primary winding coupled to an input port configured to receive an input voltage and a secondary winding configured to provide an output voltage at an output port, controller circuitry configured to switch on and off a current through the primary winding so that energy is transferred to the secondary winding while switching and supply circuitry connected to the controller circuitry, wherein the supply circuitry is coupled to an auxiliary winding of the transformer and configured to provide a supply voltage for the controller circuitry. The controller circuitry is further configured to: transition to a burst mode to switch on and off the current through the primary winding in first bursts, wherein the first bursts are separated by intervals during which switching on and off the current through the primary winding of the transformer by the first bursts is discontinued and provide second bursts during the intervals in order to keep the supply voltage of the controller circuitry between a lower bound value and an upper bound value while the output voltage ramps down to a requested valley value or provide second bursts during the intervals after reaching a timeout limit in order to provide the supply voltage to the controller circuitry while the output voltage ramps down to a requested valley value.

Power supply circuit, corresponding device and method

A control circuit is configured to control a power factor correction (PFC) pre-regulator including a power switch and being configured to operate in a transition mode of operation and a valley-skipping mode of operation. The control circuit generates a drive signal to control a switching of the power switch based on a current threshold. A current threshold generator in the control circuit is configured to modulate the current threshold as a function of a number of valleys skipped in the valley-skipping mode of operation.

Control circuit and method of a switching power supply

A method and apparatus for secondary side current mode control of a converter are provided. In the method and apparatus, an output voltage of the converter is detected, where the converter has primary and secondary windings that are galvanically isolated in respective primary and secondary sides. A secondary control signal is generated in the secondary side based at least in part on the output voltage and a reference voltage. The secondary control signal is converted to a primary control signal provided in the primary side. The converter is driven in the primary side based at least in part on the primary control signal and a current sense signal indicative of a current flowing through the primary winding.

Secondary side current mode control for a converter

A control circuit controls a switching circuit of a resonant converter where the switching circuit includes first and second power switches. A first on time of the first power switch and a second on time of the second power switch are controlled to generate a square wave signal to drive the resonant circuit. The control circuit controls the first on time based on a zero current detection time indicating detection of a zero current crossing of a resonant current generated in the resonant circuit in response to the square wave signal and on a time shift delay time based on an output voltage of the resonant converter. The second on time of the second power switch control is based on the zero current detection time detected for the first power switch and on the time shift delay time.

Symmetric time shift control for resonant converters

A controller circuit for an AC-DC converter includes a first controller circuit block configured to drive one or more switches at the primary side of a transformer in the AC-DC converter. A second controller circuit block is configured to sense, at a secondary side of the transformer in said AC-DC converter, a secondary side signal indicative of the output signal from said AC-DC converter. The second controller circuit block generates switching control signals for the first controller circuit block as a function of the secondary side signal. An isolator circuit block between the first controller circuit block and the second controller circuit block includes an isolated transmission channel of the switching control signals from the second controller circuit block to the first controller circuit block.

Controller circuit and corresponding converter device

A method and apparatus for controlling a power converter are provided. In the method and apparatus, switching from a first phase to a second phase is delayed until it is determined that both a tank current signal of the converter goes below a tank current threshold and the converter has been in the first phase for more than a first minimum time period. Then the converter determines if a resonant capacitor voltage has fallen below a first resonant capacitance voltage threshold and if a tank current signal goes above a tank current threshold. The converter switches from the first phase to the second phase in response to determining at least one of: the resonant capacitor voltage has fallen below the first resonant capacitance voltage threshold and the tank current signal goes above the tank current threshold. The converter is additionally operated in third and fourth states.

Dual independent output LLC converter control

A controller for a multiphase converter comprises a first stage controller for producing a first gate drive signal to turn on a first power transistor of a first boost converter; a delay element configured to produce a delayed signal by delaying the first gate drive signal by half a cycle length; a time difference detection element configured to: output a turn on command based on a zero crossing detection (ZCD) signal indicating that one or more zero current conditions of a second boost converter of the multiphase converter are met and the delayed signal; and a second stage controller configured to assert a second gate drive signal to turn on a second power transistor of the second boost converter based on the turn on command.

Controller for multiphase boost converters

A control device for a converter of the switched-mode type provided with an inductor element and a switch element generates a driving signal for controlling switching of the switch element and determining alternately a phase of storage of energy in the inductor element as a function of an input quantity and a phase of transfer of the energy stored in the inductor element to an output element on which an output quantity is present; the control device generates the driving signal by means of a control based on the value of the output quantity in order to regulate the same output quantity. In particular, an estimation block determines an estimated value of the output quantity, and a driving block generates the driving signal as a function of said estimated value.

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Aosta, Italy

Giuseppe Scappatura