Abstract:
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.
Abstract:
A control device for a transistor of a switching converter rectifier generates a control signal of the transistor and comprises a circuit to measure the conduction time of the body diode of the transistor cycle by cycle. When the conduction time is greater than a first threshold, the off time instant of the transistor is delayed by a first quantity in the next cycles, until the conduction time is less than the first threshold and greater than a second threshold. When the conduction time is between the first and second thresholds, the off time instant is delayed by a fixed second quantity in the next cycles until the conduction time is lower than the second threshold, with the second quantity less than the first quantity. When the conduction time is lower than the second threshold, the off time instant is advanced by the second quantity in the next cycle.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
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.