Abstract: Disclosed is a method and a control circuit. The method includes operating a buffer circuit in a first operating mode or a second operating mode. Operating the buffer circuit in the first operating mode includes buffering, by a first capacitor of the buffer circuit, power provided by a power source and received by a load. Operating the buffer circuit in the second operating mode includes connecting a second capacitor in series with the first capacitor to form a capacitor series circuit, supplying power to the load by the capacitor series circuit, and regulating a first voltage across the capacitor series circuit. Regulating the first voltage includes transferring charge from the first capacitor to the second capacitor.

Abstract: The primary side of an LLC converter includes a primary-side switch network connected to an LLC network having a first winding of an isolation transformer. The secondary side includes a secondary-side switch network having first and second rectification branches coupled to different tap points of a second winding of the isolation transformer. Switching of the secondary-side switch network is controlled based on a drive signal and a current sense signal indicative of current in the rectification branches. For a first part of each switching cycle, discontinuous conduction mode (DCM) is detected based on a falling edge of the current sense signal occurring before a falling edge of the drive signal for the first rectification branch. For a second part of each switching cycle, DCM is detected based on the falling edge of the current sense signal occurring before a falling edge of the drive signal for the second rectification branch.

Abstract: The primary side of an LLC converter includes a primary-side switch network connected to an LLC network having a first winding of an isolation transformer. The secondary side includes a secondary-side switch network having first and second rectification branches coupled to different tap points of a second winding of the isolation transformer. Switching of the secondary-side switch network is controlled based on a drive signal and a current sense signal indicative of current in the rectification branches. For a first part of each switching cycle, discontinuous conduction mode (DCM) is detected based on a falling edge of the current sense signal occurring before a falling edge of the drive signal for the first rectification branch. For a second part of each switching cycle, DCM is detected based on the falling edge of the current sense signal occurring before a falling edge of the drive signal for the second rectification branch.

Abstract: Disclosed is a method and a control circuit. The method includes operating a buffer circuit in a first operating mode or a second operating mode. Operating the buffer circuit in the first operating mode includes buffering, by a first capacitor of the buffer circuit, power provided by a power source and received by a load. Operating the buffer circuit in the second operating mode includes connecting a second capacitor in series with the first capacitor to form a capacitor series circuit, supplying power to the load by the capacitor series circuit, and regulating a first voltage across the capacitor series circuit. Regulating the first voltage includes transferring charge from the first capacitor to the second capacitor.

Abstract: Disclosed is a method and a control circuit. The method includes operating a buffer circuit (1) in a first operating mode or a second operating mode. Operating the buffer circuit (1) in the first operating mode includes buffering, by a capacitor parallel circuit including a first capacitor (11) and a second capacitor (12), power (Po) provided by a power source (3) and received by a load (4). Operating the buffer circuit (1) in the second operating mode includes supplying power to the load (4) by the second capacitor (12), and regulating a first voltage (Upn) across the second capacitor (12), wherein regulating the first voltage (Upn) comprises transferring charge from the first capacitor (11) to the second capacitor (12).

Abstract: A phase-shifted full bridge (PSFB) switching converter includes a transformer having a primary winding and a secondary winding; an input capacitor coupled to the primary winding via a first transistor full bridge; an output inductor coupled to the secondary winding via a synchronous rectifier circuit including at least one first transistor and at least one second transistor; and a controller circuit for generating switching signals for the rectifier circuit to operate the PSFB switching converter in reverse direction. During a startup phase, at the beginning of which the input capacitor is substantially discharged, the at least one first transistor is switched on in each switching cycle to allow an inductor current to pass from an output node, via the output inductor and the secondary winding, to a ground node, the at least one first transistor is again switched off when the inductor current reaches a threshold value.

Abstract: A phase-shifted full bridge (PSFB) switching converter includes a transformer having a primary winding and a secondary winding; an input capacitor coupled to the primary winding via a first transistor full bridge; an output inductor coupled to the secondary winding via a synchronous rectifier circuit including at least one first transistor and at least one second transistor; and a controller circuit for generating switching signals for the rectifier circuit to operate the PSFB switching converter in reverse direction. During a startup phase, at the beginning of which the input capacitor is substantially discharged, the at least one first transistor is switched on in each switching cycle to allow an inductor current to pass from an output node, via the output inductor and the secondary winding, to a ground node, the at least one first transistor is again switched off when the inductor current reaches a threshold value.

Abstract: A phase-shifted full bridge (PSFB) switching converter includes a transistor full-bridge having first and second half-bridges. Each half-bridge includes a high-side transistor and a low-side transistor. A controller circuit is configured to generate a drive signal for each transistor. The (first/third and second/fourth) drive signals for the transistors of each half-bridge are periodic with a cycle period, pulse-width modulated and have a temporal offset to each other that equals half of the cycle period. The drive signals for the half-bridges are phase shifted-with respect to one another. The controller circuit also is configured to generate the first drive signal so that the first high-side transistor is switched off when the third drive signal indicates to switch on the second high-side transistor, and to generate the second drive signal so that the first low-side transistor is switched off when the fourth drive signal indicates to switch on the second low-side transistor.

Abstract: A bi-directional LLC converter includes: first and second sides coupled by an isolation transformer, the first side including a switch network connected to an LLC network, the LLC network including a first winding of the isolation transformer, the second side including a switch network connected to a second winding of the isolation transformer; and a controller operable to operate the LLC converter in a forward mode in which the first side functions as an inverter and the second side functions as a rectifier, and to operate the LLC converter in a reverse mode in which the second side functions as an inverter and the first side functions as a rectifier. In the reverse mode, the controller is operable to delay turn off of the switch network on the first side at an operating frequency above resonance of the LLC converter, to yield a gain greater than one in the reverse mode.

Abstract: A bi-directional LLC converter includes: first and second sides coupled by an isolation transformer, the first side including a switch network connected to an LLC network, the LLC network including a first winding of the isolation transformer, the second side including a switch network connected to a second winding of the isolation transformer; and a controller operable to operate the LLC converter in a forward mode in which the first side functions as an inverter and the second side functions as a rectifier, and to operate the LLC converter in a reverse mode in which the second side functions as an inverter and the first side functions as a rectifier. In the reverse mode, the controller is operable to delay turn off of the switch network on the first side at an operating frequency above resonance of the LLC converter, to yield a gain greater than one in the reverse mode.

Abstract: A phase shift full bridge (PSFB) converter includes: an isolation transformer; a full-bridge having a first pair of switch devices connected in series at a first node coupled to a first terminal of the primary side of the isolation transformer, and a second pair of switch devices connected in series at a second node coupled to a second terminal of the primary side of the isolation transformer; a rectifier coupled to the secondary side of the isolation transformer; and a controller for switching the first and second pairs of switch devices out of phase with each other. Under nominal input voltage conditions for the PSFB, the controller switches the first and second pairs of switch devices at a nominal switching frequency. Under reduced input voltage conditions for the PSFB, the controller switches the first and second pairs of switch devices at a frequency lower than the nominal switching frequency.

Abstract: Driver circuits are provided for driving a power switch. The driver circuits include one or more charge pumps configured to generate a boosted positive voltage and/or a decreased voltage to a gate of the power switch. The decreased voltage may provide a negative voltage to the gate of the power switch, relative to its source, when the power switch is transitioned to its off state. The boosted positive voltage provides a voltage that is higher than the voltage that would otherwise be provided by a driver power supply. The decreased voltage generated by a turn-off charge pump has the effect of transitioning the power switch to its off state more quickly. The boosted voltage generated by a turn-on charge pump has the effect of transitioning the power switch to its on state more quickly. The decreased transition times provided by the driver circuits reduce switching losses of the power switch.

Abstract: A bidirectional phase-shift full bridge converter includes a primary side having switch devices forming a full-bridge power stage and a first inductor connected to the power stage, a secondary side having switch devices forming a power stage and a second inductor connected to that power stage, a transformer, and a controller for controlling switching of the switch devices to transfer energy from the primary to secondary side in a first mode, and to transfer energy from the secondary to primary side in a second mode. In the second mode, the controller controls switching of the switch devices to pre-charge the first inductor at, near or above a current level of the second inductor prior to transferring energy from the secondary to primary side, so that the current in the first inductor is at, near or above the current in the second inductor at the beginning of the energy transfer.

Abstract: Driver circuits are provided for driving a power switch. The driver circuits include one or more charge pumps configured to generate a boosted positive voltage and/or a decreased voltage to a gate of the power switch. The decreased voltage may provide a negative voltage to the gate of the power switch, relative to its source, when the power switch is transitioned to its off state. The boosted positive voltage provides a voltage that is higher than the voltage that would otherwise be provided by a driver power supply. The decreased voltage generated by a turn-off charge pump has the effect of transitioning the power switch to its off state more quickly. The boosted voltage generated by a turn-on charge pump has the effect of transitioning the power switch to its on state more quickly. The decreased transition times provided by the driver circuits reduce switching losses of the power switch.

Abstract: A power converter includes a primary side with switch devices that form a power transfer stage, and a secondary side with switch devices that form a rectification stage and an output filter coupled to the rectification stage and including an output inductor and output capacitor. A transformer couples the primary and secondary sides. The switch devices are controlled in DCM (discontinuous conduction mode) to transfer energy from the primary side to the secondary side during a power transfer interval in which one branch of the power transfer stage is conducting, one branch of the rectification stage is conducting and another branch of the rectification stage is blocking. As a voltage of the transformer first begins to rise at the start of a new power transfer interval in DCM, the branch of the rectification stage that is to be conducting during the new power transfer interval is hard switched on.

Abstract: A phase-shifted full bridge (PSFB) switching converter includes a transistor full-bridge having first and second half-bridges. Each half-bridge includes a high-side transistor and a low-side transistor. A controller circuit is configured to generate a drive signal for each transistor. The (first/third and second/fourth) drive signals for the transistors of each half-bridge are periodic with a cycle period, pulse-width modulated and have a temporal offset to each other that equals half of the cycle period. The drive signals for the half-bridges are phase shifted-with respect to one another. The controller circuit also is configured to generate the first drive signal so that the first high-side transistor is switched off when the third drive signal indicates to switch on the second high-side transistor, and to generate the second drive signal so that the first low-side transistor is switched off when the fourth drive signal indicates to switch on the second low-side transistor.

Abstract: A phase shift full bridge (PSFB) converter includes: an isolation transformer; a full-bridge having a first pair of switch devices connected in series at a first node coupled to a first terminal of the primary side of the isolation transformer, and a second pair of switch devices connected in series at a second node coupled to a second terminal of the primary side of the isolation transformer; a rectifier coupled to the secondary side of the isolation transformer; and a controller for switching the first and second pairs of switch devices out of phase with each other. Under nominal input voltage conditions for the PSFB, the controller switches the first and second pairs of switch devices at a nominal switching frequency. Under reduced input voltage conditions for the PSFB, the controller switches the first and second pairs of switch devices at a frequency lower than the nominal switching frequency.

Abstract: A power converter includes a primary side with switch devices that form a power transfer stage, and a secondary side with switch devices that form a rectification stage and an output filter coupled to the rectification stage and including an output inductor and output capacitor. A transformer couples the primary and secondary sides. The switch devices are controlled in DCM (discontinuous conduction mode) to transfer energy from the primary side to the secondary side during a power transfer interval in which one branch of the power transfer stage is conducting, one branch of the rectification stage is conducting and another branch of the rectification stage is blocking. As a voltage of the transformer first begins to rise at the start of a new power transfer interval in DCM, the branch of the rectification stage that is to be conducting during the new power transfer interval is hard switched on.

Abstract: A power converter includes a primary side with switch devices that form a power transfer stage, and a secondary side with switch devices that form a rectification stage and an output filter coupled to the rectification stage and including an output inductor and output capacitor. A transformer couples the primary and secondary sides. The switch devices are controlled in DCM (discontinuous conduction mode) to transfer energy from the primary side to the secondary side during a power transfer interval in which one branch of the power transfer stage is conducting, one branch of the rectification stage is conducting and another branch of the rectification stage is blocking. As a voltage of the transformer first begins to rise at the start of a new power transfer interval in DCM, the branch of the rectification stage that is to be conducting during the new power transfer interval is hard switched on.

Abstract: A bidirectional phase-shift full bridge converter includes a primary side having switch devices forming a full-bridge power stage and a first inductor connected to the power stage, a secondary side having switch devices forming a power stage and a second inductor connected to that power stage, a transformer, and a controller for controlling switching of the switch devices to transfer energy from the primary to secondary side in a first mode, and to transfer energy from the secondary to primary side in a second mode. In the second mode, the controller controls switching of the switch devices to pre-charge the first inductor at, near or above a current level of the second inductor prior to transferring energy from the secondary to primary side, so that the current in the first inductor is at, near or above the current in the second inductor at the beginning of the energy transfer.