What is quasi-resonant flyback?

A Quasi-resonant Flyback is simply a DCM Flyback having a valley switching turn on. It is also known as variable frequency or valley switching Flyback and is largely used in low power SMPS application such as charger, adapter and auxiliary supply.

What is quasi-resonant controller?

With quasi-resonant control, the energy stored in the transformer during the power MOSFET’s ON period is transferred to the secondary side during the OFF period, and when the release of energy is complete, resonance is initiated between the trans- former inductance L and the drain capacitance C, and the voltage …

How does a resonant converter work?

A regular LLC resonant half bridge converter works a combination mode of a voltage divider and amplifier of resonant inductor voltage of the resonant tank. At the resonant frequency, impedance of resonant tank is zero, which means the input voltage is 100% applied on the load.

What is valley switching?

Valley switching is a soft-switching technique that improves system efficiency of AC-DC and DC-DC converters. Significant efficiency improvements are achieved with valley switching mainly under low-load conditions where efficiency standards are difficult to meet.

What is active clamp flyback?

Active Clamp Flyback (ACF) is an evolution of the classic flyback AC/DC converter topology deployed in many Switch Mode Power Supply (SMPS) designs.

What is CCM and DCM in flyback converters?

Flyback converters can operate either in continuous-conduction mode (CCM) or discontinuous-conduction mode (DCM). DCM operation is characterized by the converter having its rectifier current decreasing to zero before the start of the next switching cycle.

What is quasi resonant mode?

In quasi-resonant switching, the device does not have a fixed switching frequency. Instead, the controller waits for one of the troughs in the drain voltage and then switches on. Older quasi-resonant devices designed for the color television market always switched on the first trough.