Verification Methods Of Snubber Circuits in Flyback Converters

In general, most of the existing electronic devices are connected to the AC mains and require a power conversion stage to convert the AC-Voltage to a smaller DC-Voltage. Voltages and frequencies of the power grid differ between different regions. However, different types of AC-DC conversion stages exist to supply the electronic equipment with adequate DC-power.

In AC-DC conversion combined with power levels less than 50W, the flyback converter is a commonplace chosen topology because of its simplicity and its low cost. The majority of consumer products make use of this converter type like wall brick power supplies or power adapters for any consumer application and other type of stand-by auxiliary power supply like used in white and brown goods. In AC to DC converter application, an electrical isolation between input and output is mandatory. The flyback topology provides this galvanic barrier.

Beside the common advantages of a flyback converter, it has inherently parasitic components, which typically produce ringing waveforms with considerably high voltage spikes. Without suppressing this unwanted ringing, it may have some negative effect on other components like the switching elements. This ringing can also influence the EMI emissions adversely. Therefore, it is an important task to adequate suppress and damp the ringing effect. This damping circuit is known as snubber circuit and provides this functionality. In the flyback converter, different snubber structures can be applied and each of the structure has its advantage and disadvantage.

The demand having a snubber circuit in the power supply topology leads to specific verification methods during the design to obtain a proper and reliable design. These verification methods are the main focus of the discussions within this document.