STEVAL-ISA015V2: 100W, 24V @ 4.3A, 230 or 400 VAC

The flyback converter is a popular choice in applications where the required power is normally less than 200W. The main reasons explaining its popularity are its simplicity, low cost and high efficiency for a small number of active components.

In switching converters power loss is caused by power dissipation within the parasitic elements of both passive and active components. Power loss in passive components can be reduced by selecting suitable passive components and carefully designing the transformer.

The aim of the proposed zero-voltage switching control is to reduce switching loss (in this application, the primary switch turn-on loss). The zero-voltage switching control also greatly reduces the EMI generated by primary switch turn-on.

Conduction loss is generated with the device fully turned-on, by the voltage drop across the conducting device. The proposed use of the Emitter-Switched Bipolar Transistor (ESBT) as the primary switch reduces conduction loss efficiently. Moreover, with its low saturation voltage and fast switching capability compared to an IGBT or a bipolar junction transistor (BJT), the ESBT is well suited for this use.