What are some examples of flyback transformers

Transformers for flyback converters

Various circuit topologies are possible for switching regulators in which transformers are used; their functionality is explained in the article. Specific application examples then show how a corresponding transformer is correctly dimensioned.

Clocked power supplies (switching regulators, switched-mode power supplies, SMPS) are used to generate a fixed output voltage from an input voltage range. The clocked power supplies are usually much more efficient than linear regulators.

The simplest switching regulators are the so-called throttle converters, the throttle down converter (buck converter, step-down converter) or the throttle up converter (boost converter, step-up converter). With these converters, a lower or higher output voltage can be generated. If the output voltage is to be in the input voltage range, i.e. one must be able to convert the voltage both upwards and downwards, the SEPIC (Single-ended Primary-Inductance Converter) is often used.

The switching regulators mentioned above have in common that there is no galvanic separation between input and output voltage. If this is required, a switching controller topology with a transformer must be selected. The flyback converter is the simplest option. However, the flyback converter is not suitable for higher powers (from around 100 W). The circuit topologies modified from the throttle step-down converter, the single-ended forward converter (forward converter) or the push-pull converter (push-pull converter) are used here.

The most important switching regulator topologies

These are characterized by a higher degree of efficiency, but also require significantly more components (e.g. additional storage choke, more active switches). Table 1 shows an overview of the switching regulator topologies and the inductive components required in the respective circuit.


1. Transformers for flyback converters
2. The flyback converter
3. 1. Non-discontinuous operation:
4. 1st step: Define the transmission ratio or the pulse duty factor
5. Step 2: Determine the inductance
6. 3rd step: Selection of the core

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