Planar advantages

Advantages of Planar Transformers

Planar offers the following advantages over traditional methods:


The use of copper foil leadframes and flat ferrite cores mean that transformers no longer need to be the bulky 3D shape that traditional wire would components necessitated.


Planar offers significant weight advantages often being 3-4 times lighter than their wire would equivalent.

Efficient Inductance

The majority of the losses incurred in the windings of a high frequency transformer are due to the AC resistance, as opposed to DC resistance. Planar Technology provides a significant reduction in these AC resistance losses when compared to conventional wire-wound equivalents, hence results in greater efficiency in the transformer.

Highly Efficient Cooling

The large surface area to volume ratio offered by the flatter cores used in planar transformers makes them ideal for heatsink mounting and forced air-cooling. These heat removal benefits again add greatly to the overall efficiency of the transformer.

Low Leakage Inductance

The laminar construction and ease of interleaving enables the magnetic coupling between windings to be very good, this in turn results in much lower leakage inductance values.

Unrivalled Repeatability

Planar components are made from pre-formed parts, thus the assembly process itself has only a few stages. This simplification of assembly allows planar transformers to be manufactured with very high repeatability.


Dimensional Accuracy

The high level of dimensional accuracy of both multi-layered printed circuits and punched leadframes assures a narrower spread of leakage inductance and winding capacitance. This enables snubbing components to be more precisely specified and the associated losses to be minimised. These are becoming important parameters in the design of modern power converters which use ZVS or ZCS (zero voltage switching / zero current switching)

Multiple Winding Options

Due to the simplified manufacturing process of planar transformers, the winding ratios can easily be amended to suit specific design requirements throughout the production cycle. This not only allows for flexibility in the design, but also reduces costs and time should design alterations be required.

Multiple Topologies

Planar transformers can be applied to any desired switch mode power supply winding topology. The manufacturing process for planar transformers allows for considerably easier transitions between topologies than attainable with traditional technology.

Customised Pin Positions

Uniquely in the market place, Himag Planar transformers do not require a bobbin, therefore non-standard pin pitches can be easily incorporated into any design. Conventionally when the number of winding terminations exceed that of the number of bobbin pins, a larger core and bobbin size would be required leading to under utilisation and increased costs.

Ideal Components

Planar components are electrically closer to an ideal component than conventional technologies. This results in better performance due to a reduction in the detrimental effects on the circuit, when compared to their wire would counterparts.