About Planar Transformers

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The demand for increased efficiency and power density in power converters is relentless since the end of last century, so the electronics world is dominated by integrated circuits. High frequency magnetic components are important elements in the electronic circuits and are changing to be more integrated with electronic devices, so the twenty-first Century is an integrated age.


Planar magnetic components are one of major group of integrated magnetics. The importance of theirs was confirmed in the last century. They have highly been used in the modern integrated power electronic devices with very good performance in high frequency operations.

A planar transformer is different from the conventional transformers. It consists of a planar winding structure and a set of planar magnetic material pieces. The windings are commonly constructed on printed circuit boards fabricated with the photographic reproduction technique. This reproduction technique can guarantee the pattern of the winding to be identical with the original design. This is very important to maintain the high frequency characteristics. So the planar transformers are targeted by designers of high frequency Switched Mode Power Supply

Compared with the conventional transformer, the main advantages of Planar Transformers are the low profiles and the good high frequency properties, which lead to a high power density. The conventional transformer has a relatively large dimension in height which is an obstacle for miniaturizing the design in electronic device. The Planar Transformer can overcome this problem with its low height, and can matches with the other electronic components sitting on the printed circuit board easily. And compared with the round wires, the very thin tracks are employed in the planar winding structure. They can significantly reduce the skin effect in the promotional products winding of the transformers. The most important thing is that the arrangement of planar windings can be precisely duplicated simply by the photographic reproduction technique. The high frequency performance of planar magnetics can be guaranteed. Planar transformers can be easily adopted by integrated circuits with their fabrication techniques.


Advantages of Planar Transformers
- Low leakage inductance
- Low eddy current losses
- High efficiency
- High power density
- Lower height
- Exactly repeatable
- Solid mechanical construction
- High process capability
- Very good thermal performance


- Switch Mode Power Supplies (AC/DC, DC/DC)
- Telecom Distributed Power Systems and Rectifiers
- Industrial Power Systems
- Automotive 42V systems
- Welding Inverters and Battery Chargers
- Avionics
- Space
- Missiles