Planar transformers are an excellent alternative to conventional transformers and inductors with a wire-wound. The basis for planar transformers are multi-layered printed circuit boards.
Today, the development of planar transformers requires the use of components with minimum dimensions, because the dimensions of the electronics is constantly decreasing.
Planar power transformers
Design of Planar Power Transformers can be performed with external components, such as small monolayer or multilayer board, or as a multilayer printed circuit board.
Advantages of planar transformers:
- have excellent temperature characteristics;
- have a low leakage inductance;
- have excellent repeatability properties.
Due to the higher surface area of the core with respect to its volume, heat resistance of such devices can be 2 times lower than in a conventional wire wound transformer. This is based on the fact that the effective volume of the core remains the same.
Therefore, due to the increased cooling capacity planar transformers coping with higher throughput power densities, and thus they keep the temperature rise within acceptable limits.
Planar transformers based on multilayer PCB
When it comes to semiconductor components, including passive, which include capacitors and resistors, given a large enough selection.
However, it will be today planar transformers.
Generally, in many cases, manufacturers use standard transformers and inductors, which have a wire winding. But we describe planar transformers (PT) based on multilayer boards.
Since the cost of multilayer boards tends to decrease, then the planar transformers are gradually replacing conventional. Especially in those cases where the small-sized magnetic component is required.
In the production technology of the planar transformer windings serve as tracks on a printed circuit board or portions of copper, are applied by a printing method, and the different layers are separated by an insulating material.
Also, the winding can be made of multilayer circuit boards. They are placed between the small-sized ferrite cores.
Planar transformers design
Relatively planar transformer design, can be divided into several types.
1. Hinged planar components – they are closest to the conventional inductive components. They can replace conventional details on one or multi-layer printed circuit boards. The height of the planar attachment component may be reduced by immersing the core in the recess of the PCB. In this winding must lie on the surface of the board.
2. Hybrid type of planar transformers. This type involves insertion of the windings into the motherboard. At the same time, another part of the winding is located on a multilayer printed circuit board which connects to the motherboard. But in this case, the motherboard must have openings for the ferrite core.
3. The winding is fully integrated into a multilayer printed circuit board. Core halves are joined as a result of gluing or clamping. It all depends on the preferences of the customer and the manufacturer.
Advantages of planar technology
When compared to a conventional wire wound, the manufacture of planar magnetic component technology has several advantages.
- Low height. Thanks to the planar components are very promising for use in rack-mount and portable equipment, the high cost of installation.
- Well suited for the development of high pulsed power converters. Ac copper loss is small in magnitude, and the high coupling coefficient enables more efficient conversion.
- Low leakage inductance reduces fluctuations and surges, which are often the cause of failure of Defense components. Can also become an additional source of noise.
- High density power throughput. It is twice greater than in conventional transformers.
- Repeatability values of parasitic parameters. With it is possible to achieve high switching frequencies and create a resonant circuit.
Use of planar transformers
The very first application of its planar transformers found in the transformation of power. To do this, planar transformers use the medium and high frequency ferrite. Buy planar transformer can be from the manufacturer.
If you are interested in the development of planar transformers to order, you can choke line filter can be increased by replacing a powerful ferrite materials with high magnetic permeability.
In pulse signaling broadband transformer located between the pulse generator IC and the cable provides isolation and impedance matching. In the case of S- or T-interface also it should be ferrite of high magnetic permeability.