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Planar transformers

Our official sales partner: Dongke Semiconductor

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Dongke is a leading manufacturer of high-frequency and high-efficiency power supply ICs, synchronous rectifiers and innovative solutions for power electronics.
Through this partnership, we can offer our customers access to a wide range of state-of-the-art technologies and products - from synchronous rectifiers for efficient energy conversion to customized solutions for industrial applications and consumer electronics.

Planar transformers for high-frequency applications

Planar transformers are innovative, energy-efficient transformer solutions for power transmission in modern electronic systems. In contrast to conventional transformers, they use flat, planar windings that are integrated into printed circuit boards. This enables a compact design with high power density and improved thermal management.

Due to their low height and efficient heat dissipation, planar transformers are particularly suitable for applications where space and energy efficiency are crucial. Typical applications include power electronics, renewable energy systems, electric vehicles and telecommunications equipment.

Rotima AG, in cooperation with Dongke Semiconductor, offers a wide range of planar transformers as well as miniature transformers for electronics that meet the latest industry standards and are optimized for a variety of applications. Our experienced engineering team with over 20 years of expertise ensures that our products meet the highest quality and performance requirements.

Discover the advantages of planar transformers for your projects and benefit from our many years of experience and our commitment to innovative solutions.

Planar transformers in the electronics industry

Buy planar transformer ICs

  • Compact and space-saving
  • Efficient heat dissipation
  • Versatile in use
  • Quality through strong partnership

Product features

Product model:
Core type:EE
Core material:HE7
Rotation ratio (Np/Ns):28T/4
Vcc winding:88
Inductance:3535
MAX operating frequency:250KHz
Topology:High-frequency DCM, CCM, QR-mode flyback and multi-mode flyback (recommended application topologies)

Electrical properties

ItemMeasuring pageStandardTest conditions
InductanceHV-SW340uH-360uH100KHz/0.25V
Stray inductanceHV-SW6uH MAX100KHz/0.25V, whereby the other windings are short-circuited
DC resistorHV-SW1250mΩ MAX/
VC-PG1350mΩ MAX/
A-B25mΩ MAX/
Winding ratioturns ratio28T:4T:8T/
Resistance to stresses(HV+SW):(A+B)No failure, flying arc3750Vac 1mA 3S
(VC+PG):(A+B)No failure, flying arc3750Vac 1mA 3S
(HV+SW):(VC+PG)No failure, flying arc1000Vac 1mA 3S
Toroidal transformers for efficiency and performance

Download data sheet

Here you will find our current Planar Transformers data sheet PDF, which provides you with detailed information on the technical specifications and possible applications of our planar transformers.
DK-EQ20-PD30W-T-V0.7-Planar-Transformer51.pdf

Materials and structure of planar transformers

Planar transformers consist of flat, planar windings that are precisely integrated into printed circuit boards. This design enables a compact and efficient structure. The windings are usually made of copper layers, which are separated from each other by thin layers of insulation. The magnetic core, usually made of ferrite material, surrounds the windings and concentrates the magnetic field, ensuring low-loss energy transmission.

Thanks to their special design, planar transformers offer excellent heat dissipation and reduce electrical losses. These properties make them the ideal solution for space-saving and high-performance applications in the electronics industry, for example in power electronics and other energy-intensive applications. Rotima AG and Dongke Semiconductor supply customized planar transformers that are optimally adapted to industrial requirements.
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Advantages of planar transformers in power electronics

Planar transformers are used in numerous high-tech areas where compact design and energy efficiency are crucial. In power electronics, they are used in switching power supplies and inverters, where they enable reliable energy transmission and efficient heat dissipation.

In the automotive industry, they are used in electric and hybrid vehicles, for example in on-board chargers, in order to control the energy flow optimally. They also ensure a stable power supply with high power density in telecommunications devices such as base stations and network equipment.

Thanks to their versatility and efficiency, planar transformers are a forward-looking solution for modern electronic systems. Rotima AG and Dongke Semiconductor offer innovative products for these demanding applications.
What can we do for you?
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Tobias Nuffer
Tobias Nuffer
Managing Director & Key Accounting DE
+49 8341 93403 20
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Roland Jungen
Roland Jungen
Key Account Manager CH
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Planar transformers

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What are the advantages of using DC voltage transformers compared to AC voltage transformers?

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Further information on plan transformers

Planar transformers are innovative, compact and energy-efficient transformers that are an ideal solution for modern electronic applications thanks to their flat design and high power density.
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