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Selecting Planar Cores For Your Power Applications

Selecting Planar Cores For Your Power Applications

Planar cores are the best alternative to conventional ferrite cores when there is a need for a low-profile magnetic device. Their shape is suitable for PCB mounting and they have low losses and high saturation levels. These cores are commonly integrated with Printed Circuit Boards (PCBs) used in the power supply market. This helps to increase the power density of the transformers and current in the output inductor.

In this blog, we’re going to discuss Planar cores & how they are an appropriate choice for your power applications. Let’s get started!

What is the purpose of using Planar Cores?

Planar cores are used to make inductive components where windings are fabricated with the help of printed circuit tracks or copper stampings. Then, they are separated by insulating sheets or constructed using multiple-layered circuit boards. 

These windings are wrapped around low profile ferrite cores. Usually, the cores with radiused corners & edges are preferred because they can have clamp recesses.


  • Planar cores use windings consistently that bring up magnetic design with stable & controllable parameters.
  • Their windings are influenced by advanced computer aided manufacturing technologies.
  • They have superior thermal features because of a larger surface-to-volume ratio as compared to other ferrite cores.
  • They have excellent modularity, so no additional components are required.
  • They are available in a variety of shapes & sizes from 10mm to 25mm.
  • The operating temperature range is between -30°C to 105°C.

Advantages of Planar Cores

  • Cost-Effective
  • Easy Assembly  
  • Low Leakage Inductance
  • Low Losses over wide temperature range
  • Excellent Magnetic Performance
  • Good Heat Dissipation
  • Good Stability Across Load Conditions
  • Strong Mechanical Integrity
  • Superior Thermal Features
  • Low Profile Construction
  • No Bobbin 

Major Types of Planar Cores

1. Planar (EI, EE) Cores
These cores are ideal for manufacturing gapped inductors where fringing losses have to be taken into consideration. These cores are a little more expensive than other cores but have no wasted space. Common applications for Planar (EI, EE) Cores are Differential Inductors, DC/DC Converters, AC/DC Converters, SMPS Transformers, Power Supply, and Common Mode Chokes.

2. EIH, EEH Cores
These cores are produced using optimum grade raw material & advanced technology. They are also a little more expensive than other conventional ferrite cores. Common applications for Planar (EIH, EEH) Cores are DC/DC Converters, AC/DC Converters, and Inductors.


Planar cores are primarily used for commercial electronics. Below are some of their common applications.

  • Power Components 
    -Power Transformers
    -Mains Filter Chokes
  • AC/DC Converter 
    -Stand Alone SMPS
    -Battery Chargers (Mobile Phones & Computers)
  • DC/DC Converter 
    -Power Converter Modules
    -Telecommunications Network
    -Mobile Phones (Mains power supply)
    -Portable Computers (Mains power supply)
    -Electric Cars
  • AC/AC Converter 
    -Induction Heating & Welding
    -Compact fluorescent lamps
  • DC/AC Inverter 
    -Mobile Phones (LCD backlights)
    -Portable Computers (LCD backlights)
    -Car rear window heating
  • Pulse Transmission Components
    -Wideband Transformers

Designing of Planar Cores

Planar cores are designed or constructed in two ways as– standalone components or integrated into a motherboard with slots for ferrite cores (namely E Cores). The height of an individual component can be decreased by sinking the ferrite core through a slot in the motherboard. This is pressed until the windings are placed on the motherboard. 

In another technique, hybrid mounting, a part of the windings are placed on the motherboard while others are joined in a multi-layered circuit board. The motherboard should have slots to maintain space for the ferrite core. 

The hybrid mounting option is mechanically stable and provides a higher copper utilisation. They are ideal for different environment conditions & temperature.


Planar cores have become an important component to achieve high efficiency and high power density converter amidst the increasing frequencies. If you are looking for planar cores for your power applications, try our products designed & produced by skilled experts & technicians.

At Cosmo Ferrites, we can even help you select the best products for your unique requirements. We manufacture & supply planar ferrite cores in a wide range of sizes for power converter solutions. We’re continuously innovating & extending our range of cores to meet the growing requirements of our customers. Contact us to discuss your requirements.