The trend toward high power density, high operating frequency, and low profile in power converters has exposed a number of limitations in the use of conventional wirewound magnetic component structures. In recent years, planar magnetics has become increasingly popular in high frequency power converters because of the unique advantages they achieve in terms of low profile, excellent thermal characteristic, extremely good repeatability, modularity, easy manufacturing and winding integration with PCB (print circuit board) based
Advantages of Planar Ferrite Cores
- Budget
- Low Leakage Inductance
- Low power loss over wide temperature range
- Excellent Magnetic Performance
- Good Heat Dissipation Performance
- Good Stability under Load Conditions
- Easy Assembly
- Strong Mechanical Integrity
- Superior Thermal Performance
- Low Profile Structure
- No wire wounded bobbin required
Structure of Planar Transformer
The pair of low profile geometries with ferrite material is used as magnetic core of the transformer. PCB winding and stamped copper turns are used for primary or secondary windings respectively. In general, the handling current in PCB winding is smaller than thicker stamped copper turn. With recent development in PCB technology, the thick copper winding from 3-oz to 16-oz is possible to be laminated with PCB prepreg. The polyimide films (Kapton) are used in each layer to prevent the short circuit. Meanwhile, its characteristics of wide range temperatures and high voltage stress are attractive to transformer applications.
Thermal Performance
Planar magnetic cores tend to have a higher surface-to-volume ratio than conventional magnetic cores. As a result, they are more effective at conducting heat and tend to have low thermal sensitivities compared with conventional wire-wound devices.
Conventional Ferrite Magnetic Core Performance
Planar Ferrite Magnetic Core Performance
Low Profile
Planar magnetic devices have intrinsically much lower profile than conventional wire-wound devices, which aids miniaturization. Typically, the height of a planar magnetic device is 25% to 50% less than its wire-wound counterpart.
Easy Production & Cost Reduction
Since manual steps or complex automatic steps such as winding are removed, and PCB techniques are easily adapted for mass production.
Modularity
Since PCB winding are used for the planar magnetic devices, the semiconductors and other passive components can also be assembled into the PCB surfaces and thus no extra connections are required.
Ease of application in intermittent winding
Since multi-layer PCBs allow the interconnection of arbitrary layers, interleaved primary and secondary windings can be implemented much more easily than in conventional magnetics.This provides a significant reduction on leakage inductance and high frequency winding losses.
ER Planar Ferrite Cores
Coding System: ER WW/HH/LL
| Part Number | Material Datasheet [PDF ] |
|---|---|
| ER9.5/2.5/5 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER11/2.5/6 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER14.5/3/7 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER18/3.2/10 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER23/3.6/13 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER32/6/25 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER41/7.6/32 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER51/10/38 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
| ER64/13/51 | 3F46 / 3C96 / 3F36 / 3C95 / 3F4 / 3C97 / 3C92 / |
EE Planar Ferrite Cores
Coding System: E WW/HH/LL
| Part Number | Material Datasheet [PDF ] |
|---|---|
| E14/3.5/5 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E18/4/10 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E22/6/16 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E32/6/20 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E38/8/25 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E43/10/28 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E58/11/38 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| E64/10/50 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
PLT Planar Ferrite Cores
Coding System: PLT WW/HH/LL
| Part Number | Material Datasheet [PDF ] |
|---|---|
| PLT14/5/1.5 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT18/10/2 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT22/16/2.5 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT32/20/3.2 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT38/25/3.8 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT43/28/4.1 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT58/38/4 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
| PLT64/50/5 | 3F4 / 3C96 / 3C90 / 4F1 / 3F36 / 3C95 / 3F46 / 3C97 / 3C92 / |
Source: Advances in Planar and Integrated Magnetics.pdf
