What are Planar Transformers?

Pre-formed Copper & PCBs

Planar transformers are wound using pre-formed turns of punched copper or printed circuit boards (PCBs) whereas conventional transformers are wound using wire. The pre-formed nature of these windings allow for greater repeatability and tighter control of parasitics.

Planar Cores

As well as using pre-formed copper and PCBs, planars are wound around planar ferrites which also differ in geometry to conventional ferrite cores. Planar ferrite cores tend to be smaller in height but larger in surface area. This unique aspect ratio provides significant advantages such as a larger thermal conduction area and also allows planars to operate at higher flux densities.

Interleaving

Primary and Secondary windings are easily interleaved in planar transformers. The interleaving nature of these windings also provides additional benefits such as reduction in leakage inductance.

Isolation

Galvanic isolation is easily catered for and doesn’t restrict the use of interleaving. The pre-formed nature of the windings allows greater control of creepage and clearances. Primary to Secondary isolation voltages of up to 4kVrms are typical.

Terminations

A variety of termination styles are available:
Bolted connections for high current
Thru hole pins for PCBs
SMT pins for PCBs

Footprints

As well as these termination styles we also provide a variety of footprint options. Bobbins are not used therefore no fixed bobbin footprints that are normally associated with conventional cores. You specify the preferred footprint and we can design your part to match.

Power Range

Planar transformers are suitable for use at virtually all power levels from 5W to 25kW. They can be used in series or parallel to achieve even greater power throughput.

Voltage Range

High and low voltage transformers are suitable for planar designs. Planars are used in single phase and 3 phase offline applications and therefore working voltages of up to 1000V are catered for. CPM has designed PCB based high voltage planar transformers for military applications which generate output voltages of up to 5kV. With the development of new insulation materials and manufacturing methods high voltage planar transformers are an ideal solution.

Edge Wound Inductors

These inductors are larger in cross section than a standard planar winding. Good for carrying DC current with a AC ripple. Multiple cross-sections and geometries are available.

CPM are experts in the design and manufacture planar transformers and inductors for a variety of end-user applications ranging from Battery Charging & Welding to Aerospace & Automotive. If you have any further questions about the suitability of planar transformers and inductors for your application, please get in touch.