Ferrite Core Transformers: EE, ETD, Pot Core, RM and PQ Types

Ferrite core transformers are the workhorses of switched-mode power supplies, gate drive circuits and signal isolation. By winding primary and secondary coils around a shaped ferrite core, designers achieve efficient energy transfer, tight magnetic coupling and high isolation in a compact footprint. ADD Components, an independent electronic components distributor, sources ferrite core transformers from leading manufacturers such as TDK, Murata, Coilcraft and Wurth Elektronik to support power, industrial, telecom and automotive designs.

Product Types / Variants

EE Core Transformers

EE core transformers use two E-shaped ferrite halves that close around the windings to form a low-leakage magnetic path. The simple, cost-effective geometry supports a wide power range, from milliwatt auxiliary supplies to multi-hundred-watt converters. EE cores are the default choice for offline flyback, forward and DC-DC converters, with an optional centre leg air gap used to control inductance and prevent saturation.

ETD Core Transformers

ETD (Economic Transformer Design) cores feature a round centre leg combined with a rectangular outer body. The round centre leg reduces the mean turn length of the winding, lowering copper losses and improving efficiency compared with a square-leg EE core of similar size. ETD transformers are widely used in high-frequency switching supplies, telecom power modules and server PSUs where low winding resistance and good heat dissipation matter.

Pot Core Transformers (POT3016)

Pot cores, such as the popular POT3016 size, enclose the winding almost entirely inside a ferrite cup-and-core assembly. This self-shielding structure contains the magnetic flux, delivering very low electromagnetic interference (EMI) and low stray field, which makes pot core transformers ideal for noise-sensitive analogue circuits, filters and low-power signal transformers. The trade-off is reduced surface area for heat dissipation, so pot cores are best suited to lower-power applications where shielding and precision are priorities.

RM Core Transformers

RM (rectangular modular) cores are a hybrid of the pot core and the EE core. They retain the low-radiation, semi-shielded benefits of a pot core while exposing the winding window for better cooling and easier termination. RM core transformers balance EMI control, size and power handling, making them a popular choice for power supplies, common-mode filtering and precision inductive components.

PQ Core Transformers

PQ cores are optimised for high power density, with a large round centre leg and generous winding window that keeps copper and core losses balanced. The round centre post minimises winding resistance while the compact outer profile maximises the ratio of power handling to board area. PQ transformers are commonly specified in high-efficiency AC-DC adapters, server power supplies and industrial converters where space and thermal performance are critical.

Key Selection Parameters

• Ferrite material grade (MnZn versus NiZn) matched to the operating frequency and power level.

• Core shape and size (EE, ETD, pot core, RM, PQ) driven by power, shielding and height constraints.

• Turns ratio and winding configuration for the required voltage transformation and isolation.

• Isolation and working voltage rating, including reinforced versus basic insulation.

• Primary inductance and leakage inductance, which affect regulation and switching losses.

• Operating frequency range and maximum flux density to avoid saturation.

• Mounting style, including through-hole, surface-mount and chassis options.

• Operating temperature range and creepage/clearance for safety compliance.

Ferrite Material Grades: MnZn and NiZn

Manganese-zinc (MnZn) ferrite offers high permeability and high saturation flux density, making it the standard material for power transformers operating from tens of kilohertz to a few megahertz. Grades such as TDK PC47 and PC95 are engineered for low core loss at high temperature and are widely used in switch-mode supplies. Nickel-zinc (NiZn) ferrite has much higher resistivity and lower eddy-current loss, so it is preferred for high-frequency signal, filter and RF transformers where operation extends into the tens of megahertz. Selecting the correct material grade is essential to balancing efficiency, temperature rise and core size.

Typical Applications

Ferrite core transformers appear wherever electrical isolation and voltage transformation are required at switching frequencies. In offline AC-DC converters and DC-DC modules, EE, ETD and PQ transformers transfer power across the isolation barrier while gate drive transformers provide the isolated pulses that switch MOSFETs and IGBTs. Current sense transformers, often built on small EE or RM cores, monitor load current for protection and control loops.

For low-noise analogue and signal paths, shielded pot core transformers such as the POT3016 contain flux and reduce EMI, while pulse transformers carry isolated digital signals in telecom and industrial interfaces. The self-shielding of pot and RM cores also helps products pass strict EMC compliance tests, making them a preferred option for medical, instrumentation and high-density consumer equipment.

Representative Transformers We Source

Send Us Your Transformer Requirements

ADD Components supplies ferrite core transformers for power conversion, gate drive, current sensing and signal isolation. Whether you need a specific EE, ETD, pot core, RM or PQ part number, or volume transformer wholesale pricing, send us your requirements and our sourcing team will respond with a competitive quotation.

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