Switch Mode Power Supply (SMPS) Transformers

Introduction

These are essential components for high-efficiency power conversion.

SMPS transformers are a critical component in Switch Mode Power Supplies (SMPS) and DC/DC converters, playing a key role in efficient power conversion. These transformers are designed to handle high-frequency operation, which is fundamental to the functionality of modern power supplies.

In an SMPS, the transformer is responsible for stepping up or stepping down the input voltage while maintaining high efficiency and low energy losses. Unlike traditional linear power supplies, which rely on heavy transformers operating at mains frequency, SMPS transformers operate at much higher frequencies (typically between 20 kHz and 1 MHz), which allows for significantly smaller and lighter designs without sacrificing performance.

SMPS transformers are designed to provide:

• Voltage Conversion: Stepping voltage up or down based on the requirements of the load while maintaining minimal power loss.
• Isolation: Electrical isolation between the input and output, crucial for safety, noise reduction, and signal integrity.
• Efficient Power Transfer: High-frequency operation allows for compact designs with improved power transfer efficiency, reducing the size and weight of the power supply unit.
• Low Ripple & Noise: These transformers help reduce electromagnetic interference (EMI) and minimize ripple in output voltage, ensuring stable performance in sensitive electronic circuits.

Common ferrite types are EFD, ETD, EP and RM.

EFD Transformers

EFD Transformers: Compact, High-Performance Solutions for SMPS Applications

EFD transformers are engineered with compact, high-efficiency cores designed to maximize magnetic coupling while minimizing physical footprint. These transformers are particularly well-suited for Switched-Mode Power Supply (SMPS) applications, where efficient space utilization is critical.

The unique EFD core design enables a significantly smaller transformer size without compromising on performance or energy efficiency. This is essential in modern electronics, where devices are becoming increasingly compact, yet still require effective power conversion within constrained spaces.

By leveraging the EFD core's high magnetic coupling, these transformers offer excellent energy efficiency, reduced heat generation, and improved overall performance. Their small form factor makes them ideal for use in a wide range of applications, from portable devices to high-performance electronics, where every millimeter of space counts without sacrificing power efficiency or reliability.

With their ability to deliver high performance in a small package, EFD transformers are an optimal choice for powering the next generation of compact, energy-efficient electronic devices.

Typical EFD Sizes

Type	A	B	C	Type	Pin hole config.	SMD Pad config.
EFD 10	12	19	5.7	SMD
EFD 12	14	21	6.5	SMD
EFD 15	16 17	17.5 23	8.0 8.0	Pin SMD
EFD 20	21.5 22	24 28	10.0 10.0	Pin SMD
EFD 25	26	29	12.5	Pin
EFD 30	31	34	12.5	Pin

Typical EFD Power Capacities

ETD Transformers

ETD transformers are engineered to provide an optimal balance between core and copper losses, resulting in high efficiency and reliable thermal performance.

Their core geometry allows for efficient winding utilization, reduced leakage inductance, and improved magnetic coupling, enabling compact designs with high power density.

ETD transformers also exhibit good thermal stability and versatility across a wide operating frequency range, making them well-suited for high-performance power electronics applications, particularly in switching power supplies and DC-DC converters.

Typical ETD Sizes

Type	A	B	C	Horizontal Vertical	Pin hole Horizontal	Pin hole Vertical
ETD 19	24 31	33 19	20 37	H V
ETD 24	29 36	34 21	22 38	H V
ETD 29	36 43	36 24	26 43	H V
ETD 34	40 47	43 27	35 45	H V
ETD 39	45 52	48 29	38 50	H V
ETD 44	50 57	53 32	41 55	H V
ETD 49	55 62	58 34	43 59	H V
ETD 54	62 68	62 37	46 66	H V
ETD 59	67 73	67 39	50 70	H V

Typical ETD Power Capacities

ETD transformers are also available in potted versions, either for horizontal or vertical mounting. Ask for more details on this.

EP Transformers

EP transformers feature a highly compact design, making them ideal for applications requiring high inductance in a limited space, such as filter chokes, pulse transformers, and small power transformers.

The unique core geometry not only enables high winding packing density and efficient magnetic utilization but also provides excellent natural shielding against electromagnetic interference (EMI).

This combination of compactness, low leakage flux, and effective shielding makes EP transformers particularly suitable for use in sensitive electronic circuits and densely packed assemblies.

Typical EP Sizes

Type	A	B	C	Type	Pin hole config.	SMD Pad config.
EP 7	9.5 9.5	7.5 12.5	9.5 8.5	Pin SMD
EP 10	11 13	11 14.5	12.0 10.3	Pin SMD
EP 13	14 13	14 20	13 12	Pin SMD
EP 17	19	19	16	Pin
EP 20	27	23	21	Pin

RM Transformers

RM transformers are widely used in applications such as filter chokes, low-frequency and pulse transformers, as well as high-frequency power transformers in power supplies up to approximately 600 W.

Their optimized core geometry allows for high power density, low leakage inductance, and efficient use of PCB space, making them well-suited for compact designs.

Surface-mount RM cores are also available, enabling their use as miniature power transformers and chokes operating at frequencies approaching 1 MHz.

Typical RM (3-7) Sizes

Type	A	B	C	Type	Pin hole config.	SMD Pad config.
RM 3	7.4	7.8	7.5	1
RM 4	9.8 11.0	11.0 15.5	10.5 8.0	1 SMD
RM 4L	9.8 13.6	11.0 17.0	8.5 8.0	1 SMD
RM 5	12.3 14.2	14.6 19.0	10.5 10.7	1 SMD
RM 5L	14.2	18.9	8.0	SMD
RM 6	14.7 16.3 15.5	17.9 24.9 22.0	12.5 13.0 12.7	1 2 SMD
RM 7	17.8	20.3	13.5	1

Typical RM (8-14) Sizes

Type	A	B	C	Type	Pin hole Type 1	Pin hole Type 2
RM 8	19.7 23.5	23.2 29.9	16.5 16.5	1 2
RM 10	24.7 23.3	28.5 39.4	18.7 19.1	1 2
RM 12	29.8 28.4	37.6 45.2	24.6 23.7	1 2
RM 14	34.8 31.4	42.2 29.2	30.2 48.4	1 2
RM 12 2-Part BOBBIN	40.3	35.1	31.1	3		Dimensions defined as per type 2
RM 6/45 RM 8/45	27 27	27 28	16 20	4 4
RM 6- RM 14	Low-profile cores are also available for these types

Typical RM Power Capacities

Custom Design

LINTRON offers a broad range of transformer types, sizes, and form factors to meet diverse application requirements.

Our product portfolio covers power ratings from 1 W to 6000 W, with options for both through-hole and surface-mount (SMD) configurations.

This flexibility allows for optimized integration into designs ranging from low-power signal applications to high-power conversion systems.

For detailed specifications, custom solutions, or application support, please contact us.