SMPS Transformers

Introduction

Switch Mode Power Supply (SMPS) transformers are an integral part of Switch Mode Power Supplies (SMPS) and DC/DC Converters.

This type of transformer operates at high frequencies, typically 200kHz–2MHz. Common ferrite types are EFD, ETD, EP and RM.

EFD Types

EFD Types are basically designed for compact DC/DC converters where low components are favourable. The bobbin part is designed to be almost fully embedded within the core contours in order to achieve a very compact design.

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 Types

ETD types are designed to give a low and optimum balance of losses, for in use in SMPS 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 Types are also available in potted versions, either for horizontal or vertical mounting. Ask for more details on this.

EP Types

EP Types are of a compact design and used mainly for high-inductance filter chokes, pulse transformers, and small power transformers where a high packing density is required. Due to the special core shape, an excellent shielding capacity is achieved.

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 Types

RM types are used in many applications e.g. as filter chokes, LF and pulse transformers and as HF power transformers in power supplies up to about 600W. Surface mounted types are available eg. for use as miniature power transformers and chokes at frquencies around 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 can offer a wide range of types, sizes and dimensions.

Power Rating: 1 to 6000W
Mounting: Through hole or Surface mounted (SMD)