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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

Note: Click on an image to view its full size.

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

Dimensions in mm. Views in mounting direction.

Typical EFD Power Capacities

Size f
kHz
Push-pull
W
Forward
W
Flyback
W
EFD 10 100 8-12 3-5 2-4
EFD 12 100 10-16 5-8 4-7
EFD 15 100 15-25 8-14 7-12
EFD 20 100 50-70 30-45 25-40
EFD 25 100 70-130 60-90 50-80
EFD 30 100 130-200 80-150 70-120

ETD Types

ETD types are designed to give a low and optimum balance of losses, for in use in SMPS converters.

Typical ETD Sizes

Note: Click on an image to view its full size.

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

Dimensions in mm. Views in mounting direction.

Typical ETD Power Capacities

Size f
kHz
Push-pull
W
Forward
W
Flyback
W
ETD 29 100
750
100-200
250-430
100-160
200-300
80-140
150-250
ETD 34 100
750
200-360
400-650
150-250
300-400
100-200
250-400
ETD 39 100
750
300-500
600-1000
200-350
400-700
200-330
400-600
ETD 44 25
100
250-400
500-900
100-240
400-600
120-200
300-530
ETD 49 25
100
400-630
800-1300
200-350
600-900
200-320
500-800
ETD 54 25
100
500-900
1200-2000
300-550
800-1400
300-500
750-1250
ETD 59 25
100
800-1500
2000-3500
600-900
1500-2400
500-800
1300-2000

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

Note: Click on an image to view its full size.

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

Dimensions in mm. Views in mounting direction.
Note: When mounting clips with ground pins, the dimensions A, B and C will be slightly increased accordingly.

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

Note: Click on an image to view its full size.

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

Dimensions in mm. Views in mounting direction.

Typical RM (8-14) Sizes

Note: Click on an image to view its full size.

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

Dimensions in mm. Views in mounting direction.

Typical RM Power Capacities

Size f
kHz
Push-pull
W
Forward
W
Flyback
W
RM4 100
750
10-16
20-30
5-8
10-20
4-7
10-18
RM5 100
750
15-25
30-45
8-14
20-30
8-12
20-30
RM6 100
750
30-40
50-80
20-30
40-55
15-25
30-50
RM7 100
750
40-60
60-110
25-40
50-80
20-35
40-65
RM8 100
750
50-80
100-160
40-60
70-110
30-50
60-100
RM10 100
750
80-150
150-280
60-100
120-200
50-90
100-170
RM12 100
750
130-220
200-400
90-150
200-300
70-130
150-250
RM14 100
750
200-340
400-600
130-240
300-450
120-200
250-400

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)

Lintron Electronics Ltd, Unit 6b, Wansbeck Bus Pk, Ashington, NE63 8QW | Tel: 01670 811888 | Fax: 01670 858910 |

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