78253 SERIES
MAX253 Compatible Converter Transformers
SELECTION GUIDE
Input
Voltage
Output
Voltage
Output
Current
Isolation
Voltage
Turns
Ratio
Package
Style
Order Code
78253/35
78253/35M
78253/55
78253/55M
78253/35V
78253/35MV
78253/55V
78253/55MV
(V)
3.3
5.0
3.3
5.0
(V)
5.0
5.0
5.0
5.0
(mA Max)
100
200
100
200
(VDC)
1500
1500
4000
4000
1:√5
1:1.31
1:√5
1:1.36
DIP
SM
DIP
SM
DIP
SM
DIP
SM
FEATURES
s
Maxim Compatible
s
3.3V and 5V Versions
s
Isolation to 4kV
s
Frequency Range to 500kHz
s
Toroidal Construction
s
Industrial Standard Pinout
s
UL 94V-0 Package Material
s
Fully Encapsulated
s
Low Profile
s
Surface Mount Available
DESCRIPTION
The 78253 series of converter transformers
are specifically designed for use with the
MAX253 chip set to provide isolated power
supplies. The 5V version can supply 1W and
the 3.3V version can supply 500mW. A
centre tapped secondary winding allows for
full bridge, half bridge or voltage doubling.
The surface mount devices are fully
compatible with CECC00802 to 280°C
which allows them to be placed and reflowed
with IC’s thus reducing time and cost in
production.
78253/35(M) CHARACTERISTICS
Parameter
Conditions
MIN
TYP
MAX
Units
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
D.C. Resistance, R
DC
Volt-time Product, E
T
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
5kHz, 5V
0.30
1.60
0.38
2.00
0.30
30
0.40
0.46
2.40
1.00
50
1.00
mH
mH
µH
pF
Ω
Vµs
50
80
78253/55(M) CHARACTERISTICS
Parameter
Conditions
MIN
TYP
MAX
Units
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
D.C. Resistance, R
DC
Volt-time Product, E
T
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
5kHz, 5V
0.60
1.10
0.83
1.40
0.35
30
0.70
1.10
1.70
1.00
50
1.50
mH
mH
µH
pF
Ω
Vµs
50
65
78253/35(M)V CHARACTERISTICS
Parameter
Conditions
MIN
TYP
MAX
Units
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
D.C. Resistance, R
DC
Volt-time Product, E
T
100kHz, 20mV
100kHz, 20mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
5kHz, 5V
110
550
142
710
3.00
4.20
0.30
185
850
5.00
8.00
0.50
µH
µH
µH
pF
Ω
Vµs
30
42
78253/55(M)V CHARACTERISTICS
Parameter
Conditions
MIN
TYP
MAX
Units
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
D.C. Resistance, R
DC
Volt-time Product, E
T
100kHz, 20mV
100kHz, 20mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
5kHz, 5V
190
350
240
444
5.20
4.20
0.40
310
540
8.00
8.00
0.60
µH
µH
µH
pF
Ω
Vµs
25
32
ABSOLUTE MAXIMUM RATINGS
Operating free air temperature range
Storage temperature range
Lead Temperature 1.5mm from case for 10 seconds
Peak current I
PK
Isolation voltage 78253/XX(M) (flash tested for 1 second)
Isolation voltage 78253/XX(M)V (flash tested for 1 second)
–40°C to 85°C
–50°C to 125°C
300°C
400mA
1500VDC
4000VDC
www.dc-dc.com
All specifications typical at T
A
=25°C.
78253 SERIES
MAX253 Compatible Converter Transformers
MECHANICAL DIMENSIONS
6 Pin DIP
9.52 max
Top View
Primary
Secondary
6 Pin SM
12.70
9.52 max
Top View
Primary
Secondary
1
8.89 max
2
3
6
5
4
8.89 max
1
2
3
6
5
4
78253
35
78250M
XYYWW
6.35
XYYWW
6.35
3.44±0.50
0.30
0.20
10.16
2.54
0.63
0.53
0.30
0.20
0.90
2.54
0.63
0.53
All dimensions in mm XX.XX ±0.25mm. All pins on a 2.54mm pitch and within ±0.25mm of true position.
TYPICAL CHARACTERISTICS (VOLTAGE CURVES)
VOLTAGE CURVES
10
8
6
4
2
0
0
20
40 60 80 100 120
Output Current (mA)
FS=Low
FS=High
78253/35(M)
10
8
6
4
2
0
0
100
200
300
Output Current (mA)
400
78253/55(M)
FS=Low/High
10
8
6
4
2
0
0
20
40
60
80
Output Current (mA)
100
FS=High
FS=Low
78253/35(M)V
10
8
6
4
2
0
0
100
200
300
Output Current (mA)
400
FS=High
FS=Low
78253/55(M)V
EFFICIENCY CURVES
100
80
60
40
20
0
0
20
40 60 80 100 120
Output Current (mA)
78253/35(M)
FS=High
FS=Low
100
80
60
40
20
0
0
100
200
300
Output Current (mA)
400
FS=Low/High
78253/55(M)
100
80
60
40
20
0
0
20
40
60
80
Output Current (mA)
100
FS=Low
78253/35(M)V
FS=High
100
80
60
40
20
0
0
100
200
300
Output Current (mA)
400
FS=High
78253/55(M)V
FS=Low
VOLTAGE DEVIATION
110
105
100
95
90
110
110
110
78253/35(M)
FS=High
78253/55(M)
105
100
FS=High
FS=Low
105
100
95
90
78253/35(M)V
FS=High
78253/55(M)V
1
05
FS=Low
FS=Low
100
FS=Low
FS=High
95
90
95
90
-50
-25
0
25 50 75 100
Temperature (°C)
-50
-25
0
25 50 75 100
Temperature (°C)
-50
-25
0
25 50 75 100
Temperature (°C)
-50
-25
0
25 50 75 100
Temperature (°C)
C&D Technologies (NCL) Limited reserve the right to alter or improve the
specification, internal design or manufacturing process at any time, without
notice. Please check with your supplier or visit our web site to ensure that
you have the current and complete specification for your product before use.
© C&D Technologies (NCL) Limited 2000
NMP 78253.2
No part of this publication may be copied, transmitted or stored in a
retrieval system or reproduced in any way including, but not limited to,
photography, photocopy, magnetic or other recording means, without prior
written permission from C&D Technologies (NCL) Limited.
Instructions for use are available from www.dc-dc.com
C&D Technologies (NCL) Ltd
Tanners Drive, Blakelands North
Milton Keynes MK14 5BU, England
Tel: +44 (0)1908 615232
Fax:+44 (0)1908 617545
email: info@cdtechno-ncl.com
www: http://www.dc-dc.com
C&D Technologies (NCL), Inc.
8917 Glenwood Avenue, Raleigh
NC 27612, USA
Tel: +1 (919) 571-9405
Fax: +1 (919) 571-9262
email: info@us.cdtechno-ncl.com
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