www.murata-ps.com
78253 Series
MAX253 Compatible Converter Transformers
SELECTION GUIDE
Order Code
78253/35C
78253/35MC
78253/55C
78253/55MC
78253/35VC
78253/35MVC
78253/55VC
78253/55MVC
Input Voltage
V
3.3
5.0
3.3
5.0
Output
Voltage
V
5.0
5.0
5.0
5.0
Max. Output
Current
mA
100
200
100
200
Isolation
Voltage
V
DC
1500
1500
4000
4000
Turns
Ratio
1:2.27
1:1.31
1:2.14
1:1.33
Package
Style
DIL
SM
DIL
SM
DIL
SM
DIL
SM
FEATURES
n
RoHS compliant
n
Maxim MAX253 compatible
n
3.3V and 5V versions
n
Isolation to 4kV
DC
n
Frequency range to 500kHZ
n
Toroidal construction
n
Industry-standard pinout
n
UL 94 V-0 package materials
n
Fully encapsulated
n
Low profile
n
Surface mount option
n
Industrial temperature range
ORDER CODE DETAILS
Order Code
78253/XXC
78253/XXMC
78253/XXMC-R
Package Type
6 Pin DIL
6 Pin SM
6 Pin SM
Packaging Type
Tube
Tube
Tape & Reel
Quantity
50
50
500
78253/35(M)C CHARACTERISTICS
Parameter
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
Primary D.C. Resistance, R
DC
Volt-time Product, Et
Conditions
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
Pins 1/2 or 2/3
Min.
0.30
1.60
Typ.
0.38
2.00
0.30
30
0.40
35
Max.
0.46
2.40
1.00
50
1.00
Units
mH
mH
μH
pF
Ω
Vμs
30
78253/55(M)C CHARACTERISTICS
Parameter
Conditions
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
Pins 1/2 or 2/3
Min.
0.60
1.10
Typ.
0.83
1.40
0.35
30
0.70
50
Max.
1.10
1.70
1.00
50
1.50
Units
mH
mH
μH
pF
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.
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
Primary D.C. Resistance, R
DC
Volt-time Product, Et
Ω
Vμs
40
78253/35(M)VC CHARACTERISTICS
Parameter
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
Primary D.C. Resistance, R
DC
Volt-time Product, Et
Conditions
100kHz, 20mV
100kHz, 20mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
Pins 1/2 or 2/3
Min.
110
550
Typ.
142
710
3.00
4.20
0.30
22
Max.
185
850
5.00
8.00
0.50
Units
μH
μH
μH
pF
Surface-mount parts
The surface-mount (M suffix) products are not
recommended for new designs. For existing designs,
however, Murata Power Solutions will continue to
manufacture and fully support these parts.
For recommended alternatives please refer to the
78253J Series datasheet.
Ω
Vμs
18
78253/55(M)VC CHARACTERISTICS
Parameter
Primary Inductance, L
P
Secondary Inductance, L
S
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
Primary D.C. Resistance, R
DC
Volt-time Product, Et
All specifications typical at T
A
=25°C
Conditions
100kHz, 20mV
100kHz, 20mV
100kHz, 250mV
100kHz, 250mV
>0.1VDC
Pins 1/2 or 2/3
Min.
190
350
Typ.
240
444
5.20
4.20
0.40
28
Max.
310
540
8.00
8.00
0.60
Units
μH
μH
μH
pF
Ω
Vμs
25
For full details go to
www.cd4power.com/rohs
www.murata-ps.com/rohs
For full details go to
www.murata-ps.com/support
KMP_78253C_D04
Page 1 of 5
78253 Series
MAX253 Compatible Converter Transformers
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)C (flash tested for 1 second)
Isolation voltage 78253/XX(M)VC (flash tested for 1 second)
-40°C to 85°C
-50°C to 125°C
300°C
400mA
1500V
DC
4000V
DC
PACKAGE SPECIFICATIONS
MECHANICAL DIMENSIONS
6 Pin DIL
0.375
(9.52) MAX
6 Pin SM
Top View
1
Primary
Secondary
6
5
4
0.354
(9.0) MAX
0.5
(12.70)
0.375
(9.52) MAX
Top View
1
2
Primary
Secondary
6
5
4
0.354
(9.0) MAX
78253/35C
XYYWW
2
3
78253/55MC
XYYWW
3
0.25
(6.35)
0.25
(6.35)
0.135±0.02
(3.44±0.50)
0.012(0.30)
0.008(0.20)
0.025 (0.63)
0.021 (0.53)
0.1 (2.54)
0.012 0.30
(0.008 0.20)
0.035
(0.90)
0.1
(2.54)
0.025 (0.63)
0.021 (0.53)
0.40
(10.16)
Unless otherwise stated all dimensions in inches (mm) ±0.01 (0.25).
All pins on a 0.1 (2.54) pitch and within ±0.01 (0.25) of true position.
Package weight 1.0g Typ.
RECOMMENDED FOOTPRINT DETAILS
6 Pin DIL
0.10 (2.54) 0.10 (2.54)
0.10 (2.54) 0.10 (2.54)
0.06 (1.60) 0.06 (1.60)
6 Pin SM
Ø0.05 (1.20) +0.006(1.20) +0.006 (0.15)
Ø0.05 (0.15)
-0.000 (0.00) -0.000 (0.00)
0.04
(1.00)
0.04
(1.00)
0.10 (2.54) 0.10 (2.54)
0.45
(11.50)
0.45
(11.50)
Unless otherwise stated all dimensions in inches (mm) ±0.01 (0.25).
All pins on a 0.1 (2.54) pitch and within ±0.01 (0.25) of true position.
www.murata-ps.com/support
KMP_78253C_D04
Page 2 of 5
78253 Series
MAX253 Compatible Converter Transformers
TYPICAL CHARACTERISTICS (VOLTAGE CURVES) continued
VOLTAGE DEVIATION
110
Voltage Deviation from Nominal
25°C Output (%)
105
100
95
90
-50
78253/35(M)C
Voltage Deviation from Nominal
25°C Output (%)
110
105
100
95
90
-50
78253/55(M)C
-25
50
0
25
Temperature (°C)
78253/35(M)VC
75
100
-25
50
0
25
Temperature (°C)
78253/55(M)VC
75
100
110
Voltage Deviation from Nominal
25°C Output (%)
105
100
95
90
-50
110
Voltage Deviation from Nominal
25°C Output (%)
105
100
95
90
-50
-25
50
0
25
Temperature (°C)
75
100
-25
25
50
0
Temperature (°C)
75
100
TECHNICAL NOTES
ISOLATION
VOLTAGE
‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Volt-
age’, ‘Proof Voltage’, ‘Dielectric Withstand
Voltage’ & ‘Isolation Test Voltage’ are all terms
that relate to the same thing, a test voltage,
applied for a specified time, across a compo-
nent designed to provide electrical isolation, to
verify the integrity of that isolation.
All products in this series are 100% production
tested at their stated isolation voltage.
A question commonly asked is, “What is the
continuous voltage that can be applied across
the part in normal operation?”
For a part holding no specific agency approv-
als both input and output should normally be
maintained within SELV limits i.e. less than
42.4V peak, or 60VDC. The isolation test
voltage represents a measure of immunity to
transient voltages and the part should never
be used as an element of a safety isolation
system. The part could be expected to function
correctly with several hundred volts offset
applied continuously across the isolation bar-
rier; but then the circuitry on both sides of the
barrier must be regarded as operating at an
unsafe voltage and further isolation/insulation
systems must form a barrier between these
circuits and any user-accessible circuitry ac-
cording to safety standard requirements.
SOLDERING INFORMATION
1
REPEATED HIGH-VOLTAGE
ISOLATION TESTING
It is well known that repeated high-voltage
isolation testing of a barrier component can
actually degrade isolation capability, to a
lesser or greater degree depending on ma-
terials, construction and environment. This
series has toroidal isolation transformers,
with no additional insulation between pri-
mary and secondary windings of enameled
wire. While parts can be expected to with-
stand several times the stated test voltage,
the isolation capability does depend on the
wire insulation. Any material, including this
enamel (typically polyurethane) is suscep-
tible to eventual chemical degradation when
subject to very high applied voltages thus
implying that the number of tests should be
strictly limited. We therefore strongly advise
against repeated high voltage isolation test-
ing, but if it is absolutely required, that the
voltage be reduced by 20% from specified
test voltage.
This consideration equally applies to agency
recognized parts rated for better than
functional isolation where the wire enamel
insulation is always supplemented by a
further insulation system of physical spacing
or barriers.
Pin finish
Peak wave solder temperature
Peak reflow temperature
TUBE OUTLINE DIMENSIONS
0.43
(10.95)
0.16 (4.00)
0.023±0.005
(0.60±0.15)
0.22 (5.50)
0.15
(3.80)
0.62 (15.70)
Matte tin
300˚C for 10 seconds
220˚C
2
0.51
(12.95)
Tube length: 18.3±0.08 (465±2). Tube quantity: 50.
Tube material: Antistatic coated clear pvc.
Unless otherwise stated all dimensions in inches(mm) ±0.01 (0.25).
All specifications typical at T
A
=25°C
1 For further information, please visit www.murata-ps.com/rohs
2 For high temperature reflow parts see 78253J series.
www.murata-ps.com/support
KMP_78253C_D04
Page 4 of 5
78253 Series
MAX253 Compatible Converter Transformers
TAPE & REEL SPECIFICATIONS
REEL OUTLINE DIMENSIONS
Ø15.039 (382) Max.
2.36 (60) Min.
0.94-1.08 (23.9-27.4)
*
Ø 0.53 (13.50)
0.50 (12.80)
Leader section
15.7 (400) Min.
3.9 (100)
Min.
0.059 (1.50)
Min.
1.20
(30.4) Max.
Goods
enclosure
section
0.96 (24.4)
1.04 (26.4)
Reel quantity: 500
Unless otherwise stated all
dimensions in inches (mm) ±0.01(0.25).
* Includes flange distortion at outer edge.
Measured at hub.
Trailer section
6.3 (160) Min.
Ø 0.80 (20.20) Min.
TAPE OUTLINE DIMENSIONS
0.069 (1.75)
0.157 (4.00)
0.079 (2.00)
+0.004
+0.10
0.059 -0.000 (1.50 -0.00 )
+0.012
+0.30
0.945
-0.004
(24.00
-0.10
)
0.453 (11.50)
XYYWW
78253
35MC
Cover tape
0.369 (9.37)
0.472 (12.00)
0.024 (0.60) Max.
0.283 (7.20)
Unless otherwise stated all
dimensions in inches (mm) ±0.01(0.25).
Direction of unreeling
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
notice.
© 2011 Murata Power Solutions, Inc.
www.murata-ps.com/support
KMP_78253C_D04
Page 5 of 5
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