KMP_7625XENC_B04 Page 1 of 4
76250ENC, 76253/XXENC
EN Approved MAX250/251/253 Compatible Converter Transformers
www.murata-ps.com
www.murata-ps.com/support
For full details go to
www.murata-ps.com/rohs
FEATURES
RoHS compliant
Maxim MAX250/MAX251/MAX253
compatible
BS EN 60950 approved
Isolation to 6kVDC
Toroidal construction
Industry-standard pinout
UL 94 V-0 package materials
Fully encapsulated
Compatible with RoHS soldering systems
Backward compatible with
Sn/Pb soldering systems
DESCRIPTION
The 76250ENC converter transformer is
specifi cally designed for use with Maxim
chipsets to provide isolated RS232 interfaces. A
carefully controlled turns ratio ensures consistent
performance whilst a toroidal construction
minimises EMI.
The 76253/XXENC converter transformers are
specifi cally 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 devices are fully approved to BS EN 60950 for
use in telecoms applications.
SELECTION GUIDE
Order Code Input Voltage Output
Voltage
Max. Output
Current
Isolation
Voltage Turns
Ratio
V V mA VDC
76250ENC - - - 6000 1CT:1
76253/35ENC 3.3 5.0 100 6000 1:√5
76253/55ENC 5.0 5.0 200 6000 1:1.33
76250ENC CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP (1&5) 10kHz, 100mV 1.0 2.0 2.5 mH
Leakage Inductance, LL (1&5)2100kHz, 100mV 35 40 μH
Interwinding Capacitance, CWW (1&2) 100kHz, 100mV 1.5 3.0 pF
D.C. Resistance, RDC (1&5) <0.1VDC 1.0 2.0 Ω
Volt-time Product, ET (1&5) 50 Vμs
76253/35ENC CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP (1&5) 100kHz, 250mV 140 200 μH
Secondary Inductance, LS (2&6) 100kHz, 250mV 700 1000 μH
Leakage Inductance, LL (1&5)2100kHz, 250mV 5.0 7.0 μH
Interwinding Capacitance, CWW (1&2) 100kHz, 250mV 2.7 3.5 pF
D.C. Resistance, RDC (1&5) <0.1VDC 0.4 0.8 Ω
Volt-time Product, ET (1&5) 25 35 Vμs
76253/55ENC CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP (1&5) 100kHz, 250mV 80 150 μH
Secondary Inductance, LS (2&6) 100kHz, 250mV 142 267 μH
Leakage Inductance, LL (1&5)2100kHz, 250mV 7.0 10.0 μH
Interwinding Capacitance, CWW (1&2) 100kHz, 250mV 2.7 3.5 pF
D.C. Resistance, RDC (1&5) <0.1VDC 0.5 0.9 Ω
Volt-time Product, ET (1&5) 30 40 Vμs
ABSOLUTE MAXIMUM RATINGS
Operating free air temperature range 76250EN 0°C to 70°C
Operating free air temperature range 76253/XXEN -40°C to 85°C
Storage temperature range -50°C to 125°C
Lead temperature 1.5mm from case for 10 seconds 300°C
Peak current, IPK 76250EN 300mA
Peak current, IPK 76253/XXEN 400mA
Isolation voltage (fl ash tested for 1 second) 6000VDC
SOLDERING INFORMATION3
Peak wave solder temperature 300˚C for 10 seconds
Pin fi nish Matte tin
All specifi cations typical at TA=25°C
1 Refer to mechanical dimensions for pin locations shown in brackets.
2 With pins 2 & 6 short circuited.
3 For further information, please visit www.murata-ps.com/rohs
KMP_7625XENC_B04 Page 2 of 4
76250ENC, 76253/XXENC
EN Approved MAX250/251/253 Compatible Converter Transformers
www.murata-ps.com/support
TYPICAL CHARACTERISTICS (VOLTAGE CURVES)
VOLTAGE CURVES
Output Voltage (V)
Output Voltage (V)
Output Current (mA) Output Current (mA)
EFFICIENCY CURVES
Effi ciency (%)
Effi ciency (%)
Output Current (mA) Output Current (mA)
VOLTAGE DEVIATION
Voltage deviation from nominal
25ºC output (%)
Voltage deviation from nominal
25ºC output (%)
Temperature (ºC) Temperature (ºC)
All curves are derived from testing with the Maxim MAX235 IC using the circuit shown in application note MPAN-03 (download at http://www.murata-ps.com/data/apnotes/mpan-03.pdf).
0 20 40 60 80 100
10
8
6
4
2
0
0 100 200 300 400
10
8
6
4
2
0
76253/35ENC 76253/55ENC
0 20 40 60 80 100
100
80
60
40
20
0
0 100 200 300 400
100
80
60
40
20
0
76253/35ENC 76253/55ENC
-50 -25 0 25 50 75 100
110
105
100
95
90
-50 -25 0 25 50 75 100
76253/35ENC 76253/55ENC
110
105
100
95
90
KMP_7625XENC_B04 Page 3 of 4
76250ENC, 76253/XXENC
EN Approved MAX250/251/253 Compatible Converter Transformers
www.murata-ps.com/support
PACKAGE SPECIFICATIONS
MECHANICAL DIMENSIONS
TUBE DIMENSIONS RECOMMENDED FOOTPRINT DETAILS
* 76250EN Pin not fi tted.
Unless otherwise stated all dimensions in mm (inches) ±0.25mm (±0.01).
All pins on a 2.54mm (0.1") pitch and within ±0.25mm (0.01") of true position.
3
Tube length: 480±2.00mm (18.90±0.079"). Tube quantity: 30
Tube material: Antistatic coated clear pvc.
Unless otherwise stated all dimensions in mm (inches) -0.00 +0.50 (-0.00 +0.020).
Holes may be omitted for variants with fewer than 6 pins.
Unless otherwise stated all dimensions in mm (inches) ±0.25 (0.01).
All pins on a 2.54 (0.1) pitch and within ±0.25 (0.01) of true position.
2.54 (0.100)
2.54 (0.100)
x6 HOLES*
Ø1.00+0.15-0.00 (Ø0.039+0.006-0.000)
Primary
4.10
(0.161)
12.50
(0.492)
12.00
(0.472) 2.54
(0.1)
7.50
(0.295)
10.16 (0.4) 2.42 (0.095)
15.00
(0.59)
15.00 (0.59)
76250ENC
XYYWW
1
3
5
2
6
1
3
5
2
6
4*
Ø0.56±0.05
(Ø0.022±0.002)
Primary Secondary Secondary
1
34
5
2
6
Pin Connections 76250EN (Top View) Pin Connections 76253/XXEN (Top View)
KMP_7625XENC_B04 Page 4 of 4
76250ENC, 76253/XXENC
EN Approved MAX250/251/253 Compatible Converter Transformers
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. Specifi cations are subject to change without
notice. © 2011 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
www.murata-ps.com/support
TECHNICAL NOTES
ISOLATION VOLTAGE
‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Voltage’, ‘Proof Voltage’, ‘Dielectric Withstand
Voltage’ & ‘Isolation Test Voltage’ are all terms that relate to the same thing, a test
voltage, applied for a specifi ed time, across a component 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.
This series is recognised by the British Standards Institution to a working voltage of
300Vrms for Reinforced Insulation systems.
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 materi-
als, construction and environment. We therefore strongly advise against repeated high
voltage isolation testing, but if it is absolutely required, that the voltage be reduced by
20% from the specifi ed test voltage.
