78250 Series
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MAX250/MAX251 Compatible Converter Transformers
CHARACTERISTICS 78250C/78250MC
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, L 10kHz, 100mV 1.0 2.0 2.5 mH
P
Leakage Inductance, L 100kHz, 100mV 2.0 3.0 H
L
Interwinding Capacitance, C 100kHz, 100mV 69 90 pF
WW
Primary D.C. Resistance, R <0.1VDC 1.0 2.0
DC
Volt-time Product, Et Pins1/2 or 2/3 50 Vs
FEATURES CHARACTERISTICS 78250VC/78250MVC
Parameter Conditions Min. Typ. Max. Units
RoHS compliant
Primary Inductance, L 10kHz, 100mV 1.0 2.0 2.5 mH
P
Maxim MAX250/MAX251 compatible
Leakage Inductance, L 100kHz, 100mV 35 40 H
L
Interwinding Capacitance, C 100kHz, 100mV 9 12 pF
Isolation to 4kVrms
WW
Primary D.C. Resistance, R <0.1VDC 1.4 1.8
DC
Industry-standard pinout
Volt-time Product, Et Pins1/2 or 2/3 50 Vs
Surface mount option
ORDER CODE DETAILS
UL 94 V-0 package materials
Order Code Package Type Packaging Type Quantity
Low prole
78250C / 78250VC 6 Pin DIL Tube 50
78250MC / 78250MVC 6 Pin SM Tube 50
Toroidal construction
78250MC-R / 78250MVC-R 6 Pin SM Tape & Reel 500
Fully encapsulated
ABSOLUTE MAXIMUM RATINGS
Industrial temperature range
-40C to 85C
Operating free air temperature range
-50C to 125C
Storage temperature range
DESCRIPTION
300C
Lead temperature 1.5mm from case for 10 seconds
The 78250 series of converter transformers Peak current, I 300mA
PK
Isolation voltage 78250(M)C (ash tested for 1 second) 1.5kVrms
are specically designed for use with Maxim
4.0kVrms
Isolation voltage 78250(M)VC (ash tested for 1 second)
chipsets to provide isolated RS232 interfaces.
Carefully controlled turns ratios ensure consistent
All specications typical at T =25C
A
performance whilst a toroidal construction
TECHNICAL NOTES
minimises EMI.
ISOLATION VOLTAGE REPEATED HIGH-VOLTAGE ISOLATION TESTING
Hi Pot Test, Flash Tested, Withstand Voltage, Proof Volt- It is well known that repeated high-voltage isolation
Surface-mount parts
age, Dielectric Withstand Voltage & Isolation Test Voltage testing of a barrier component can actually degrade
are all terms that relate to the same thing, a test voltage, isolation capability, to a lesser or greater degree
The surface-mount (M sufx) products are not
applied for a specied time, across a component designed depending on materials, construction and environ-
recommended for new designs. For existing designs,
to provide electrical isolation, to verify the integrity of that ment. This series has toroidal isolation transformers,
however, Murata Power Solutions will continue to
isolation. with no additional insulation between primary and
manufacture and fully support these parts.
secondary windings of enameled wire. While parts
All products in this series are 100% production tested at
For recommended alternatives please refer to the can be expected to withstand several times the
their stated isolation voltage.
stated test voltage, the isolation capability does de-
78250J Series datasheet.
A question commonly asked is, What is the continuous
pend on the wire insulation. Any material, including
voltage that can be applied across the part in normal opera-
this enamel (typically polyurethane) is susceptible
tion?
to eventual chemical degradation when subject to
For a part holding no specic agency approvals both input
very high applied voltages thus implying that the
and output should normally be maintained within SELV limits
number of tests should be strictly limited. We there-
i.e. less than 42.4V peak, or 60VDC. The isolation test volt-
fore strongly advise against repeated high voltage
age represents a measure of immunity to transient voltages
isolation testing, but if it is absolutely required, that
and the part should never be used as an element of a safety
the voltage be reduced by 20% from specied test
isolation system. The part could be expected to function cor-
voltage.
rectly with several hundred volts offset applied continuously
This consideration equally applies to agency recog-
across the isolation barrier; but then the circuitry on both
nised parts rated for better than functional isolation
sides of the barrier must be regarded as operating at an
where the wire enamel insulation is always supple-
unsafe voltage and further isolation/insulation systems must
mented by a further insulation system of physical
form a barrier between these circuits and any user-acces-
For full details go to
spacing or barriers.
www.murata-ps.com/rohs sible circuitry according to safety standard requirements.
www.murata-ps.com/support
KMP_78250C_C08 Page 1 of 378250 Series
MAX250/MAX251 Compatible Converter Transformers
PACKAGE SPECIFICATIONS
MECHANICAL DIMENSIONS
0.5
6 Pin DIL 6 Pin SM
(12.70)
0.375
0.375
(9.52) MAX (9.52) Max.
Primary Secondary Primary Secondary
1 6 1 6
0.354
0.354
2 2 5*
(9.0) Max.
(9.0) Max.
78250MC
78250C
3 4 3 4
XYYWW XYYWW
0.25 0.25
(6.35)
(6.35)
0.1350.02 0.0120.30
0.025 (0.63)
(3.440.50)
(0.0080.20) 0.035 (0.90)
0.021 (0.53)
0.1 (2.54)
0.025 (0.63)
0.012(0.30)
0.021 (0.53)
0.008(0.20)
0.40 0.1
(10.16)
(2.54)
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.
* Pin 5 is connected to secondary center tap. Package Weight 1.0g TYP.
RECOMMENDED FOOTPRINT DETAILS
6 Pin DIL
6 Pin SM
0.10 (2.54)
0.06 (1.60)
0.10 (2.54)
0.10 (2.54)
+0.006 (0.15)
0.05 (1.20)
-0.000 (0.00)
0.04
(1.00)
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.
1
TUBE OUTLINE DIMENSIONS
SOLDERING INFORMATION
0.43
Pin nish Matte tin
(10.95)
Peak wave solder temperature 300C for 10 seconds
Unless otherwise stated all
2
0.16 (4.00)
dimensions in inches (mm) Peak reow temperature 220C
0.01 (0.25).
1 For further information, please visit www.murata-ps.com/rohs
0.0230.005
0.51
Tube length: 18.30.08 (4652).
2 For high temperature reow parts see 78250J Series.
(0.600.15)
(12.95)
Tube material: Antistatic coated
clear pvc.
0.22 (5.50)
0.15
(3.80)
0.62 (15.70)
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KMP_78250C_C08 Page 2 of 3