KMP_782485C_A04 Page 1 of 2
782485 Series
ADM2485 Compatible Converter Transformers
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SELECTION GUIDE
Order Code
Nominal Input
Voltage
Nominal
Output Voltage
Max. Output
Current
Isolation
Voltage Turns
Ratio
Package
Style
V V mA VRMS
782485/35C 3.3 6.0 200 2500 1CT:2.2CT DIL
782485/55C 5.0 6.0 200 2500 1CT:1.5CT DIL
CHARACTERISTICS 782485/35C
Parameter Conditions 782485/35C 782485/55C Units
Typ. Max. Typ. Max.
Primary Inductance, LP100kHz, 10mV 234 513 μH
Leakage Inductance, LL100kHz, 10mV 168 192 nH
Interwinding Capacitance, CWW 100kHz, 10mV 24 50 37 50 pF
Primary DC Resistance, RDC <0.1VDC 273 500 383 600 mΩ
Volt-time Product, Et15kHz, 5V 12 19 Vμs
ABSOLUTE MAXIMUM RATINGS
Operating free air temperature range -40°C to 85°C
Storage temperature range -50°C to 125°C
Isolation voltage (fl ash tested for 1 second) 2.5kVrms
SOLDERING INFORMATION2
Peak wave solder temperature 300˚C for 10 seconds
Pin fi nish Matte tin
Specifi cations typical at TA = 25°C
1 Where pulse applied across pins 1 and 2.
2 For further information, please visit www.murata-ps.com/rohs
TECHNICAL NOTES
ISOLATION VOLTAGE
‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Voltage’, ‘Proof Volt-
age’, ‘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.
A question commonly asked is, “What is the continuous
voltage that can be applied across the part in normal opera-
tion?”
For a part holding no specifi c agency approvals both input
and output should normally be maintained within SELV limits
i.e. less than 42.4V peak, or 60VDC. The isolation test volt-
age 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 cor-
rectly with several hundred volts offset applied continuously
across the isolation barrier; 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-acces-
sible circuitry according to safety standard requirements.
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 materials, construction and environ-
ment. This series has toroidal isolation transformers,
with no additional insulation between primary and
secondary windings of enameled wire. While parts
can be expected to withstand several times the
stated test voltage, the isolation capability does de-
pend on the wire insulation. Any material, including
this enamel (typically polyurethane) is susceptible
to eventual chemical degradation when subject to
very high applied voltages thus implying that the
number of tests should be strictly limited. We there-
fore strongly advise against repeated high voltage
isolation testing, but if it is absolutely required, that
the voltage be reduced by 20% from specifi ed test
voltage.
This consideration equally applies to agency recog-
nized parts rated for better than functional isolation
where the wire enamel insulation is always supple-
mented by a further insulation system of physical
spacing or barriers.
FEATURES
RoHS compliant
Analog Devices ADM2485 compatible
2.5kVrms isolation
Industry-standard pinout
UL 94 V-0 package materials
Low profi le
Toroidal construction
Fully encapsulated
Industrial temperature range
Surface mount versions available soon
Recommended by Analog Devices, Inc.
Backward compatible with
Sn/Pb soldering systems
DESCRIPTION
The 782485 series of converter transformers are
specifi cally designed for use with Analog Devices
chipsets to provide isolated RS-485 and RS-422
interfaces. Carefully controlled turns ratios
ensure consistent performance whilst a toroidal
construction minimises EMI.