782485 Просмотр технического описания (PDF) - Murata Power Solutions
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782485 Datasheet PDF : 2 Pages
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www.murata-ps.com
782485 Series
ADM2485 Compatible Converter Transformers
FEATURES
RoHS compliant
Analog Devices ADM2485 compatible
2.5kVrms isolation
Industry-standard pinout
UL 94 V-0 package materials
Low profile
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
specifically 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.
For full details go to
www.murata-ps.com/rohs
SELECTION GUIDE
Nominal Input
Order Code
Voltage
V
782485/35C
3.3
782485/55C
5.0
Nominal
Output Voltage
V
6.0
6.0
Max. Output
Current
mA
200
200
Isolation
Voltage
VRMS
2500
2500
Turns Package
Ratio
Style
1CT:2.2CT DIL
1CT:1.5CT DIL
CHARACTERISTICS 782485/35C
Parameter
Conditions
Primary Inductance, L
P
Leakage Inductance, L
L
Interwinding Capacitance, C
WW
Primary DC Resistance, R
DC
Volt-time Product, Et1
100kHz, 10mV
100kHz, 10mV
100kHz, 10mV
<0.1VDC
5kHz, 5V
782485/35C
782485/55C
Units
Typ. Max. Typ. Max.
234
513
μH
168
192
nH
24
50
37
50
pF
273
500
383
600
mΩ
12
19
Vμs
ABSOLUTE MAXIMUM RATINGS
Operating free air temperature range
Storage temperature range
Isolation voltage (flash tested for 1 second)
SOLDERING INFORMATION2
Peak wave solder temperature
Pin finish
Specifications typical at T = 25°C
A
1 Where pulse applied across pins 1 and 2.
2 For further information, please visit www.murata-ps.com/rohs
-40°C to 85°C
-50°C to 125°C
2.5kVrms
300˚C for 10 seconds
Matte tin
TECHNICAL NOTES
ISOLATION VOLTAGE
REPEATED HIGH-VOLTAGE ISOLATION TESTING
‘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 specified 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 specific 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.
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 specified 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.
www.murata-ps.com/support
KMP_782485C_A04 Page 1 of 2
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