The voltage tolerance envelope shows typical load regulation characteristics for this
product series. The tolerance envelope is the maximum output voltage variation due
to changes in output loading.
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 specified time, across a component designed to provide electrical isolation, to verify the integrity of that isolation.
Murata Power Solutions MEA1 series of DC/DC converters are all 100% production tested at their stated isolation voltage. This is 1kVDC for 1 second.
A question commonly asked is, “What is the continuous voltage that can be applied across the part in normal operation?”
The MEA1 has been recognised by Underwriters Laboratory for functional insulation, 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 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-accessible 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 environment. The MEA1 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 depend 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
therefore 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 recognised 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.
SAFETY APPROVAL
The MEA1 series has been recognised by Underwriters Laboratory (UL) to UL 60950 for functional insulation in a maximum ambient temperature of 85°C and/or case temperature
limit of 130°C (case temperature measured on the face opposite the pins). File number E151252 applies.
The MEA1 Series of converters are not internally fused so to meet the requirements of UL 60950 an anti-surge input line fuse should always be used with ratings as defined below.
MEA1D05xxxC: 1A
MEA1D12xxxC: 0.375A
MEA1D15xxxC: 0.375A
MEA1D24xxxC: 0.2A
MEA1D48xxSC: 0.1A
All fuses should be UL approved and rated to at least the maximum allowable DC input voltage.
www.murata-ps.com/support
KDC_MEA1.C08
Page 3 of 8
MEA1 Series
1kVDC Isolated 1W Dual Output DC/DC Converters
APPLICATION NOTES
Minimum load
The minimum load to meet datasheet specification is 10% of the full rated load across the specified input voltage range. Lower than 10% minimum loading will result in
an increase in output voltage, which may rise to typically double the specified output voltage if the output load falls to less than 5%.
Capacitive loading and start up
Typical start up times for this series, with a typical input voltage rise time of 2.2μs and output capacitance of 10μF, are shown in the table below. The product
series will start into a capacitance of 47μF with an increased start time, however, the maximum recommended output capacitance is 10μF.
Start-up time
μs
939
2872
5325
8895
1150
3716
6912
10810
883
3160
Start-up time
μs
5630
8585
472
1473
2643
4348
586
1705
2995
4722
Typical Start-Up Wave Form
MEA1D0505xC
MEA1D0509xC
MEA1D0512xC
MEA1D0515xC
MEA1D1205xC
MEA1D1209xC
MEA1D1212xC
MEA1D1215xC
MEA1D1505xC
MEA1D1509xC
MEA1D1512xC
MEA1D1515xC
MEA1D2405xC
MEA1D2409xC
MEA1D2412xC
MEA1D2415xC
MEA1D4805xC
MEA1D4809xC
MEA1D4812xC
MEA1D4815xC
Ripple & Noise Characterisation Method
Ripple and noise measurements are performed with the following test configuration.
1μF X7R multilayer ceramic capacitor, voltage rating to be a minimum of 3 times the output voltage of the DC/DC converter
10μF tantalum capacitor, voltage rating to be a minimum of 1.5 times the output voltage of the DC/DC converter with an ESR of less
C2
than 100mΩ at 100 kHz
C3
100nF multilayer ceramic capacitor, general purpose
R1
450Ω resistor, carbon film, ±1% tolerance
R2
50Ω BNC termination
T1
3T of the coax cable through a ferrite toroid
RLOAD
Resistive load to the maximum power rating of the DC/DC converter. Connections should be made via twisted wires
Measured values are multiplied by 10 to obtain the specified values.
C1
Differential Mode Noise Test Schematic
DC/DC Converter
OSCILLOSCOPE
C1 C2 C3
+
SUPPLY
Input
R1
T1
R2
Y INPUT
+
Output
-
-
R LOAD
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KDC_MEA1.C08
Page 4 of 8
MEA1 Series
1kVDC Isolated 1W Dual Output DC/DC Converters
APPLICATION NOTES (continued)
Output Ripple Reduction
By using the values of inductance and capacitance stated, the output ripple at the rated load is lowered to 5mV p-p max.
Component selection
Capacitor: It is required that the ESR (Equivalent Series Resistance) should be as low as possible, ceramic types are recommended.
The voltage rating should be at least twice (except for 15V output), the rated output voltage of the DC/DC converter.
Inductor: The rated current of the inductor should not be less than that of the output of the DC/DC converter. At the rated current, the DC resistance of the inductor
should be such that the voltage drop across the inductor is <2% of the rated voltage of the DC/DC converter. The SRF (Self Resonant Frequency) should be
L
>20MHz.
+V
OUT
Power
Source
DC
DC
C
OV
C
-V
OUT
L
Load
Load
MEA1D0505xC
MEA1D0509xC
MEA1D0512xC
MEA1D0515xC
MEA1D1205xC
MEA1D1209xC
MEA1D1212xC
MEA1D1215xC
MEA1D1505xC
MEA1D1509xC
MEA1D1512xC
MEA1D1515xC
MEA1D2405xC
MEA1D2409xC
MEA1D2412xC
MEA1D2415xC
MEA1D4805xC
MEA1D4809xC
MEA1D4812xC
MEA1D4815xC
L, μH
10
22
47
47
10
22
47
47
10
22
47
47
10
22
47
47
10
22
47
47
Inductor
SMD
82103C
82223C
82473C
82473C
82103C
82223C
82473C
82473C
82103C
82223C
82473C
82473C
82103C
82223C
82473C
82473C
82103C
82223C
82473C
82473C
Through Hole
11R103C
11R223C
11R473C
11R473C
11R103C
11R223C
11R473C
11R473C
11R103C
11R223C
11R473C
11R473C
11R103C
11R223C
11R473C
11R473C
11R103C
11R223C
11R473C
11R473C
Capacitor
C, μF
4.7
2.2
1
1
4.7
2.2
1
1
4.7
2.2
1
1
4.7
2.2
1
1
4.7
2.2
1
1
RoHS COMPLIANT INFORMATION
This series is compatible with RoHS soldering systems with a peak wave solder temperature of
260°C for 10 seconds. The pin termination finish on the SIP package type is Tin Plate, Hot Dipped
over Matte Tin with Nickel Preplate. The DIP types are Matte Tin over Nickel Preplate. Both types in
this series are backward compatible with Sn/Pb soldering systems.
For further information, please visit www.murata-ps.com/rohs
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