Datasheet

ManualsBrandsMURATA POWER SOLUTIONS ManualsPSU ComponentsDC/DC converter (SMD) 24 V

MTU2 Series

Isolated 2W Single & Dual Output SM DC/DC Converters

KDC_MTU2.C02 Page 2 of 9

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TEMPERATURE CHARACTERISTICS

Parameter Conditions Min. Typ. Max. Units

Speciﬁcation All output types -40 85

°C

Storage -50 125

Case temperature rise above ambient

0305, 1205, 2405 30 45

All other variants

25 35

Cooling Free air convection

1 . Measured after 1 hour continuous operation at nominal VIN full load at the center of each PCB.

TECHNICAL NOTES

ISOLATION VOLTAGE

‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Voltage’, ‘Proof Voltage’, ‘Dielectric Withstand Volt-

age’ & ‘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 MTU2 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 MTU2 has been recognized 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 bar-

rier 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 materi-

als, construction and environment. The MTU2 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 test-

ing, but if it is absolutely required, that the voltage be reduced by 20% from speciﬁed

test voltage.

This consideration equally applies to agency recognized parts rated for better than func-

tional isolation where the wire enamel insulation is always supplemented by a further

insulation system of physical spacing or barriers.

SAFETY APPROVAL

The MTU2 series has been recognized by Underwriters Laboratory (UL) to UL 60950 for functional insulation to a maximum product PCB temperature of 120°C. Forced air cooling

may be used to maintain this temperature requirement. File number E151252 applies.

The MTU2 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.

MTU2S03xxxC: 1.5A

MTU2S05xxxC: 0.63A

MTU2S12xxxC: 0.3A

MTU2S24xxxC: 0.25A

All fuses should be UL approved and rated to at least the maximum allowable DC input voltage.