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NDXS0512C Datasheet(PDF) 4 Page - Murata Manufacturing Co., Ltd.
MURATA [Murata Manufacturing Co., Ltd.]
NDXS0512C Datasheet(HTML) 4 Page - Murata Manufacturing Co., Ltd.
/ 6 page
Isolated 7.5W Wide Input Single & Dual Output DC/DC Converters
KDC_NDXC.G01 Page 4 of 6
All enquiries: www.murata-ps.com/support
Although these converters will work without external capacitors, they are
necessary in order to guarantee the full parametric performance over the full
line and load range. All parts have been tested and characterised using the
following values and test circuit.
5V & 12V
0.1μF, 25V multi-layer
100μF, 25V (low ESR)
24V & 48V
Recommended Input & Output Capacitors
Dual Output: This provides an OFF function, which puts the converter into a low
power mode. When the pin is high the converter is OFF. Standard TTL levels can
be used but the maximum high level must not exceed 7.0V. The pin can be left
open for normal operation or at voltage below 0.8V with respect to the -V
Single Output: As per dual output, however a series diode must be ﬁtted when
the control pin is used on the single output variants. Recommended diode
1N4148 or similar (direction of ﬁtting is cathode to control pin).
Load regulation is at its best when the positive and negative loads are balanced.
When the loads are asymmetric, the negative output is not as tightly regulated as the
positive output. To meet ripple speciﬁcation a total minimum load of 25% full load
is required, however, the NDX can be used with much lighter loading at the expense
of increased ripple. A small load of 150mW is required on the negative output to
ensure the maximum negative output voltage is not exceeded. NDX cross regulation
is deﬁned on page 2.
The minimum load for correct operation is 25% of the full rated load across the speciﬁed input voltage range. Lower loads may cause a signiﬁcant increase in output ripple
and may cause the output voltage to exceed its speciﬁcation transiently during power-down when the input voltage also falls below its rated minimum. A minimum loading
of 30% load is required on NDXD4805 to prevent output voltage rise above speciﬁcation during power-down.
‘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 NDX 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?”
For a part holding no speciﬁc agency approvals, such as the NDX series, 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 NDX series has an EI ferrite core, 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 recognized 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.
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