NDTD Series
Isolated 3W Wide Input Dual Output DC/DC Converters
OUTPUT CHARACTERISTICS
Parameter
Conditions
Min.
Typ.
2
Max.
5
3
Units
%
3.3V & 5V outputs
12V & 15V outputs
Voltage set point accuracy
Line regulation
With external input/output capacitors
1
Low line to high line with external input/output capacitors
0.15
0.5
%
3.3V & 5V outputs
12V & 15V outputs
0.5
0.2
15
1.0
0.5
40
%
25% load to 100% load with external input/output
capacitors with balanced load
Load regulation
%
Ripple
BW = 20Hz to 300kHz with external input/output capacitors
BW = DC to 20MHz with external input/output capacitors
mV rms
mV p-p
Ripple & noise
90
150
NDTD05XXC, NDTD1203C,
NDTD1205C, NDTD2403C,
NDTD2405C, NDTD4803C,
NDTD4805C
5.0
% voltage change on negative output when
positive load varies from 12% to 50% of 3W rating,
with negative load fixed at 50%
Cross regulation
%
NDTD1212C, NDTD1215C,
NDTD2412C, NDTD2415C,
NDTD4812C, NDTD4815C
2.1
3.0
Short circuit protection
Continuous
GENERAL CHARACTERISTICS
Parameter
Switching frequency
Conditions
100% to 25% load, VIN min to max
Min.
60
Typ.
Typ.
Max.
620
Units
kHz
TEMPERATURE CHARACTERISTICS
Parameter
Operation
Storage
Conditions
Min.
-40
Max.
85
Units
ºC
-50
130
NDTD0503
54
40
35
NDTD1203C, NDTD2403C, NDTD4803C
Case temperature rise above
ambient in still air
NDTD0505C, NDTD0512C, NDTD1205C, NDTD2405C, NDTD4805C
NDTD0515C, NDTD1212C, NDTD1215C, NDTD2412C, NDTD4812C, NDTD2415C,
NDTD4815C
28
ISOLATION CHARACTERISTICS
Parameter
Isolation voltage
Conditions
Flash tested for 1 second
Viso=1KVDC
Min.
1000
1
Typ.
Max.
Units
VDC
GΩ
Resistance
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 NDTD 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 NDTD 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 NDTD 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.
Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232
www.murata-ps.com
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