NCS12 Series

Isolated 12W 4:1 Input Single & Dual Output DC/DC Converters

KDC_NCS12C.A02 Page 3 of 14

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APPLICATION NOTES

Output Capacitance and start-up times

The NCS12 series does not require output capacitors to meet datasheet specification. To meet datasheet specification, total output capacitance should not exceed:

Part No.

Maximun Load Capacitance (per output)

Start-up times

μF

ms

NCS12S1203C

470

16

NCS12S1205C

470

22

NCS12S1212C

220

7

NCS12S1215C

220

8.5

NCS12S4803C

470

14

NCS12S4805C

470

22

NCS12S4812C

220

8

NCS12S4815C

220

8.5

NCS12D1205C

220

5

NCS12D1212C

100

8

NCS12D1215C

100

9

NCS12D4805C

220

5

NCS12D4812C

100

7.5

NCS12D4815C

100

7

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 specifi ed time, across a component designed to provide electrical isolation, to verify the integrity of that isolation.

Murata Power Solutions NCS12 series of DC/DC converters are all 100% production tested at their stated isolation voltage. This is 1.5kVDC 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 specifi c agency approvals, such as the NCS12 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 NCS12 series has an ER 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 polyure-

thane) 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 specifi ed 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.

RoHS COMPLIANCE INFORMATION

This series is compatible with RoHS soldering systems with a peak wave solder temperature of 260ºC for 10 seconds. The pin termination finish

on this product series is a Gold flash (0.05-0.10 micron) over Nickel Preplate. The series is backward compatible with Sn/Pb soldering systems.

For further information, please visit www.murata-ps.com/rohs