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SELECTION GUIDE
Efficiency
Input
Voltage Output Output 5V or 24V Input.
Voltage Current
Nom.
V
NCS1S1203SC
NCS1S1205SC
NCS1S1212SC
NCS1S2403SC
NCS1S2405SC
NCS1S2412SC
12
12
12
24
24
24
NCS1 Series
Isolated 1W 4:1 Input Single Output DC/DC Converters
Isolation
Capacitance
pF
24
30
35
28
42
42
Order Code
Efficiency
12V Input.
Min.
%
71
74
75
73
77
77
Ripple and Noise
Typ.
Max.
mVp/p mVp/p
24
25
40
35
27
28
70
50
120
70
50
120
MTTF
1
V
3.3
5
12
3.3
5
12
mA
303
200
83
303
200
83
Min.
%
73
76
75
76
79
80
Typ.
%
77
79
78
78.5
82
83
Typ.
%
75
77
79
76
80
80
kHrs
1020
915
1130
1217
1022
943
FEATURES
UL 60950 recognised
4:1 Wide range voltage input
Operating temperature range -40°C to
105°C with derating
1kVDC Isolation “Hi Pot Test”
3.3V, 5V & 12V outputs
No electrolytic capacitors
Continuous short circuit protection
INPUT CHARACTERISTICS
Parameter
Voltage range
Conditions
12V input types
24V input types
NCS1S12XX
5V input voltage
12V input voltage
12V input voltage
24V input voltage
Min.
4.5
9
Typ.
12
24
0.26
0.1
0.1
0.05
5
5
Max.
18
36
Units
V
Input current
NCS1S24XX
Input reflected ripple
current
NCS1S12XX
NCS1S24XX
A
30
15
mA p-p
OUTPUT CHARACTERISTICS
PRODUCT OVERVIEW
The NCS1 series of DC/DC converters offers a
single output voltage from input voltage ranges
of 4.5-18V and 9-36V. The NCS1 is housed in an
industry standard package with a standard pinout.
Applications include telecommunications, battery
powered systems, process control and distributed
power systems.
Parameter
Conditions
Min.
10
Typ.
Max.
1
Rated power
All output types
Minimal load to meet datasheet specification
Voltage set point accuracy All output types
Line regulation
Low line to high line
Load regulation
All output types
Peak deviation (12.5-37.5% & 37.5-12.5% swing)
Transient response
Settling time
(within 5% V
out
Nom.)
Units
W
%
%
%
%
%V
out
ms
±1
±2
±0.5
0.5
5
2
ISOLATION CHARACTERISTICS
Parameter
Isolation test voltage
Resistance
Conditions
Flash tested for 1 second
Viso = 1kVDC
Min.
1000
1
Typ.
Max.
Units
VDC
GΩ
GENERAL CHARACTERISTICS
Parameter
Switching frequency
Control pin input
Module on, pin unconnected or open collector floating
Module off
Conditions
Min.
100
Typ.
Max.
400
0.8
Units
kHz
V
1 Calculated using MIL-HDBK-217 FN2, parts stress method with nominal input voltage at full load.
For full details go to
www.murata-ps.com/rohs
All specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
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KDC_NCS1.D01
Page 1 of 8
NCS1 Series
Isolated 1W 4:1 Input Single Output DC/DC Converters
TEMPERATURE CHARACTERISTICS
Parameter
Operation
Storage
Case temperature rise above ambient
Conditions
Min.
-40
-50
Typ.
Max.
105
125
22
Units
°C
100% Load, Nom V
IN
, Still Air
15
ABSOLUTE MAXIMUM RATINGS
Short-circuit protection (for SELV input voltages)
Control pin input voltage
Lead temperature 1.0mm from case for 10 seconds (to JEDEC JESD22-B106 ISS C)
Input voltage, NCS1 12V input types
Input voltage, NCS1 24V input types
Continuous
18V Max
260°C
25V
40V
APPLICATION NOTES
Maximum Output Capacitance
Maximum output capacitance should not exceed:
Output Voltage
V
3.3
5
12
Maximum Load Capacitance
μF
470
470
220
Start-up times
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 the maximum output capacitance with increased start times.
Part No.
NCS1S1203SC
NCS1S1205SC
NCS1S1212SC
NCS1S2403SC
NCS1S2405SC
NCS1S2412SC
Start-up times
ms
6
9
20
12
7
12
Control Pin
The NCS1 converters have a shutdown feature which enables the user to put the converter into a low power state. The control pin connects directly to the base of an internal
transistor, and the switch off mechanism for the NCS1 works by forward biasing this NPN transistor. If the pin is left open (high impedance), the converter will be ON (there is
no allowed low state for this pin), but once a control voltage is applied with sufficient drive current, the converter will be switched OFF. A suitable application circuit is shown
below.
V
IN
NCS1
R
2
D
1
(e.g. 1N4003) is required to provide high impedence when the signal is
low. From the NCS1 specification, the drive current to operate this function is
recommended to be 3mA, and hence the value of R
1
can be derived as follows:
R
1
=
V
C
- V
D
- V
Q
I
C
V
C
OV
-V
IN
R
1
D
1
CTRL
Q
1
Assuming V
C
=5V, V
D
=0.7V and V
Q
=1V:
R
1
=
5 - 0.7 - 1.0
= 1100Ω
3 x 10
-3
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KDC_NCS1.D01
Page 2 of 8
NCS1 Series
Isolated 1W 4:1 Input Single Output DC/DC Converters
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 NCS1 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 NCS1 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 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 NCS1 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 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.
SAFETY APPROVAL
The NCS1 series has been recognized by Underwriters Laboratory (UL) to UL 60950 for functional insulation to a maximum case temperature of 105°C. File number E151252
applies.
The NCS1 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.
NCS1S12xxSC: 1A
NCS1S24xxSC: 0.5A
All fuses should be UL approved and rated to at least the maximum allowable DC input voltage.
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 Tin Plate, Hot Dipped over Matte Tin with Nickel Preplate. The series is backward compatible with Sn/Pb soldering
systems.
CHARACTERISATION TEST METHODS
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_NCS1.D01
Page 3 of 8
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