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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 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.
NCS1 Series
Isolated 1W 4:1 Input Single Output DC/DC Converters
SELECTION GUIDE
Isolation Capacitance
Order Code
Input Voltage
Output Voltage
Output Current
Efficiency 5V or 24V Input.
Nom. VV
Min. Typ. mA % %
NCS1S1203SC 12 3.3 303 73 77
NCS1S1205SC 12
5 200 76 79
NCS1S1212SC 12 12 83 75 78
NCS1S2403SC 24 3.3 303 76 78.5
NCS1S2405SC 24
5 200 79 82
NCS1S2412SC 24 12 83 80 83
Efficiency 12V Input.
Min. Typ. %% 71 75 74 77 75 79 73 76 77 80 77 80
Ripple and Noise
Typ. mVp/p
24 25 40 35 27 28
Max. mVp/p
70 50 120 70 50 120
pF 24 30 35 28 42 42
MTTF1
kHrs 1020 915 1130 1217 1022 943
INPUT CHARACTERISTICS
Parameter
Conditions
Voltage range
12V input types 24V input types
Input current
NCS1S12XX NCS1S24XX
Input reflected ripple current
NCS1S12XX NCS1S24XX
5V input voltage 12V input voltage 12V input voltage 24V input voltage
Min. Typ. Max. Units
4.5 12 18 9 24 36
V
0.26
0.1 A
0.1
0.05
5 30 mA p-p
5 15
OUTPUT CHARACTERISTICS
Parameter
Conditions
Min. Typ. Max. Units
Rated power
All output types
1W
Minimal load to meet datasheet specification
10 %
Voltage set point accuracy All output types
±1 ±2 %
Line regulation
Low line to high line
±0.5 %
Load regulation
All output types
0.5 %
Transient response
Peak deviation (12.5-37.5% & 37.5-12.5% swing) Settling time (within 5% Vout Nom.)
5 %Vout 2 ms
ISOLATION CHARACTERISTICS
Parameter
Conditions
Isolation test voltage
Flash tested for 1 second
Resistance
Viso = 1kVDC
Min. Typ. Max. Units 1000 VDC
1 GΩ
GENERAL CHARACTERISTICS
Parameter
Conditions
Min. Typ. Max. Units
Switching frequency
100 400 kHz
Control pin input
Module on, pin unconnected or open collector floating Module off
0.8 V
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1 Calculated using MIL-HDBK-217 FN2, parts stress method with nominal input voltage at full load. All specifications typical at TA=25°C, nominal input voltage and rated output current unless otherwise specified.
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NCS1 Series
Isolated 1W 4:1 Input Single Output DC/DC Converters
TEMPERATURE CHARACTERISTICS Parameter Operation Storage Case temperature rise above ambient
Conditions 100% Load, Nom VIN, Still Air
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
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
Min. Typ. Max. Units -40 105 -50 125 °C
15 22
Continuous 18V Max 260°C 25V 40V
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
V C
OV
-V IN
R 1
NCS1
D 1 CTRL
R 2
Q1
D (e.g. 1N4003) is required to provide high impedence when the signal is 1
low. From the NCS1 specification, the drive current to operate this function is
recommended to be 3mA, and hence the value of R can be derived as follows: 1
V -V -V
R= 1
CD
I
Q
C
Assuming V =5V, V =0.7V and V =1V:
CD
Q
R= 1
5
- 0.7 - 1.0 3 x 10-3
=
1100Ω
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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 relat.