Datasheet

NCS1 Series
Isolated 1W 4:1 Input Single Output DC/DC Converters
KDC_NCS1.D01 Page 2 of 8
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TEMPERATURE CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Operation -40 105
°CStorage -50 125
Case temperature rise above ambient 100% Load, Nom V
IN, Still Air 15 22
ABSOLUTE MAXIMUM RATINGS
Short-circuit protection (for SELV input voltages) Continuous
Control pin input voltage 18V Max
Lead temperature 1.0mm from case for 10 seconds (to JEDEC JESD22-B106 ISS C) 260°C
Input voltage, NCS1 12V input types 25V
Input voltage, NCS1 24V input types 40V
APPLICATION NOTES
Maximum Output Capacitance
Output Voltage Maximum Load Capacitance
VF
3.3 470
5 470
12 220
Start-up times
Part No.
Start-up times
ms
NCS1S1203SC 6
NCS1S1205SC 9
NCS1S1212SC 20
NCS1S2403SC 12
NCS1S2405SC 7
NCS1S2412SC 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.
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
=
Assuming V
C
=5V, V
D
=0.7V and V
Q
=1V:
R
1
= = 1100
NCS1
V
IN
V
C
OV
-V
IN
CTRL
R
1
D
1
Q
1
R
2
V
C
- V
D
- V
Q
I
C
5 - 0.7 - 1.0
3 x 10
-3
Maximum output capacitance should not exceed:
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.