NTF Series
Isolated 1W Wide Input DC/DC Converters
KDC_NTF.D01 Page 6 of 8
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APPLICATION NOTES
Recommended input & output capacitors
Although these converters will work without external capacitors, they are
necessary in order to guarantee the full parametric performance over the full
line and load range. All parts have been tested and characterized using the
following values and test circuit.
Value
CIN COUT
10µF, 200V
good low esr capacitor
22µF, 16V
good low esr capacitor
Test circuit, 5V, 12V and 15V output
ON/OFF Pin
This provides an OFF function, which puts the converter into a low power mode. When the pin is un-connected, the converter is on. The circuit used must be able to sink a peak
curent of 50mA to guarantee turning the converter off. The circuit should be an open collector arrangement, an example circuit is shown below. Voltages should not be applied
directly to the ON/OFF pin. The BC547 should be fitted close to the NTF ON/OFF pin to prevent the addition of excess wiring capacitance.
Output voltage adjustment
The trim resistor equations are:
Where:
TRIM UP TRIM DOWN
When the output voltage is trimmed up, output current must be derated so that the maximum output power is not exceeded.
NTF
COUT
CIN
- V
IN
+ V
IN
+ V
OUT
- V
OUT
CONTROL PIN CIRCUIT INPUT VOLTAGE VCONTROL
Min. Max. Units
Module ON 0 0.2 V
Module OFF 1.6 30 V
+VIN +VOUT
-VOUT
TRIM
R
UP
NTF
+VIN
+VOUT
-VOUT
TRIM
R
DOWN
NTF
RDOWN = (VDOWN - L) x G
V
NOM - VDOWN
RUP = G x L
V
UP - L - K
GLK
NTFS0505MC
30100 1.24 3.76
NTFS1205MC, NTFS2405MC
100000 1.24 3.76
NTFSXX12MC
38300 2.5 9.5
NTSFXX15MC
49900 2.5 12.5
NTF
CTRL
- V
IN
BC547
100nF
47k
V
CONTROL
