NCP1203
*
+
NCP1203
1
2
EMI
FILTER
UNIVERSAL
INPUT
3
4
Adj
FB
CS V
CC
GND Drv
HV
8
7
6
5
Aux.
+
V
OUT
+
*Please refer to the application information section
Figure 1. Typical Application Example
PIN FUNCTION DESCRIPTION
Pin No.
1
Pin Name
Adj
Function
Adjust the skipping peak current
Pin Description
This pin lets you adjust the level at which the cycle skipping process takes
place. Shorting this pin to ground, permanently disables the skip cycle
feature.
By connecting an optocoupler to this pin, the peak current setpoint is
adjusted accordingly to the output power demand. Skip cycle occurs when
FB falls below Vpin1.
This pin senses the primary current and routes it to the internal comparator
via an L.E.B.
−
The driver’s output to an external MOSFET.
This pin is connected to an external bulk capacitor of typically 22
mF.
This unconnected pin ensures adequate creepage distance.
Connected to the high−voltage rail, this pin injects a constant current into
the V
CC
capacitor during the startup sequence.
2
FB
Sets the peak current setpoint
3
4
5
6
7
8
CS
GND
Drv
V
CC
NC
HV
Current sense input
The IC ground
Driving pulses
Supplies the IC
−
Ensure a clean and lossless
startup sequence
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2
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