NCP1217_05 Datasheet, PDF (2/18 Pages) ON Semiconductor – Enhanced PWM Current−Mode Controller for High−Power Universal Off−Line Supplies

EMI
FILTER
UNIVERSAL
INPUT
NCP1217, NCP1217A
See Application
Section
+
NCP1217
1 ^{Adj HV} 8
2 ^FB
7
3 ^{CS VCC} 6
Gnd Drv
4
5
Aux.
Ramp Adjustment ₊
V_OUT
+
Figure 1. Typical Application Example
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1
Adj
Adjust the skipping peak current 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 bringing this pin above 3.1 V, you permanently shut off the device.
2
FB
Sets the peak current setpoint By connecting an optocoupler to this pin, the peak current setpoint is ad-
justed accordingly to the output power demand.
3
CS
Current sense input
This pin senses the primary current and routes it to the internal compara-
tor via an L.E.B. By inserting a resistor in series with the pin, you control
the amount of ramp compensation you need.
4
Gnd
The IC ground
−
5
Drv
Driving pulses
The driver’s output to an external MOSFET.
6
V_CC
Supplies the IC
7
NC
−
This pin is connected to an external bulk capacitor of typically 22 mF.
This unconnected pin ensures adequate creepage distance.
8
HV
Ensures a clean and lossless
Connected to the high−voltage rail, this pin injects a constant current into
startup sequence
the V_CC capacitor during the startup sequence.
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