ncp1377 ON Semiconductor, ncp1377 Datasheet - Page 2

• Manufacturer Part Number: ncp1377
• Description: Current-mode Controller For Free Running Quasi-resonant Operation
• Manufacturer: ON Semiconductor

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PIN FUNCTION DESCRIPTION
Pin
1
2
3
4
5
6
7
8
Symbol
Demag
GND
V
Drv
CS
NC
HV
FB
CC
*Please refer to the application information section.
Core reset detection and OVP
Sets the peak current setpoint
Current sense input and skip
cycle level selection
High-voltage pin
Supplies the IC
The IC ground
Driving pulses
+
Function
-
OVP and
Demag
Figure 1. Typical Application Schematic
1
2
3
4
NCP1377
NCP1377, NCP1377B
The auxiliary FLYBACK signal ensures discontinuous operation and offers a fixed
overvoltage detection level of 7.2 V.
By connecting an optocoupler to this pin, the peak current setpoint is adjusted
accordingly to the output power demand. By bringing this pin below the internal
skip level, you shut off the device.
This pin senses the primary current and routes it to the internal comparator via an
L.E.B. By inserting a resistor in series with the pin, you control the level at which
the skip operation takes place.
-
The driver's output to an external MOSFET.
This pin is connected to an external bulk capacitor of typically 10 mF.
This unconnected pin ensures adequate creepage distance.
Connected to the high-voltage rail, this pin injects a constant current into the V
bulk capacitor and ensures a clean lossless startup sequence.
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8
7
6
5
2
R*
+
Description
Y1 Type
+
12 V @ 1 A
GND
CC