© Semiconductor Components Industries, LLC, 2011
July, 2011 − Rev. 2
1 Publication Order Number:
NCP1379/D
NCP1379
Quasi-Resonant
Current-Mode Controller for
High-Power Universal
Off-line Supplies
The NCP1379 hosts a high−performance circuitry aimed to
powering quasi−resonant converters. Capitalizing on a proprietary
valley−lockout system, the controller shifts gears and reduces the
switching frequency as the power loading becomes lighter. This
results in a stable operation despite switching events always occurring
in the drain−source valley. This system works down to the 4
th
valley
and toggles to a variable frequency mode beyond, ensuring an
excellent standby power performance.
The controller includes an Over Power Protection circuit which
clamps the delivered power at high−line. Safety−wise, a fixed internal
timer relies on the feedback voltage to detect a fault. Once the timer
elapses, the controller stops and enters auto−recovery mode, ensuring
a low duty−cycle burst operation. To further improve the safety of the
power supply, the NCP1379 features a pin to implement a combined
brown−out/overvoltage protection.
Particularly well suited for TVs power supply applications, the
controller features a low startup voltage allowing the use of an
auxiliary power supply to power the device.
Features
• Quasi−Resonant Peak Current−Mode Control Operation
• Valley Switching Operation with Valley−Lockout for Noise−Immune
Operation
• Frequency Foldback at Light Load to Improve the Light Load
Efficiency
• Adjustable Over Power Protection
• Auto−Recovery Output Short−Circuit Protection
• Fixed Internal 80 ms Timer for Short−Circuit Protection
• Combined Overvoltage Protection and Brown−out
• +500 mA / −800 mA Peak Current Source/Sink Capability
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• Low V
CC(on)
Allowing to Use a Standby Power Supply to Power the
Device
• Extremely Low No−Load Standby Power
• SO8 Package
• These Devices are Pb−Free and are RoHS Compliant
Typical Applications
• High Power ac−dc Converters for TVs, Set−Top Boxes etc.
• Offline Adapters for Notebooks
http://onsemi.com
See detailed ordering and shipping information in the package
dimensions section on page 21 of this data sheet.
ORDERING INFORMATION
1
8
1379
ALYW
G
1
8
1379 = Specific Device Code
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G = Pb−Free Package
MARKING
DIAGRAMS
SOIC−8
D SUFFIX
CASE 751
1
2
3
4
8
7
6
5
PIN CONNECTIONS
ZCD
FB
CS
GND
CT
FAULT
VCC
DRV
QUASI−RESONANT PWM
CONTROLLER FOR HIGH
POWER AC−DC WALL AD-
APTERS
