High Frequency Quasi-
Resonant Flyback Controller
NCP1343
The NCP1343 is a highly integrated quasi−resonant flyback
controller suitable for designing high−performance off−line power
converters.
www.onsemi.com
The NCP1343 features a proprietary valley−lockout circuitry,
th
ensuring stable valley switching. This system works down to the 6
valley and transitions to frequency foldback mode to reduce switching
losses. As the load decreases further, the NCP1343 enters quiet−skip
mode to manage the power delivery while minimizing acoustic noise.
Additionally, the NCP1343 integrates power excursion mode
(PEM) to minimize transformer size in designs requiring high
transient load capability. If transient load capability is not desired, the
NCP1342 offers the same performance and features without PEM.
To ensure light load performance with high frequency designs, the
NCP1343 incorporates Rapid Frequency Foldback with Minimum
Peak Current Modulation to reduce the switching frequency quickly.
To help ensure converter ruggedness, the NCP1343 implements
several key protective features such as internal brownout detection, a
non−dissipative Over Power Protection (OPP) for constant maximum
output power regardless of input voltage, and a latched overvoltage
and NTC−ready overtemperature protection through a dedicated pin.
8
9
1
1
SOIC−9 NB
D SUFFIX
CASE 751BP
SOIC−8 NB
D SUFFIX
CASE 751
MARKING DIAGRAMS
8
9
1
343abcdef
ALYWg
G
343abcdef
ALYWg
G
1
Features
343abcdef = Specific Device Code
• Integrated High−Voltage Startup Circuit with Brownout Detection
A
L
= Assembly Location
= Wafer Lot
• Wide V Range from 9 V to 28 V
CC
Y
W
g
G
= Year
= Work Week
= Additional Options Code
= Pb−Free Package
• 28 V V Overvoltage Protection
CC
• Abnormal Overcurrent Fault Protection for Winding Short Circuit or
Saturation Detection
• Internal Temperature Shutdown
• Valley Switching Operation with Valley−Lockout for Noise−Free
Operation
• Frequency Foldback with 25 kHz Minimum Frequency Clamp for
Increased Efficiency at Light Loads
• Rapid Frequency Foldback for Fast Reduction of Switching
Frequency at Light Loads
PIN CONNECTIONS
1
Fault
HV
FMAX
FB
ZCD/OPP
CS
VCC
DRV
GND
• Skip Mode with Quiet−Skip Technology for Highest Performance
During Light Loads
1
HV
FMAX
FB
• Minimized Current Consumption for No Load Power Below 30 mW
• Frequency Jittering for Reduced EMI Signature
VCC
DRV
GND
ZCD/OPP
CS
• Latching or Auto−Recovery Timer−Based Overload Protection
• Adjustable Overpower Protection (OPP)
(Top Views)
• Adjustable Maximum Frequency Clamp
ORDERING INFORMATION
See detailed ordering and shipping information on page 3 of
this data sheet.
• CCM Operation During Power Excursion Mode (PEM)
• Fault Pin for Severe Fault Conditions, NTC Compatible for OTP
© Semiconductor Components Industries, LLC, 2018
1
Publication Order Number:
March, 2021 − Rev. 2
NCP1343/D