© Semiconductor Components Industries, LLC, 2016
October, 2016 − Rev. 13
1 Publication Order Number
NCP1239/D
NCP1239
Fixed Frequency
Current‐Mode Controller for
Flyback Converter
The NCP1239 is a fixed-frequency current-mode controller
featuring a high-voltage start-up current source to provide a quick and
lossless power-on sequence. This function greatly simplifies the
design of the auxiliary supply and the V
CC
capacitor by activating the
internal start-up current source to supply the controller during start-up,
transients, latch, stand-by etc.
With a supply range up to 35 V, the controller hosts a jittered 65 or
100-kHz switching circuitry operated in peak current mode control.
When the power on the secondary side starts to decrease, the controller
automatically folds back its switching frequency down to minimum
level of 26 kHz. As the power further goes down, the part enters skip
cycle while limiting the peak current that insures excellent efficiency
in light load condition.
NCP1239 features a timer-based fault detection circuitry that
ensures a quasi-flat overload detection, independent of the input
voltage.
Features
• Fixed-Frequency 65-kHz or 100-kHz Current-Mode Control
Operation
• Frequency Foldback Down to 26 kHz and Skip Mode to
Maximize Performance in Light Load Conditions
• Adjustable Over Power Protection (OPP) Circuit
• High-Voltage Current Source with Brown-Out (BO) Detection
• Internal Slope Compensation
• Internal Fixed Soft-Start
• Frequency Jittering in Normal and Frequency Foldback Modes
• 64-ms Timer-Based Short-Circuit Protection with Auto-Recovery
or Latched Operation
• Pre-Short Ready for Latched OCP Versions
• Latched OVP on VCC – Autorecovery for C and E Versions
• Latched OVP/OTP Input for Improved Robustness
• 35-V V
CC
Operation
• ±500 mA Peak Source/Sink Drive Capability
• Internal Thermal Shutdown
• Extremely Low No-Load Standby Power
• Pin-to-Pin Compatible with the Existing NCP1236/1247 Series
• These Devices are Pb-Free and are RoHS Compliant
Typical Applications
• AC-DC Converters for TVs, Set-Top Boxes and Printers
• Offline Adapters for Notebooks and Netbooks
MARKING DIAGRAM
SOIC−7
CASE 751U
www.onsemi.com
PIN CONNECTIONS
1239xfff = Specific Device Code
x = A, B, C, D, E, F, G, H, I or J
fff = 065 or 100
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G = Pb−Free Package
1239xfff
ALYWX
G
1
8
HV
VCC
DRV
Fault
FB
CS
GND
ORDERING INFORMATION
8
6
5
1
3
4
2
See detailed ordering and shipping information on page 25 o
this data sheet.
