NCP1246 Datasheet, PDF (1/38 Pages) ON Semiconductor – Fixed Frequency Current Mode Controller for Flyback Converters

NCP1246
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Fixed Frequency Current
Mode Controller for Flyback
Converters
The NCP1246 is a new fixedïfrequency currentïmode controller
featuring the Dynamic SelfïSupply. This function greatly simplifies
the design of the auxiliary supply and the V_CC capacitor by activating
the internal startup current source to supply the controller during
startïup, transients, latch, standïby etc. This device contains a special
HV detector which detect the application unplug from the AC input
line and triggers the X2 discharge current. This HV structure allows
the brownïout detection as well.
It features a timerïbased fault detection that ensures the detection of
overload and an adjustable compensation to help keep the maximum
power independent of the input voltage.
Due to frequency foldback, the controller exhibits excellent
efficiency in light load condition while still achieving very low
standby power consumption. Internal frequency jittering, ramp
compensation, and a versatile latch input make this controller an
excellent candidate for the robust power supply designs.
A dedicated Off mode allows to reach the extremely low no load
input power consumption via “sleeping” whole device and thus
minimize the power consumption of the control circuitry.
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MARKING
DIAGRAM
SOICï7
CASE 751U
8
46Xff
ALYWX
G
1
46Xff = Specific Device Code
X = A or B
ff = 65 or 100
A = Assembly Location
L = Wafer Lot
Y = Year
W = Work Week
G
= PbïFree Package
PIN CONNECTIONS
Latch 1
8 HV
Features
FB 2
• FixedïFrequency CurrentïMode Operation (65 kHz and 100 kHz
CS 3
6 V_CC
frequency options)
• Frequency Foldback then Skip Mode for Maximized Performance in
Light Load and Standby Conditions
GND 4
5 DRV
(Top View)
• TimerïBased Overload Protection with Latched (option A) or
AutoïRecovery (Option B) Operation
• Highïvoltage Current Source with BrownïOut Detection and
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 37 of this data sheet.
Dynamic SelfïSupply, Simplifying the Design of the V_CC Circuitry
• Frequency Modulation for Softened EMI Signature
• NoïLoad Standby Power < 30 mW
• Adjustable Overpower Protection Dependant on the
• X2 Capacitor in EMI Filter Discharging Feature
Bulk Voltage
• Latchïoff Input Combined with the Overpower
Protection Sensing Input
• V_CC Operation up to 28 V, With Overvoltage Detection
• 500/800 mA Source/Sink Drive Peak Current
Capability
• 10 ms SoftïStart
• Internal Thermal Shutdown
• These are PbïFree Devices
Typical Applications
• ACïDC Adapters for Notebooks, LCD, and Printers
• Offline Battery Chargers
• Consumer Electronic Power Supplies
• Auxiliary/Housekeeping Power Supplies
• Offline Adapters for Notebooks
This document contains information on a product under development. ON Semiconductor
reserves the right to change or discontinue this product without notice.
© Semiconductor Components Industries, LLC, 2012
1
April, 2012 ï Rev. P0
Publication Order Number:
NCP1246/D