Document
NCP1244
Fixed Frequency Current Mode Controller for Flyback Converters
The NCP1244 is a new fixed−frequency current−mode controller featuring the Dynamic Self−Supply. This function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal startup current source to supply the controller during start−up, transients, latch, stand−by etc. This device contains a special HV detector which detect the application unplug from the AC input line and triggers the X2 discharge current.
It features a timer−based 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
SOIC−7 CASE 751U
8
44Xfff ALYWX
G 1
44Xfff = Specific Device Code X = A or B fff = 065 or 100
A = Assembly Location L = Wafer Lot Y = Year W = Work Week
G = Pb−Free Package
Features
PIN CONNECTIONS
• Fixed−Frequency Current−Mode Operation (65 kHz and 100 kHz
frequency options)
• Frequency Foldback then Skip Mode for Maximized Performance in
Light Load and Standby Conditions
• Timer−Based Overload Protection with Latched (Option A) or
Latch 1 FB 2 CS 3
GND 4
8 HV
6 VCC 5 DRV
Auto−Recovery (Option B) Operation
(Top View)
• High−voltage Current Source with Dynamic Self−Supply,
Simplifying the Design of the VCC Circuitry
• Frequency Modulation for Softened EMI Signature
• Adjustable Overpower Protection Dependant on the Bulk Voltage
ORDERING INFORMATION
See detailed ordering and shipping information in the package dimensions section on page 39 of this data sheet.
• Latch−off Input Combined with the Overpower Protection Sensing
Input
• VCC Operation up to 28 V, With Overvoltage Detection
• 500/800 mA Source/Sink Drive Peak Current
Capability
Typical Applications
• AC−DC Adapters for Notebooks, LCD, and Printers
• 10 ms Soft−Start
• Offline Battery Chargers
• Internal Thermal Shutdown
• Consumer Electronic Power Supplies
• No−Load Standby Power < 30 mW
• Auxiliary/Housekeeping Power Supplies
• X2 Capacitor in EMI Filter Discharging Feature
• Offline Adapters for Notebooks
• These Devices are Pb−Free and Halogen Free/BFR Free
© Semiconductor Components Industries, LLC, 2014
December, 2018 − Rev. 2
1
Publication Order Number: NCP1244/D
NCP1244
TYPICAL APPLICATION EXAMPLE
Figure 1. Flyback Converter Application Using the NCP1244
PIN FUNCTION DESCRIPTION
Pin No Pin Name
Function
1 LATCH
Latch−Off Input
2 FB Feedback.