NCP1077A: Enhanced Off line Switcher for Robust and Highly Efficient Power Supplies
Description: The NCP1077A & NCP1077B products integrate a fixed...
The NCP1077A & NCP1077B products integrate a fixed frequency current mode controller with a 700 V MOSFET. Available in a two different pin out of the very common PDIP 7 package, it offers a high level of integration, including soft start, frequency jittering, short circuit protection, skip cycle, a maximum peak current set point, ramp compensation, and a dynamic self supply (DSS, eliminating the need for an auxiliary winding).
Unlike other monolithic solutions, the NCP1077A & NCP1077B is quiet by nature: during nominal load operation, the part switches at one of the available frequencies (65 or 100 kHz). When the output power demand diminishes, the IC automatically enters frequency foldback mode and provides excellent efficiency at light loads. When the power demand reduces further, it enters into a skip mode to reduce the standby consumption down to a no load condition.
Protection features include: a timer to detect an overload or a short circuit event, Over voltage Protection with auto recovery. Ac input line voltage detection prevents lethal runaway in low input voltage conditions (Brown-out) as well as too high an input line (Ac line Over voltage Protection). This also allows an Over power Protection to compensate all internal delays in high input voltage conditions and optimize the maximum output current capability.
For improved standby performance, the connection of an auxiliary winding stops the DSS operation and helps to reduce input power consumption below 50 mW at high line.
Integrated 700 V MOSFET with RDS(on) of 4.7 Ω - Up to 30W output SMPS design capability
Current-Mode Fixed Frequency Operation (65 & 100 kHz) - 130 kHz for B version only - Ability to scale for efficiency or size
Peak Current: NCP1076A/B = 650mA and NCP1077A/B = 800 mA - Adjust output current protection based on output power demand
Skip-Cycle Operation at Low Peak Current - Eliminate acoustic noise
Dynamic Self-Supply (DSS) - Eliminate Aux winding
Auto-Recovery Output Short Circuit Protection with Timer-Based Detection - Provides more robust protection without worrying about the coupling of the aux winding
Frequency Foldback Operation - Improved efficiency at light load / Improved EMI over the entire load
300 µA No Load Power Consumption - <50mW no Load Power Consumption
Frequency Jittering (including during frequency foldback mode) - Better EMI Signature Over the Entire Operating Range
Adjustable Brown-out Protection and OVP - Enhanced Protection Against too Low or too High Input Voltage
Over Power Protection - Higher Protection of the load in wide Mains Conditions
2nd Level Current Protection - Protection in case of secondary diode short
Auxiliary & Standby Power Supply
Major Home Appliances power supplies
Low to medium Power Chargers & Adapters
Consumer Equipment Power Supply
Technical Documentation & Design Resources
fsw Typ (kHz):
fJitter Typ (%):
RDS(ON) Typ (Ω):
V(BR)DSS Max (V):
HV Start-up Min (V):
Short Circuit Protection:
Over Power Compensation:
PDIP8 Less Pin 3