Onsemi NCP11377 | Demoboard AND9652/D

Description

The NCP11377 offers a new integrated FET solutiontargeting output power levels up to 12 W continuously in a universal−mains flyback application.Thanks to a Novel Method, this new controller saves the secondary feedback circuitry for Constant Voltage and Constant Current regulation, achieving excellent line and load regulation without traditional opto coupler and TL431 voltage reference.The NCP11377 operates in valley lockout quasi−resonant peak current mode control mode at high load to provide high efficiency. When the power on the secondary side starts to diminish, the controller automatically adjusts the duty−cycle then at lower load the controller enters in pulse frequency modulation at fixed peak current with a valley switching detection. This technique allows keeping the output regulation with tiny dummy load. Valley lockout at the first 4 valleys prevent valley jumping operation and then a valley switching at lower load provides high efficiency.This application note focuses on the experimental results of a 12−W adaptor driven by the NCP11377 and on the general behavior of this controller.

Features

• Integrated 650V Power MOSFET with rds (on) of 3.2 Ω Typical @ 25°C
• Constant Voltage Primary−Side Regulation < ± 5%
• Internal Line FeedForward\
• Quasi−Resonant with Valley Switching Operation
• Optimized light load efficiency and Stand−by performance
• Frequency clamp options
• LFF and BO Feature on a Dedicated Pin
• Cycle by Cycle Peak Current Limit
• Output Voltage Under Voltage and Over Voltage Protection (UVP or OVP)
• Secondary diode or winding Short−Circuit Protection
• UVP Built−in Blanking Time to support 5000 μF Capacitive Load Capability
• Cable Drop compensation adjustment
• Wide Operation VCC range (up to 28 V)
• Low Start−up current
• CS & Vs/ZCD pin Short and Open Protection
• Internal Temperature Shutdown
• Internal and fixed Frequency Jittering for Better EMI Signature
• These are Pb−Free Devices @ 25°C

Typical applications

• Low power AC/DC Adapters for Routers and Set−Top Box

More information

• Datasheet
• IC product information