On Semi’s NCP1611 is a drive PFC boost stage using an innovative current-controlled frequency foldback (CCFF) method, with a power factor close to 1, high drive capability of −500 mA / +800 mA, VCC range from 9.5V to 35V, with Non-latching and overvoltage protection, voltage detection, soft start and overcurrent limiting, mainly used in PC power supplies, all offline appliance power supplies that require PFC. This article introduces the main features of NCP1611, block diagram, general application circuit and 160W PFC power supply evaluation board specifications , circuit diagram and bill of materials.
The NCP1611 is designed to drive PFC boost stages based on an innovative Current Controlled Frequency Fold−back (CCFF) method. In this mode, the circuit classically operates in Critical conduction Mode (CrM) when the Inductor current exceeds a programmable value. When the current is below this preset level, the NCP1611 linearly decays the frequency down to about 20 kHz when the current is null. CCFF maximizes the efficiency at both nominal and light load. In particular, the standby losses are reduced to a minimum.
Like in FCCrM controllers, internal circuitry allows near−unity power factor even when the switching frequency is reduced. Housed in a SO−8 package, the circuit also incorporates the features necessary for robust and compact PFC stages, with few external components.
Main features of NCP1611:
Near−Unity Power Factor
Critical Conduction Mode (CrM)
Current Controlled Frequency Fold−back (CCFF): Low Frequency Operation is Forced at Low Current Levels
On−time Modulation to Maintain a Proper Current Shaping in CCFF Mode
Skip Mode Near the Line Zero Crossing
Fast Line / Load Transient Compensation (Dynamic Response Enhancer)
Valley Turn on
High Drive Capability: −500 mA / +800 mA
VCC Range: from 9.5 V to 35 V
Low Start−up Consumption
A Version: Low VCC Start-up Level (10.5 V), B Version: High VCC Start-up level (17.0 V)
Line Range Detection
This is a Pb−Free Device
NCP1611 Security Features:
Non−latching, Over−Voltage Protection
Brown−Out Detection
Soft−Start for Smooth Start−up Operation (A version)
Over Current Limitation
Disable Protection if the Feedback Pin is Not Connected
Thermal Shutdown
Low Duty−Cycle Operation if the Bypass Diode is Shorted
Open Ground Pin Fault Monitoring
Typical applications of NCP1611:
PC Power Supplies
All Off Line Appliances Requiring Power Factor Correction
Figure 1. NCP1611 block diagram
Figure 2. NCP1611 general application circuit diagram
160W Power Evaluation Board
The NCP1611 is active power factor corrected (PFC) controller specifically designed for use as a boost preconverter in ac-dc adapters, flat TVs, lighting ballasts and other medium powered offline applications. The controller is based on an innovative Current Controlled Frequency Foldback(CCFF ) method. In this mode, the circuit classically operates in Critical conduction Mode (CrM) when the inductor current exceeds a programmable value. When the current is below this preset level, the NCP1611 linearly reduces the frequency down to about 20 kHz when the current is at a null. CCFF maximizes the efficiency at both nominal and light load. In particular, the standby losses are reduced to a minimum. The controller features a robust suite of protection features to properly handle an array of power supply operating and fault conditions.
Figure 3. 160W Power Evaluation Board Outline Diagram
160W Power Evaluation Board Specifications:
Figure 4. 160W Power Supply Evaluation Board Circuit Diagram: Power Section
Figure 5. 160W Power Supply Evaluation Board Circuit Diagram: Control Section
160W Power Supply Evaluation Board Bill of Materials:
For details, see:
http://www.onsemi.cn/pub_link/Collateral/NCP1611-D.PDF
and
http://www.onsemi.cn/pub_link/Collateral/AND9062-D.PDF
as well as
http://www.onsemi.cn/pub_link/Collateral/NCP1611GEVB_BOM_ROHS.PDF
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