原标题：On Semi NCP1631 300W SLIM LCD TV电源解决方案

　　On Semi公司的NCP1631是2相功率因素控制器,功率因素接近1,在所有条件下具有180度的相移,具有精确的零电流检测和快速线路/负载变化补偿, 驱动能力−500mA/+800 mA,主要用在计算机电源,LCD/等离子平板电视以及所有需要PFC的离线电源.本文介绍了NCP1631主要特性和安全特性,功能方框图,典型应用电路以及300W SLIM LCD TV电源参考设计考卷和方框图,电路图与材料清单.

　　The NCP1631 integrates a dual MOSFET driver for interleaved PFC applications. Interleaving consists of paralleling two small stages in lieu of a bigger one, more difficult to design. This approach has several merits like the ease of implementation, the use of smaller components or a better distribution of the heating.

　　Also, Interleaving extends the power range of Critical Conduction Mode that is an efficient and cost−effective technique (no need for low trr diodes). In addition, the NCP1631 drivers are 180phase shift for a significantly reduced current ripple.

　　Housed in a SOIC16 package, the circuit incorporates all the features necessary for building robust and compact interleaved PFC stages, with a minimum of external components.

　　NCP1631主要特性:

　　Near−Unity Power Factor

　　Substantial 180 Phase Shift in All Conditions Including Transient Phases

　　frequency Clamped Critical Conduction Mode (FCCrM)i.e.Fixed Frequency, Discontinuous Conduction Mode Operation with Critical Conduction Achievable in Most Stressful Conditions

　　FCCrM Operation Optimizes the PFC Stage Efficiency Over the Load Range

　　Out−of−phase Control for Low EMI and a Reduced rms Current in the Bulk Capacitor

　　Frequency Fold−back at Low Power to Further Improve the Light Load Efficiency

　　Accurate Zero Current Detection by Auxiliary Winding for Valley Turn On

　　Fast Line / Load Transient Compensation

　　High Drive Capability: −500 mA / +800 mA

　　Signal to Indicate that the PFC is Ready for Operation (“pfcOK” Pin)

　　VCC Range: from 10 V to 20 V

　　NCP1631安全特性:

　　Output Over and Under Voltage Protection

　　Brown−Out Detection with a 50−ms Delay to Help Meet Hold−up Time Specifications

　　Soft−Start for Smooth Start−up Operation

　　Programmable Adjustment of the Maximum Power

　　Over Current Limitation

　　Detection of Inrush Currents

　　NCP1631应用:

　　Computer Power Supplies

　　LCD / Plasma Flat Panels

　　All Off Line Appliances Requiring Power Factor Correction

　　图1.NCP1631功能方框图

　　图2.NCP1631典型应用电路图

　　300W SLIM LCD TV电源参考设计

　　This reference document describes a built-and-tested, GreenPoint® solution for an LCD-TV power solution that combines the main system power without a backlight power converter. In this architecture, the backlight power converter is designed on a separated board to allow full design flexibility and easier adaptation to any backlight solution and technology (Classical 24 V Hall Bridge resonance Power Supply or LIPS / High Voltage Inverter for CCFL, Power converter for Fronts or Edge LED Backlight or finally Power converter for PDP /Plasma panel).

　　This reference design circuit consists of a 290 mm x 310 mm printed circuit board designed to fit into the chassis of a Flat-TV. The height is limited to 8 mm to allow advanced Slim & low depth LCD TV design. All the circuitry is resident in on a single-sided PCB as might be found on an LCD-TV but with FR4 / Glass Epoxy material. This allows large holes in the PCB without adding issues in drop or vibration tests.

　　The low profile design has a direct impact on the passive component definitions.

　　The overall winding parts (common mode EMI filters, PFC coils, Standby and Flyback transformers) have been defined with a low profile ferrite core and a new bobbin, allowing the parts to be lower than 8 mm with holes in the PCB included.

　　The large electrolytic capacitors have been split into multiple lower values and inserted flat on the board. They measure a diameter of 10 mm, and also include holes in the PCB. The heat sinks have been designed with a new low profile allowing them to be below 7 mm.

　　The ON Semiconductor devices utilized are from the latest generation of controllers. This design has been engineered to achieve optimum performance compared to traditional LCD-TV power architectures, while simplifying the overall bill of materials. This is done by selecting a proprietary high performance low power mode standby integrated switcher, a high efficiency interleaved Frequency Clamp Critical Conduction Mode (FCCrM) PFC, and a Flyback controller topology that provides the power to the overall TV signal processing and audio amplifiers. To provide higher design flexibility, 2 types of Flyback controllers have been considered requiring minimal changes to move from one to the other. The first one is a new Quasi Resonance (QR) mode while the second is a fixed frequency PWM.

　　图3.300W SLIM LCD TV电源参考设计外形图

　　300W 8毫米LCD TV电源材料清单:

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