OnSemiNCP1631300WSLIMLCDTV电源解决方案

作者：时间：2012-03-12来源：网络收藏

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.