原标题：TI UCC28810 100W PFC LED照明驱动方案

　　TI公司的ucc28810 和UCC28811是通用照明电源控制器,适合于需要功率因素修正和EMC兼容的中低功率亮度应用.

　　UCC28810/11可控制反激,降压或升压转换器.它还集成了用来处理反馈误差的跨导电压放大器,用来产生正比于输入电压的电流基准发生器,电流检测(PWM)比较器,PWM逻辑以及用来驱动外接FET的图腾柱驱动器.本文介绍了UCC28810 和UCC28811的主要特性,方框图和简化应用电路图,以及5W PFC反激转换器电路图, 用于LED照明的100W PFC AC/DC电路图和相应的材料清单(BOM).

　　The UCC28810 and UCC28811 are general lighting power controllers for low to medium power lumens applications requiring power factor correction and EMC compliance. It is designed for controlling a flyback, buck or boost converter operating in critical conduction mode. It features a transconductance voltage amplifier for feedback error processing, a simple current reference generator for generating a current command proportional to the input voltage, a current-sense (PWM) comparator, PWM logic and a totem-pole driver for driving an external FET.

　　In the critical conduction mode operation, the PWM circuit is self-oscillating with the turn-on being governed by a transformer zero energy detector (TZE pin) and the turn-off being governed by the current sense comparator. Additionally, the controller provides features such as peak current limit, restart timer, overvoltage protection (OVP), and enable.

　　The efficient system performance is attained by incorporation of zero power detect function which allows the controller output to shut down at light load conditions without running into overvoltage. The device also features an innovative slew rate enhancement circuit which improves the large signal transient performance of the voltage error amplifier. The low start-up and operating currents of the device result in low power consumption and ease of start-up. The highly-accurate internal bandgap reference leads to tight regulation of the output voltage in normal and OVP conditions, resulting in higher system reliability. The enable comparator ensures that the controller is off if the feedback sense path is broken or if the input voltage is very low.

　　There are two key parametric differences between UCC28810 and UCC28811, the UVLO turn-on threshold and the gM amplifier source current. The UVLO turn-on threshold of the UCC28810 is 15.8 V and for the UCC28811 it is 12.5 V. The gM amplifier source current for UCC28810 is typically 1.3 mA, and for the UCC28811 it is 300µA. The higher UVLO turn-on threshold of the UCC28810 allows quicker and easier start-up with a smaller VDD capacitance while the lower UVLO turn-on threshold of UCC28811 allows operation of the critical conduction mode controller to be easily controlled by the downstream PWM controller in two-stage power converters. The UCC28810 gM amplifier also provides a full 1.3-mA typical source current for faster start-up and improved transient response when the output is low either at start-up or during transient conditions. The UCC28811 is suitable for applications such as street lights and larger area luminaires where a two-stage power conversion is needed. The UCC28810 is suitable for applications such as commercial or residential retrofit luminaires where there is no down-stream PWM conversion and the advantages of smaller VDD capacitor and improved transient response can be realized.

　　Devices are available in the industrial temperature range of –40°C to 105°C. Package offering is an 8-pin SOIC (D) package.

　　UCC28810/11主要特性:

　　Transition Mode Controller for Low Implementation Cost of AC Input LED Lighting Applications

　　Implements Single Stage Power Factor Corrected LED Driver

　　Enhanced Transient Response With Slew-Rate Comparator

　　Interfaces with Traditional Wall Dimmers

　　Accurate Internal VREF for Tight Output Regulation

　　Two UVLO Options

　　Overvoltage Protection (OVP), Open-Feedback Protection and Enable Circuits

　　±750-mA Peak Gate Drive Current

　　Low Start-Up and Operating Currents

　　Lead (Pb)-Free Packages

　　UCC28810/11应用:

　　AC Input General Lighting Applications Using HB LEDs

　　Industrial, Commercial and Residential Lighting Fixtures

　　Outdoor Lighting: Street, Roadway, Parking, Construction and Ornamental LED Lighting Fixtures

图1. UCC28810/11方框图

图2.UCC28810/11简化应用电路图

图3.25W PFC反激转换器电路图

　　The PR788 is a 100 W offline AC to DC LED current driver with power factor correction. This design is a two stage converter design with a universal input boost PFC stage providing a 240 V to 400 V DC output and a low side buck stage providing the current source to power the LED’s. This design was designed to support up to 30 high brightness LED’s in series up to 900 mA average current. The design incorporates interface for microprocessor control to allow for shutdown into a low power mode (<0.5 W) and PWM dimming of the LED’s.

　　图4.用于LED照明的100W  PFC AC/DC电路图(1)

　　图5.用于LED照明的100W PFC AC/DC电路图(2)

　　用于LED照明的100W PFC AC/DC电路图PR788材料清单(BOM):

　　PR788_REVB BOM