原标题：On Semi FL7734低功率相切可调光LED 照明解决方案

　　On Semi公司的FL7734是具有高级初级端调节 (PSR) 技术的高度集成 PWM控制器,用于低功率相切可调光LED照明解决方案,可以自动检测是否有调光,能实现优秀的调光兼容而不会出现闪烁,具有开路LED保护, 短路LED保护, 检测电阻短路保护,逐周期限流和过温保护(带自动重启).主要用在相位切割调光LED照明.本文介绍了FL7734主要特性,以及评估板FEBFL7734-L55H008A-GEVB主要特性,电路图和材料清单.

　　The FL7734 is a highly integrated PWM controller with advanced Primary-Side-Regulation (PSR) technique to minimize components for low power LED lighting solutions. Using the innovative TRUECURRENT technology for tight constant-current control, it enables designs with constant-current (CC) tolerance of less than ±1% in the wide line voltage range to meet stringent LED brightness requirements.

　　FL7734 can operate with all types of phase cut dimmers. Phase cut dimming is managed smoothly by bleeding current control to achieve excellent dimmer compatibility without flicker.

　　The controller can automatically detect whether there is a dimmer connection. In non dimming mode, the operating mode is set to optimize power factor and THD by enabling linear frequency control and voltage mode based on DCM.

　　An external high-voltage bleeding circuit is utilized to implement fast startup and high system efficiency. The FL7734 also provides powerful protections, such as LED open / short, sensing resistor shorted, and over-temperature for high system reliability. The FL7734 is available in 16-pin Small-Outline Package (SOP).

　　FL7734主要特性:

　　Excellent Dimmer Compatibility by Active Dimming Control

　　Programmable Dimming Curve and Input Current Management

　　Constant LED Current Regulation in Large Phase Angle Range

　　Cost-Effective Solution without Input Bulk Capacitor and Feedback Circuitry

　　Accurate Constant-Current (CC) Control, Independent on Line Voltage, Output Voltage, Magnetizing Inductance Variation

　　Power Factor Correction (PFC)

　　Fast Startup utilizing Bleeding Circuit

　　Open-LED Protection

　　Short-LED Protection

　　Sensing Resistor Short Protection

　　Cycle-by-Cycle Current Limiting

　　Over-Temperature Protection with Auto Restart

　　FL7734应用:

　　Lighting

　　LED Lighting – Low Power – Phase-cut dimming

　　LED Lighting – Mid Power – Phase-cut dimming

　　LED Lighting – High Power – Phase-cut dimming

　　FL7733A 是带有高级初级端调节 (PSR) 技术的高度集成 PWM 控制器，用于将低至中等功率 LED 照明转换器内的部件数量控制到最少。

　　通过为恒流控制而采用的创新性 TRUECURRENT® 技术，此 LED 驱动器使得通用线路电压范围内少于 ±1% 的恒流 (CC) 容差符合严格的 LED 亮度要求。

　　通过最小化导通时间波动，高功率因数和较低的 THD，可以在 FL7733A 内通用线路范围得到。 采用一个集成式高电压启动电路实现快速启动和高系统效率。 在启动期间，通过自适应反馈回路控制，预测稳态状况并设置接近于稳态的初始反馈状况，从而避免出现 LED 电流过高或过低。FL7733A 提供多种强大的保护功能，如 LED 短路/开路、输出二极管短路、检测电阻短路/开路、以及过温保护，从而实现较高的系统可靠性。

　　FL7733A 控制器采用 8 引脚小尺寸封装 (SOP)。

　　特性

　　性能

　　< 在所有条件下总恒流容差为 ±3%

　　< 在通用线路电压变化范围内为 ±1%

　　< 在负载电压变化范围是 50% - 100% 时为 ±1%

　　< 在初级电感变化范围是 ±20% 为 ±1%

　　高性价比解决方案的初级端调节 (PSR) 控制，无需输入大电容和次级反馈电路

　　应用输入电压范围： 80 VAC - 308 VAC

　　><通用线路输入范围的 0.9 高 PF 和 10% 低 THD

　　通过内部高压启动实现的快速< 200 ms 启动(需 85 VAC)带 VDD 调节

　　通过自适应反馈回路控制，实现无过冲启动系统保护

　　LED 短路/开路保护

　　输出二极管短路保护

　　检测电阻短路/开路保护

　　VDD过压保护 (OVP)

　　VDD欠压锁定 (UVLO)

　　所有保护功能都是在自动重启 (AR) 模式下实现

　　过温保护(OTP)

　　逐周期限流

　　评估板FEBFL7734-L55H008A-GEVB

　　The FEBFL7734-L55H008A-GEVB Evaluation Board is a highly integrated PWM controller with advanced Primary-Side-Regulation (PSR) technique to minimize components in low power LED lighting solutions. Using the innovative TRUECURRENT® technology for tight constant current control, it enables design with Constant Current (CC) tolerance of less than ±1% over universal line voltage range to meet stringent LED brightness requirements. FL7734 operates with all types of phase cut dimmers. Phase cut dimming is managed smoothly by Fairchild’s proprietary constant input current control, switching mode control and bleeding current control to achieve excellent dimmer compatibility without visible flicker. The controller can automatically detect when there is no dimmer connected. In non dimming mode, the operating mode is set to optimize Power Factor (PF) and Total Harmonic Discharge (THD) by enabling linear frequency control and voltage mode control with Discontinuous Conduction Mode (DCM) operation. An external bleeding MOSFET also acts as the high-voltage startup circuit to implement fast startup and high system efficiency. The FL7734 also provides powerful protections, such as LED open / short, sensing resistor shorted, and over-temperature for high system reliability.

　　图2. 评估板FEBFL7734-L55H008A-GEVB外形图

　　评估板FEBFL7734-L55H008A-GEVB主要特性:

　　性能:

　　 < ±2.6% Total Constant Current Tolerance Over All Conditions

　　 < ±1.8% Over Universal Line Voltage Variation

　　 <± 1.1% from 70% to 100% Load Voltage Variation

　　 Excellent Dimmer Compatibility by Active Dimming Control

　　 Programmable Dimming Curve and Input Current Management

　　 Fast Startup utilizing Bleeding Circuit

　　< 0.1 s at the Max. Dimmer Phase Angle

　　<0.5 s at the Min. Dimmer Phase Angle

　　 Power Factor Correction in Non-dimming Mode

　　 Constant LED Current Regulation in Large Phase Angle Range

　　系统保护:

　　 LED Short / Open Protection

　　 Output Diode Short Protection, Sensing Resistor Short / Open Protection

　　 VDD Over-Voltage Protection (OVP)

　　 VDD Under-Voltage Lockout (UVLO)

　　 Over-Temperature Protection (OTP)

　　 All Protections are Auto Restart (AR)

　　 Cycle-by-Cycle Current Limit

　　特性

　　Over-Temperature Protection (OTP)

　　LED Short / Open Protection

　　Constant LED Current Regulation in Large Phase Angle Range

　　Cost-Effective Solution without Input Bulk Capacitor and Feedback Circuitry

　　Programmable Dimming Curve and Input Current Management

　　Excellent Dimmer Compatibility by Active Dimming Control

　　All Protections are Auto Restart

　　图3. 评估板FEBFL7734-L55H008A-GEVB电路图

　　评估板FEBFL7734-L55H008A-GEVB材料清单: