原标题：Powerint LNK457DG RDR251 5W TRIAC调光LED驱动方案

　　powerint公司的LNK454/456-458/460 LinkSwitch-PL系列具有小型体积和低成本的单级PFC的恒流驱动器,集成了725V功率MOSFER,新颖的不连续模式可变频率控制器,频率抖动器,逐个周期的电流限制和滞后的热关断.输入电压很宽,输出功率高达16W.本文介绍了LNK454/456-458/460产品亮点,方框图以及 5W 15V LED驱动器电路图,采用LNK4570的5W可调光PFC LED驱动器(非隔离)参考设计电路图,变压器电路图和材料清单.

　　Reference Design Report for a 5 W Dimmable Power Factor Corrected LED Driver (Non-Isolated) Using LinkSwitchTM-PL LNK457DG LNK454/456-458/460 LinkSwitch-PL Family LED Driver IC with TRIAC Dimming, Single-Stage PFC and Constant Current Control for Non-Isolated Applications

　　The LinkSwitch-PL family enables a very small and low cost single-stage power factor corrected constant current driver for solid state lighting. Optimized for direct LED current sensing, the LinkSwitch-PL operates over a wide input voltage range delivering an output power of up to 16 W. The LinkSwitch-PL control algorithm provides flicker-free TRIAC dimming with minimal external components.

　　Each device incorporates a 725 V rated power MOSFET, a novel discontinuous mode variable frequency variable on-time controller, frequency jitter, cycle by cycle current limit and hysteretic thermal shutdown in a monolithic 4-pin IC, available in SO-8C, eSOP-12, and eDIP-12 packages.

　　LNK454/456-458/460产品亮点:

　　Dramatically Simplifies Off-line LED Drivers

　　• Flicker-free phase-controlled TRIAC dimming

　　• Single stage power factor correction and accurate constant current (CC) output

　　• Very low component count with small non-electrolytic bulk capacitor for compact replacement lamp designs

　　• Compact SO8, eSOP, and eDIP packages

　　• Completely eliminates control loop compensation Advanced Performance Features

　　• Optimized for non-isolated flyback designs

　　• Frequency jitter greatly reduces EMI filter size and costs

　　• Low dissipation direct sensing of LED current Advanced Protection and Safety Features

　　• Cycle skipping regulation for abnormally low output power to clamp peak output current delivered

　　• 725 V integrated power MOSFET allows small bulk capacitance and maximizes power capability

　　• Short-circuit, overload, open feedback and output overvoltage protection

　　• Hysteretic thermal shutdown

　　• Meets high-voltage creepage between DRAIN and all other pins both on PCB and at package EcoSmart™ - Energy Efficient

　　• High power factor optimizes system lumen per input VA

　　• Control algorithm balances switching and conduction losses over line and load to maintain optimum efficiency

　　图1.LNK454/456-458/460功能方框图

　　图2.LNK454/456-458/460典型应用电路图

　　图3.采用LNK4570的5W 15V LED驱动器电路图

　　采用LNK4570的5W可调光PFC LED驱动器(非隔离)参考设计

　　Reference Design Report for a 5 W Dimmable Power Factor Corrected LED Driver (Non- Isolated) Using LinkSwitchTM-PL LNK457DG

　　参考设计主要特性:

　　Single stage power factor correction and accurate constant current (CC) output Low cost, low component count and small PCB footprint solution Superior performance and end user experience

　　>100:1 dimming range even with low cost leading edge TRIAC dimmers

　　Clean monotonic start-up – no output blinking

　　Fast start-up (<300 ms) – no perceptible delay

　　Consistent dimming performance unit to unit Highly energy efficient

　　>73% at 115 VAC / 230 VAC (dimmable configuration)

　　>78% at 115 VAC / 230 VAC (non-dimmable configuration)

　　Integrated protection and reliability features

　　Output open-circuit protected / output short-circuit protected with auto-recovery

　　Auto-recovering thermal shutdown with large hysteresis protects both components and printed circuit board

　　No damage during brown out conditions

　　Extended pin creepage distance between device DRAIN pin and other pins for reliable operation in high pollution and humid environments

　　Meets IEC ringwave and EN55015 conducted EMI

　　PF >0.9 at 115 VAC / 230 VAC

　　%ATHD <10% at 115 VAC and <15% at 230 VAC

　　Meets EN61000-3-2 harmonics contents

　　This document is an engineering report describing a non-isolated LED driver (power supply) utilizing a LNK457DG from the LinkSwitch-PL family of devices.

　　The RD-251 provides a single constant current output of 350 mA over an LED string voltage of 12 V and 18 V. The output current can be reduced using a standard AC mains TRIAC dimmer down to 1% (3 mA) without instability and flickering of the LED load. The board is compatible with both low cost leading edge and more sophisticated trailing edge dimmers.

　　The board was optimized to operate over the universal AC input voltage range (85 VAC to 265 VAC, 47 Hz to 63 Hz) but suffers no damage over an input range of 0 VAC to 300 VAC. This increases field reliability and lifetime during line sags and swells. LinkSwitch- PL based designs provide a high power factor (>0.9) meeting current international requirements and enabling a single design to be used worldwide.

　　The form factor of the board was chosen to meet the requirements for standard pear shaped (A19) LED replacement lamps. The output is non-isolated and requires the mechanical design of the enclosure to isolate the output of the supply and the LED load from the user.

　　The document contains the power supply specification, schematic, bill of materials,transformer documentation, printed circuit layout, and performance data.

　　图4. 5W参考设计外形图

　　图5. 5W可调光参考设计电路图

　　5W可调光参考设计材料清单(BOM):

　　图6.参考设计边压器电路图