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