Powerint LNK605DG高效3.6W LED驱动方案
Powerint公司的LinkSwitch-II系列 LNK605DG集成了700V功率MOSFET，新颖的OM/OFF控制状态机，用于自偏压的高压开关电流源，逐个周期的电流限制以及延迟的热关断电路。由于不需要光耦合器和次级控制电路，因此大大地简化了低功率CV/CC充电器的设计。230VAC时无负载的功耗低于30mW，主要用于手机/无绳电话，PDA，MP3/手提音频设备的充电器，以及LED驱动器等。本文介绍了LinkSwitch-II系列 LNK605DG主要特性，功能方框图，高能效USB充电器电路图，无偏压电源的反激电源电路图以及采用LinkSwitchTM-II LNK605DG的高效（≥75%) 3.6W绝缘led驱动器参考设计主编要特性与指标，电路图和材料清单（BOM）。
The LinkSwitch-II dramatically simplifies low power CV/CC charger designs by ELiminating an optocoupler and secondary control circuitry. The device introduces a revolutionary control technique to provide very tight output voltage and current regulation, compensating for transformer and internal parameter tolerances along with input voltage variations.
The device incorporates a 700 V power MOSFET, a novel ON/OFF control state machine, a high voltage switched current source for self biasing, frequency jittering, cycle-by-cycle current limit and hysteretic thermal shutdown circuitry onto a monolithic IC.
LNK605DG 产品亮点：
Dramatically Simplifies CV/CC Converters
? Eliminates optocoupler and all secondary CV/CC control circuitry
? Eliminates all control loop compensation circuitry
Advanced Performance Features
? Compensates for transformer inductance tolerances
? Compensates for input line voltage variations
? Compensates for cable voltage drop (LNK61X series)
? Compensates for external component temperature variations
? Very tight IC parameter tolerances using proprietary trimming technology
? Frequency jittering greatly reduces EMI filter cost
? Even tighter output tolerances achievable with external resistor selection/trimming
? Programmable switching frequency up to 85 kHz to reduce transformer size
Advanced Protection/Safety Features
? Auto-restart protection reduces power delivered by >95% for output short circuit and control loop faults (open and shorted components)
? Hysteretic thermal shutdown – automatic recovery reduces power supply returns from the field
? Meets high voltage creepage requirements between DRAIN and all other pins both on the PCB and at the package
EcoSmart® – Energy Efficient
? Easily meets all global energy efficiency regulations
? No-load consumption below 30 mW at 230 VAC with optional external bias winding
? ON/OFF control provides constant efficiency down to very light loads – ideal for CEC and ENERGY STAR 2.0 regulations
? No current sense resistors – maximizes efficiency
Green Package
? Halogen free and RoHS compliant package
LNK605DG 应用：
? Chargers for cell/cordless phones, PDAs, MP3/portable audio devices, adapters, LED drivers, etc.
图1。LNK605DG功能方框图
图2。LNK605DG高能效USB充电器电路图（平均效率74%，无负载输入功率小于30mW）
图2。无偏压电源的LinkSwitch-II 反激电源电路图
采用LinkSwitchTM-II LNK605DG的高效（≥75%) 3.6W绝缘LED驱动器参考设计
The document describes a high efficiency LED driver designed to drive 12 V at 0.3 A from an input voltage range of 90 VAC to 265 VAC. The LED driver uses the LNK605DG from the LinkSwitch-II family by Power Integrations.
LinkSwitch-II ICs allow the implementation of cost effective and low component count LED drivers meeting the compact design and high efficiency requirements necessary for high temperature operating environments.
The topology used is an isolated flyback operating in discontinuous conduction mode. Output current regulation is sensed entirely from the primary side eliminating the need for secondary side feedback components. No external current sensing is required on the primary side either as this is performed inside the IC further reducing components and losses.
The LNK605DG also provides a sophisticated range of protection features including autorestart for open control loop and output short-circuit conditions. Accurate hysteretic thermal shutdown ensures safe average PCB temperatures under all conditions. In LED luminaires the driver determines many of the performance attributes experienced by the end user including startup time and unit to unit consistency. For this design, the LNK605DG device ensures unit to unit consistency with an output CC tolerance of <?10%, fast startup time of <5 ms for instant on performance and long lifetime and high reliability due to the low component count.
This document contains the LED driver specification, schematic, PCB diagram, bill of materials, transformer documentation and typical performance characteristics.
3.6W绝缘LED驱动器参考设计主要特性：
?
Low cost, low component count and small printed circuit board footprint solution
Frequency jitter for smaller, lower cost EMI filter components
Primary side control eliminates secondary side control and optocoupler and provides +/-5% CV and +/-10% CC accuracy
?
Integrated protection and reliability features
Output open circuit / output short-circuit protected with auto-recovery
Over-temperature protection – tight tolerance (+/-5%) with hysteretic recovery for safe PCB temperature under all conditions
Extended package pin creepage distance for reliable operation in humid environments - >3.2mm at package Designed to meet
EN55015B conducted EMI with >10 dBμV margin
IEC61000-4-5 Class 3 AC line surge
IEC61000-4-2 ESD at 4 kV contact / 8 kV air.
Ultra-low AC leakage current: <5 μA at 265 VAC input (no Y capacitor required) EcoSmartTM
No-load consumption: <50 mW at 265 VAC
Efficiency: ≥75% at both 115 VAC and 230 VAC
图3。3.6W绝缘LED驱动器参考设计外形图
3.6W绝缘LED驱动器电源指标：
图4。3.6W绝缘LED驱动器参考设计电路图
3.6W绝缘LED驱动器参考设计材料清单（BOM）：
图5。变压器电路图
