OnSemi公司的NCL30081是一款定位在隔離反激式拓撲和非隔離恒流拓撲的PWM電流模式控制器。該控制器采用準諧振模式提供高效率，這種新穎的控制方法可以從原邊精確控制輸出恒定LED電流，該控制輸出通過副邊反饋電路系統、偏置電路和一個光耦合器實現。本文首先介紹芯片的簡介、特性、內部框圖及應用領域，并給出相應設計方案的設計原理圖、元器件列表及PCB元件布局圖。
The NCL30081 is a PWM current mode controller targeting isolated flyback and non−isolated constant current topologies. The controller operates in a quasi−resonant mode to provide high efficiency. Thanks to a novel control method, the device is able to precisely regulate a constant LED current from the primary side. This removes the need for secondary side feedback circuitry, biasing and an optocoupler.
The device is highly integrated with a minimum number of external components. A robust suite of safety protection is built in to simplify the design. This device is specifically intended for very compact space efficient designs. It supports step dimming by monitoring the AC line and detecting when the line has been toggled on−off−on by the user to
reduce the light intensity in 5 steps down to 5% dimming.
NCL30081主要特性：
• Quasi−resonant Peak Current−mode Control Operation
• Primary Side Sensing (no optocoupler needed)
• Wide VCC Range
• Precise LED Constant Current Regulation ±1% Typical
• Line Feed−forward for Enhanced Regulation Accuracy
• Low LED Current Ripple
• 250 mV ±2% Guaranteed Voltage Reference for Current Regulation
• ~ 0.9 Power Factor with Valley Fill Input Stage
• Low Start−up Current (10 _A typ.)
• Small Space Saving Low Profile Package
• 5 State Quasi−log Dimmable
• Wide Temperature Range of −40 to +125°C
• Pb−free, Halide−free MSL1 Product
• Robust Protection Features
♦ Over Voltage / LED Open Circuit Protection
♦ Secondary Diode Short Protection
♦ Output Short Circuit Protection
♦ Shorted Current Sense Pin Fault Detection
♦ Latched and Auto−recoverable Versions
♦ Brown−out
♦ VCC Under Voltage Lockout
♦ Thermal Shutdown
NCL30081應用：
• Integral LED Bulbs
• LED Power Driver Supplies
• LED Light Engines
圖1. NCL30081內部方框圖
NCL30081方案介紹：
This documentation package covers an NCL30081 LED driver for use in a GU10 based LED lamp. The output is mains isolated by double insulation. Maximum input power is 5 W. The ECA (Electronic Circuit Assembly) supports 2 versions; one step dimming and one non-dimming version. The version is controlled through minor bill-of-material changes. The LED current dims in 5 discrete levels sequentially by detecting the interruption of the AC mains briefly (about 1 s) to step the LED current down one level until it cycles back to full current.
NCL30081方案原理圖：
圖2. NCL30081方案原理圖
NCL30081方案材料清單：
PCB元件布局圖：
