NS公司的LM3433共阳高亮度LED驱动器具有高频调光功能,采用恒流方式给高亮LED供电,输入电压从-9V到-14V,输出电流大于6A,PWM频率大于30kHz,开关频率高达1MHz,静态电流低到1mA,可广泛应用于LCD背景光照明,投影系统,固态照明以便及汽车电子照明等.本文介绍了LM3433的主要性能,方框图,应用电路以及输出电流2A 到6A应用电路图与输出电流2A 到14A应用电路图.

Common Anode Capable High Brightness LED Driver with High Frequency Dimming
General Description
The LM3433 is an adaptive constant on-time DC/DC buck (step-down) constant current controller (a true current source). The LM3433 provides a constant current for illuminating
high power LEDs. The output configuration allows the anodes of multiple LEDs to be tied directly to the ground referenced chassis for maximum heat sink efficacy. The high
frequency capable architecture allows the use of small external passive components and no output capacitor while maintaining low LED ripple current. Two control inputs are used to modulate LED brightness. An analog current control input is provided so the LM3433 can be adjusted to compensate for LED manufacturing variations and/or color temperature correction.
The other input is a logic level PWM control of LED current. The PWM functions by shorting out the LED with a parallel switch allowing high PWM dimming frequencies. High
frequency PWM dimming allows digital color temperature control, interference blanking, field sequential illumination, and brightness control. Additional features include thermal
shutdown, VCC under-voltage lockout, and logic level shutdown mode. The LM3433 is available in a low profile LLP-24 package.
主要特性:

■ Operating input voltage range of -9V to -14V w.r.t. LED anode
■ Control inputs are referenced to the LED anode
■ Output current greater than 6A
■ Greater than 30kHz PWM frequency capable
■ Negative output voltage capability allows LED anode to be tied directly to chassis for maximum heat sink efficacy
■ No output capacitor required
■ Up to 1MHz switching frequency
■ Low IQ, 1mA typical
■ Soft start
■ Adaptive programmable ON time allows for constant ripple current
■ LLP-24 package
应用:
■ LCD backlighting
■ Projection systems
■ Solid state lighting
■ Automotive lighting




图1. LM3433方框图




图2. LM3433应用电路图



图3. 输出电流2A 到6A应用电路图



图4. 输出电流2A 到14A应用电路图

详情请见:

>http://cache.national.com/ds/LM/LM3433.pdf

来源：中电网