NS LM3463四路高压LED驱动解决方案
发布时间：2011-6-2 12:43
发布者：Liming
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NS 公司的LM3463是四路高压LED驱动器，LM3464输入电压为12V-80V，LM3464A输入电压为12V-95V，四路输出可单独电流稳压，通路间的精度高，数字PWM/模拟调光控制接口，动态静空控制最大化效率，主要用于街灯照明和固态照明解决方案。本文介绍了LM3464/64A 主要特性，方框图，典型应用电路图，LM3464 4路LED驱动器评估板主要特性，电路图，材料清单和PCB元件布局图。 LED Driver with Dynamic Headroom Control and Thermal Control Interfaces The LM3464/64A is a 4-channel high voltage current regulator that provides a simple solution for LED lighting applications. The LM3464/64A provides four individual current regulator channels and works in conjunction with external Nchannel MOSFETs and sense resistors to give accurate driving current for every LED string. Additionally, the Dynamic Headroom Control (DHC) output can be interfaced to the external power supply to adjust the LED supply voltage to the lowest level that is adequate to maintain all the string currents in regulation, yielding the optimal overall efficiency. Digital PWM or analog voltage signals can be used to control the duty cycle of the all the channels. When analog control is used, the dimming frequency can be programmed via an external capacitor. A minimum duty cycle control is provided in the conditions that the analog dimming is configured as thermal feedback. Protection features include VIN under-voltage lock-out, LED open/short circuit and over-temperature fault signaling to the system controller. LM3464/64A 主要特性： ■ Wide input voltage range 12V-80V (LM3464) 12V–95V (LM3464A) ■ Dynamic Headroom Control ensures maximum efficiency ■ 4 output channels with individual current regulation ■ High channel to channel accuracy ■ Digital PWM/Analog dimming control interface ■ Resistor programmable dimming frequency & minimum duty cycle (analog dimming mode) ■ Direct interface to thermal sensor ■ Fault detection ■ Over temperature protection ■ Thermal shutdown ■ Under voltage lockout ■ Thermal enhanced eTSSOP-28 package LM3464/64A应用： ■ Streetlights ■ Solid State Lighting Solutions 
图1。LM3464/64A方框图 
图2。LM3464/64A典型应用电路图 
图3。LM3464/64A和反激AC/DC转换器的典型应用电路图 
图4。LM3464/64A带热折返控制的级联应用电路图 LM3464 4路LED驱动器评估板 The LM3464 is a linear LED driver with Dynamic Headroom Control (DHC) technology designed to drive four serial high power / high brightness LED strings. Four individual linear current regulators with low-side N-channel MOSFETs realize regulations of LED currents. The DHC optimizes system efficiency automatically while maintaining stable and accurate LED currents. The LM3464 includes a voltage regulator for powering the internal circuits that operates over wide input range of 12V to 80V, eases the design of driver stage for different source voltage. The Thermal foldback feature is designed to prolong the lifetime of the LEDs by reducing the average LED current for applications with high ambient temperature. The LM3464 features a fault handling circuit that avoids system failure due to accidentally short or open circuit of LED strings. Two or more LM3464 can be cascaded to expand the number of output channels, enabling flexible system architectural design. This evaluation board demonstrates the system efficiency and LED current regulation accuracy of the LM3464 LED driver typical application circuit as a 50W LED lighting system. The schematic, bill of material and PCB layout for the evaluation board are provided in this document. The evaluation board can adapt to different types of primary power supplies with changes of value of a few components only. LM3464 4路LED驱动器评估板主要特性： • Vin range 12V to 80V • 48V LED turn ON voltage • 350mA LED current per channel • 2kHz thermal foldback dimming frequency As the LED turn-on voltage of the LM3464 evaluation board is designed to 48V, it is recommended to set the supply voltage to the evaluation board no more than 60V to avoid high power dissipation on the MOSFETs of the low-side current regulators upon system startup. For driving different number of LEDs, the startup voltage will need to be adjusted by changing the value of the resistors RFB1 and RFB2. LM3464 4路LED驱动器评估板主要特性： • Dynamic Headroom Control (DHC) • Thermal foldback control • High speed PWM dimming • Minimum brightness limit for thermal foldback control • Cascade operation for output channel expansion • Vin Under-Voltage-Lockout • Fault protection and indication • Programmable startup voltage • Thermal Shutdown 
图5。LM3464 4路LED驱动器评估板外形图 
图6。LM3464 4路LED驱动器评估板电路图 LM3464 4路LED驱动器评估板材料清单： 
图7。LM3464 4路LED驱动器评估板级联扩展输出通路 
图8。LM3464 4路LED驱动器评估板PCB元件布局图 详情请见： http://www.national.com/ds/LM/LM3464.pdf 和 http://www.national.com/an/AN/AN-2071.pdf |
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