Freescale MC3484410路LED电视背光驱动解决方案 Freescale公司的MC34844/A是集成了电源的10路LED背光驱动器，工作电压7.0-28V，能驱动160个10路并联的LED串。每串的电流匹配在±2%内，可通过I2C/SM总线接口进行编程。LED亮度调光256级，可编程到65,000:1(256:1PWM,256:1电流DAC)，集成的DC/DC转换器效率为90%，MC34844每路LED电流多达50mA，MC34844A每路LED电流多达80mA，主要用在宽达43吋HDTV，笔记本电脑，GPS屏等。本文介绍了MC34844/A 主要特性，方框图，多种应用电路以及KIT34844AEPEVBE评估板主要特性，电路图和材料清单。 10Channel LED Backlight Driver with Integrated Power Supply
The34844/A is a high efficiency,LED driver for use in backlighting LCD displays from10"to 20"+.Operating from supplies of7.0to28V,the MC34844/A is capable of driving up to160 LEDs in10parallel strings.Current in the10strings is matched to within±2%,and can be programmed via the I2C/SM Bus interface.
The34844/A also includes a Pulse Width Monitor(PWM)generator for LED dimming.The LEDs can be dimmed to one of256levels,programmed through the I2C/SM Bus interface.Up to 65,000:1(256:1PWM,256:1Current DAC)dimming ratio.
The integrated boost converter generates the minimum output voltage required to keep all LEDs illuminated with the selected current,providing the highest efficiency possible.
600x22助燃剂The34844has an integrated boost self-clocks at a default frequency of600kHz,but may be programmed via I2C to150/300/600/1200kHz.The PWM frequency can be set from100Hz to 25kHz,or can be synchronized to an external input.If not synchronized to another source,the internal PWM rate outputs on the CK pin.This enables multiple devices to be synchronized together.
The34844A has a default boost frequency of320kHz,but may be programmed via I2C to 160/320/650/1300kHz.The PWM frequency can be set from110Hz to27kHz,or can be synchronized to an external input.If not synchronized to another source,the internal PWM rate outputs on the CK pin.This enables multiple devices to be synchronized together.
The34844/A also supports optical/temperature closed loop operation and also features LED over-temperature protection,LED short protection,and LED open circuit protection.The IC also includes over-voltage protection,over-current protection,and under-voltage lockout.
石墨钢
MC34844主要特性：
•Input voltage of7.0to28V
图1。MC34844简化方框图
高压氮气压缩机
图2。MC34844简化应用框图（SM总线模式）电动牙刷结构
图4。MC34844人工模式应用电路图（单线控制）
图5。MC34844人工模式应用电路图（两线控制）
图6。MC34844SM总线模式应用电路图
楼板伸缩缝图7。MC34844SM主-从连接电路图脱硫塔内衬防腐
图8。MC34844A高输出应用电路（人工模式）：条件：VIN=60-72V,VOUT=120V，负载= 40S8P,ILED=60mA,OVP=125V,fSW=300
KIT34844AEPEVBE评估板
The KIT34844AEPEVBE Evaluation board supports the34844/A,which is a high efficiency, LED driver for use in backlighting LCD displays from10"to20"+.Operating from supplies of7.0 to28V,the MC34844/A is capable of driving up to160LEDs in10parallel strings.Current in the 10strings is matched to within±2%,and can be programmed via the I2C/SM Bus interface.
The34844/A also includes a Pulse Width Monitor(PWM)generator for LED dimming.The LEDs can be dimmed to one of256levels,programmed through the I2C/SM Bus interface.Up to 65,000:1(256:1PWM,256:1Current DAC)dimming ratio.
The integrated boost converter generates the minimum output voltage required to keep all LEDs illuminated with the selected current,providing the highest efficiency possible.
图9。KIT34844AEPEVBE评估板外形图
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