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| TI TPS6118x白光LED驱动方案 |
| 作者： 时间：2008-09-03 来源:eaw |
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TI 公司的TPS6118x是媒体LCD背景光高度集成的解决方案,有内置的集成了1.5A/40C功率MOSFET的高效升压稳压器,6个高精度电流和匹配的稳压器,器件支持总数高达60个白光LED(WLED).此外,升压稳压器的输出能根据自动WLED的正向压降来调整,以提高效率. TPS6118x的输入电压5 V 到24 V,100:1的PWM亮度调整,可广泛应用于笔记本电脑和UMPC LCD显示器背景光,以及各种媒体尺寸的LCD显示器背景光.本文介绍了TPS61180/1/2的主要性能, 功能方框图, 典型应用电路图, 评估板电路图和材料清单(BONM)以及音频降噪电路和多种高亮度LED串驱动电路图.
The TPS61180/1/2 ICs provide highly integrated solutions for media size LCD backlight. These devices have a built-in high efficiency boost regulator with integrated 1.5A/40V power MOSFET. The six current sink regulators provide high precision current regulation and matching. In total, the device can support up to 60 WLED. In addition, the boost output automatically adjusts its voltage to the WLED forward voltage to improve efficiency.
The devices support pulse width modulation (PWM) brightness dimming. During dimming, the WLED current is turned on/off at the duty cycle and frequency determined by the PWM signal input on the DCRTL pin. One potential issue of PWM dimming is audible noises from the output ceramic capacitors. The TPS61180/1/2 family is designed to minimize this output AC ripple across a wide dimming duty cycle and frequency range; and, therefore reduce the audible noise.
The TPS61180/1/2 ICs provide a driver output for an external PFET connected between the input and inductor. During short circuit or over-current conditions, the ICs turn off the external PFET and disconnect the battery from the WLEDs. The PFET is also turned off during IC shutdown (true shutdown) to prevent any leakage current of the battery. The device also integrates over-voltage protection, soft-start and thermal shutdown.
The TPS61180 IC requires external 3.3V IC supply, while TPS61181 and TPS61182 ICs have a built-in linear regulator for the IC supply. All the devices are in a 3×3 mm QFN package.
TPS6118x主要特性:
5 V to 24 V Input Voltage
Integrated 1.5 A 40 V MOSFET
1.0 MHz/1.3 MHz Switching Frequency
Boost Output Auto-Adaptive to WLED Voltages
Small External Components
Integrated Loop Compensation
Six Current Sink of 25 mA
Up to 10 WLED in Series
Less Than 3% Current Matching and Accuracy
100:1 PWM Brightness Dimming Range
Minimized Output Ripple Under PWM Dimming
Driver for Input/Output Isolation PFET
True Shutdown
Over Voltage Protection
WLED Open/Short Protection
Built-in Soft Start
16L 3 mm×3 mm QFN
TPS6118x应用:
Notebook LCD Display Backlight
UMPC LCD Display Backlight
Backlight for Media Form Factor LCD display
图1.TPS6118x功能方框图
图2.TPS61181/1典型应用电路图
图3.TPS6118x评估板电路图
表1. TPS6118x评估板元件清单(BOM)
图4.音频降噪电路图
图5.TPS6118x单输入控制电路图
图6.TPS61180典型应用电路
图7 TPS6118x.驱动3串LED 电路图
图8 TPS6118x.驱动3串LED双电流电路图
图9 TPS6118x.驱动2串高亮度LED 电路图
图10 TPS6118x.驱动1串高亮度LED 电路图
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