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AAT3166IWP-T1 参数 Datasheet PDF下载

AAT3166IWP-T1图片预览
型号: AAT3166IWP-T1
PDF下载: 下载PDF文件 查看货源
内容描述: 高效率1X / 1.5X / 2X电荷泵白光LED应用 [High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications]
分类和应用:
文件页数/大小: 14 页 / 429 K
品牌: ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
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AAT3166  
High Efficiency 1X/1.5X/2X Charge  
Pump for White LED Applications  
AS2Cwire Serial Interface Timing  
Address  
Data  
THI  
TLAT  
TLO  
TLAT  
EN/SET  
Address  
1
2
17  
18  
1
2 . . .  
n <= 16  
0
1
0
0
n - 1  
Data Reg 1  
Data Reg 2  
Device Switching Noise Performance  
Applications Information  
The AAT3166 operates at a fixed frequency of  
approximately 1MHz to control noise and limit har-  
monics that can interfere with the RF operation of  
cellular telephone handsets or other communica-  
tion devices. Back-injected noise appearing on the  
input pin of the charge pump is 20mV peak-to-  
peak, typically ten times less than inductor-based  
DC/DC boost converter white LED backlight solu-  
tions. The AAT3166 soft-start feature prevents  
noise transient effects associated with inrush cur-  
rents during start-up of the charge pump circuit.  
LED Selection  
Although the AAT3166 is designed for driving white  
LEDs, the device also can be used to drive most  
types of LEDs with forward voltage specifications  
ranging from 2.0V to 4.7V. LED applications may  
include main and sub-LCD display backlighting,  
camera photo-flash applications, color (RGB)  
LEDs, infrared (IR) diodes for remotes, and other  
loads benefiting from a controlled output current  
generated from a varying input voltage. Since the  
D1 to D4 input current sinks are matched with neg-  
ligible voltage dependence, the LED brightness will  
be matched regardless of the specific LED forward  
voltage (VF) levels.  
Capacitor Selection  
Careful selection of the four external capacitors  
(CIN, C1, C2, COUT) is important because they will  
affect turn-on time, output ripple, and transient per-  
formance. Optimum performance will be obtained  
when low equivalent series resistance (ESR)  
ceramic capacitors are used; in general, low ESR  
may be defined as less than 100mΩ. A value of  
1µF for all four capacitors is a good starting point  
when choosing capacitors. If the LED current  
sources are programmed only for light current lev-  
els, then the capacitor size may be decreased.  
In some instances (e.g., in high-luminous-output  
applications such as photo flash), it may be neces-  
sary to drive high-VF type LEDs. The low-dropout  
current sinks in the AAT3166 make it capable of  
driving LEDs with forward voltages as high as 4.7V  
at full current from an input supply as low as 3.0V.  
Outputs can be paralleled to drive high-current  
LEDs without complication.  
3166.2006.05.1.2  
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