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| 型号： | LM3445-208277EV/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 26/40页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL LED DRIVER LM3445 |
| 标准包装： | 1 |
| 系列： | PowerWise® |
| 电流 - 输出 / 通道： | 500mA |
| 输出及类型： | 1，非隔离 |
| 特点： | 可调光，带标准型三端双向可控硅调光器，功率因数修正 |
| 输入电压： | 176 ~ 305 VAC |
| 已供物品： | 板 |
| 已用 IC / 零件： | LM3445 |
| 产品目录页面： | 1285 (CN2011-ZH PDF) |
| 其它名称： | LM3445-208277EV |
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SNVS570L – JANUARY 2009 – REVISED MAY 2013
V +
θ = 45°
V PEAK
t
V +
θ = 90°
V PEAK
t
V +
θ = 135°
V PEAK
t
Figure 31. AC Line with Various Firing Angles
V PEAK
V PEAK
V DC
V +
V DC
t
V +
V DC
t
Figure 32. V BUCK Waveforms with Various Firing Angles
To determine how many LEDs can be driven, take the minimum voltage the buck converter will see (42.5V) and
divide it by the worst case forward voltage drop of a single LED.
Example: 42.5V/3.7V = 11.5 LEDs (11 LEDs with margin)
OUTPUT CAPACITOR
A capacitor placed in parallel with the LED or array of LEDs can be used to reduce the LED current ripple while
keeping the same average current through both the inductor and the LED array. With a buck topology the output
inductance (L2) can now be lowered, making the magnetics smaller and less expensive. With a well designed
converter, you can assume that all of the ripple will be seen by the capacitor, and not the LEDs. One must
ensure that the capacitor you choose can handle the RMS current of the inductor. Refer to manufacture’s
datasheets to ensure compliance. Usually an X5R or X7R capacitor between 1 μF and 10 μF of the proper
voltage rating will be sufficient.
SWITCHING MOSFET
The main switching MOSFET should be chosen with efficiency and robustness in mind. The maximum voltage
across the switching MOSFET will equal:
V DS(MAX) = V AC-RMS(MAX) 2
The average current rating should be greater than:
I DS-MAX = I LED(-AVE) (D MAX )
(31)
(32)
26
Product Folder Links: LM3445
Copyright ? 2009–2013, Texas Instruments Incorporated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3445-220VEVAL/NOPB | 功能描述:BOARD EVAL LM3445 220V RoHS:是 类别:编程器，开发系统 >> 过时/停产零件编号 系列:PowerWise® 标准包装:1 系列:- 传感器类型:CMOS 成像，彩色（RGB） 传感范围:WVGA 接口:I²C 灵敏度:60 fps 电源电压:5.7 V ~ 6.3 V 嵌入式:否 已供物品:成像器板 已用 IC / 零件:KAC-00401 相关产品:4H2099-ND - SENSOR IMAGE WVGA COLOR 48-PQFP4H2094-ND - SENSOR IMAGE WVGA MONO 48-PQFP |
| LM3445-220VEVAL/NOPB | 制造商:Texas Instruments 功能描述:LED Driver Eval. Board |
| LM3445-230VFLBK/NOPB | 功能描述:LED 照明开发工具 LM3445-230VFLBK EVAL BOARD RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装: |
| LM3445A | 制造商:NSC 制造商全称:National Semiconductor 功能描述:A19 Edison Retrofit Evaluation Board Can drive up to 18 series LEDs |
| LM3445-EDSNEV/NOPB | 功能描述:LED 照明开发工具 LM3445-EDSN EVAL BOARD RoHS:否 制造商:Fairchild Semiconductor 产品:Evaluation Kits 用于:FL7732 核心: 电源电压:120V 系列: 封装: |
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