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| 型号： | LM3445-208277EV/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 15/40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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LM3445MM
D10
C12
V BUCK
L2
SNVS570L – JANUARY 2009 – REVISED MAY 2013
R4
Q3
I COLL
GATE
8
Q2
4
COFF
ISNS
7
R3
GND
6
C11
Figure 21. LM3445 Buck Regulation Circuit
OVERVIEW OF CONSTANT OFF-TIME CONTROL
A buck converter’s conversion ratio is defined as:
V IN = D = t ON + t OFF = t ON x f SW
V O t ON
(3)
Constant off-time control architecture operates by simply defining the off-time and allowing the on-time, and
therefore the switching frequency, to vary as either V IN or V O changes. The output voltage is equal to the LED
string voltage (V LED ), and should not change significantly for a given application. The input voltage or V BUCK in
this analysis will vary as the input line varies. The length of the on-time is determined by the sensed inductor
current through a resistor to a voltage reference at a comparator. During the on-time, denoted by t ON , MOSFET
switch Q2 is on causing the inductor current to increase. During the on-time, current flows from V BUCK , through
the LEDs, through L2, Q2, and finally through R3 to ground. At some point in time, the inductor current reaches a
maximum (I L2-PK ) determined by the voltage sensed at R3 and the ISNS pin. This sensed voltage across R3 is
compared against the voltage of dim decoder output, FLTR2, at which point Q2 is turned off by the controller.
Copyright ? 2009–2013, Texas Instruments Incorporated
Product Folder Links: LM3445
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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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