- 您现在的位置：买卖IC网 > PDF目录15734 > LM3445TRIACEVAL (National Semiconductor)BOARD EVAL LM3445MM PDF资料下载
参数资料
| 型号： | LM3445TRIACEVAL |
| 厂商： | National Semiconductor |
| 文件页数： | 22/40页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL LM3445MM |
| 标准包装： | 1 |
| 系列： | PowerWise® |
| 电流 - 输出 / 通道： | 770mA |
| 输出及类型： | 1，非隔离 |
| 特点： | 可调光 |
| 输入电压： | 8 ~ 12V |
| 已供物品： | 板 |
| 已用 IC / 零件： | LM3445MM |
| 相关产品： | LM3445MMX-ND - IC LED DRIVER TRIAC DIMM 10-MSOP LM3445MMDKR-ND - IC LED DRIVER TRIAC DIMM 10-MSOP LM3445MMCT-ND - IC LED DRIVER TRIAC DIMM 10-MSOP LM3445MMTR-ND - IC LED DRIVER TRIAC DIMM 10-MSOP |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页当前第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页
SNVS570L – JANUARY 2009 – REVISED MAY 2013
C12
D10
V BUCK
V LED
-
L2
V L2
-
Q2
R3
Figure 27. LM3445 External Components of the Buck Converter
The equation for an ideal inductor is:
Q = L di
dt
(14)
Given a fixed inductor value, L, this equation states that the change in the inductor current over time is
proportional to the voltage applied across the inductor.
During the on-time, the voltage applied across the inductor is,
V L(ON-TIME) = V BUCK - (V LED + V DS(Q2) + I L2 x R3)
(15)
Since the voltage across the MOSFET switch (Q2) is relatively small, as is the voltage across sense resistor R3,
we can simplify this to approximately,
V L(ON-TIME) = V BUCK - V LED
During the off-time, the voltage seen by the inductor is approximately:
V L(OFF-TIME) = V LED
(16)
(17)
The value of V L(OFF-TIME) will be relatively constant, because the LED stack voltage will remain constant. If we
rewrite the equation for an inductor inserting what we know about the circuit during the off-time, we get:
V L(OFF-TIME) = V LED = L x ' ' t i
' i # t OFF x V L2
V L(OFF-TIME) = V LED = L x
Re-arranging this gives:
LED
(I (MAX) - I (MIN) )
' t
(18)
(19)
From this we can see that the ripple current ( Δ i) is proportional to off-time (t OFF ) multiplied by a voltage which is
dominated by V LED divided by a constant (L2).
These equations can be rearranged to calculate the desired value for inductor L2.
L2 # t OFF x ' LED
Where:
V
i
(20)
22
Product Folder Links: LM3445
Copyright ? 2009–2013, Texas Instruments Incorporated
相关PDF资料 |
PDF描述 |
|---|---|
| VE-B00-EY-F1 | CONVERTER MOD DC/DC 5V 50W |
| ISC1812RXR39K | INDUCTOR WW 390NH 10% 1812 |
| HCM12DSEH | CONN EDGECARD 24POS .156 EYELET |
| MAX6441KADGWD7+T | IC BATTERY MON DUAL SOT23-8 |
| VE-B00-EX-S | CONVERTER MOD DC/DC 5V 75W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3445TRIACEVAL/NOPB | 制造商:Texas Instruments 功能描述:TRIAC Dimmable Offline LED Driver Evaluation Board |
| LM3447 | 制造商:TI 制造商全称:Texas Instruments 功能描述:Phase Dimmable, Primary Side Power Regulated PFC Flyback Controller for LED Lighting |
| LM3447-A19-120VEVM | 功能描述:LED 照明开发工具 LM3447 Eval Mod 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: |
| LM3447-A19-230VEVM | 功能描述:LED 照明开发工具 LM3447 Eval Mod 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: |
| LM3447MT | 制造商:TI 制造商全称:Texas Instruments 功能描述:a Phase-Dimmable, Primary-Side Regulated LED Driver |
发布紧急采购，3分钟左右您将得到回复。