- 您现在的位置：买卖IC网 > PDF目录20782 > LM3421MHX/NOPB (National Semiconductor)IC LED DRVR HP CONS CURR 16TSSOP PDF资料下载
参数资料
| 型号： | LM3421MHX/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 11/67页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR HP CONS CURR 16TSSOP |
| 产品培训模块： | LED Design Solutions |
| 标准包装： | 2,500 |
| 系列： | PowerWise® |
| 恒定电流： | 是 |
| 拓扑： | PWM，SEPIC，降压（降压），升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 无 |
| 类型 - 主要： | 车载 |
| 类型 - 次要： | 高亮度 LED（HBLED） |
| 频率： | 2MHz |
| 电源电压： | 4.5 V ~ 75 V |
| 输出电压： | 3 V ~ 72 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 供应商设备封装： | 16-TSSOP-EP |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 125°C |
| 其它名称： | LM3421MHX |
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页当前第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页第41页第42页第43页第44页第45页第46页第47页第48页第49页第50页第51页第52页第53页第54页第55页第56页第57页第58页第59页第60页第61页第62页第63页第64页第65页第66页第67页
SNVS574E – JULY 2008 – REVISED MAY 2013
function with external dimming FET driver allows for fast PWM dimming of the LED load. When designing, the
maximum attainable LED current is not internally limited because the LM3421/23 is a controller. Instead it is a
function of the system operating point, component choices, and switching frequency allowing the LM3421/23 to
easily provide constant currents up to 5A. This controller contains all the features necessary to implement a high
efficiency versatile LED driver.
i L (t)
I L-MAX
I L
0
t ON = DT S
t OFF = (1-D)T S
? i L-PP
I L-MIN
t
T S
Figure 15. Ideal CCM Regulator Inductor Current i L (t)
CURRENT REGULATORS
Current regulators can be designed to accomplish three basic functions: buck, boost, and buck-boost. All three
topologies in their most basic form contain a main switching MosFET, a recirculating diode, an inductor and
capacitors. The LM3421/23 is designed to drive a ground referenced NFET which is perfect for a standard boost
regulator. Buck and buck-boost regulators, on the other hand, usually have a high-side switch. When driving an
LED load, a ground referenced load is often not necessary, therefore a ground referenced switch can be used to
drive a floating load instead. The LM3421/23 can then be used to drive all three basic topologies as shown in the
Basic Topology Schematics section. Other topologies such as the SEPIC and flyback converter (both derivatives
of the buck-boost) can be implemented as well.
Looking at the buck-boost design, the basic operation of a current regulator can be analyzed. During the time
that the NFET (Q1) is turned on (t ON ), the input voltage source stores energy in the inductor (L1) while the output
capacitor (C O ) provides energy to the LED load. When Q1 is turned off (t OFF ), the re-circulating diode (D1)
becomes forward biased and L1 provides energy to both C O and the LED load. Figure 15 shows the inductor
current (i L (t)) waveform for a regulator operating in CCM.
The average output LED current (I LED ) is proportional to the average inductor current (I L ) , therefore if I L is tightly
controlled, I LED will be well regulated. As the system changes input voltage or output voltage, the ideal duty cycle
(D) is varied to regulate I L and ultimately I LED . For any current regulator, D is a function of the conversion ratio:
Buck
D=
Boost
D=
V O
V IN
V O - V IN
V O
(1)
(2)
Buck-boost
D=
V O
V O + V IN
(3)
Copyright ? 2008–2013, Texas Instruments Incorporated
11
Product Folder Links: LM3421 LM3421-Q1 LM3423 LM3423-Q1
相关PDF资料 |
PDF描述 |
|---|---|
| ECC07DRYN | CONN EDGECARD 14POS DIP .100 SLD |
| RS3-4809D | CONV DC/DC 3W 36-72VIN +/-09VOUT |
| GEM10DRSN-S288 | CONN EDGECARD 20POS .156 EXTEND |
| EVW020A0A41-HZ | CONVERTER DC/DC 5.0V 20A OUTPUT |
| RS3-4805D | CONV DC/DC 3W 36-72VIN +/-05VOUT |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3421Q0 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:N-Channel Controllers for Constant Current LED Drivers |
| LM3421Q0MH | 制造商:NSC 制造商全称:National Semiconductor 功能描述:N-Channel Controllers for Constant Current LED Drivers |
| LM3421Q0MH/NOPB | 功能描述:LED照明驱动器 RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| LM3421Q0MHNOPB | 制造商:National Semiconductor 功能描述:LED DRVR 5V/9V/12V/15V/18V/24V 16-Pin TSSOP EP Tube |
| LM3421Q0MHX | 制造商:NSC 制造商全称:National Semiconductor 功能描述:N-Channel Controllers for Constant Current LED Drivers |
发布紧急采购，3分钟左右您将得到回复。