欢迎访问ic37.com |
会员登录 免费注册
发布采购

LP38691SD-ADJ 参数 Datasheet PDF下载

LP38691SD-ADJ图片预览
型号: LP38691SD-ADJ
PDF下载: 下载PDF文件 查看货源
内容描述: 500毫安低压降CMOS线性稳压器,可调输出/稳定器用陶瓷输出电容器 [500mA Low Dropout CMOS Linear Regulators with Adjustable Output / Stable with Ceramic Output Capacitors]
分类和应用: 稳压器电容器
文件页数/大小: 13 页 / 749 K
品牌: NSC [ National Semiconductor ]
 浏览型号LP38691SD-ADJ的Datasheet PDF文件第5页浏览型号LP38691SD-ADJ的Datasheet PDF文件第6页浏览型号LP38691SD-ADJ的Datasheet PDF文件第7页浏览型号LP38691SD-ADJ的Datasheet PDF文件第8页浏览型号LP38691SD-ADJ的Datasheet PDF文件第9页浏览型号LP38691SD-ADJ的Datasheet PDF文件第10页浏览型号LP38691SD-ADJ的Datasheet PDF文件第12页浏览型号LP38691SD-ADJ的Datasheet PDF文件第13页  
OUTPUT NOISE  
Application Hints (Continued)  
Noise is specified in two ways- Spot Noise or Output Noise  
density is the RMS sum of all noise sources, measured at  
the regulator output, at a specific frequency (measured with  
a 1Hz bandwidth). This type of noise is usually plotted on a  
curve as a function of frequency. Total Output Noise or  
Broad-Band Noise is the RMS sum of spot noise over a  
specified bandwidth, usually several decades of frequencies.  
load changes above that frequency. This means the effective  
output impedance of the IC at frequencies above 100 kHz is  
determined only by the output capacitor(s).  
In applications where the load is switching at high speed, the  
output of the IC may need RF isolation from the load. It is  
recommended that some inductance be placed between the  
output capacitor and the load, and good RF bypass capaci-  
tors be placed directly across the load.  
Attention should be paid to the units of measurement. Spot  
noise is measured in units µV/root-Hz or nV/root-Hz and total  
output noise is measured in µV(rms)  
PCB layout is also critical in high noise environments, since  
RFI/EMI is easily radiated directly into PC traces. Noisy  
circuitry should be isolated from "clean" circuits where pos-  
sible, and grounded through a separate path. At MHz fre-  
quencies, ground planes begin to look inductive and RFI/  
EMI can cause ground bounce across the ground plane. In  
multi-layer PCB applications, care should be taken in layout  
so that noisy power and ground planes do not radiate directly  
into adjacent layers which carry analog power and ground.  
The primary source of noise in low-dropout regulators is the  
internal reference. Noise can be reduced in two ways: by  
increasing the transistor area or by increasing the current  
drawn by the internal reference. Increasing the area will  
decrease the chance of fitting the die into a smaller package.  
Increasing the current drawn by the internal reference in-  
creases the total supply current (ground pin current).  
11  
www.national.com