How to Read a Datasheet
Prepared for the WIMS outreach program
5/6/02, D. Grover
In order to use a PIC microcontroller, a flip-flop, a photodetector, or practically any electronic device, you need to consult a datasheet.  This is the document that the manufacturer provides telling you
• the typical device performance
• minimum and maximum requirements and characteristics
• what you can do to the device without harming it
• suggested uses and hints
LM555 datasheet from National Semiconductor is on their website at www.national.
LM555Timer
General Description
The LM555is a highly stable device for generating accurate
time delays or oscillation.Additional terminals are provided for triggering or resetting if desired.In the time delay mode of operation,the time is precisely controlled by one external re-sistor and capacitor.For astable operation as an oscillator,the free running frequency and duty cycle are accurately
controlled with two external resistors and one capacitor.The
circuit may be triggered and reset on falling waveforms,and the output circuit can source or sink up to 200mA or drive
TTL circuits.
Features n Direct n Timing n Operates n Adjustable n Output n Output n Temperature n Normally n Available Applications
n Precision n Pulse n Sequential DS007851-1
LM555Timer
©2000National Semiconductor Corporation DS007851www.national
especially if Preliminary or Advance.  Check the date!总会有一个日期。数据手册变动，尤其是预备版或者修正版，核对一下日期。
Look up here to see if the datasheet is Advance Information or Preliminary.检查这里看数据手册是修正信息或是者预备的。
Sometimes the General Description
will tell you about a feature or usage not mentioned anywhere else!  For 低。
Features tell you general characteristics--always check the Electrical Characteristics for conditions and exceptions.特性（Features ）提供常规特性信息--确认电气特性所在的条件以及特殊情况。
Usually called the Equivalent Schematic Diagram, this schematic isn't what is
necessarily in the device, but the device acts as if this was what was inside.  It can help explain behavior that isn't otherwise described in the datasheet.  Could you duplicate this circuit on a breadboard?  Only if you knew what the characteristics of the transistors were--which are not given.
通常叫做等效原理图，该原理不是该芯片中必须的，但是该芯片将按照里面的来运作。它能帮助解释在数据手册中未被描述的行为。能把这个电路在面包板上搭出来吗？除非您知道那些并未给出参数的晶体管的参数。
您所需要的领域，但这个列表非常概要。
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5
5
M
L
DS007851-3
Top View
Number Package Marking Media Transport
LM555CM LM555CM Rails
LM555CMX LM555CM  2.5k Units Tape
LM555CMM Z551k Units Tape
LM555CMMX Z55  3.5k Units Tape
LM555CN LM555CN Rails
Under Ordering Information you'll find a list of every variation of this device along with the
COMPLETE part number.  Often the first few letters are either industry-standard or identify
the manufacturer (e.g., PIC).  The generic identifier comes next ("555").  Suffixes generally
give package type (surface mount and through hole types), temperature range (wider range = more expensive), speed (faster = more expensive), and other variations such as power,
Ordering Information ）下，可以到带有完整零件编号的该器件的每个变种的列表。通常开始的几个字母是行业标准或者厂商标识（例如，PIC）。紧接着的
是常规标识（“555”）。后缀通常给出封装类型（贴片安装型或直插型），温度范围
（宽范围型，当然也会更贵），速度（快速型，当然也会更贵），以及其它各种如功Other elements in datasheets:
--Related devices, such as devices this supercedes, exactly replaces, or is replaced
--Block diagrams of internalsfaster怎么读?
--Information to support programming or configuring the device (registers, etc.)
--Interfacing with other devices (including input/output characteristics)
--相关器件，如它可替换的，可直接替换的，或者可以被其它替换的器件
--提供编程或者配置该器件的信息（寄存器等）
--与其它器件之间的连接（包括输入/输出特性）
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www.national
www.national4

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