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need good reference for analog design

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scorrpeio

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Hello,

At present moment, I am working on microcontroller coding part. I have basic idea of analog and digital ICs and associated design.

If, I am asked to design a system(analog or digital), I can't do it in an accurate way. My concepts of fan in, fan out, current surge, sink, source and so on are not yet clear. I cant answer why it is preferred to use PNP and not NPN while driving LEDs using 8051.

In short, though I can work at some part of embedded system, most of my basic concepts(especially of analog) are yet not clear.

Can anyone please tell me, which books/website tutorials should I read to clear my basics of analog design and digital design as well?
 

leo_o2

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LED can be drived by NPN. LED+ is connected to a supply voltage. LED- is connected to NPN's collector. 8051 is connected to NPN's base. NPN's emitter is connected to ground.
 

FvM

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LED can be drived by NPN. LED+ is connected to a supply voltage. LED- is connected to NPN's collector. 8051 is connected to NPN's base. NPN's emitter is connected to ground.
The problem with the suggested circuit is, that standard 8051 ports have either no (PORT A) or rather low current sourcing capability. Driving the outputs active low gives mA range current on all ports, sufficient to drive low current LEDs even without a transistor.

A current limiting transistor in series with the LED should be provided anyway.
 
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