How To Select An Operational Amplifier?
There are some basic questions you should ask before looking for a suitable op amp.
（1）What is the input signal going to look like?
（2）Current-input or voltage-input?
（3）What is the expected operating frequency range? Maximum range?
（4）What amplitude is needed? (Typical and maximum values.)
（5）What’s the impedance of the circuit it’s going into?
（6）What is an acceptable output signal going to look like?
（7）What is the expected range of frequencies the output signal might cover?
（8）What is the expected amplitude range?
（9）Will the op-amp be driving another device? If so, how much power will be needed?
（10）How accurate or precise does the op-amp need to be?
The operating environment:
What supply voltage(s) are available?
Is there a physical size limitation? You may need to make a list of packages of an acceptable size.
What is your operating temperature range? Figure out a Max, Min, and Typical.
Look at how the temperature affects your most critical parameters using the graphs in the datasheet. If the information you need is missing, you can contact the company or set it aside and move on to another spec that is more thorough.
Are you restricted to certain manufacturers that your company deals with?
Will you need to second source the op amp?
What is the lifecycle of the op amp? Do not select any op amp that is Not Recommended for New Design (NRND), End of Life (EOL), or otherwise a special factory order (this might mean that it’s about to go EOL).
Price might be a specification of a sort, but this should be one of the last parameters you look at when you are deciding between otherwise identical op amps.
When selecting parameters, it's good to allow a margin of error on the specifications. Not every op amp will be precisely the values as listed, and op amp values change with temperature, age, and stress.
Make sure the finalists in your part selection are actually for sale. “Vapor-ware” is when a manufacturer announces a part to be released in the near future, but some parts have been known as “about to release” for a year or more, depending upon the manufacturer. That’s why you second source your product, and why you confirm the product's lifecycle prior to finalizing.
Okay above all is all you need to know before getting an op amp, hope's this article helps!
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