How to choose the right operational amplifier

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How to choose the right operational amplifier [Copy link]

LM358 is an operational amplifier composed of two op amps. It can be powered by a single power supply or a dual power supply. It is often used as a front-end voltage follower for voltage signal acquisition. It also increases the input impedance to avoid affecting the measured voltage value.

When the LM358 is powered by a single 5V power supply, when the IN+ input is from 0 to 5V, its output voltage OUT can only be from 0 to 3.7V, not 0 to 5V. That is to say, when the IN+ input is 0 to 3.7V, the voltage can follow to OUT. When the input is greater than 3.7V, the output will still be 3.7V, which is not a big deal.

Since LM358 is emitter output, the maximum output range is VEE+0.7~VCC-0.7. Like TL082, it does not have rail to rail performance and the maximum output is 3.xV.

Solution:

1. Use rail to rail op amps, change IC, do not use LM358, use a full voltage op amp, the industry called rail to rail op amps, such as TLC2262 commonly used in industry, the pin function is the same as LM358, that is to say, the two can be interchanged, but when IN+ is 0~5V, the OUT of TLC2262 can be from 0~5V, of course, the price of TLC2262 is more expensive than LM358. This chip has been widely used in various industrial occasions, under the premise that the cost is not very sensitive, please feel free to use it!

2. In the design, the full-scale output voltage is designed to be 2V lower than the power supply to ensure that the output is within the working range of LM358.