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I have a project to complete and i have been told to use the MCP602 Operational Amplifier, but since that model is nowhere to be found where i am living, i wonder if i can use two LM741 op-amp instead? does is really matter to use the exact same chip for the result?

Apart from number of pins, package & etc of op-amps, are the output gain of all the different models the same? (Assuming a constant configuration of resistors, caps & etc).

Sorry for the very basic questions, thanks in advance.

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  • \$\begingroup\$ Welcome FF2A. If treated as ideal devices, op amp types are pretty similar, however in the real world, there can be HUGE differences in their bandwidths, slew rates, etc. so it matters what you are trying to actually do with them. Do you have a schematic you can share? \$\endgroup\$
    – mike65535
    Commented Oct 1, 2018 at 19:49
  • \$\begingroup\$ You should post this question to the person who told you to use the MCP602. He knows about objectives and details of your project enough to make a recommendation. We don't know that. You haven't conveyed that to us. On that note, -1. \$\endgroup\$
    – Nick Alexeev
    Commented Oct 2, 2018 at 1:57

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The MCP602 and the UA741 are vastly different.

  1. The MCP602 is rated for rail to rail operation. The 741 isn't

  2. The MCP602 is a low power device. The 741 isn't. The difference is from hundreds of microamps of supply current (MCP602) to tens of milliamperes (741.)

  3. The MCP602 operates on a single supply of 2.6 to 6 volts. The 741 is normally described as a dual supply opamp operating on +-12V - though it will, in fact, operate on a single supply down to maybe 7V. Depending which particular 741 you got (and what kind of mood it is in.)

Those are off the top of my head. So, no, the 741 is not a good replacement for an MCP602.

What opamp would be a good replacement depends on the actual circuit - and what you can readily get. The MCP602 is not by any means a rare part. That you can't get one makes it likely you would have trouble finding any substitute that anyone here could name.

There also many reasons not to use the 741 (or the 1458 dual version.)

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I'm sure there are folks here that can go into a lot more detail, but here's some basic ways to compare op-amps. Ultimately you need to know what kind of signal it's going to be seeing, because that will dictate which specs are important.

  1. Rail-to-rail (or not). If the voltage is going to get near the positive or negative supply voltage, then you need a special "rail to rail" op-amp.

  2. Gain-bandwidth product. The gain of an op-amp decreases with frequency, so if your application includes fast signals make sure to do the math and make sure this won't be a problem.

  3. Slew rate. Op-amps have a maximum slew rate, for a given output amplitude this will create a maximum output frequency.

  4. Supply voltage ranges. Obviously the new op-amp has to be cool with your existing rail voltages.

  5. Input parameters. Each op-amp has specs for input current, and offset voltage which will effect the accuracy.

  6. Output current. Make sure that this will not be exceeded.

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