I was thinking of using LF356N as an alternative to the general purpose op-amp UA741. Can someone outline the major differences between the two op-amps?


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    \$\begingroup\$ Have you consulted the datasheets? \$\endgroup\$ – Peter Bennett Sep 13 '16 at 22:51
  • \$\begingroup\$ yeep. they almost have the same feature. I just wanted to make sure if I was missing some fine detail. \$\endgroup\$ – user3709772 Sep 13 '16 at 23:07
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    \$\begingroup\$ They so do not. A 10x difference in slew rate for a start is not "almost the same feature"... What are you planning to use the op-amp for? That knowledge should come before deciding which op-amp to use. \$\endgroup\$ – Majenko Sep 13 '16 at 23:12

The 741 op-amp is an extremely old design based on bipolar transistors, dating back to 1968 (nearly 50 years ago!!). Due to its simplicity, it is commonly used for teaching purposes, but it has no place in modern circuits. Its characteristics are generally much worse than any modern op-amp.

The LF356 is a rather old part as well (from around 1978), but it's still newer than the 741. It uses a JFET input stage, and performs considerably better:

  • Bandwidth: LM741 = 1.5 MHz; LF356 = 5 MHz (3.3x better)
  • Slew rate: LM741 = 0.7 V/µS; LF356 = 7.5 V/µS (10x better)
  • Input impedance: LM741 = 2 MΩ, LF356 = 1012 Ω (6 orders of magnitude better)
  • \$\begingroup\$ Might also want to take a look at things like input offset voltages, output impedance too. \$\endgroup\$ – quickly_now Oct 14 '16 at 1:46
  • \$\begingroup\$ JFET input stages are (unless specific circuitry is added) susceptible to output phase reversal if the input goes below the input common mode range. \$\endgroup\$ – Peter Smith Oct 14 '16 at 11:42

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