0
\$\begingroup\$

I'm trying OpenModelica and I'm going to simulate an Op-amp.

(No it's not Windows 95, it's IceWM + Ubuntu 20.04) enter image description here

But I wonder where I can find the slope Vout/Vin when Vin = 0 in the datahseet? I have heard that the slope from an Op-amp is so large so not even the datasheet write it out. Is that true? Or can I find it?

Assume that we are using this datasheet: https://www.mouser.se/datasheet/2/389/cd00001046-1795623.pdf

\$\endgroup\$
8
  • \$\begingroup\$ Is that true? - is it true that you have heard it - you may have heard this but it's untrue. \$\endgroup\$
    – Andy aka
    Mar 14 at 11:22
  • \$\begingroup\$ @Andyaka So why does OpenModelica ask about it? \$\endgroup\$
    – MrYui
    Mar 14 at 11:33
  • \$\begingroup\$ I have heard that the slope from an Op-amp is so large so not even the datasheet write it out. That's pure nonsense, writing a large number is easy. Next time, when in doubt, immediately ask WHY?. That should help detecting BS like this. Anyway, the term "slope" is confusing as it often refers to change of a signal over time. Vout/Vin (at Vin = 0) is simply the (small signal) gain. Which is listed in every opamp's datasheet. \$\endgroup\$ Mar 14 at 11:34
  • \$\begingroup\$ Please see this: youtu.be/7FYHt5XviKc?t=163 \$\endgroup\$
    – MrYui
    Mar 14 at 11:37
  • \$\begingroup\$ Most of us (including me) have seen Dave's video already, I think that the chance that you misunderstood Dave's story is much more likely than Dave telling nonsense. Dave's audience consists of beginners but also many old-farts (like myself) who will immediately point out any mistakes. So you can assume what Dave says is not nonsense. \$\endgroup\$ Mar 14 at 11:40
2
\$\begingroup\$

Look at the large signal voltage gain Avd in the datasheet. 100,000 typical (under the specified conditions).

Also refer to figures 17 and 19 for typical behavior under different conditions.

\$\endgroup\$
5
  • \$\begingroup\$ So "Large voltage gain: 100 dB" in the datasheet is the gain Vout/Vin at Vin = 0? \$\endgroup\$
    – MrYui
    Mar 14 at 11:16
  • \$\begingroup\$ Look carefully, there is no 100 dB anywhere in the datasheet. It is \$A_{vd}\$ = 100 V/mV which is the same as 100 000 V/V or a factor 100 000. \$\endgroup\$ Mar 14 at 11:37
  • \$\begingroup\$ @Bimpelrekkie 100 dB is quoted on page 1 and 100 dB = 100,000 V/V. \$\endgroup\$
    – Andy aka
    Mar 14 at 11:57
  • \$\begingroup\$ About figures 17 and 19. What should I look at? Large voltage gain, is that the gain when I'm exceeding the maximum or minimum voltage? \$\endgroup\$
    – MrYui
    Mar 14 at 12:01
  • \$\begingroup\$ They show you how the gain typically varies with temperature and supply voltage. The gain of 100,000 is only at one specific supply voltage and temperature. \$\endgroup\$ Mar 14 at 12:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.