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| Why is the 741 op amp still produced? |
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| exe:
--- Quote from: David Hess on September 29, 2020, 09:04:26 pm --- --- Quote from: exe on September 29, 2020, 11:17:55 am --- --- Quote from: David Hess on September 28, 2020, 11:13:00 pm --- --- Quote from: Zero999 on September 28, 2020, 07:53:43 am ---Not all '741s are rated to 44V. The LM741C is only rated to 36V maxium. --- End quote --- Nothing stops you from testing and grading your own LM741Cs for a 40 or 44 volt operation. Tektronix used to do exactly this for some reason. --- End quote --- Doesn't this compromise reliability? How to know if they can sustain this for prolonged period? --- End quote --- --- End quote --- Shouldn't parts be designed to withstand a certain voltage? I can try, say, supply a 5V opamp with 10V and it might even work for a while, but I bet it won't last long due to overstress (of course, 100% increase in voltage is on the extreme side.). |
| floobydust:
I can't see how we're getting more - rail voltages are lower, costs are much higher even with the cheaper packages. Semi manufacturers could easily modernize the IC (i.e. 741) as a new part - but it makes sense to not upset the op-amp portfolio by offering a medium performance part that is low cost, and scuttle profits. I noticed TI added new LM358B with 36V rail, 3mV VOS, up from 0.7 to 1.2MHz bandwidth. 44 years of progress as the near cheapest op-amp they offer at $0.05/1ku. Wow still the same 1971 Ford Pinto 0.5V/usec slew rate, can you feel the speed. |
| james_s:
There are lots of cases where more speed is not needed, or could even be a detriment. Faster parts are more likely to oscillate or pick up and amplify noise. If you're doing something where a slow part is fast enough and the cost is lower, there's nothing wrong with using the slow part. |
| tszaboo:
--- Quote from: floobydust on September 29, 2020, 10:44:51 pm ---Are we saying there's been no improvements in analog IC technology? --- End quote --- Yes, or almost yes. Look at all the improvements that were made in the realm of reference voltages. The LTZ1000, 30 years ago could do sub ppm tempco. The LM399 ditto. In the meantime, there was the REF102 with 2.5ppm, released in 2000. Meanwhile in the last 20 years, the biggest improvement is probably the LTC6655. 2ppm. But whoopty do, they placed it in a hermetically sealed package, and charged 8 dollars for it. You know, the same package, that every 10 cent crystal oscillator comes in. You want to measure something accurately? Use the 30 year old part, because nobody managed to make any new parts that come close to it. And all these things are a handful of PN junctions and precision resistors. So yes, we have 24 bit ADCs in 2020, and nothing to drive them properly. |
| rsjsouza:
Don't forget that evolution usually is also tied to potential revenue. The fact nobody ever refined a process to reach LTZ or LM levels may be due simply to a lack of interest or too narrow of a market to be tapped into. The number of different voltage references available when compared to 30 years ago is impressive, but they are all competing in a segment with more relaxed demands. |
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