Maximum speed of LM358 dual op amp ic

Audioguru

Joined Dec 20, 2007
11,248
The lousy old LM358 (and its LM324 quad sister) were the first Low Power opamps. Low Power causes noise, crossover distortion and poor slew rate at high output levels.

The graphs on a datasheet are for a "typical" device then some could have minimum specs such as a poorer slew rate then some can barely output 2kHz at a high level.
Audio opamps have low noise, low distortion and easily produce 100kHz.
 

MrAl

Joined Jun 17, 2014
13,859
The lousy old LM358 (and its LM324 quad sister) were the first Low Power opamps. Low Power causes noise, crossover distortion and poor slew rate at high output levels.

The graphs on a datasheet are for a "typical" device then some could have minimum specs such as a poorer slew rate then some can barely output 2kHz at a high level.
Audio opamps have low noise, low distortion and easily produce 100kHz.
Hi,

What does the price comparison look like, and what input range and what output range compared to the LM358. Maybe you could make a chart or something that compares specs as well as single piece prices.
 
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Thread Starter

-live wire-

Joined Dec 22, 2017
959
Yeah, you can get the LM358 at 16 cents apiece. But CMOS op amps, though they have many advantages, can often be more expensive, and unnecessary in some applications.
 

OBW0549

Joined Mar 2, 2015
3,565
Yeah, you can get the LM358 at 16 cents apiece. But CMOS op amps, though they have many advantages, can often be more expensive, and unnecessary in some applications.
And there are a whole lot of applications in which something better than an LM358 is necessary. The trick is in learning how to tell when any particular op amp will suffice in an application, and when it will fall short in some respect such as by causing unacceptable errors or by failing to function altogether (such as expecting it to process 100 kHz signals without mangling them). And the key to doing that successfully is in learning to read an op amp data sheet and understand the various terms and their implications as to performance.
 

MrAl

Joined Jun 17, 2014
13,859
Cheap usually means poor performance.
Hi,

Yes that is mostly true but 'cheap' and 'poor performance' are both relative terms. We dont use a 5 dollar part in an application that can get away with a 50 cent part. Similarly, we dont use a 50 cent part in an application that absolutely needs a 5 dollar part.

I ran into this multiple times in the past. My last encounter was when i was building a linear voltage regulator that needed to be able to be adjustable with a pot by about plus and minus 10mv (plus and minus 0.010 volts). I wanted to use the LM358 and actually did, but the performance was better with a part that was around 5 dollars (USD).
In another encounter i needed a super low input offset op amp and so had to go to a chopper stabilized op amp which of course was more expensive.

This is why i suggested making a chart. You could include the LM358 and parts you like and show the more important aspects like power supply voltage range, input range, output range, input offset, etc. That would help other readers i believe.
 

MisterBill2

Joined Jan 23, 2018
28,508
One big benefit of using such a "slow" device is the lack of high frequency instability, and much less tendency to oscillate at a few MHz and causing you many headaches finding the problem. So the answer is to not buy performance that you don't need. That higher gain and higher gain-bandwidth product can get you into trouble. There is a time and place for them that is not everywhere.
 

danadak

Joined Mar 10, 2018
4,057
I often wonder about older parts vs ESD performance, as older parts
were on geometries that handled higher breakdowns and punch thru
due to their larger geometries.

That's qualified of course by how internal ESD is handled in newer parts.
ESD of course affects not only MOS but also Bipolar, beta degradation, etc..

Regards, Dana.
 

ebp

Joined Feb 8, 2018
2,332
What OBW said!

Good engineering is about matching solutions to requirements. I've designed in or routinely used parts that some other designers would cringe at. I like stainless steel for small machine screws. I generally use 1% tolerance resistors when even 5% tolerance is more than adequate just because it reduces type variation in bills of materials and the cost of inventory management for clients. But most of what I designed was industrial stuff where cost was not super critical. Someone who designed high-volume consumer stuff would be appalled at the waste of spending an extra tenth of a cent on a resistor and need a trip to the fainting couch at the very notion of spending a whole penny extra for a #4 hex nut.

Selecting an op amp for a circuit requires an understanding of what is important to that circuit. The LM358/324 is entirely adequate for a great many applications in spite of its limitations. It is grossly unsuitable for other applications. I've designed things where I've used several 324s on the same board as other amps costing at least 50 times as much per amp.I've used op amps that make the 324 look like a turbo-charged speed demon and an obscene power hog. Lots of amps that are much better in most ways and much more expensive than the 324 would still be dismal failures in many of the things I've designed.
Trying to use the 324 for everything is no more and no less ridiculous than using some much more expensive amp for everything.

one minor note: If the 358 and 324 aren't adequate in terms of DC performance, consider the "A" versions. They now seem to generally be only very slightly more expensive and considerably better. I used to use the LT1014 quite often for substantially better DC performance, but it was a lot more expensive.

Voltage references
There are lots of voltage references that are quite inexpensive and OK for non-demanding applications. I've used a ton of TL431s which is a study in mediocrity by today's standards, but still very useful for lots of things. Again, it comes down to determining what matters in the specific design at hand. When I was still doing design, every time I wanted a fairly good reference (something in the $5-20 bracket), I'd go through the tedium of reviewing a bunch of datasheets again because every year would bring at least one or two new references worth considering. When you get into circuits that demand high-performance references, you must remember that they will also demand high-performance amplifiers and high-performance resistors. You can get some reasonably good surface mount resistors for a dollar apiece.
 

ebp

Joined Feb 8, 2018
2,332
I often wonder about older parts vs ESD performance, as older parts
were on geometries that handled higher breakdowns and punch thru
due to their larger geometries.....
Newer parts usually are much better specified, which may or may not mean they actually are more robust with regard to ESD.

The LM324 has an interesting input structure that allows it to withstand input voltage up to the maximum allowable for the part, even when the part runs on much lower voltage. This is due to the use of lateral PNP input transistors that have exceptionally high base-emitter reverse breakdown voltage. There are no protection diodes to the positive rail and no diodes between the inputs that limit differential voltage when used as a comparator.

DigiKey has well over half a million LM324 variants in full reels of assorted surface mount packages, counting only those from T, sitting on the shelf. Somehow I doubt that they will all be sold to people who are just too stupid to realize that they are terrible awful bad amplifiers that no one should use. In fact, I'll wager a good fraction of the people who specify them are very confident in the ability of those parts to meet their requirements.
(The A version I mentioned in a previous post is about a tenth of a cent per amp more expensive than the non-A version for the 324AD in SO-8 at 2.5k qty)
 

MrAl

Joined Jun 17, 2014
13,859
I don't use lousy old 741 and LM324/LM358 opamps so I do not need a chart. Maybe a teacher here is a member and could make a chart.
Hi again,

Actually i have crossed off the 741 op amp from my list but not the LM358 because it is still so useful. It is still made by at least five major manufacturers too and i bet there are millions sold per year. I tried to find out the number sold per year but could not find a good reference. I would bet it is up there with the 555.
When i worked in the industry we bought these by the 100's.
MIT still uses them in some course work as far as i know.
 

OBW0549

Joined Mar 2, 2015
3,565
Attached is a spreadsheet I made up, listing several dozen op amps and their key characteristics. These include the ones I listed in this post, some of the ones other participants mentioned in that thread, plus some more that I found rummaging through my "hobby stash."

For the sake of "comparing apples and apples", all of the parameters listed are the "typical" values, and for 25 °C; for min/max values, and for values across the operating temperature range, consult the data sheet. And as always, consult the data sheet for any possible "gotchas" and special features.

The spreadsheet is provided in comma-separated values (.csv) format so it can be imported into any spreadsheet program; a .pdf is also included.
 

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